NATIONAL INSTITUTE OF DISASTER

NATIONAL INSTITUTE OF DISASTER MANAGEMENT

(Ministry of Home Affairs; Government of India)

1. Name of the course: National Programme on “Disaster Risk Communication through

HAM”

2. Duration : 24 – 28 September 2018

3. Venue : YMCA, New Delhi

4. Objectives
 To develop better understanding about disaster risk management
 To assess the needs and gaps in early warning and communications for disaster
situations
 To promote linkages among stakeholders from disaster management and nodal
agencies for early warning and communication
 To explore possibilities for disaster resilient communication systems, technologies
and networks
 To discuss the effective implementation of communications options and provisions
related to disaster situations

5. Methodology: Lectures, Presentations, Demonstrations, Group Exercises, Panel

Discussions and Field Visit

6. Schedule: Copy attached at the end of this report

7. Participant's profile
The participants included senior level functionaries and officials from Indian
Administrative Services, officers from NDRF, SDMAs, SEOCs, DDMAs, Civil Defence,
NIT and University etc.
 National Level Training programme on `Disaster Risk Communication through HAM’ from 24-
28 September, 2018 at YMCA New Delhi
List of Participants

S.No. Name, Designation and address Contact details State

1. Shri Sandeep Kumar Email. sosandeep85@gmail.com Andhra
SI/RO, 10thBn NDRF Pradesh
2. Shri Irfan Raza Email. irfankhan5157@gmail.com
SI/RO, 10thBn NDRF
3. Dr. Mihir Kumar Shome Tel: 0360-2284801 Arunachal
Registrar (Officiating) Fax: 0360-2284972 Pradesh
National Institute of Technology, registrarnitap@gmail.comprof.mihir
Arunachal Pradesh YUPIA near D.C. .shome@gmail.com
Office, Dist. Papumpare-791112 A.P.

4. Shri Moferjal Sarkar, Tel: 03662-231149 Assam

District Project Officer (DPO) johnehapar@yahoo.com
DDMA, O/o the Dy. Commissioner,
Dhubri District Dhubri (Disaster
Management Branch) Assam
5. Shri Riki B. Phukan Tel: 03673-236324
District Project Officer ricki214993@gmail.com
DDMADimaHasao, D.C. Office
Haflong-788819
6. Shri Jayanta Talukdar Email. jtalukdarbsf@gmail.com
HC/RO
1stBn NDRF
7. Shri Abhijeet Kumar Verma Email. abhijeet.verma618@gmail.c
Inspector om
1stBn NDRF (Guwahati)
8. Shri Kannogiya Pankaj Kumar Email. pankajkpk12345@gmail. Bihar
INSP/GD, 9thBn NDRF com

9. Md. Hanan Kamri Email. kamri1965@gmail.com

ASI/GD, 9thBn NDRF
10. Shri Rahul Sudan Off: 011-23937201 Delhi
S.S.O. (SD) ra949@yahoo.com
Directorate of Civil Defence, 1 Kripa
Narayan Marg, Delhi-54

11. Shri Yogesh Kakkar Off: 011-23937349

Sr. Instructor (CD) yogesh.kakkar33@gmail.com
Directorate of Civil Defence, 1 Kripa
Narayan Marg, Delhi-54
S.No. Name, Designation and address Contact details State
12. Shri Karam Chand Sharma Tel: 011-23072624
Sr. Instructor (Civil Defence) Email.kesharmaicd@gmail.com
Directorate of Civil Defence, NCT of
Delhi, Working under District
Magistrate/Controller, CD, New Delhi

13. Shri Jasbir Singh Tel: 011-23072624

Sr. Chief Warden CD DDMA, Delhi Email. Jbss1953@gmail.com
Civil Defence New Delhi District Office:
10/11 Jam Nagar House, Shahajahan
Road New Delhi-110011

14. Shri Vinod Kumar Bhardwaj Tel: 011-23072624

Additional Chief Warden (CD- DDMA) vinodbhardwaj677@gmail.com
Civil Defence District Office: 10/11 Jam
Nagar House, Shahajahan Road New
Delhi-110011
15. Ms. UshaSaha Tel: 011-26471803
H.F.P. in Civil Defence Email. ushasaha1988@gmail.co
NishkamSewaBhawan, CTI Complex m
Raja Garden
New Delhi-110027

16. Shri Narendra Kumar Email. yadavnarender28@gmail Gujarat

Insp./RO, 6thBn NDRF .com

17. Shri Alok Kumar Singh

HC/RO, 6thBn NDRF

18. Shri Pardeep Kumar Email. pjkumar8893@gmail.com Haryana

ASI/Comm, 12thBn NDRF

19. Shri Suraj Parkash Rukwal, KAS surajrukwal@gmail.com Jammu &

Additional Secretary to Govt. Kashmir
Department of Disaster Management,
Relief, Rehabilitation and
Reconstruction (DMRRR)

20. Shri Aamir Ali Ph. : 0194-2506499

Director Fax: 0194-2506499
Disaster Management Jammu &Kashmir, aamiralimir@gmail.com
Govt. of J&K, Srinagar, Kashmir -
190001,
S.No. Name, Designation and address Contact details State
21. Shri Arun Peter, Email. palbickakrala@gmail.com Kerala
Hazard Analyst Kerala State Disaster
Management Authority

22. Shri D.S. Chopade Email. dnyaneshwarchopade96@g Maharashtra

HC/RO, 5thBn NDRF mail.com

23. Shri Satish Kumar Email. Sstishkumar7323@gmail.co

HC/RO, 5thBn NDRF m

24. Shri Prasad Namdeo Dalvi Tel: 022-22027990

Control Room Operator (CRO) Fax: 022-22023039
SEOC Maharashtra Mantralay Control prasaddalvi.pd@gmail.com
Room, 1st Floor, Madam Cama Road,
Mantralay Mumbai-400032

25. Shri Srikrishna, BhalchandraDeshpande, Tel. 022-22027990

SEOC, Maharashtra Mantralay, Mumbai
26. Shri.Mahendra Beldar, Email. mpatil1555@gmail.com
N. Tahsildar,
Raigad (Maharashtra)
27. Ms. Vandana Sharma Off: 07582-811336 Madhya
Assistant Professor Email. vandana20488@gmail.comh Pradesh
Department of Disaster Management, oddisastermanaggement@gmail.co
Swami Vivekanand University, N.H.-26 m
Narsinghpur Road, Sironja, Sagar-
470001 M.P.

28. Ms. Sarita Yadav, IAS Email.saritayadav.rp@gmail.coms Nagaland

Addl. DC arita.yadav@ias.nic.in
Office of The Deputy Commissioner,
Peren, Nagaland

29. Shri Sunil Rajwar Email. sunilrajwar71@gmail.com Odisha

Inspector/Exe.
3rdBn NDRF
30. Shri Pradeep Kr. Samantray Email.pradeepsamantray18@gmail.
SI/GD, 3rdBn NDRF com
S.No. Name, Designation and address Contact details State
31. Shri Vijay Kumar Email. vijukrchouhan1987@gm Punjab
HC/TELE, 7thBn NDRF ail.com

32. Shri Savit Kumar Email. savity57@gmail.com

HC/TELE, 7thBn NDRF

33. Shri Shibu S. Email. shibu4appu@gmail.com Tamilnadu

SI/RO, 4thBn NDRF

34. Shri Ravi C. Email. ravirajani12@rediffm

HC/RO, 4thBn NDRF ail.com

35. Shri Ranjit Debnath Tripura

ASI/Comm, 12thBn NDRF

36. Dr. Manibhushan Pant manipant2013@gmail.com Uttarakhand

MOIC,
Community Health Centre (CHC),
GairsainChamoli

37. Dr. Satish Pant, Email. sabir-pant@yahoo.com

Block Medical Officer Betalghat,
Nainital

38. Dr. Harish Thapliyal Tel: 01363-244225

Medical Officer, thapliyalharish@gmail.com
Community Health Centre, Karanprayag,
Chamoli-246444

39. Shri Neeraj Sharma Tel: 0135-2410197

Sub-Inspector Fax: 0135-2719792
SDRF Jolly Grant Dehradun neeraj3030sharma@gmail.com

40. Shri Om Omeshwar Tiwari Uttar Pradesh

SI/TELE, 8thBn NDRF

41. Shri Alakh Niranjan Email. alakhaniranjan0@gmail.

HC/TELE, 8thBn NDRF com

42. Shri Prashant Kumar Tel: 0591-2412728

Disaster Expert ddmamoradabad@gmail.coms.pras
D.M. Office, Collectorate Moradabad hant4@gmail.com
S.No. Name, Designation and address Contact details State
43. Shri Vishwajeet Tripathi Email. vishwajeetssb@gmail.com
SI/Comm.
NDRF 11Bn NDRF Mazbool Alam
Road, Sanskriti Sankool Bhawan,
Varanasi-221002
44. Shri Ashish Kumar Tel: 0542-2501101 –(O)
HC/RO No. 042548421 Email. ashuporwal04@gmail.com
11Bn NDRF, Gautam Budh Bhawan,
Maqbool Alam Road, Varanasi-221002
45. Shri Sandeep Kr. Jha Email. sandeepjha374@gmail.com West Bengal
Inspector
2ndBn NDRF

46. Shri P. Mukundarao Email. mukunda.amma@gmail.

HC/Tech com
2ndBn NDRF
Photo gallery
 Tentative Schedule for the National Level Training Course on
DISASTER RISK COMMUNICATION THROUGH HAM
(24 – 28 September 2018 at NIDM, New Delhi)
Pre-Lunch Session (Time in hours) Post-Lunch Session (Time in hours)
Day / Date
0930 – 1000 1000 - 1100 1100-1200 1215-1315 1415-1515 1530-1630 1630-1730
Welcome, Disaster Risk National Introduction to Video Presentation and Practical
Course Intro, Communication – Guidelines on HAM, Short Demonstration of HAM Radio,
Registration Intro by Facilities, Information and Distance and Basic Radio and Electronic
Monday, of Participants participants Infrastructure and Communication Long Distance Theory -1
24 ED NIDM Services with Management Radio
September Vote of Thanks NDRF Communication
2018 Mr. Sumit K. Ground Rules
Sharma, DEO Dr. Surya Sh. Sandeep Sh. Sandeep Baruah, Vigyan
Sh. Ravi Joseph, Parkash, NIDM Baruah, Vigyan Prasar and Dr. Surya Parkash,
IPS, IG NDRF Prasar NIDM
Radio Rules (Indian Wireless Operating SOPs for DM Radio & Electronics Theory and

LUNCH BREAK (1315 – 1415 Hrs.)

Library Visit / Tea (1200 – 1215 Hrs.)

Library Visit / Tea (1515 – 1530 Hrs.)

Telegraphs (Amateur Service Rules) Procedures for Practice: Resistance, Capacitance,
Tuesday, and Regulations HAM Radio Diodes, Transistors, Circuits
25
Recapitulation
September
2018 Sh. Atanu Dasgupta
Sh. Arvind Mrinu NRMH and Sh. Dr. Surya Dr. Surya (VU2ATN), GM Telecom
Rajani Mohan, DARTS Parkash, NIDM Parkash, NIDM (Retd.), PGCL
Different Modes of Amateur Radio Principles of Analog and Nomenclature of the Frequency
Transmission, Transmitter, Receivers Communication Digital and Wavelength Bands in Radio
Wednesday,
Recapitulation and Antennas; Characteristics and Communication Communication; Q-Code,
26
& Group Properties of Ionosphere for Radio Phonetics and other
September
Photograph Wave Propagation Abbreviations
2018
Shri Rajani Mohan (VU3CAV), Dr. Surya Dr. Surya Dr. Sandeep Baruah,
DARTS Parkash, NIDM Parkash, NIDM HAM Expert, Vigyan Prasar
Modulation – Amplitude, Frequency Distress Signals, Portable and Demonstration and Experience
Thursday, and Pulse Modulation Urgency Signals, Mobile Amateur Sharing on HAM Operations
27 Call and Message Station
September Recapitulation
2018
Shri Rajani Mohan (VU3CAV), Dr. Surya Dr. Surya Sh. Rajani Mohan, DARTS and
DARTS Parkash Parkash, NIDM Dr. Surya Parkash, NIDM
Friday, Exam for Amateur Station Operators Morse Code Feedback and Valediction,
28 Recapitulation Certificate (ASOC) Exam Evaluation Certification,
September and Exam Sh. Sukhbir, Sh. B.K. Ram and Sh. Vote of Thanks
2018 Manoj Kumar, NRMH Sh. B.K. Ram Participants ED and Faculty NIDM
 Sandeep Baruah, Scientist-E
Vigyan Prasar
Department of Science & Technology
C-24, Qutab Institutional Area
New Delhi-110 016
E-mail: sandeep@vigyanprasar.gov.in
 CONTENT

Part-I: Introduction to ham radio PAGE

A. What is Ham Radio? 1

B. Why an Amateur Radio Operator is called a ham? 2
C. What is the minimum qualification to become a ham? 3
D. What is an amateur radio call-sign? 3

Part-II: Amateur Radio Rules & Regulation

A. Detailed procedures related to application for a ham radio licence. 4

B. Different grades of licencing examinations and licences. 5
C. The Indian Wireless Telegraphs (Amateur Service) Rules, 1978. 6
D. Syllabus of Amateur Station Operator's Certificate (ASOC) Examination. 28
E. Question and answer section on amateur radio rules & regulations 33
F. Radio telephony operating procedure. 41
G. Radio telegraphy operating procedure. 43

Part-III: Radio Theory and Practice

A. Elementary theory of electricity & magnetism 47

B. Thermionic emission & valves 77
C. Semiconductor devices 80
D. Radio receivers 86
E. Transmitter 97
F. Radio wave propagation 103
G. Aerials 109

Part-IV: Learning the International Morse Code. 117

Part-V: Safety measures in a ham radio shack. 121

Annexure-I: List of Wireless Monitoring Stations

Annexure-II: Call-sign Prefixes of Amateur Radio Stations of different countries allotted

by the International Telecommunication Union (ITU)

Annexure-III: Sample Question Papers for the Amateur Radio Licencing Examination
 TIFAC-IDRiM Conference
28th –30th October 2015
New Delhi, India

RADIO BASED APPROACH FOR DISASTER RISK REDUCTION AND

MANAGEMENT USING AUTOMATIC PACKET REPORTING SYSTEM
(APRS®) AND HAM RADIO (AMATEUR RADIO) DIGITAL
COMMUNICATION TECHNOLOGIES

S. BARUAH

Vigyan Prasar, Department of Science & Technology

C-24, Qutab Institutional Area
New Delhi 110 016
sandeep@vigyanprasar.gov.in

ABSTRACT
In the event of any large scale disaster, due to the breakdown of conventional modes of
communication (mobile phone, land line phone, Internet etc.) disaster management becomes a
difficult task for various governmental and non-governmental emergency responders. So it is
of utmost importance to keep in place an alternative communication service up and running
which can work as a second line of communication utilizing radio waves. During many of the
past large scale disasters all over the world, Amateur Radio Service (ham radio) proved its
efficacy in quick dissemination of disaster management information (search and rescue, relief
work, tracking of missing person, real-time plotting of vehicles and personnel involved in
disaster management, transmission of weather telemetry data etc.). Amateur Radio Service is
a non-commercial licensed service utilized by voluntary radio experimenters and radio
enthusiasts regulated by the telecommunication authority. Automatic Packet Reporting
System -- APRS® (Registered Trademark of Bob Bruninga, US Naval Academy) is a digital
radio communication technology which augments the scope of application of Geographical
Information System (GIS) for disaster management. Vigyan Prasar is involved in coordination
of disaster management activities during many of the past large scale disasters gaining
expertise in digital technologies for disaster risk reduction and management through its state-
of-the-art radio communication system.

1. INTRODUCTION
Most of the disasters are unpredictable and in a country as big as India with population
exceeding 120 crore, it creates havoc in terms of loss of human life and other valuable
property. Governmental agencies and NGOs employ different means to predict location, route
and extent of disaster with a probable time frame. Due to the lack of adequate low-cost radio
technology infrastructure in our country, the emergency responders are facing problems in
disaster risk reduction works, pre-disaster communication in disaster prone areas and post-
disaster management.
 The author being a licensed amateur radio experimenter (ham radio hobbyist) with the
government allotted call-sign VU2MUE (Baruah, 1999a) for the last twenty five years
(licensed in 1989) was involved in emergency disaster communication during many of the
large scale disasters (Arya, A.S., et. al. 2005 and 2006) that our country has gone through. A
study was done by Baruah in 2004a on Ham Radio for Disaster Communication. The role of
ham radio operators in India during the Tsunami disaster in 2004 was documented in details
by Baruah, 2004b. Baruah, 2012 discussed in detail about live RF data on an interactive
Internet map. It is realized that without the integration of GIS Technology and Amateur Radio
Digital Communication Technology at grass root level Emergency Operation Centres (EOCs),
it would remain a far flung dream for the government to come out with a mechanism that
would not only ensure an effective linkage between the people living is disaster prone areas
with that of those who are involved in disaster management. A countrywide Amateur Radio
emergency digital communication network can be established under the Indian Wireless
Telegraph Amateur Service Rules of the Department of Telecommunications (Baruah,
1999b).

2. MATERIALS AND METHOD

2.1 GEOGRAPHICAL INFORMATION SYSTEM (GIS) AND PACKET RADIO
Geographical Information System (GIS) broadly describes any information system that
integrates, stores, edits, analyses, shares and displays geographic information (called the
geospatial data) for decision making in an interactive map. For government licensed amateur
radio experimenters (most of whom might not have the professional knowledge of GIS) to
use their two-way radio communication equipment for automatic transmission of GIS
data/information, Automatic Packet Reporting System (APRS) is the most suitable mode.
APRS (Bruninga, 2002) is evolved from its predecessor ham radio communication technology
called Packet Radio (Ackermann, 2002) which is a digital mode of Amateur Radio (Ham
Radio) communications which corresponds to computer telecommunications. The telephone
modem is replaced by a "magic" box called a terminal node controller (TNC); the telephone is
replaced by an amateur radio transceiver (a combined unit of radio transmitter and receiver),
and the phone system is replaced by the "free" amateur radio waves. Packet radio takes any
data stream sent from a computer and sends that via radio to another amateur radio station
similarly equipped. Packet radio is so named because it sends the data in small bursts, or
packets (Kenney, 1995). Interfacing of the computer through its serial communication port
(RS232) to the two-way radios is done through suitable radio modems. In the absence of
RS232 serial ports, serial to USB adaptor cables are utilized by radio experimenters which
provide 1200 baud and 9600 baud data transmission speed in the government allotted Very
High Frequency amateur band (VHF: 144-146 MHz) and Ultra High Frequency (UHF: 434 to
438 MHz) amateur bands. 9600 baud is approximately 960 unencrypted digitally transmitted
characters in one second. Though amateur radio experimenters have been utilizing the AX.25
Packet Radio protocol (Beech et.al, 1998) since late 70s for transmission of texts (transfer of
text files from one computer to another computer using radio waves), data, binary file transfer
over the radio and for two way interactive digital communication (text chat as well as Bulletin
Board System for file/mail storage and retrieval) using walkie-talkies interfaced to the
computer, in the recent time Automatic Packet Radio System (APRS®) is gaining popularity
as it provides all the information graphically on a map that is of immense utility in disaster
management. Graphical representation (through standardized icons) of various geospatial
information (e.g. Earthquake, cyclone, relief camp, Emergency Operation Centre-EOC,
ambulances, hospitals, different type of vehicles etc. (Figure 1, 2 and 3) make all emergency
management related information available to the emergency responders just at the click of the
mouse button. Open source and free computer software like UI-VIEW (Barker, 2004) and
APRSIS32 (Deffenbough, 2009) are available on the internet for different operating system
which can be utilized at the Emergency Operation Centres (EOCs) for transmission and
monitoring of geospatial information on maps using radio. IGate (Bruninga, 2015) is a radio
to internet gateway system utilized by ham radio operators to feed radio frequency data to
internet and make these available all over the world.

2.2 PACKET RADIO STATION

For APRS® to be utilized for disaster risk reduction and disaster management, the basic
packet radio station consist of a Very High Frequency (VHF) two-way radio interfaced to the
computer through a TNC (Terminal Node Controller) and a software application for digital
communication (Figure 1) The two way radio is connected to an external antenna for
transmission and reception of digital data. The function of the TNC is to encode and decode
the data. The software, also sometime called a terminal programme displays the data in
human readable format. The GUI (Graphical User Interface) software also allows the user to
connect to a station, sending text message as well as transfer of files from his/her computer to
the other connected computer (connected through radio waves). Packet is communications
between people either director indirect. Emergency responders can work keyboard to
keyboard or use electronic mailboxes to leave messages. Due to error checking by the TNC,
all of it is error free, too. As the data is received it is continuously checked for errors, and isn't
accepted unless it is correct. We don't miss the information if it has errors because the
information is resent again. The data that is to be transmitted is collected by the TNC and sent
in bursts, or packets, of information; hence the name. Each packet has the call-sign (Baruah,
1999c) or address of who it's going to, who it's coming from and the route between the two
stations included, along with the data and error checking. Since up to 256 characters can be
included in each packet, more than three lines of text can be sent in a matter of a couple of
seconds. Packet Networks allow amateurs to widen the area of communications past their line
of sight, by having a series of packet stations linked by radio that can be used to get their
packet messages to where ever the network goes.

Figure 1: Packet radio stations when use APRS technology, the radio originated information are displayed
graphically. In the above figure four radio stations are plotted on a map as per the position information
transmitted by these stations. Distance, bearing, time of reporting on map are all automatically archived and
available to the radio user.
2.3 AUTOMATIC PACKET REPORTING SYSTEM (APRS®)
APRS is a real-time tactical digital communications protocol for exchanging information
between a large number of stations covering a large (local) area. As a multi-user data
network, it is quite different from conventional packet radio (Bruninga, 2002) APRS is
different from regular packet in four ways. First by the integration of maps and other data
displays to organize and display data, second, by using a one-to-many protocol to update
everyone in real time, third, by using generic digipeating so that prior knowledge of the
network is not required, since 1997, a worldwide transparent internet backbone, linking
everyone worldwide. APRS turns packet radio into a real-time tactical communications and
display system for emergencies and public service applications (and global communications).
Normal packet radio is useful in passing bulk message traffic (Email) from point-to-point, but
it does not do well at real time events where information has a very short life time and needs
to get to everyone quickly. APRS is a LOCAL RF network. Although the Internet monitors
APRS worldwide, this is not the primary objective. But like all of our other radios, how we
use APRS in an emergency of special event is what drives the design of the APRS protocol.
Although APRS is used 99% of the time over great distances, and benign conditions, the
protocol is designed to be optimized for short distance real-time crisis operations on RF
(Bruninga, 2002). An Internet Gateway (IGate) station can feed the local RF originated
Geospatial packet data to a network of worldwide APRS-IS (Internet Server) extending the
range of APRS communication. These data can be viewed even a layman by accessing
websites like http://aprs.fi and http://www.riverdevil.org/APRS/vu2mue . Peter Loveall's
javAPRS (Loveall, 2006) enables demonstration of ham to non-ham communication (Non-
hams can only monitor APRS ham activities using their Internet Browsers). Its utility during
an emergency situation is self-explanatory.

2.4 INTEGRATION OF RADIO AND INTERNET

Figure 2: The author’s website http://www.riverdevil.org/APRS/vu2mue demonstrates the ham radio capability
to feed radio originated data to Internet, which can be represented graphically on a user customized map. In the
above figure, text messages transmitted from the car is received by another radio connected to computer is
displayed on the Java console. The car can be plotted in real-time on the map.
The author has developed a technology demonstration web page
http://www.riverdevil.org/APRS/vu2mue to demonstrate the amateur radio capability in
penetrating the Internet to serve useful purposes for disaster management. This is a live
APRS® data feed page utilizing javAPRS where radio originated emergency messages can be
read on the Microsoft Sun JAVA console. APRS® is not to be mistaken just as a mere
automatic vehicle tracking system. It is real-time two way digital radio communication where
many of the vital geospatial information are exchanged almost automatically. People can
monitor APRS® digital communication using this type of Internet web page as well as on
their radios. GUI application like UI-VIEW enables creation and calibration of localized maps
even without the use of GPS receivers and accurate plotting of real-time geospatial data for
disaster management is possible on these maps which can be of immense utility during
disaster management. The map demonstrates the utility of an Interactive Internet map. This
APRS map is accessible to hams as well non hams too. Text messages originated from RF
stations (stations who are in remote places and not connected to Internet) can be monitored by
non-hams. This has utility in ham radio emergency communication too. By pressing 'M' the
RF originated messages can be read the read message on the Java Console.

2.6 APRS® APPLICATIONs IN DISASTER MANAGEMENT

Accurate automatic position information (graphical plotting on map) about mobile & fixed
stations in real-time including web based archiving of positions of resources (people, vehicle,
property); Direction (Bearing/Angle) information for prompt Search and Rescue Operation;
Tracking a mobile station (useful during emergency operation/tactical situation when prompt
receipt of information about positions and progress of mobile stations is of utmost necessity
for efficient coordination); Line-of-Sight (LoS) Distance and bearing of stations from base
station available just at the click of a button; Monitoring of 'radio to radio digital text
messages' on an Internet browser. During emergencies, if the Internet does not fail, this would
help people to monitor emergency messages using Sun Java console on the Internet browser;
Monitoring of real-time weather information originated from ham radio weather stations
(Real-time Weather information like Wind Speed, Wind Direction, Temperature, Barometric
Pressure, Humidity, Rainfall etc. are available on this map with just the click of a button e.g.
at the URL http://aprs.fi/?call=VU2MUE-2 ; Plotting of objects on the map. For example an
accident site, crash site, intimation about a traffic jam for route planning, fire site, flood,
cyclone, earthquake, land-slide, road blockage or information about an event etc.; Allows
important information to be exchanged without human intervention. This is important during
a tactical or emergency situation, when emergency responders have to concentrate on other
important jobs,e.g. 'Search & Rescue Operation’.

Figure 3: Real time plotting of mobile stations on internet as well as standalone computers connected to radio.
Last reported time and position, bearing and distance from control room etc. are just at the click of a button.
 Figure 4: Author’s radio setup with an assembled radio
modem which can be interfaced to a GPS receiver and
weather sensors for real-time transmission of location as well
as weather information. These information can be received by
a similarly equipped radio station interfaced to the computer.
The received information are displayed graphically in UI-
view software as in shown in figure 1 and 3.

CONCLUSION
As radio waves allotted by the government to the amateur radio experimenters are free of cost
and the cost of two-way radio communication devices are going down, a countrywide
network of voluntary hams utilizing APRS® is a need of the hour which can involve a vast
section of the society to be self-reliant in disaster risk reduction and disaster management
would become more efficient.

REFERENCES
Ackermann, J., (2002) Packet Radio Basics
http://nebula.wsimg.com/956808877754f8b2e3e5107ab910f4a9?AccessKeyId=13BB62BA17
C994AA56AC&disposition=0&alloworigin=1
Arya, A.S., Agarwal, A., Nagaraju, A., Karanth, A., Menon, K., Venkatachalam, A., Dey, B.,
Karelia, H., Narayanan, M., (2005 and 2006) TOGETHER, TOWARDS, A SAFER INDIA
PART-III A textbook on disaster management for class X: 28
http://www.cbse.nic.in/DM%20ENGLISH.pdf
Baruah, S., (1999a) Ham Radio for the wireless Enthusiasts
http://www.qsl.net/vu2msy/sandeep_baruah.htm
Baruah S., (1999b) The Indian Wireless Telegraph (Amateur Service) Rules, 1978
http://www.qsl.net/vu2msy/asocrules.htm
Baruah, S., (1999c) What is an amateur radio call-sign?
http://www.qsl.net/vu2msy/callsignFAQ.htm
Barker, R. (2004) UI-view http://www.ui-view.net/
Baruah, S., (2004a) Ham Radio for Disaster Communication. VIPNET NEWS (8): 10
http://www.qsl.net/vu2msy/Emergency_Ham_Communication_in_India.pdf
Baruah, S., (2004b) Hams came to the rescue of Tsunami struck distresed people in India.
http://www.qsl.net/vu2msy/Hams_came
to_the_rescue_of_Tsunami_struck_distresed_people_in India.htm
Baruah, S., (2012) Live RF data on an interactive Internet map.
http://www.riverdevil.org/APRS/vu2mue
Beech, W., Nielsen D., Taylor, J., (1998) AX.25 Link Access Protocol
for Amateur Packet Radio http://www.ax25.net/AX25.2.2-Jul%2098-2.pdf
Bruninga, B., (2002) Automatic Packet/Position Reporting System (APRS)
http://www.aprs.org/APRS-docs/APRS.TXT
Bruninga, B., (2015) IGate Design http://www.aprs-is.net/IGating.aspx
Deffenbough, L., (2009) APRSISCE/32 The future of Amateur Radio APRS
http://aprsisce.wikidot.com/
Kenney, L., (1995) Introduction to Packet Radio http://choisser.com/packet/
Loveall, P., (2006) http://www.ae5pl.net/
 Part-I

Introduction to Ham Radio

A. What is Ham Radio?

Ham radio operators are a group of people nurturing a special interest in wireless
communication technology. People from all the spheres of life are found among the
ham radio operators. They operate their wireless transceivers (a combined unit of
radio transmitter and receiver) during their spare time for the sheer joy, thrill and
excitement involved in doing a worldwide radio communication. Unlike the broadcast
radio stations (to whom we usually tune our radio receivers to listen to), ham radio is
a two-way communication system. Ham radio operators can put their voice on-the-air
to be listened into and at the same time replied back by their fellow radio operators
around the world, usually with very low power devices.
Despite the existence of other communication facilities, ham radio operators
run their own wireless communication network with entirely personal effort, out of
the love for this medium of communication. There are some hams who, build their
own wireless transceivers (a combined unit of transmitter and receiver) and transmit
their voice signals throughout the world to be replied back by their fellow hams.
These are the experiment oriented hams who try to achieve some sort of a perfection
in developing electronic circuits for radio frequency work, or at a lower level, they
may like to assemble a piece of wireless equipment designed by their fellow experts,
modify it in their own way to improve its performance till they are satisfied with its
performance. Hams located in the other parts of the world reply back exchanging
information about the quality and strength of their radio signals.
They exchange personal as well as technical information, which are not
related to business or commerce, politics and religion. Though a ham cannot use his
radio station for any pecuniary gain, a creative mind can still find numerous utility of
ham radio. It is a pursuit, which attracts people from all the spheres of life. There are
hundred and thousands of people who are laymen so far as their knowledge of
electronics is concerned, yet, they are expert ham radio operators. It is an exciting
way to discover new friends and disseminate knowledge on-the-air. One interesting
fact about ham radio communication is that hams don’t have to pay any money to the
authority for their on-the-air conversation.
With the availability of low cost easily replicable circuits of radio transmitters
and receivers, the number of ham radio operators increased to millions. The growth of
electronics communication technology is also considered to be going hand in hand
with the progress of ham radio. The advancement in the field of electronics and the
flourishing growth of electronics industry in countries like Japan has been very often
attributed to the presence of large group of dedicated ham radio operators (to the tune
of 13,50,127).
Though ham radio is a highly specialized technical hobby, it requires no
special qualification (except that the person going to be a ham has attained 12 years
of age). However, it demands immense interest in radio communication and sufficient
enthusiasm to operate a radio station of your own. Ham radio, also known as
"Amateur Radio" does not provide any pecuniary gain. However, what you gain
from being a ham is more than what money can give and for that you got to be
imaginative! Many of the foremost radio and electronics engineers and technicians
operate as amateurs during times when they are not occupied professionally. Seeing
the growth of ham radio population around the world, many professional companies
started manufacturing ham radio equipment to meet the needs of the vast group of
ham radio operators, who prefer readymade professionally built equipment instead of
homemade ones. So, what had once been a hobby for somebody, turned out to be a
profitable industry for some others. Hams never accept money for their on-the-air
communication.
Young students can learn the principles of electronics through practical
experimentation by assembling wireless transmitter and receiver kits in the ham radio
clubs established in their schools. Without a valid ham licence, it is illegal to operate
wireless equipment. In India, the Central Board of Secondary Education (CBSE)
has also taken some initiative to include 'ham radio' in their course curriculum under
the scheme of Work Experience. The Member of Parliament Local Area
Development Scheme has also included 'Ham Radio' as one of its projects. As per the
directive of the Ministry of Programme Implementation, a Member of
Parliament (MP) can spend money to establish ham radio stations in the schools
located in his area. If these schemes are fruitfully utilised, many youngsters would
be able to take interest in ham radio which they may also make into career. There are
many activities people perform out of their scientific curiosity or to satisfy their
inquisitive mind. Many people are attracted towards ham radio for this reason also.

B. Why an Amateur Radio Operator is called a ham?

As per the Florida Skip Magazine (1959), the word "HAM" was coined in 1908 from
the station CALL of the first amateur wireless station operated by some amateurs of
the Harvard Radio Club. They were Albert S. Hyman, Bob Almy and Poogie
Murray. At first they called their station "Hyman- Almy-Murray". Tapping out such
a long name in code soon became tiresome and called for a revision. They changed it
to "Hy-Al-Mu", using the first two letters of each of their names. Early in 1901 some
confusion resulted between signal from amateur wireless station "Hy-Al-Mu" and a
Mexican ship named "HYALMO". They then decided to use only the first letter of
each name and the station CALL became "HAM”.
During those days of unregulated radio, amateur radio operators picked their
own frequency and call letters. Then as now, some amateurs had better signals than
commercial stations. The resulting interference came to the attention of US
congressional committees in Washington DC and the Congress proposed a
legislation to critically limit the amateur radio activity. In 1911, Albert Hyman
chose the controversial Wireless Regulation Bill as the topic for his thesis at
Harvard. His instructor insisted that a copy be sent to Senator David L. Walsh, a
member of one of the committees hearing the Bill. The Senator was so impressed
with the thesis that he asked Hyman to appear before the committee. Albert Hyman
took the stand and described how the little station was built and almost cried when he
told the crowded committee room that if the BILL went through they would have to
close down the station because they could not afford the license fee and all the other

2
requirements which the BILL imposed on amateur stations. Congressional debate
began on the Wireless Regulation Bill and little station "HAM" became the
symbol for all the little amateur stations in the country crying to be saved from
the menace and greed of the big commercial stations who didn't want them
around. The BILL finally got to the floor of Congress and every speaker talked about
the "....poor little station HAM." That's how it all started. The whole story can be
found in the US Congressional Record. Nation-wide publicity associated the station
"HAM" with other amateur radio operators. From that day to this, and probably until
the end of time in radio; an amateur radio operator is a "HAM”.

C. What is the minimum qualification to become a ham?

No educational qualification is specified to become a ham. Anybody who has
attained 12 years of age can become a ham radio operator after passing the Amateur
Station Operator's Certificate (ASOC) Examination conducted by the Ministry of
Communications, Govt. of India. You have to send a "Birth Certificate" or the
"High School Leaving Certificate" (which mentions your date-of-birth) as a proof of
your age.
There are four different grades of Amateur Wireless Telegraph Station
Licence. Those between the age group of 14-18 years can apply for Grade-I,
Grade-II, Restricted Grade or a Short Wave Listener's licence (listening to the
ham radio operators without this licence is considered illegal). Those between the age
group of 12-14 years can apply for Grade-II, Restricted Grade or a Short Wave
Listener's Licence. The application for the grant of such licences should be
accompanied by a certificate from the head of the educational institution recognized
by a board or university in India, attended by the consent of the applicant or from his
legal guardian that the applicant is interested in and is competent to conduct
experiment in wireless communication.

D. What is an amateur radio call-sign?

Each amateur radio station (ham radio station) has its own unique "name"
allotted by the authorities. In amateur radio, the unique name assigned to a ham
radio station and its owner helps you to know its operator as well as the country
to which he/she belongs. A particular ham radio station is authorized to be operated
by that particular ham radio operator only. However, other licensed ham radio
operators are also eligible to operate his station, provided, the owner of that particular
station is physically present during the operation. A person who does not hold a
ham radio licence is not authorized to operate a ham radio station. This also
means that only a single station with a particular call-sign can exist in a particular
location. A person having a ham radio call-sign is not authorized to set up more than
one ham radio station.
A call-sign consists of a set of letters and numbers, assigned by the authority.
For example VU2XYZ is a call-sign which belongs to a particular ham in India. No
other hams anywhere in the world can have this call-sign! Similarly, 4S7VK is a call-
sign which belongs to a ham from Sri Lanka. In a call-sign, the first 2 (or 3)

3
characters are called the prefix. So, there might be a ham with the call-sign 4S7XYZ
in Sri Lanka. Similarly, a call-sign like VU2VK may exist in India! Each country has
its own prefix. The knowledge of prefix helps us in identifying the country of origin
of a particular amateur radio transmission (List of prefix at Annexure-II).
When a ham radio station is set up on board a ship, the call-sign should be
followed by the suffix /MM. So, VU2XYZ would become VU2XYZ/MM (maritime
mobile) when it operates from a ship. If it operates from a vehicle, then the call-sign
becomes VU2XYZ/M (mobile).

Part-II

Amateur Radio Rules & Regulation

A. Detailed procedures related to application for a ham radio
licence
An examination is held for licensing of Amateur Stations. It is conducted by the
Wireless Planning and Co-ordination wing (WPC) of the Ministry of
Communications, New Delhi at 22 Wireless Monitoring Stations located
throughout the country. You should apply to the ‘Officer-in-Charge’ (OC) of the
Monitoring Station nearest to your hometown. Basically the examination consists of a
100 marks question paper (50 marks related to basic radio/electronics theory as per
the syllabus and 50 marks related to Amateur Radio Rules & Regulations) which is of
one, two or three hours duration as per the “grade” of licence you intend to appear.
There are 4 grades. You can apply for more than one grade at a time, provided,
separate application forms along with the prescribed examination fees, for each grade
in the form of Demand Draft issued from a “State Bank of India” branch drawn in
favour of the "Pay & Accounts Officer (Headquarters), Department of
Telecommunications, New Delhi-110 001, payable at SBI New Delhi Service
Branch (Code No. 7687) are sent to the "Officer-in-Charge" of the Wireless
Monitoring Station (in no case application be forwarded to WPC Wing, New Delhi)
where you will be appearing for the ASOC examination.
The particulars of the "Venue" and "Date" etc. of the examination will be
communicated by the Officer-in-Charge of the concerned Wireless Monitoring
Station on receipt of completed application form with the requisite examination fees
Following should accompany the application:
(1) Nationality Certificate/Character Certificate in the prescribed proforma (find
the proforma in “Indian Rules & Regulation” section of this book) from a
gazetted officer.
(2) 2 copies of recent passport size (3 x 4 cms) photographs duly signed by
you on the front side.
(3) Examination fees in the form of Bank Draft (DD) drawn from a SBI
branch of appropriate amount.
(4) Personal particulars (4 copies) in the prescribed proforma (find the proforma
in “Indian Rules & Regulation” section)

4
 (5) An attested copy of birth certificate or School Leaving certificate as a
proof of your age (the minimum age requirement to appear for the
examination is 12 years)
After the declaration of the result, a copy of the result and your "Personal
particulars" will be forwarded by the Wireless Monitoring Station to the WPC Wing
of the Ministry of Communications, New Delhi. The WPC Wing, New Delhi will
then inform the concerned Department of the Ministry of Home Affairs for a
‘Security Clearance/Police Verification’. After the police verification report is
received with a clearance, the WPC Wing will write to you that you will be awarded
an "Amateur Wireless Telegraph Station Licence" on payment of the requisite
"Licence fee". Remember that ‘Examination Fee’ and ‘Licence fee’ are different and
the ‘Licence fee’ should be sent only when asked for. This time, the mode of
payment is same as above, but you have to send it directly to:
The Assistant Wireless Adviser to the Govt. of India,
WPC Wing, Ministry of Communications,
Amateur Radio Section,
Dak Bhawan, Parliament Street,
New Delhi-110 001

B. Different grades of licencing examinations & licences

(1) Restricted Grade Amateur Station Operator’s Licence (if you pass Restricted
Grade licensing Examination): Permits short distance terrestrial communication
using a power output of 10 Watts (dc input power) in the Very High Frequency
(VHF) & Ultra High Frequency (UHF) bands. The frequencies allocated in these
bands ranges from 144 to 146 MHz and 434 to 438 MHz. Modes of communication
allowed are: Radio Telephony(Voice) using Amplitude Modulation (AM), Single
Side Band (SSB), SSB Suppressed Carrier, SSB reduced carrier and Frequency
Modulation (FM). It is advisable not to go for this Grade of licence because
communication is limited to a very short distance (a typical possible range may be
35 km only depending on the height of the antenna or the type of terrain). This type
of licence is useful in a place where there are large number of ham radio
operators.

(2) Grade II Licence (if you pass Grade-II licensing examination): Permits
worldwide long distance communication in AM, SSB, FM using a power output of
50 watts in different allotted short wave bands (high frequency-HF bands ranging
from 1.8 to 30 MHz) including the VHF/UHF bands mentioned above. But
entitlement for authorization of voice communication (radio telephony) is on the
basis of providing proof of having made 100 contacts with other amateur radio
stations using Morse Code (Called Continuous Wave-CW communication). This
means that you have to send back your original licence to the WPC wing for “Voice
endorsement” along with the photocopies of your log book (see Rules & Regulation
Section).

(3) Grade-I: (if you pass Grade-I licensing examination): Power output is 150 watts
in short waves (in the allotted HF bands), 25 watts in VHF & UHF (Ultra High
Frequency). An additional UHF spectrum from 1260 to 1300 MHz including a range

5
of frequencies in Super High Frequency (SHF: 3300-3400 & 5725-5840 MHz)
spectrum is available to this category of licensees. With this licence you can directly
use voice including Morse Code. Other advanced modes like Radio Tele-Typing
(RTTY), Amateur Radio Teleprinting Over Radio (AMTOR), Packet Radio (-an
advanced technique of digital data communication through computer connected
to a wireless transceiver), PSK31 (the latest digital communication mode in which a
computer equipped with a sound-blaster card can be directly connected to a wireless
transceiver for data reception and transmission), Amateur Television (ATV using
Slow Scan Telecast: SSTV) are also allowed. You are also permitted to work amateur
radio communication satellites with this licence.

(4) Advanced Grade: Same as Grade-I licence but allowed to use 400 watts of
power in selected sub-bands. This is the highest grade licence in India. Every ham
radio enthusiast in India aspires to get it.

Practical Test
There is a practical test on Morse Code sending and receiving (except for Restricted
Grade Licence where this test is not required). This is a 10 minutes duration test to
examine the candidates proficiency in sending and receiving Morse Code. To learn
Morse code, a Morse Code Practice Oscillator can be assembled along with a Morse
Key and a Morse Code learning Cassette can be found useful (See Morse Code
learning Section of this book).

C. The Indian Wireless Telegraphs (Amateur Service) Rules, 1978

GOVERNMENT OF INDIA
MINISTRY OF COMMUNICATIONS
(WPC Wing)

Notification
The Indian Wireless Telegraphs (Amateur Service) Rules, 1978

G.S.R No. 1499/78- In exercise of the powers conferred by section 4 and section 7 of
the Indian Telegraph Act, 1885 (13 of 1885), the Central Government hereby makes
the following rules for the conduct of wireless telegraphs in the amateur service,
established, maintained, and worked by persons licenced under the said Act.

1. Short title and commencement

(1) These rules may be called the Indian Wireless Telegraphs (Amateur Service)
Rules, 1978.
(2) They shall come into force on the 1st January, 1979.

2. Definitions
In these rules, unless the context otherwise requires-
(a) ‘Act’ means the Indian Telegraph Act, 1885 (13 of 1885);

6
(b) ‘Amateur service’ means a service of self training, inter-communication and
technical investigations carried on by amateurs that is, by persons duly authorized
under these rules interested in radio technique solely with a personal aim and
without pecuniary interest; ‘amateur station’, and ‘station’ shall have the meaning
respectively assigned to them in the Convention;
(c) ‘Convention’ means the International Telecommunication Convention,
Malaga-Torremolinos, 1973, for the time being in force and the Radio Regulations
and the Additional / Radio Regulations annexed thereto but does not include any
portion of the said Convention or Regulations regarding which the Central
Government makes any reservation;
(d) ‘Licence’ means a licence granted under section 4 of the Act for an amateur
wireless telegraph station.

3. Necessity for licence

No persons shall establish, maintain and work an amateur wireless telegraph station,
except under and in accordance with the terms and conditions of an appropriate
licence under these rules.

4. Categories of licence
There shall be five categories of licences, namely :
(i) Advanced Amateur Wireless telegraph Station Licence
(ii) Amateur Wireless Telegraph Station Licence, Grade - I
(iii) Amateur Wireless Telegraph Station Licence, Grade - II
(iv) Restricted Amateur Wireless Telegraph Station Licence
(v) Short Wave Listener's Amateur Wireless Telegraph Station Licence.

5. Eligibility for Licence

(1) A licence may be granted subject to such conditions contained in Annexure I to
these rules
(i) to a person-
(a) who is a citizen of India;
(b) who is not less that 18 years of age;
(c) who qualifies the Amateur Station Operator's Examination for the award of licence
or holds either of the following certificate of proficiency, namely:
(i) Radio-communication Operators’ General Certificates;
(ii)First or Second Class Telegraph Operators’ Certificates:
Provided that the holder of a Special Radio Telegraph Operator's Certificate may
also be considered eligible for the award of Amateur Wireless Telegraph Station
Licence Grade II.
(iii) To a bonafide amateur radio society, club, a school, college, institute or
university in India, which has the aim of participating in the 'amateur service':
Provided that the licence shall be issued in the name of an authorized official of the
society, club, school, college, institute or university in India, holding a category of
licence appropriate to the transmission to be conducted by the station, including
amateur radio beacon transmissions.
(2) Notwithstanding anything contained in sub-clause (b) of clause (i) of sub-rule (1),
the central government may grant, to bonafide experimenters between the ages of

7
 14 and 18 years, Amateur Wireless telegraph Station Licence, Grade I and to those
between the ages of 12 and 18, Amateur Wireless Telegraph Station Licence,
Grade II or Restricted Amateur Wireless Telegraph Station Licence or Short Wave
Listeners' Amateur Wireless Telegraph Station Licence: Provided that the
application for the grant of such licences shall be accompanied by a certificate
from the head of the educational institution, recognized by a board or university in
India, attended by the applicant or from his legal guardian that the applicant is
interested in and competent to conduct experiment in wireless telegraphy.
(3) Notwithstanding anything contained in sub-clause (c) of clause (i) of sub-rule (1),
the Central Government may recognize, subject to any conditions it may prescribe
from time to time, such other Radiotelegraph Operators’ Certificates or Amateur
Station Operators’ Certificate as are issued by a competent authority in India or
any other country as equivalent to qualifications referred to in aforesaid sub-rule,
for the purpose of grant of a licence under those rules.

6. Application for licence

(a) an individual, or
(b) an amateur radio society or club or a school, college or an institute or an
university in India
-shall be made to the central government in Annexure II or Annexure III
respectively to these rules, together with all the subsidiary forms and documents
duly filled in and completed in all respects.

7. Eligibility for admission to Amateur Station Operator's Examination

No person shall be eligible for admission to an examination for the grant of licence
unless-
(a) such a person fulfils the provisions contained in sub-clause (a) of clause (i) of sub-
rule (1) and either sub-clause (b) of clause (i) of sub-rule (i) or sub-rule (2) of rule 5;
(b) such person pays the fees on the following scale, namely:
(i) Advanced Amateur Station Operator's Examination Rs. 25.00
(ii) Amateur Station Operator's Grade I Examination Rs. 20.00
(ii) Amateur Station Operator's Grade II Examination and
Restricted Wireless Telegraph Station Examination Rs. 10.00
(c) a period of at least one month has elapsed since he last appeared in an examination
and failed.

8. Examinations
(1) The examinations for the grant of a licence shall be held at a place and on a date as
may be notified by the Central Government from time to time.
(2) An application for licence in Annexure II to the rules shall be submitted not later
than the 15th of the month preceding that in which it is desired to take the
examination.
(3) Any person admitted to the examination and found guilty of impersonation or of
submitting fabricated documents or documents which have been tampered with or
of making statements which are incorrect or false or of suppressing material
information or of using or attempting to use unfair means in the examination hall
or otherwise resorting to any other irregular or improper means for obtaining
admission to the examination may, in addition to rendering himself liable to

8
 criminal prosecution, be debarred either permanently or for a specified period
from appearing in any of the examinations held for the award of licence under
these rules:
Provided that no order under this sub-rule shall be made unless the person
concerned has been given a reasonable opportunity for making a representation
against the action proposed to be taken.
(4) If any person is found guilty of any malpractice referred to in sub-rule (3) after the
grant of a licence to such person, the central government may, in addition to
prosecuting him cancel the licence so given:
Provided that the central government may, pending the cancellation of the licence,
suspend or endorse such licence:
Provided further that no order under this sub-rule shall be made unless the person
concerned has been given a reasonable opportunity for making a representation
against the action proposed to be taken.

9. Grant of Licence
Every category of licence shall be in the form set out in Annexure III to these rules.

10. Observance of conditions of licence, Convention and rules under the Act
(1) Every licenced amateur wireless telegraph station shall be established, maintained
and worked in accordance with:
(a) the conditions contained in Annexure I to these rules;
(b) the provisions of the Convention;
(c) the rules made by the Central Government under section 7 of the Act for the
conduct of wireless telegraphs in so far as they are applicable.
(2) Notwithstanding sub-rule (1) the Central Government may modify, vary, cancel or
revoke any of the conditions of licence contained in the said Annexure I at any
time either by specific notice in writing to the licencee, or by means of a general
notice published in the Official Gazette or in a newspaper published in New
Delhi.
(3) The licencee shall at his own expense, give effect to any variations in the
conditions of licence,

11. Period of validity

A licence granted under these rules shall be issued for a period of 2 years or 5 years,
as the case may be, commencing on the date of issue of the licence and expiring on
the last day of the month preceding the month of issue.

12. Fee for licence

(1) A licence fee on the following scale shall be paid to the Central Government on
receipt of instructions from that Government and in the manner directed by it -
_____________________________________________________________________
Category of licence Fee for 2 years Fee for 5 years

9
_____________________________________________________________________
(i) Advanced Amateur Wireless Telegraph Station Rs.50/- Rs.125/-
Licence
(ii) Amateur Wireless Telegraph Station Licence, Rs.40/- Rs.100/-
Grade I
(iii)Amateur Wireless Telegraph Station Licence, Rs.25/- Rs.60/-
Grade II; Restricted Amateur Wireless
Telegraph Station Licence;
(iv)Short wave Listener’s Amateur Wireless Nil
Telegraph Station Licence
_____________________________________________________________________

The licence fee shall not be refundable on ground of licensee's inability to establish or
make use of the licensed amateur wireless telegraph station or for adjustments
towards higher category of licence.
(2) No holder of a licence shall be entitled to a refund of fees paid therefore on the
ground of his inability to establish or make use of the licensed amateur station.

13. Authorized frequency bands, power and emission

A holder of licence shall use, as appropriate to the licence, such frequency bands,
power and classes of emission as are set out in Annexure V of these rules:
Provided that the central government may by special or general order make changes
in the usage of frequency bands, power and types of emission where that Government
is satisfied, that it is expedient to do so keeping in view, among others, the provisions
of the convention need for enforcement of better technical standards in respect of
equipment and national and international radio interference pattern.

14. Renewal of licence

(1) On the expiry of the validity of a licence, it may be renewed for a period of two or
five years, as the case may be, if the licencee-
(a) makes an application for renewal, not earlier than 2 months but before the date of
expiry;
(b) has actively operated an amateur wireless telegraph station during the validity of
his licence and provides a certificate to the effect that he has made contacts with
other amateur stations on at least 40 occasions per year, and in case of short wave
listener, has intercepted amateur station on at least 40 occasions per year;
(c) Pays, a fee on the following scale, namely:

_____________________________________________________________________
Category of licence Fee for: 2 years/5 years
_____________________________________________________________________

(i) Advanced Amateur Wireless Telegraph Station Rs.50/- Rs.125/-

Licence
(ii) Amateur Wireless Telegraph Station Licence, Rs.40/- Rs.100/-

10
 Grade I
(iii)Amateur Wireless Telegraph Station Licence, Rs.25/- Rs.60/-
Grade II; Restricted Amateur Wireless
Telegraph Station Licence;
(iv) Short wave Listener’s Amateur Wireless Nil
Telegraph Station Licence.
_____________________________________________________________________

(2) The licence fee shall not be refundable on ground of licensee's inability to
establish or make use of the licensed amateur wireless telegraph station or for
adjustments towards higher category of licence.
(3) The document showing the renewal of licence issued by the Central Government
shall be kept along with the licence to which it refers.
(4) It shall not be obligatory for the Central Government to issue a notice that the
licence is due for renewal.

15. Surcharge for late renewal

In case the holder of licence does not apply for its renewal prior to the date of expiry
of the licence referred to in sub-rule (1) of rule 14, he may apply for the renewal of
licence subsequently also but within a period of two years after the date of expiry of
the licence on payment of a surcharge at the rate of Rs. 10/- for every half year or part
thereof. The licence in such a case, shall be renewed from the date of expiry of
licence.

16. Register for wireless telegraphy apparatus

Every licensee shall maintain a register in respect of all wireless telegraphy apparatus
established, maintained and worked by him at the amateur station in the form set out
in Annexure VI of these rules.

17. Location of Amateur Station

The location of the amateur station shall be specified in the licence along with the
usual residence of the licensee endorsed therein and it shall be operated only from the
place so fixed.
Provided that the central government may permit the change of location if the licensee
applies for it in writing giving particulars of the change and submits the licence for
endorsement, and pays a fee of rupees five.

18. Portable and mobile amateur station

The central government may in addition to an amateur station licensed for a specified
location issue a special authorization to establish, maintain and work an amateur
station as a mobile station installed on board a motor vehicle or as a portable station
or for the purpose of exhibiting the operation of amateur station at jamborees or for
specific technical investigations in radio if -
(i) Application for such authorization is made at least 10 weeks in advance indicating,
amongst other, the period for which the authorization is required, area of operation
and the purpose;

11
(ii) The applicant holds an Advanced Amateur Wireless Telegraph Station Licence or
an Amateur Wireless Telegraph Station Licence Grade I;
(iii) The applicant pays an additional fee of Rs. 10.
(2) The special authorization shall, in addition to the conditions specified in rule 10,
be subject to conditions, namely:
(i) The special authorization shall not be issued for a period more than 90 days and
may be extended for a further period of 90 days on request and on payment of fee
of Rs.10/-;.
(ii) The licencee's amateur station at the fixed location and the mobile station shall not
communicate with each other;
(iii) The suffix ‘MO’ shall be added to the call-sign already authorized to the licensee,
such call-sign shall be followed by the location of the station;
(iv) such other conditions as the central government may determine from time to time.
(3) The special authorization may be withdrawn or the conditions contained therein
varied at any time by the central government.

19. Amateur Station on board ship

(1) Without prejudice to rule 17, the Central Government may on receipt of an
application authorize establishment, maintenance and working of an amateur
station on board a ship registered in India. Applications for such authorization
shall be accompanied by a written approval of the master or owner of the ship
concerned.
(2) The establishment, maintenance and working of amateur station on board ships
shall, in addition to the conditions specified under rule 10, be subject to such other
conditions as the Central Government may determine from time to time and such
conditions, among others, shall include the following, namely:
(i) The amateur station on board ship shall be operated only while the ship is in
international waters or Indian territorial waters. Its operation within the territorial
waters of another country shall be in conformity with laws and regulations of the
country concerned.
(ii) It shall not be operated whilst the ship is in any harbour in India;
(iii)The call-sign allotted to such stations shall have suffix ‘MS’ followed by the call-
sign of the ships in case of radiotelegraphy/official name of the ship in case of
radiotelephony.
(iv)The amateur station on board a ship shall be independent of ship radio
communication, radio navigation and other safety services radio equipment and
shall be operated in such a manner as not to cause harmful interference to these
services of the ship. The amateur station shall have source of electrical energy
independent of the ship station and shall also be electrically independent of it.
(v) The amateur station on board a ship shall discontinue operation at any time on
request of an officer of the Central Government, the master or radio officer of the
ship or any land station.

20. Loss and Issue of Duplicate of Licence and Document showing the Renewal of
Licence
(1) A person whose Licence or the document showing the renewal of licence has been
lost, mutilated or destroyed shall notify the same to the central government. An

12
 application in Annexure VII of these rules for the duplicate shall be made to the
central government embodying a statement of the circumstances involved in the
loss, mutilation or destruction of the licence or the document showing the renewal
of licence for which a duplicate is required. If the licence or the document
showing the renewal of licence has been lost, the applicant must state the
circumstances in which it was lost and that reasonable search has been made for it,
and further that in the event it be found, either the original or the duplicate shall
be returned for cancellation. The mutilated licence or the document showing the
renewal of licence for which the duplicate is required should be forwarded along
with the application for cancellation.
(2) The central government may issue duplicate copy of any licence or the document
showing the renewal of the licence and the following charges shall be levied for
such issue:
(i) For duplicate of licence - Rs. 10
(ii) For duplicate of the document showing the renewal of licence- Rs. 5

21. Revocation of licence

(1) The central government may, at any time, revoke the licence-
(i) On the breach of any of the conditions of licence contained in
Annexure I; or
(ii) In default of payment of any fees payable under these rules;
Provided that, before revoking a licence, the licensee shall be given a reasonable
opportunity of making a representation against the action proposed to be taken.
(2) The licensee shall not be entitled to any compensation arising out of revocation of
his licence nor will any part of the fees paid for the licence shall be refunded for
the period a licence stands revoked.

22. Transfer of licence

A licence shall not be transferable:
Provided that the central government may permit the transfer of a licence granted to
an authorized official of an amateur radio society or club or a school, college or an
institute or an university in India in favour of his successor if such successor holds a
category of licence appropriate to the transmissions to be conducted by the amateur
station.

23. Operation of licenced amateur station

No person other than the licensee shall be permitted to operate the licensed amateur
station:
Provided that -
(a) In the presence of the licensee himself, the station may be operated by another
person holding a valid licence of comparable or higher category. The licensee,
however, shall be personally responsible for the observance of these rules as if he
operates the station.
(b) In case of a licence issued to an authorized official of an amateur radio society,
club, school, college, institute or university in India, the station may be operated
by-
(i) a person who holds a licence equivalent or of higher category;

13
(ii) a person who holds a lower category of licence, where he operates the station on
the frequency bands, emissions and power allocated to his category.In each of the
cases aforesaid the licensee shall be responsible for the observance of this rule.

24. Surrender of licence

A licence which is revoked or which has become invalid and licensee does not desire
to renew it shall be surrendered to the central government for cancellation and record.

25. Dual holding of licence

No person shall be granted more than one licence at the same time: Provided that the
central government may exempt a person, holding a licence is his name for amateur
radio society or a school, college or an institute or an university in India, from the
operation of this rule.

26. Admission of foreign nationals in examination and grant of licence

(1) Notwithstanding anything contained in these rules the central government may,
subject to such terms and conditions as it may impose from time to time, admit a
person, who is not a citizen of India, to an examination for the grant of a licence
or grant him a licence if otherwise qualified.
(2) The conditions under sub-section (1) shall, among others, include the following,
namely:
(i) The country of which the applicant is citizen, grants reciprocal facilities to Indian
nationals:
Provided that it shall not apply where the central government considers that
reciprocal facilities are not necessary;
(ii) The applicant is above the age of 18 years.
(iii) The applicant is holder of an appropriate category of amateur station operator's
certificate or licence issued by a competent authority in any other country and
recognised by the central government.
(iv) The licence under this rule shall be initially granted for a period of one year or for
the period of validity of visa, for which the applicant's passport is endorsed,
whichever is less, on payment of a proportionate licence fee as prescribed in Rule
12 subject to a minimum of fees payable of one year.

27. Penalty for breach of these rules

Any breach of these rules, other than a breach, which is an offence under section 20
or 21 of the Act, shall be punishable with fine, which may extend-
(i) when the person is licenced under the Act, to Rs.1000 and in the case of continuing
breach a further fine of Rs.200 for every day after the first during the whole or any
part of which the breach continues;
(ii) when a servant of the person so licenced or another person is punishable for the
breach one fourth of the amounts specified in clause (i).

28. Repeal and saving

(1) On the commencement of these rules, the Indian Wireless Telegraphy (Amateur
Service) Rules 1958, shall cease to be in force,

14
(2) Notwithstanding such cesser-
(a) where before such commencement any person had passed the Amateur Station
Operators Certificate Grade I or Grade II Examination, such person shall not be
required to pass any such examination under these rules;
(b) where, before such commencement any person was granted Amateur Wireless
Telegraph Station Licence Grade-I, or any such Licence was renewed and the
period for which such Licence was granted or renewed extends beyond the
commencement of these rules, then, such Licence shall continue to be in force for
the period specified in the licence.

Annexure I

CONDITIONS
FOR
THE CONDUCT OF
AMATEUR WIRELESS TELEGRAPH STATION
[See rules 5 & 10]

1. Use of the Amateur Station

(1) The amateur station shall be used as part of self-training, intercommunication and
technical investigations in radio techniques solely with a personal aim and without
pecuniary interest:
Provided that when the station is licensed to an amateur radio society or club, or a
school, college or an institute or a University, the use of the station shall be
confined to technical investigations and training in radio communication
techniques without pecuniary interest.
(2) The station may also be used for the purpose of receiving transmissions in the
standard frequency service to facilitate operation of the station within the
authorized frequency bands.
(3) Except as provided in these rules, the licensee shall not assign, under-let or
otherwise dispose of or admit any person to participate in the benefits of the
licence.

II. Messages
(1) (a) Radio communications may be exchanged with other stations similarly
authorized. The amateur stations are forbidden to communicate with amateur
stations of countries whose administrations have notified the International
Telecommunication Union of their objection to such radio communication.
(b) Transmissions shall be made in plain language and limited to messages of a
technical nature relating to tests and to remarks of personal character (excluding
business affairs or transactions) in which the licensee, or the person with whom he
is in communication, are directly concerned and for which, by reason of their
unimportance, recourse to the public telecommunication service is not justified.
(c) Special recordings for reproducing sinusoidal tone or tones within the audio
frequency spectrum that may be either constant or steadily changing in frequency
may be used.
(2) The licensee is forbidden to transmit-

15
(a) Messages like the reproduction of broadcast programmes or tape recordings or
transmissions of entertainment value or music;
(b) False or misleading calls, or signals, news, advertisements, communications of
business, statements on topics of political or industrial controversy;
(c) Superfluous signals or any matter which is indecent or of obscene character or of a
seditious tendency or which is grossly offensive or such as is likely to arouse
racial, religious, or communal animosity; and
(d) Messages for pecuniary reward or any messages for, or on behalf of third parties;
(3) Notwithstanding clause (a), sub-condition (1) and clause (d), sub-condition (2) the
licensees in case of failure of normal telecommunication facilities, are permitted
to handle third party messages, pertaining to natural calamities such as
earthquake, flood, cyclones and wide spread fires, originating from and addressed
to a competent civil authority namely, (a) district magistrates or deputy
commissioners or collectors of the district and (b) any other officer authorized by
authorities mentioned at (a) above. The licensee shall inform by letter addressed
to the licensing authority regarding the use of his amateur station for such
purposes on each such occasion.

III. Frequencies, Emission and Power

The amateur station shall be operated on frequencies that are within the frequency
bands authorized to respective categories of licences under rule 13 and on such
classes of emissions and power not exceeding that specified in the said rule.

IV. Frequency control and measurement

(1) The transmitting apparatus shall be tuned as accurately as possible to ensure that
no energy is radiated on any frequency outside the limits of the authorized
frequency bands.
(2) The licensee shall have at the licensed amateur station a reliable frequency
measuring equipment to verify, each time the frequency of the transmitter is
changed and whenever it is necessary to check the transmitted frequency that
emissions are within the authorized frequency bands. The licensee shall take all
steps necessary to maintain the accuracy of the frequency measuring equipment.

V. Non-Interference
(1) The amateur station shall be so designed, constructed, erected, maintained and
worked as not to cause interference with any wireless telegraph service
functioning, within or without India, in accordance with the provisions of the
convention or the wireless signaling between any fixed, land or mobile stations of
Indian land, naval or air force or between such stations and any station abroad:
Provided that in the event of interference being caused by the station the licensee
shall discontinue or restrict transmissions, pending adjustment of the equipment,
on request from-
(a) The Central Government; or
(b) Any land station.
(2) The licensee shall deploy all necessary means to ensure that the radiated
frequency in free from harmonics, key clicks, hum and other forms of spurious
emissions.
(3) The licensee shall ensure that the transmitter is not over modulated.

16
(4) The use of class B emissions (damped waves) is forbidden.

VI. Log (Diary of the radio service)

(1) A chronological record of all transmissions emanating from or received at the
amateur station shall be kept in bound book (not loose leaf) showing the
following:
(a) Date and time of each transmission;
(b) A summary of the communications exchanged;
(c) A brief description of the experiments and tests undertaken;
(d) The call-sign of station or stations with which messages have been exchanged,
times of establishing and terminating communication with each station and the
frequency and type of emission employed in each case:
(e) Time of opening and closing down the amateur station;
(f) In case of portable or mobile amateur station the particulars of temporary location.
(2) All times in the log shall be stated in the Indian Standard Time.
(3) No gaps shall be left between entries in the long and they shall be made and
initialed at the time of receiving and transmitting.
(4) In case the station is operated by a person other than the licensee (see rule 23), the
licence shall ensure that log is signed by that person indicating his name, call-sign
and licence number.
(5) Licensee shall preserve the log for a period of one year from the date of last entry
therein before it is destroyed:
Provided that no log shall be destroyed for such further period as the Central
Government may direct.
(6) The form of log is shown in the Table attached to these conditions.

VII. Wireless Telegraphy Apparatus

(1) The amateur station shall be equipped for reception as well as transmission except
in the case of Short Wave Listeners Amateur Wireless Telegraph Station Licence
when it shall be equipped for the former only.
(2) The wireless telegraphy apparatus and other accessory equipment used or intended
to be used by the licencee shall be so arranged as not to endanger the safety of
licensee or other persons.
(3) The wireless telegraph apparatus shall be kept in a safe condition and housed in
such manner as to preclude access to unauthorized persons.
(4) The transmitter shall be of a type that has frequency stability comparable to that of
a crystal control.
(5) Meters of standard accuracy shall be installed to measure the D.C. power input to
the anode circuit of the final radio frequency stage of the transmitter.
(6) The aerial used or intended to be used shall be so erected, fixed, or placed a not to
cross above or fall on to any power, telegraph or telephone line. If required, the
licensee shall take necessary steps to guard, to the satisfaction of the owner or
owners concerned, so as to prevent any damage being done in the event of a break
occurring in the aerial. The aerial installation shall not cause hazard to flight of
aircraft and their heights shall be within the limits specified by the Director
General of Civil Aviation in India from time to time. The licensee shall, if so
directed, install and maintain beacon lights on and paint the mast of the station at
his own cost.

17
VIII. Secrecy of Correspondence
If any message which the licensee is not entitled to receive is, nevertheless received,
the licencee shall not make known or allow to be made known its contents, its origin
or destination, its existence or the fact of its receipt to any person (Other than duly
authorized officer of the Central Government or a competent of legal tribunal) and
shall not reproduce in writing, copy or make any use of such message or allow the
same to be reproduced in writing, copied or made use of.

IX. (1) General Radiotelegraph and Radiotelephone Procedure

(a) Before transmitting, the station shall take precautions to ensure that its emissions
will not interfere with transmissions already in progress. If such interference is
likely the transmission shall not commence till there is an appropriate break in the
communications in progress.
(b) The call sign endorsed in the licence shall be sent for identification at the
beginning and at the end of each period of transmission. When the period of
transmission exceeds 10 minutes the call sign shall be repeated. Licencee shall not
make transmission without identification or with false identification.
(c) Prolonged calls and transmissions shall be avoided.
(d) When it is necessary to spell out call sign, certain expressions, difficult words,
abbreviations, figures etc., the phonetic alphabet and figure code given in the
Convention shall be used.
(2) Call and Reply Procedure
(a) The call shall consist of The call sign of the station called not more than three
times; The word DE (in case of radiotelegraphy) and the words ‘This is’ (in case
of radiotelephony) and the call sign of the calling station, not more than three
times.
(b) The reply to call shall consist of the call sign of the calling station, not more than
three times; The word DE (in case of a radiotelegraphy) and the words ‘This is’
(in case of radiotelephony) the call sign of the station called, not more than three
times.
(c) The call may be sent three times at intervals of two minutes; thereafter it shall not
be repeated until an interval of 10 minutes during which the operator shall list in
the frequency band in which the call has been made.
(d) In case of general call to all stations the signal ‘CQ’ (in case of radiotelegraphy)
and the words ‘Hello all stations’ or the signal ‘CQ’ (in case of radiotelephony)
shall replace the call sign of the station called in the calling procedure.

(3) End of Transmission and Work

(a) Transmissions of a message shall be terminated by the signal AR (in case of radio,
telegraphy) and by the word ‘Over’ (in case of radiotelephony).
(b) The end of work between two stations shall be indicated by each of them by
means of the signal VA (in case of radiotelegraph) and by the word ‘OUT’ (or VA
spoken as Victor Alfa) in case of radiotelephony.
(4) Tests:

18
(a) When it is necessary to make test signals either for the adjustment of a transmitter
or a receiver or for any experiment, such signals shall not be continued for more
than 3 seconds and shall be composed of series of VVV followed by the call-sign
of the station emitting the test signals. In case of radiotelephony series of VVV
shall be replaced by the figures 1,2,3,4... spoken in the figure code.
(b) For tests exceeding 30 seconds an artificial aerial shall be used.
(c) Emission of carrier wave is forbidden unless such wave is subjected to intelligible
modulation.

X. Inspection
(1) Any officer authorized by the Central Government in that behalf in writing by
them, may at all reasonable times enter the station solely or jointly with any other
person or persons for the purpose of inspecting and may inspect, examine or test
any apparatus conduct of such inspections and tests and make available the
licence, the station log or other records for examination by the inspecting officer.
(2) The licencee when called upon to do so by the Central Government shall arrange
to forward the licence, the logbook, or any other record or date for examination by
that Government.

XI. Powers to take possession of the Amateur Station and to order interception
of message:
(1) On the occurrence of any public emergency, or in the interest of the public safety,
the Central Government or a State Government or any officer specially authorized
in this behalf by the Central Government or a State Government may, if satisfied
that it is necessary or expedient so to do, take temporary possession (for so long as
the public emergency exists or the interest of the public safety requires the taking
of such action) of the Amateur Station.
(2) On the occurrence of any public emergency or in the interest of the public safety,
the central government or a State Government or any officer specifically
authorized in this behalf by the Central Government or a State Government may,
if satisfied that it is necessary or expedient so to do in the interests of the
sovereignty and integrity of India, the security of the State, friendly relations with
foreign states or public order or for preventing incitement to the commission of an
offence, for reasons to be recorded in writing, by order, direct that any message of
class of messages relating to any particular subject, shall not be transmitted or
received or shall be intercepted by the station or shall be disclosed to the
Government making the order or an officer thereof mentioned in the disclosed to
the Government making the order or an officer thereof mentioned in the order.
(3) The licencee shall not be entitled to any compensation in respect of the exercise of
the powers conferred by sub condition (1) and (2) of this condition.

XII. The licencee shall indemnify the Central Government against all actions, claims
and demands which may be brought or made by any person, body corporate or
company in respect of any injury arising from any act licenced or permitted by
the licence.
XIII. A copy of the Indian Wireless telegraphs (Amateur Service) Rules, 1978 shall
be kept at the Amateur Station.
Table

19
 [See Condition VI(6)]

Specimen Form of Log

Sl. No. Date Time Frequency Station Station Report Time of Time of QSL Initials
of & Type of Called heard Received Termi- Record Card
Contact Emission by or (RST) nating Experiment & (Sent/
& power worked QSO tests received)
input to (RST) /summary of
final stage communication
(FEP)

Under the above rules, a licence may be granted, subject to certain conditions
to a person, who is a citizen of India and not less than 18 years of age (subject to
relaxation indicated at para 1 below) and who qualifies Amateur Station Operators's
Examination Certificate of Proficiency issued by this Ministry i.e. (I) Radio
Communication operator's General Certificate; (ii) First or Second Class Radio
Telegraph Operator's Certificate; (iii) The holder of a special radio telegraph
Operator's Certificate may also be considered eligible for the award of Grade II
licence.

The following categories of licences are issued:

(The fees for examination are shown alongside)
(i) Advanced Amateur Wireless Telegraph Station Licence Rs. 25/-
(ii) Amateur Wireless Telegraph Station licence Grade I Rs. 20/-
(iii) Amateur Wireless Telegraph Station Licence Grade II Rs. 10/-
(iv) Restricted Amateur Wireless Telegraph Station Licence Rs. 10/-
(v) Shortwave Listener’s Amateur Wireless Telegraph Station Licence Nil

The central government may grant to bonafide experimenters between the

agees of 14 and 18 years, Amateur Wireless Telegraph Station Licenc Grade I and to
those between the ages of 12 and 18 years, Amateur Wireless Telegraph Station
Licence Grade II, Restricted Amateur Wireless Telegraph Station Licence or
Shortwave Listeners Amateur Wireless Telegraph Station Licence.
The examination for the award of various categories of Amateur Wireless
Telegraph Station Licence are held at various Monitoring Stations of this ministry, as
per the syllabus contained in the above mentioned rules. A person desiring to
appear in these examinations should apply on the prescribed application form
(enclosed) to the nearest monitoring station along with the prescribed
examination fee. In no case the application may be forwarded to WPC, Ministry
of Communications, New Delhi.
The examination fee varies from Rs. 10/- to Rs.25/- depending upon the
category of examination. After a decision is taken to grant the licence, an additional
fee of Rs. 25/- to Rs.50/- as the case may be, will be required towards the grant of
licence. The fees are required to be paid in the form of bank draft obtainable
from any branch of the State Bank of India and drawn in favour of Pay &
Accounts Officer (Headquarters), Department of Telecommunications, New
Delhi 110001 (code 7687).

20
 The particulars of the venue and date, etc. of the examination will be
communicated to the candidates by the officer-in-charge of the concerned monitoring
station on receipt of the complete application form with requisite fee.
Following should accompany the application:
1. Nationality Certificate/Character Certificate in the prescribed proforma enclosed.
2. 2 copies of photograph duly signed on front side. The size of the photograph must
be 3x4 cms.
3. Examination fees, in the form of bank draft, of the appropriate amount. The draft
should be obtained from any branch of State bank of India and drawn in favour of
'Pay & Accounts Officer (Headquarters), Department of
Telecommunications'. It should be payable at State Bank of India, New Delhi
Service Branch (Code No. 7687).
4. Result Sheet, duly filled in (in duplicate).
5. Personal particulars (in quadriplicate) in the prescribed proforma.

Annexure-II
APPLICATION FROM AN INDIVIDUAL FOR A LICENCE TO
ESTABLSISH, MAINTAIN AND WORK AN AMATEUR WIRELESS
TELEGRAPH STATION IN INDIA.
(See rules 6 & 8)

1. Name (In Block letters):

..........................................................................................…………………………..
(Last name) (First) (Middle)

2. Father’s/Husband’s Name and address : .................................................................

………….....................................................................................................……….…

3. (a) Address (Present)

.............................................................................................................................…….

.............................................................................................................................……

(b)Address (Permanent)
.......................................................................................................................... ……..

.........................................................................................................................………

4. ( a )Date of Birth ( b )Place of Birth ( c )Nationality (d )Occupation

5. (a) Category of Licence applied for (b) exact location of the Station

6. (a) If you are exempted from appearing in any part of the examination, give details
of your qualifications

21
 (b) If you wish to appear for the qualifying examination, give the preferred centre
and date of examination
Centre Month of Examination

(c) Do you hold any other licence earlier, if so give details

Licence No._____________________Call-sign, if any____________________

(Duly filled in application form should be submitted to the concerned Wireless

Monitoring Station only)

DECLARATION
I hereby solemnly declare that the foregoing facts are true and correct and
nothing is false therein and nothing material has been concealed therefrom. I also
agree that in case any information given by me herein before is found false at a later
date, the licence, if granted, will be cancelled.
I further solemnly give an undertaking that I will not either directly or
indirectly divulge to any person, except when lawful authorized or directed to do so,
the purport of any message which I may transmit or receive by means of any wireless
apparatus operated by me or which may come to my knowledge in connection with
the operation of said apparatus.
I have carefully read and understood the rules contained n the Indian Wireless
Telegraphs (Amateur Service) Rules, 1978 and undertake to abide by them and
observe the conditions of the licence. The licensed station shall not be made
accessible to any unauthorized person at any time.

Signature of witness: Signature of applicant

Name (in block letters) Name (in block letters)

Address:
Date: Date:
Place:

Note :
1. An attested copy of birth certificate or school leaving certificate must be
accompanied along-with the application.
2. Enclose a certificate in support of nationality in the prescribed Performa, indicated
in Appendix III from one of the officers listed therein.

Annexure-III

APPLICATION FOR A LICENCE TO ESTABLISH, MAINTAIN AND WORK

AN AMATEUR WIRELES TELEGRAPH STATION BY AN AMATEUR
RADIO SOCIETY OR CLUB OR A SCHOOL, COLLEGE OR AN
INSTITUTE OR A UNIVERSITY IN INDIA
(See rules 6 & 8)

1. Name and address of the Amateur Radio Society/Club/School/Institute etc.

22
2. Particulars of authorized official of the Society/Club/School etc. in whose favour
licence is desired

Name Designation

Date of Birth Place of Birth Nationality Occupation

3. (a) Category of licence applied for (b) exact location of the station

4. Particulars of Amateur Wireless Telegraph Station Licence held by the authorized

official

Category of Licence Licence No. Date of Issue

5. Particulars of the Amateur Radio Society or club, school etc.

(a) If registered, given its particulars:

(b) In case of school, college or institute, give the name of Board or University by
which it is recognized.

(c) Give in brief its aims and objectives:

(d) If affiliated to any radio amateur organization, give its particulars:

(e) Give the names of office bearers:

(f) Mode of operation of the station including its normal hours of working :

6. Particulars of Apparatus to be used:

Category of Apparatus/ Manufacturer’s name /Type No/ Frequency Range /RF power
output/
Transmitter :
Receiver :
Frequency Measuring Device :

DECLARATION
I hereby solemnly declare that the foregoing facts are true and correct and
nothing is false therein and nothing material has been concealed therefrom. I also
agree that in case any information given by me herein before is found false at a later
date, the licence, if granted, will be cancelled.
I further solemnly give an undertaking that I will not either directly or
indirectly divulge to any person, except when lawful authorized or directed to do so,

23
the purport of any message which I may transmit or receive by means of any wireless
apparatus operated by me or which may come to my knowledge in connection with
the operation of said apparatus.
I have carefully read and understood the rules contained n the Indian Wireless
Telegraphs (Amateur Service) Rules, 1978 and undertake to abide by them and
observe the conditions of the licence. The licensed station shall not be made
accessible to any unauthorized person at any time.

Signature of witness: Signature

of applicant

Name (in block letters) Name (in block letters)

Address:
Date: Date:
Place:

Note :
1. An attested copy of birth certificate or school leaving certificate must be
accompanied along with the application.
2. Enclose a certificate in support of nationality in the prescribed Performa, indicated
in Appendix III from one of the officers listed therein.
3. Attach a copy of the rules and regulations or constitution.
4. Attach the minutes of the relevant meeting.

PERSONAL DETAILS OF THE APPLICANT

(To be submitted with three extra copies on separate sheet)
1.Full Name (In Block letters): ___________________________________
2.Date & Place of Birth: ___________________________________
3. Age: ______ Years_______Months.
4. Height: ___________cm
5. Colour of: (i)Eyes_________(ii)Hair______________
6. Complexion: ___________________________________

24
7. Any special peculiarities of mark: ___________________________________
8. Present Address: ___________________________________
___________________________________
9. Permanent home address: ___________________________________
___________________________________
10. Nationality: ___________________________________
11. Occupation (Major work ___________________________________
or profession for which you ___________________________________
receive money or activity ___________________________________
which occupies the ___________________________________
majority of your time)
12. Father's name and home address ___________________________________
(if dead, give last address)Aliases ___________________________________
if any: ___________________________________
13. Type of license applied for: ___________________________________
14. Proposed location of station: ___________________________________
(Details of house No., Street ___________________________________
No., Road No.) ___________________________________
Dated:____________
Signature of the applicant
(Full name giving expansion of initials)

NATIONALITY CERTIFICATE

Certified that I have known Shri/Smt./Km. __________________________________,

Son/Daughter of Shri_________________________for the last__________________
Years and that to the best of my knowledge and belief he/she bears a good moral
character. He/She is of _______________nationality.
He/She is not related to me.
Address: Signature

NOTE:
This certificate should be from one of the officers listed below:
1. Gazetted Officers of Central or State Governments.

25
2. Members of Parliament or State Legislatures.
3. Sub-divisional Magistrate/Officer.
4. Tehsildars or Naib/Deputy Tehsildars, authorized to exercise magisterial powers.

ANNEXURE IV
[See rule 9]
Licence No.
GOVERNMENT OF INDIA
MINISTRY OF COMMUNICAITON

LICENCE TO ESTABLISH, MAINTAIN AND WORK AN AMATEUR

WIRELESS TELEGRAPH STATION IN INDIA.

Having satisfied, by examination or otherwise, that Shri ....................................

possesses the requisite technical qualifications as prescribed under the Indian,
Wireless Telegraphs (Amateur Service) Rules, 1978, the Central Government in
exercise of the powers conferred under the authority of section 4 of the Indian
Telegraph Act, 1885 (13 of 1885), hereby grant to him an
................................................... to establish, maintain and work a wireless telegraph
transmitting and receiving station, detailed below, during the term of period
commencing on the day of the date hereof and terminating on the .......................19
................. when this licence becomes invalid unless renewed further by way of a
document showing the renewal of Licence.
The licence is governed by the Indian Wireless Telegraphs (Amateur Service) Rules,
1978, Particulars of the Station :
Location: Call-sign:
Issued by the Government of India in the
Ministry of Communication
New Delhi :
Dated :
Deputy/Assistant Wireless
Adviser to the Govt. of India
in the presence of ............................. Date ....................................
Signature of Licencee
Date ...........................

Latest amendment to the Indian Wireless Telegraph (Amateur Service) Rules,

1978, vide Notification dated 4th October, 1985.

In pursuance of the provisions of rule 13 of the Indian Wireless Telegraph (Amateur

Service) Rules, 1978 the Central Government hereby authorises the following
frequency bands, emission and power to the holder of Amateur Wireless Telegraph
Station Licence. This supercedes the frequency bands, emission and power prescribed
in the Annexure-V to the above said rules in pursuance to Notification No, R-
11014/14/82-L.R. dated 23rd May, 1983.

ANNEXURE V

Frequency bands, emission and power

26
Category of Frequency bands Emission Maximum D.C.
Licence input power
unless otherwise
specified
(a) Restricted 144-146 MHz A3E, H3E, J3E, 10 Watts
Amateur 434-438 @ R3E, F3E (terrestrial service
Wireless only authorised)
Telegraph
Station
Licence. See
Note (v) below.
(b) Amateur 1820-1860 kHz* A1A, A3E, H3E, 50 Watts
Wireless 3500-3700 kHz J3E, R3E
Telegraph 3890-3900 kHz
Station Licence 7000-7100 kHz
Grade II. See 14000-14350 kHz
Note (vi) below. 18068-18168 kHz $
21000-21450 kHz
24890-24990 kHz $
28000-29700 kHz
144-146 MHz A1A, A2A, A3E, 10 Watts
434-438 MHz @ H3E, R3E, J3E, (terrestrial service
F1B, F2A, F3E only authorised)
(c) Amateur 1820-1860 kHz* A1A, A2A, A3E, 150 Watts
Wireless 3500-3700 kHz H3E, R3E, J3E,
Telegraph 3890-3900 kHz F1B, F2A, F3E,
Station Licence 7000-7100 kHz F3C, A3C, A3F
Grade I. See 14000-14350 kHz
Note (vi) below. 18068-18168 kHz $
21000-21450 kHz
24890-24990 kHz $
28000-29700 kHz
144-146 MHz 25 Watts for
434-438 MHz @ terrestrial service.
1260-1300 MHz @ & Amateur Satellite
3300-3400 MHz Service is
@5725-5840 MHz @ permitted in the
appropriate sub-
bands in
accordance with
Radio Regulations
and in those cases
the maximum
output RF power
(e.i.r.p.) is 30 dbw.
Category of Frequency bands Emission Maximum D.C.
Licence input power
unless otherwise

27
 specified
(d) Advanced 1820-1860 kHz* A1A, A2A, A3E, 150 Watts
Amateur 3500-3700 kHz H3E, R3E, J3E,
Telegraph 3890-3900 kHz F1B, F2A, F3E,
Station 7000-7100 kHz F3C, A3C, A3F
Licence. 14000-14350 kHz
See Note (i) 18068-18168 kHz $
below 21000-21450 kHz
24890-24990 kHz $
28000-29700 kHz
144-146 MHz 50 Watts for
434-438 MHz @ terrestrial service.
1260-1300 MHz @ & Amateur Satellite
3300-3400 MHz @ Service is
5725-5840 MHz @ permitted in the
appropriate sub-
bands in
accordance with
Radio Regulations
and in those cases
the maximum
output RF power
(e.i.r.p.) is 30 dbw.

* On primary shared basis as per the relevant provisions of Radio Regulations.

$ The authorisation is on non-interference and non-protection basis.
@ On secondary basis as per the relevant provisions of Radio Regulations.
& 1260-1270 MHz for Earth to space satellite service only.

The above authorisation is subject to site clearance as per the procedure prescribed by
the Standing Advisory Committee on Radio Frequency Allocation (SACFA) as
applicable.

Note: (i) Following sub-bands of frequencies are authorised with enhanced R.F.
power to holder of Advanced Amateur Telegraph Station Licence

3520-3540 kHz All emissions 400 Watts

3890-3900 kHz as authorised
7050-7100 kHz
14050-14150 kHz
14220-14320 kHz
21100-21400 kHz

(ii) For A3F emission, the transmission shall be restricted to call-sign of the station,
location and other particular of the amateur station. They shall be limited to
point to point test transmission employing a standard interlace and scanning
with a bandwidth not more than 4 kHz.

28
(iii) DC input power is the total direct current power input to the final stage of the
transmitter.
(iv) In case of Short Wave Listener’s Amateur Licence, the holders are permitted to
listen to all the bands authorised to Amateur Service.
(v) The syllabus for the examination of the Restricted Amateur Wireless Telegraph
Station Licence shall be same as per Part I of Amateur Station Operator’s Grade
II examination.
(vi) The holder of Amateur Wireless Telegraph Station Licence, Grade II shall be
entitled for authorisation of radio telephony emission on his providing proof of
having made 100 contacts with other amateur stations using CW (Morse Code).

D. Syllabus of Amateur Station Operator's Certificate (ASOC)

Examination for the award of Amateur Station Operator's
Licence

The ham radio licensing examination is conducted to ascertain that the person going
to be a ham radio operator is equipped with the knowledge and proficiency which is
necessary to communicate using a wireless transceiver without causing interference to
the other radio communication services. The course covers basic electronics and radio
theories as well as the existing national and international rules related to amateur
radio communication in radiotelephony (voice) and radio telegraphy (Morse Code).
The person who wants to become a ham should at the same time be able to show his
proficiency in Morse Code sending and receiving. The examination is conducted at
the 22 Wireless Monitoring Stations (Annexure-I) located throughout the country.
The examination is held for four different categories of licence. They are the :

(1) Advanced Grade Licence

(2) Grade I Licence
(3) Grade II Licence
(4) Restricted Grade Licence.

Anyone above 12 years of age can obtain Amateur Radio Station Operator’s
Licence after passing the examination/s mentioned above. It is also possible to
establish an Amateur Radio Club Station with a licensed ham in charge of it.
The application form for Amateur Radio Station Operator's Certificate
Examination can be obtained from :
The Assistant Wireless Advisor to the Govt. of India,
Wireless Planning & Coordination (WPC) Wing, Amateur Radio Section,
Ministry of Communications, Dak Bhavan,
Parliament Street, New Delhi-110001

The application form can also be obtained from the Wireless Monitoring Station of
the Ministry of Communications located nearest to your hometown. The filled-in
Application Form along with all other necessary documents should be sent to the
Wireless Monitoring Station located nearest to your home town or where you
wish to appear for the examination.

29
 Syllabus

Part-I
Section I
Radio Theory and Practice (Applicants holding degree in telecommunication, or
electronics and electrical communication, or a degree recognized by the central
government as equivalent to the above degree shall be exempted from appearing
in SECTION I of the test).

Section II
National and International regulations applicable to the operation of amateur radio
station and those relating to the working of station generally.

Part II - Morse Code

Section I
Morse code receiving.

Section II
Morse code sending.

Detailed Syllabus

Amateur Radio Operator’s Grade I & II Certificate Examination

Part-I

Section I : Radio Theory and Practice

Elementary electricity and magnetism

Elementary theory of electricity, conductors and insulators, units, Ohm's law,
resistance in-series and parallel, conductance, power and energy, permanent magnets
and electromagnets and their use in radio work; self and mutual inductance; types of
inductors used in receiving and transmitting circuits, capacitance; construction of
various types of capacitors and their arrangements in series and/or parallel.

Elementary theory of alternating currents

Sinusoidal alternating quantities-peak, instantaneous, RMS, average values, phase;
reactance, impedance; series and parallel circuits containing resistance, inductance,
capacitance; power factor, resonance in series and parallel circuits; coupled circuits;
transformers for audio and radio frequencies.

Thermionic valves
Construction of valves; thermionic emission, characteristic curves, diodes, triodes and
multi-electrode valves; use of valves as rectifiers, oscillators, amplifiers, detectors and
frequency changers, power packs, stabilization and smoothing.

30
Elementary theory and construction of semiconductor devices
Diodes and Transistors.

Radio receivers
Principles and operation of TRF and super-heterodyne receivers, CW reception,
receiver characteristics-sensitivity, selectivity, fidelity; adjacent channel and image
interference; AVC and squelch circuits; signal to noise ratio.

Transmitter
Principles and operation of low power transmitter; crystal oscillators, stability of
oscillators.

Radio propagation
Wavelength, frequency, nature and propagation of radio waves; ground and sky
waves; skip distance; fading.

Aerials
Common types of transmitting and receiving aerials.

Frequency measurement
Measurement of frequency and use of simple frequency meters.

SECTION II : Radio Regulations

(a) Knowledge of :
(i) the Indian Wireless Telegraph Rules, 1973; and
(ii) the Indian Wireless Telegraphs (Amateur Service) Rules, 1978.
(b) Knowledge of International Radio Regulations as relating to the operation of
amateur stations with particular emphasis on the following:
Designation of Emission,
Nomenclature of the frequency and wavelength,
Frequency allocation to amateur radio service,
Measures against Interference,
Interference and tests, Identification of stations,
distress and urgency transmissions,
Amateur Stations,
Phonetic alphabets and figure code.

(c) Standard frequency and time signal services in the world.

(d) The following 'Q' codes and abbreviations which shall have meaning as assigned
to them in the International Telecommunication Union (ITU) convention :

QRA, QRG, QRH, QRI, QRK, QRL, QRM, QRN, QRQ, QRS, QRT, QRU, QRV,
QRW, QRX, QRZ, QSA, QSB, QSL, QSL, QSO, QSU, QSV, QSW, QSX, QSY,
QSZ, QTC, QTH, QTR and QUM.

31
Telegraphic (Morse code) abbreviations: AA, AB, AR, AS, BT, C, CFM, CL, CQ,
DE, K, KN, NIL, OK, R, TU, VA, WA, WB.

The written examination for Grade II licence is of one hours duration. The
maximum number of marks is 100. Candidates must secure at least 40 per cent in
each section and 50 per cent in aggregate to pass. The syllabus for Grade I licence
is the same as that for Grade II licence, but the written examination for Grade I
licence is of two hours duration. The maximum number of marks is 100 and
candidates must secure at least 50 per cent in each section and 55 per cent in
aggregate for a pass.

Part II : Morse Code

(a) Section I : Morse Receiving (Speed: 5 words per minute)

The test piece will consist of a plain language passage of 125 letters, five letters
counting as one word. Candidates are required to receive for five consecutive minutes
at the speed of 5 words per minute from a double headgear headphone receiver,
international Morse code signals from an audio frequency oscillator keyed either
manually or automatically. A short practice piece may be sent at the prescribed speed
before the start of the actual test. Candidates will not be allowed more than one
attempt in each test. The test may be written in ink or pencil but must be legible. Bad
handwriting and over-writing will render a candidate liable to disqualification. More
than five errors will disqualify a candidate.

(b) Section II : Morse Sending (Speed: 5 words per minute)

The test piece will consist of a plain language passage of 125 letters, five letters
counting as one word. Candidates are required to send on an ordinary key for five
consecutive minutes at the minimum speed of five words per minute. A short practice
piece may be allowed before the actual test. Candidates will not be allowed more than
one attempt in the test. Efforts should be made to correct all errors. However, more
than five uncorrected errors will disqualify a candidate. The accuracy of signaling,
correct formation of characters and the correctness of spacing shall be taken into
account.
A candidate is required to pass both in Part I and Part II. In the case of
candidates qualifying in Part I only, the licence shall be restricted to radiotelephone
operations in the VHF ham band only.

Morse Code test for Grade I

Receiving-(Speed: 12 words per minute)

The test piece will consist of a plain language passage of 300 characters which may
comprise letters, figures and punctuation (punctuation are indicated below). The
average words shall contain five characters and each figure and punctuation will be
counted as two characters. Candidates are required to receive for five consecutive

32
minutes at a speed of 12 words per minute. Other conditions are the same as
applicable to Grade II Examination.

Punctuations
Full stop, Comma, Semi-colon, Break sign (BT), Hyphen and Question mark.

Sending-(Speed: 12 words per minute)

The test piece will be similar to Morse receiving test. Candidates are required to send
for five consecutive minutes at a speed not less than 12 words per minute. Other
conditions are the same as applicable to Grade II examination.

A candidate is required to pass both in Part I and Part II simultaneously.

Advanced Amateur Station Operators' Examination

Part I-Written Test

(a) Section 1: Radio Theory and Practice

In addition to the syllabus prescribed for Grade II Examination, following items shall
be included in the syllabus of Advanced Amateur Station Operators' Examinations :-
(i) Motors and generators: Elementary principles and construction of alternators,
motors and generators.
(ii) Alternating current: Construction of transformers, transformer losses,
transformer as a matching device.
(iii) Measuring instruments: Moving coil and moving iron meters, frequency
meters.
(iv) Semiconductor devices and transistors: Elementary principles of conduction
and construction, symbols, biasing methods.
(v) Power supplies: Half-wave and full-wave rectifiers, smoothing and regulation,
bridge rectifier.
(vi) Modulation: Principles of frequency modulation.
(vii) Transmitters and receivers: Elementary principles of transmission and
reception of facsimile and television signals, elementary principles of transmitters
and receivers employing single side band.
(viii) Propagation: Characteristics of ionosphere and troposphere. Properties of
different reflecting layers, optimum working frequency, day and night
frequencies.
(ix) Aerials: Principles of radiation, aerials for different frequency bands including
aerials for microwave.
(x) Space communications: Elementary principles of communication via satellite.

33
(b) Section 2: Radio Regulations

Syllabus is same as prescribed for Grade II Examination. The test is of 3 hours

duration. The maximum number of marks is 100 and candidate must secure at least 50
per cent in each section and 60 per cent in aggregate for a pass.

Part II- Morse Code

Syllabus is same as prescribed for Grade I Examination.

E. Question and Answer Section on Amateur Radio Rules &

Regulations

Q. What do you mean by 'Amateur Radio Service'?

'Amateur Radio Service' is a two-way radio communication service available to

persons who are licensed by the communication authority to carry out
experimentation in the field of radio communication techniques. The Indian Wireless
Telegraphs (Amateur Service) Rules 1978 defines 'Amateur Service' as "a service of
self training, inter-communication and technical investigations carried on by
amateurs that is, by persons duly authorised under these rules interested in radio
technique solely with a personal aim and without pecuniary interest".

Q. What types of messages are forbidden to be transmitted from an

amateur radio station?

A ham radio operator is allowed to transmit in plain language (Morse Code, RTTY,
Packet radio etc. included) and his message shall be of a technical nature related to
tests, remarks of personal character which are not related to business affairs or
transactions. He is forbidden to transmit:
(i) Messages like the reproduction of broadcast programmes or tape recordings or
transmissions of entertainment value or music.
(ii) False or misleading calls, or signals, news, advertisements, communications of
business, statements on topics of political or industrial controversy.
(iii) Superfluous signals or any matter which is indecent or of obscene character or
of a seditious tendency or which is grossly offensive or such as is likely to
arouse racial, religious, or communal animosity; and
(iv) Messages for pecuniary reward or any messages for, or on behalf of third
parties (i.e. non-amateurs).

Q. Is third party communication allowed in India in 'Amateur Radio

Service'?

Third party messages originating from a non-amateur or meant for a non-amateur are
not allowed in India, except in case of failure of normal telecommunication facilities

34
during earthquake, flood, cyclones, widespread fires or during any other disasters.
Under such circumstances, a ham radio operator can handle third party messages
pertaining to disasters. Such messages should originate from or addressed to a
competent civil authority namely, (a) district magistrates or deputy commissioners or
collectors of the district and (b) any other officer authorized by the authorities
mentioned at (a) above.

Q. What is 'Secrecy of Correspondence'?

If any message which the ham radio operator is not entitled to receive is, nevertheless
received, the ham radio operator shall not make known or allow to be known its
contents, its origin or destination, its existence or the fact of its receipt to any person
(other than duly authorized officer of the central government or a competent legal
tribunal) and shall not reproduce in writing, copy or make any use of such message or
allow the same to be reproduced in writing, copied or made use of.

Q. What is a 'Ham Radio Net'?

A ham radio net is a voluntary radio communication network formed under the
initiative of a few hams which is maintained at scheduled time/times of the day
(everyday or at scheduled days). The heart of the net is the 'net controller', who takes
messages from the hams joining the net and pass it on to its respective destination.
Different nets may have different objectives. For example 'Air NET India' is the
National Emergency Traffic (NET) net run by the Amateur Radio Society of India
(ARSI). This net is conducted everyday from 7:00 PM or 7:30 PM on 14.150 MHz ±
QRM to handle any emergency medical traffic, other emergency traffic and to check
the radio wave propagation condition. But one of the main objectives of this net is to
provide the facility to the Indian hams to establish contact between two hams. A ham
'X' can pass on the request to the 'net controller' regarding his willingness to contact a
ham 'Y'. The 'net controller' then helps both the station to make the contact on a
mutually decided frequency. So every active hams should have the habit of checking
into this kind of net regularly.

Q. What is a distress call?

A distress call is a call given from a ship, aircraft or vehicle indicating that the caller
is threatened by grave and imminent danger, which requires immediate assistance. In
radiotelephony transmission, the distress signal consists of the word MAYDAY
(pronounced as the French expression 'm'aider') spoken three times followed by the
words THIS IS and the identification of the station seeking assistance. A distress
message should be followed by the distress call.
It contains name of the ship, aircraft or vehicle, position, type of distress and
the type of assistance asked for including any other relevant information to facilitate
rescue operation.
In radiotelegraphy, the distress signal consists of the letters SOS sent in
Morse Code characters . . . _ _ _ . . . (SOS). All these characters should be
transmitted three times as a single signal where dashes are to be emphasized to enable
distinguish them clearly from the dots. A typical distress message may look like: S0S

35
SOS SOS CQ CQ CQ DE followed by the call-sign. When the distress traffic is
over, the distress station should end its transmission with the Q-Code. It looks like:
SOS CQ CQ CQ DE 'call-sign' QUM SK.

Q. What action should you take if you receive a distress call?

The distress call has absolute priority over all other transmissions. Hence it would be
your utmost duty to
- listen to the distress call and stop your transmissions if you were previously
occupying that frequency;
- acknowledge receipt of the distress message if the station in distress can copy
your signal.
- At the same time, it would be your duty to ensure that your transmission does not
interfere with transmissions of other stations, which may be better situated to
render assistance.
- Even if you cannot render assistance, you should direct the attention of other
stations in the nearby frequencies, because they might be in a position to render
immediate assistance.
- You shall also try to inform the appropriate authorities, who might be able to
conduct a rescue operation.

Q. What is an 'Urgency Signal'?

Urgency signal is a wireless message which indicates that the calling station has a
vary urgent message to transmit concerning the safety of a ship/vehicle or that of a
person but the message cannot be ranked as distress message. Obviously, the
urgency signal should be given priority over all other transmissions except
distress call.
In radio telephony, the word PAN is repeated three times pronouncing it as
the French word 'panne'. Other procedures to be followed in this type of traffic is
same as that in distress traffic.
In radio telegraphy, the urgency signal consists of the group XXX ( _ . . _ _
. . _ _ . . _ ) sent slowly three times. Letters of each group should be clearly
separated from each other. The urgency signal transmitted by a ship can be addressed
to a specific station. However, a coast station can transmit its urgency signal to all the
ship stations after the approval of a responsible authority.

Q. What is a 'Safety Signal'?

A safety signal is a message concerned with the safety of ships/vehicles indicating a

meteorological warning (e.g. storm), danger to navigation warning or other
navigational-aid message. Safety Signal is an important message because a delay in
its transmission or reception can bring a disaster.
In radio telephony, safety signal consists of the word 'SECURITY'
pronounced as 'say-cure-ity'.

36
 In radio telegraphy, it consists of the three repetitions of the group TTT ( _ _
_ ) sent slowly followed by the station call-sign. Letters of each successive group
should be clearly separated from each other.

Q.What do you understand by the word 'phonetics' in amateur radio

communication?

If we listen to a two-way amateur wireless conversation for the first time in our life,
we would come across certain words, which perhaps we never heard before! There is
every possibility that we mistake these words for some kind of secret codes! These
words in fact are internationally used for plain language (conversation in secret code
language is not allowed in amateur radio communication) conversation and are
known as phonetics.
A ham radio operator has to face different types of hurdles during an ongoing
communication. There may be static noise, signal fading, interference from other
station operating at close frequencies, local noises in the radio room, unusual voice
accents of the other operator, improper pronunciation of words etc.. During these and
many other difficulties, it has been found that use of phonetics improves the
intelligibility in communication. For example, the letter 'D' is represented by the
word 'Delta' in phonetics while the letter 'B' is represented by 'Bravo'. To
distinguish 'M' from 'N', hams use the words 'Mike' and 'November' respectively.
Phonetic alphabet is useful when calling distant station or when the band is
crowded, or when for any reason the station called is expected to have difficulty in
copying voice signals. For example, the word 'Solstice' can be spelt using phonetic
alphabet as Sierra Oscar Lima Sierra Tango India Charlie Echo. A person
conversant in listening to such phonetics gets habituated in spontaneously writing
down the exact word out of these phonetics! He feels more comfortable at writing
down a message spelt out in phonetics rather than simple mentioning of each letters.
Phonetics are to avoid confusion and not to create confusion! Many letters of
the alphabet sound similar unless very clearly heard. B may be heard as G or D or V.
The word 'bed' may be heard as 'bet' or 'pet'. So, if we spell it out with phonetics like
Bravo Echo Delta, the confusion easily gets eliminated! Good operating procedures
include using the standard phonetic alphabet to help communicate more clearly. The
recommended phonetics are those prescribed by the International Radio Regulations.
The numbers are spelled differently to suggest a particular pronunciation. Also, nine
was changed to "niner" to avoid confusion with the German word "nein" for "no".
When first making contact with another Ham, it is a good idea to say call signs in
phonetics to give the other side a better chance of understanding them correctly.

Phonetics used by amateur radio operators

Letter Word used as phonetics Spoken as

A Alpha AL FAH
B Bravo BRAH VOH
C Charlie CHAR LEE
D Delta DELL TAH

37
 E Echo ECK OH
F Foxtrot FOKS TROT
G Golf GOLF
H Hotel HOH TELL
I India IN DEE AH
J Juliet JEW LEE ETT
K Kilo KEY LOH
L Lima LEE MAH
M Mike MIKE
N November NO VEM BER
O Oscar OSS CAH
P Papa PAH PAH
Q Quebec KEH BECK
R Romeo ROW ME OH
S Sierra SEE AIR RAH
T Tango TAN GO
U Uniform YOU NEE FORM
V Victor VIK TAH
W Whiskey WISS KEY
X X-ray ECKS RAY
Y Yankee YANK KEY
Z Zulu ZOO LOO

Phonetics used against figures or marks

Figure or mark Word used as phonetics Spoken as

0 NADAZERO NAH-DAH-ZAY-ROH
1 UNAONE OO-NAH-WUN
2 BASSOTWO BESS-SOH-TOO
3 TERRATHREE TAY-RAH-TREE
4 KARTEFOUR KAY-TAY-FOWER
5 PANTAFIVE PAN-TAH-FIVE
6 SOXISIX SOK-SEE-SIX
7 SETTENSEVEN SAY-TAY-SEVEN
8 OKTOEIGHT OK-TOH-AIT
9 NOVENINE N0-VAY-NINER
Decimal point DECIMAL DAY-SEE-MAL
Full stop STOP STOP
Q. What are Q-codes?

A 'Q-code' consists of three letters starting with the letter 'Q'. Q-codes are devised to
facilitate faster communication in Morse code. Instead of sending a long sentence, the
amateur radio operator can just send a combination of three letters to represent a long
sentence. If the amateur radio operator asks something to his fellow operator, then the
Q-code is followed by a question mark. If the Q-code is used to represent a statement
(not a question), then it is not ended with a question mark. For example, if you want
to ask your friend on the air whether he is busy (Are you busy?), the Q-code will be
'QRL?'. If you want to say that you are busy, send 'QRL'. There are nearly 100 Q-
Codes used by the marine radio operators. We have mentioned below the Q-codes

38
required to be learnt by an amateur radio operator. Q-codes are very often used during
the voice communication also.

QRA? What is the name of your station?

QRA The name of my station is ……..
QRG? Will you tell me my exact frequency (or, that of ……)?
QRG Your exact frequency (or, that of …..) is ….kHz (or MHz).
QRH? Does my frequency vary?
QRH Your frequency varies.
QRI? How is the tone of my transmission?
QRI The tone of your transmission is: (1) Good. (2) Variable. (3) Bad.
QRK? What is the readability of my signals (or, those of….)?
QRK Readability is: (1) Unreadable. (2) Readable now and then. (3) Readable with
difficulty. (4) Readable. (5) Perfectly readable.
QRL? Are you busy?
QRL I am busy (or, busy with …….). Please do not interfere.
QRM? Are you being interfered with?
QRM I am being interfered with.
QRN? Are you troubled by static noise?
QRN I am troubled by static noise.
QRQ? Shall I send faster?
QRQ Send faster (…. wpm)
QRS? Shall I send more slowly?
QRS Send more slowly.
QRT? Shall I stop sending?
QRT Stop sending
QRU? Have you anything for me?
QRU I have nothing for you.
QRV? Are you ready?
QRV I am ready.
QRW? Shall I inform …… that you are calling him on ……kHz?
QRW Please inform ……. That I am calling him on ….. kHz.
QRX? When will you call me again?
QRX I will call you again at ……..hours.
QRZ? Who is calling me?
QRZ You are being called by.
QSA? What is the strength of my signals (or those of ……)?
QSA Your signals are (1) Scarcely perceptible. (2) Weak. (3) Fairly good. (4) Good.
(5) Very good.
QSB? Are my signals fading?
QSB Your signals are fading.
QSL? Can you acknowledge receipt?
QSL I am acknowledging receipt.
QSO? Can you communicate with ….. direct or by relay?
QSO I can communicate with …. Direct or by relay through …….
QSU? Shall I send or reply on this frequency (or, on ….kHz)(with emissions of
class…)?
QSU Send or reply on this frequency (or, on …. KHz) (with emissions of class ….).
QSV? Shall I send a series of 'V's on this frequency (or, …. KHz).

39
QSV Send a series of 'V's on this frequency (or, ……kHz).
QSW? Will you send on this frequency (or, … kHz)(with emissions of class …)?
QSW I am going to send on this frequency (or, …..kHz) (with emissions of class
….).
QSX? Will you listen to ….(call-sign) on …..kHz?
QSX I am listening to … (call-sign) on …..kHz.
QSY? Shall I change my transmission to another frequency?
QSY Change your transmission to another frequency.
QSZ? Shall I send each word or group more than once?
QSZ Send each word or group twice (or, ….. times).
QTC? How many telegrams have you to send?
QTC I have ….. telegrams for you (or, for ……).
QTH? What is your position in latitude and longitude (or, according to any other
indication)
QTH My position is …latitude ……longitude (or, according to any other
indication).
QTR? What is the correct time?
QTR The correct time is …..hours.
QUM? Is the distress traffic ended?
QUM The distress traffic is ended.

Q. What are the designation of emissions allotted to amateur radio

service?

The most common designation of emissions, which are allotted to hams, are:
A1A : Continuous Wave (CW) Double side-band telegraphy for aural reception which
contains quantized digital information without the use of modulating sub-carrier.
(allotted to Grade II , Grade I and Advanced Grade Licence holders)
A2A: Continuous Wave (CW) Double side-band telegraphy for aural reception,
which contains quantized digital information with the use of modulating
subcarrier.
A3E: Double side-band single channel analog transmission containing telephony
(including sound broadcasting). Commonly known as AM (Amplitude
Modulation).
H3E: Single side band, full carrier single channel analog transmission containing
telephony (including sound broadcasting).
J3E: Single side band, suppressed carrier single channel analog transmission
containing telephony (including sound broadcasting).
R3E: Single side band, reduced or variable-level carrier single channel analog
transmission containing telephony (including sound broadcasting).
F3E: Frequency modulated single channel analog transmission containing telephony
(including sound broadcasting).
F1B: Frequency modulated single channel telegraphy transmission containing
quantized digital information for automatic reception.
F2A: Frequency modulated single channel telegraphy transmission containing
quantized digital information for aural reception.

40
F2B: Frequency modulated single channel telegraphy transmission containing
quantized digital information with modulating sub-carrier for automatic
reception.
F3C: Frequency modulated single channel analog facsimile transmission.
A3C: Amplitude modulated double side-band single channel analog facsimile
transmission.
A3F: Amplitude modulated double side-band single channel analog video
transmission.
Each letter/digit of the designation of emission represent independent meaning
as assigned to them.

Q. What are the frequencies allotted to a Grade-I licence holder in India?

How much power is allowed to a Grade-I licence holder?

The radio frequencies allotted to a Grade-I licence holder in India are:

Short wave/High Frequencies (HF) : VHF/UHF/SHF:
1820-1860 kHz 144-146 MHz
3500-3700 kHz 434-438 MHz
3890-3900 kHz 1260-1300 MHz
7000-7100 kHz 3300-3400 MHz
14000-14350 kHz 5725-5840 MHz
18068-18168 kHz
21000-21450 kHz
24890-24990 kHz
28000-29700 kHz

In India, a Grade-I licence holder is allowed to use 150 watts in the HF bands
and 25 watts in the VHF/UHF bands.

F. Radio Telephony Operating Procedure

Once you get your ham radio licence and the call-sign, it is time for you to start
transmission. Radio waves are now-a-days a precious commodity and so the ham
should not misuse them for his/her own ends. It is the duty of the ham to know the
correct operating procedure. If a newly licensed ham radio operator is ignorant about
the correct operating procedures, he may create nuisance in the band. A ham should
also be aware about the International Operating Code devised by Paul M. Segal.

Code for a ham radio operator

1. The ham is considerate. He/she never knowingly uses the air (radio waves) in
such a way as to lessen the pleasure of others.
2. The ham is loyal. He/she offers his/her loyality, encouragement and support to
his/her fellow hams, his/her local clubs.
3. The ham is progressive. He/she keeps his/her station (radio equipment) abreast of
science. It is well-built and efficient. His/her operating practice is above reproach.

41
4. The ham is friendly. Slow and patient sending when requested, friendly advice
and councel to the beginner, kindly assistance, co-operation and consideration for
the interests of other; these are the mark of the ham spirit.
5. The ham is balanced. Radio is his/her hobby. He/she never allows it to interfere
with any of his/her duties he/she owes to his/her home, his/her job, his/her school
or community-and lastly his/her knowledge and his/her radio station are always
ready for the service of his/her country and his/her community.

Calling another station

A call may be given to another station either in voice or using the Morse code. But
before giving a call, it is the duty of the ham to check whether the frequency he/she is
going to use is already in use by other ham/s or not. Even though a particular
frequency seems to be idle, it may not be so. Because, there may still be a ham
sending his message whose signals are in skip with us (see questions & answers
related to radio wave propagation) and another ham at a different location is listening
to him. Giving a transmission in the same frequency in such a situation may interfere
with the ongoing communication. So, prior to transmission, it should be ascertained
by sending the message-“Is the frequency in use?”. This should be repeated two more
times and if no reply is received, we can occupy the frequency. After occupying a
frequency, we can give a ‘General Call’ or a ‘Directional Call’. A ‘General Call’ is
a call given to all the stations. This means that you will reply to anybody from any
part of the world. The message sounds like –“CQ CQ CQ this is Victor Uniform
Two…. (your call-sign suffix in phonetics) calling CQ on 20 metre and standing
by”. The ‘CQ’ message may be repeated for three time before giving the ‘standing
by’ message. As you ‘stand by’, listen carefully for any possible reply. If no reply is
received, you can continue giving your CQ call. There is also a ‘Directional Call’
which is directed to a particular country or a particular station. A call directed to
a particular country is like-“CQ Japan CQ Japan CQ Japan this is Victor Uniform
Two …….”. This means that you will reply to stations from Japan only. A call may
be directed to a particular station also. In this case, the country name is to be replaced
with the intended station ‘call-sign’. A person with the true ham spirit does not
adhere strictly to his directional call, and as such should not deny reply to a ham
from another country replying to his directional call (in the above example) until
and unless he is in real emergency. Also there is nothing official about a ham
radio operation. Ham radio operators also form net. When a net is going on, you can
also join the net once somebody in the net ‘pulls you’ into the net. To indicate that
you want to join the net, a short ‘BREAK’ call may be given.
After establishing contact and offering the initial greetings, a signal report
should be given to the other station. Your name (Handle) and location (QTH) should
then be spelled out clearly in internationally accepted phonetics. If the other ham
finds difficulty in copying your voice signal due to poor propagation condition or due
to the difference in pronunciation, you should not loose patience and the message
should be repeated if requested. You can also give the weather report (WX report) by
mentioning the temperature in degrees Celsius. After this, discussion regarding the
antenna system and equipment (called-“Working condition”) begins. Before closing
the conversation with a particular station, 73 message (meaning ‘Best of Regards’)
should be conveyed to the ham and his family and indication should be given whether
you are closing down (going QRT) your station, you are changing your frequency

42
(QSYing) or you are still occupying the frequency. This will help other stations to
follow you in case they want to make a contact with you. If the conversation takes
long time, both the stations should repeat their call-sign at least at ten minutes
interval.

Signal Report in Radio Telephony

When on-the-air contact between amateur radio stations is established, both the
stations exchange signal reports. This gives the idea about how strongly the ham radio
stations are receiving each other. For telephony (voice), Readability and Signal
strength scale is devised.

Readability Scale Signal Strength Scale

R1 Hardly perceptible; S1 Unintelligible; barely
unreadable perceptible
R2 Weak; readable now S2 Weak signals; barely
and then readable
R3 Fairly good; readable S3 Weak signals; but can be
but with difficulty copied
R4 Good; readable S4 Fair signals
R5 Very good; perfectly S5 Fairly good signals
readable
S6 Good signals
S7 Moderately strong signals
S8 Strong signals
S9 Extremely strong signals

A 59 (5 and 9) report is the best report in radiotelephony. You should be

honest in giving a signal report. Don’t give a good report just to please your friend!
There may be some problem in the antenna system of your friend’s station due to
which you are receiving him poorly. Or there may be some problem in the audio
quality of your friend’s transmission. Under such a situation, giving a false report will
just misguide your friend and your friend may not be able to detect/rectify the fault in
his/her system.

G. Radio Telegraphy Operating Procedure

In radio telegraphy contact using Morse Code, the RST (Readability, Signal Strength
and Quality of Tone) system of reporting is followed. Throughout the world, Morse
code is still used very affectionately by thousands of ham radio operators. They make
conversation as fluently as they do in voice using Morse code. In fact Morse Code has
many advantages over voice communication in certain situations, as well as for the
sheer joy involved in this art of communication, which we have discussed in the
chapter on Morse code learning. In Morse code also, either general CQ call or
directional call can be given. The calling format is as follows:
General call:
CQ CQ CQ DE VU2XYZ VU2XYZ VU2XYZ AR PSE K
Specific/Directional Call:

43
CQ/VU2ABC CQ/VU2ABC CQ/VU2ABC DE VU2XYZ VU2XYZ VU2XYZ AR
KN
In Morse code, long words are usually avoided and hence only the abbreviated
form of the words are sent. There are certain Internationally accepted Morse Code
abbreviations which you should remember and use during communication. 'AR' is
synonymous to saying 'over' in voice (A voice message should be ended with the
word 'over to …..'). 'K' is the invitation to transmit which is synonymous to saying 'go
ahead' in voice communication. A message ended with KN indicates that the
message was directed to a particular station only. During an ongoing communication
also, the message should be ended with 'KN' which provides the information to the
other stations that communication was already in progress between two stations. Each
sentence of the message should be separated by 'BT'. Given below is a typical Morse
code message.

VU2XYZ DE VU2ABC BT TNX FER CALL BT UR RST RST IS 579 BT MY

NAME IS …………..ES QTH IS ……… BT OK? AR VU2XYZ DE VU2ABC
KN
When you finally close your conversation with a particular station, indication
should be given, i.e. the message should be ended with 'VA' (meaning 'over and out
with ……). A typical closing message may look like-…………. VU2ABC DE
VU2XYZ VA. This means that VU2XYZ is now free to communicate with other
stations.

The RST System

Readability Signal Strength Tone

R1-Unreadable S1-Faint, signals barely T1-Extremely rough
hissing note
R2-Barely readable, S2-Very weak signals T2-Very rough AC note,
occasional words no trace of musicality
distinguishable
R3-Readable with S3-Weak signals T3-Rough. Low-pitched
considerable difficulty AC note, slightly
musical
Readability Signal Strength Tone
R4-Readable with S4-Fair signals T4-Rather rough AC note,
practically no difficulty moderately musical
R5-Perfectly readable S5-Fairly good signals T5-Musically modulated
note
S6-Good signals T6-Modulated note, slight
trace of whistle
S7-Moderately strong T7-Near DC note, smooth
signals ripple
S8-Strong signals T8-Good DC note, just
trace of ripple
S9-Extremely strong signals T9-Purest DC note

44
Abbreviations used in Radio Telegraphy (Morse Code)

AA Artficial antenna or all after

AB All before
ABT About
AGN Again
ANI Any
ANT Antenna
AR Over
AS Wait
BK Break
BC Broadcast
BCL Broadcast band Listener
BCNU Be seeing you
BT Separation
C Yes
CFM Confirm
CL Closed
CO Crystal Oscillator
CQ General Call
CONDX Conditions
CU See you
CUL See you later
CK Check
CANS Headphone
DE This is
DF Direction Finding
DX Long distance
ECO Electron Coupled Oscillator
ERE/HR Here
ES And
FER For
FB Fine Business
FR For
FONE Telephony (voice)
CKT Circuit
GA Go ahead/Good afternoon
CLG Calling
GE Good evening
GM Good morning
CPSE Counterpoise
GLD Glad
GND Ground
GUD Good
HI Laughter
HPE Hope
HR Here
HRD Heard

45
HV Have
K Go ahead (general request)
KN Go ahead (directional request)
KCS Kilocycles
LID Bad operator
MNI Many
MO Master Oscillator
MCS Megacycles
ND Nothing doing
NW Now
NIL Nothing
OB Old Boy (Young male operator: a novice)
OM Old Man (Male operator: not a novice)
OK All correct
OP Operator
PSE Please
PX Press
QRP Very low power
QSL Received
R Roger (Copied OK)
RCVD Received
RCVR Receiver
RPRT Report
RPT Repeat the message
RX Receiver
SA Say
SED Said
SIGS Signals
SWL Short Wave Listener
TKS Thanks
TNX Thanks
TX Transmitter
TU Thank you
U You
UR Your/ You are
VA End of work
VY Very
WA Word after
WB Word before
WX Weather
WID With
WKD Worked
WL Will
WUD Would
XMTR Transmitter
XTAL Crystal
XYL Wife
YF Wife
YL Young Lady (unmarried)

46
73 Best of regards
88 Love & Kisses
Ham terminology
BAREFOOT- A transmitter running without an external linear RF amplifier.
HARMONIC- Daughter or Son of the ham radio operator (just as the harmonic
frequency generated out of the fundamental frequency!)
HANDLE- Name of the ham radio operator
TICKET-The Amateur Wireless Telegraph Licence
RIG- Wireless apparatus
HOMEBREWED EQUIPMENT- A home made apparatus
SHACK- Radio room

Part-III

Radio Theory and Practice

A. Elementary Theory of Electricity & Magnetism

What is electronics?
Electronics is the field of manipulating electrical currents and voltages using passive
and active components that are connected together to create circuits. Electronic
circuits range from a simple load resistor that converts a current to a voltage, to
computer central processing units (CPUs) that can contain millions of transistors.
Electronic devices operate by the movement of electrons through conductors, e.g.
wires, and electronic components.

What are passive components?

Resistors, inductors, transformers and capacitors are called passive devices. They
don’t alter their resistance, impedance or reactance when alternating currents (ac) are
applied to them.

What are active components?

Vacuum tubes, diodes, transistors etc. are called active devices. They change their
resistance or impedance when varying voltages are applied to them and as a result can
amplify, rectify, modify or distort ac waveforms. Passive devices normally don’t
distort waveforms.

Matter and electricity

Before going to discuss the different theories related to electricity and magnetism, we
would like to give a brief idea about matter. All matter consist of molecules. A
molecule can be defined as the smallest particle, which shows all the characteristics of
a particular matter. For example, molecule of water is obtained by dividing a drop of

47
water again and again until it cannot be divided and still be water. Further division of
this water molecule will yield three particles which are not water. Molecule of water
contains two atoms of hydrogen (H) and one atom of oxygen (O). A molecule may
contain one atom or more than one atom. An atom can be further divided into three
particles known as protons, electrons and neutrons. Protons and electrons are the
particles possessing electrical properties whereas neutron is electrically neutral.
Electrons are the negatively charged particles, which revolve around the
positively charged protons (which constitute the nucleus of an atom along with
neutrons). Proton is about 1800 times heavier than electron. There is always
attraction between unlike charges. Because electron is much lighter than proton,
hence it is pulled towards the proton. If the force of attraction is enough, then the
electron comes too closer to the proton and both the particles together form a neutral
particle to be known as neutron. Atoms, of all elements, except hydrogen contain
one or more neutron in their nucleus.
The electrical charge of an electron can be explained with the help of an
imagination that there exist lines of forces, which are outward pointing. Though the
size & weight of electron and proton varies significantly, the negative field of an
electron is just as strong negatively as the positive field of a proton is positive. Small
though it is physically, the field near the electron is quite strong. The strength of the
field varies inversely with the distance squared.
Though electrons and protons have different kind of charge in them, both have
charges of equal magnitude. An electron (negatively charged) repels another electron,
while a proton (positively charged) repels another proton. So the basic physical law
states:
”Like charges repel; unlike charges attract”.

What is charge?
When the electrons are stored up and not moving, there is no current, but there is
charge. The amount of charge is measured in terms of ‘coulomb’. One coulomb is
equivalent to 6.28 x 1018 electrons.

What is current?
Atoms of a metal form a crystal lattice, and in the spaces between the lattice points
free electrons move chaotically, wandering aimlessly here and there. But it is enough
to connect a metal plate to the two poles of a voltage source for the electrons
immediately to acquire an aim. They will move towards the positive pole of the
battery, and an electric current will begin to flow in the metal. An electric current can
also flow in a gas. A voltage applied across a gas-filled tube causes ionization of the
gas: free electrons stream towards the plate with the positive potential, colliding with
the atoms in their way and detaching electrons from their orbits. The positive ions
move toward the opposite end of the tube. Current is the rate of flow of charge, i.e.,
the number of coulombs flowing past a point per second. Its unit is ampere (A)
or amp. One amp is equal to one coulomb per second.

48
What is voltage?
Voltage is also called potential (Potential is defined as the work required from some
energy source in moving a unit positive charge between two points in an electric
field), potential difference, potential drop, or electromotive force-EMF. It is the
electronic potential energy between two points, and is the driving force that causes
charge to flow. Its unit is volt (V). One volt is defined as the potential difference that
requires one joule of energy to move one coulomb of charge. Voltage is always
measured relative to some other point in a circuit, e.g. the potential across a resistor.
Voltage measurement made at a single point in a circuit are made relative to the earth
(ground), which is assigned an “absolute” voltage of zero.

Types of Electricity

Direct Current (DC)

The direct current flows in one direction in a circuit. DC voltage has a fixed polarity
(e.g. a battery or an electrical cell) and the magnitude of the voltage remains constant.
In an electrical circuit, the flow of electric current is indicated by an arrow mark
originating from the positive terminal of the battery towards the negative terminal of
the battery. This is the conventional method of showing the direction of current flow.
But the real direction of electron flow is from the negative terminal of the battery to
the positive terminal.

Alternating Current (AC)

Alternating current flows first in one direction for one-half cycle and then in the
opposite direction during the other half cycle. The same definitions apply to
alternating voltage. AC voltage switches polarity back and forth. AC voltage/current
has a wave-form which represent the frequency of the source. The wave-form of the
household ac is known as the ‘sine’ wave. The magnitude of the A.C. voltage changes
with time. AC is obtained from A.C. generators.

Advantage of AC
Heat is developed in all type of electrical circuits due to the flow of electric current.
The magnitude of the D.C. being constant produces more heat in a circuit compared
to the heat produced by an A.C. In long distance transmission lines, large amount of

49
power will be dissipated in the form of heat if D.C. is used which can be reduced by
the use of A.C.
A.C. Voltage can be measured in four different ways.

Peak Voltage
The value or amplitude of an A.C. voltage never remains constant. With an initial
voltage of zero, the amplitude rises to a peak value, after which it again falls back to
zero. After reaching zero, the direction of the current changes and the voltage rises to
its negative peak. Peak voltage measurement is necessary to ensure or know that the
amplitude of the A.C. voltage does not exceed a limit.

Instantaneous Voltage
It is also called the average voltage. The voltages, if measured, at different points of
the half cycle of the sine wave will be the instantaneous voltages. But practically it is
not possible. So one way to denote instantaneous voltage is to take the average
voltage. In a sine wave A.C. voltage, the average voltage can be found out by
multiplying the ‘peak voltage’ by a constant (value of the constant can be worked out
to be equal to 0.367).

Root-Mean-Square Voltage
Measuring an A.C. voltage involves the use of a meter which measures AC Voltage in
terms of how much DC voltage it would take to have the same effect in a circuit.
Since during most of the cycle the AC has a value less than the value at its peak, or
for that matter, than of a constant DC voltage, it will not be able to produce as much
heat (in a heating element) as produced by the same amount of DC voltage. Power
being proportional to either E2 or I2 (P=E2/R=I2R), if all the instantaneous values of a
half cycle of sine-wave current (or voltage) are squared and then the average, or
mean, of all the squared values is found, the square root of this mean value will be
0.707 of the peak value. This root-mean-square, or rms, value represents how
effective a sinusoidal AC will be in comparison with its peak value.
The RMS value is the value of voltage of an AC source, the power consumed
by whom is the same as by a d.c. voltage. That is, it is the effective value (Veff) of a

50
sine-wave voltage found from the formula:
Veff=Vmax X 0.707

Effective Voltage
In a domestic AC supply, 230 volts is actually the effective voltage (Veff). The actual
voltage or the peak voltage (Vmax) of the supply is : Vmax = Veff /0.707 =325 volts. Or,
to determine a peak value of AC that will be as effective as a given DC, it is
necessary to multiply the effective value given by the reciprocal of 0.707 (1/0.707),
which is 1.414.

Magnetism
What is a magnet?

A piece of iron, nickel, cobalt, steel, alloy (e.g. alloy made from non-magnetic
copper, manganese and aluminum) etc. usually in the form of a bar having properties
of attracting or repelling iron and other materials which contain iron is called a
magnet. But what gives it its force is not completely known. One of the theories to
describe magnetism is the-“Theory of Domains”. It says that materials that can be
made into magnets have many tiny crystal like structures called domains. Each
domain is made up of many atoms. Each domain has a small magnetic force of its
own. When the material is not magnetized, the domains are haphazardly arranged-
pointing in all directions-so that their tiny forces cancel each other. To make the
material into a magnet, the domains need to be lined up so that their individual
magnetic forces all help each other pull the same way. When most of the domains line
up, the magnet becomes strong. When all of the domains line up in one direction, the
magnet is saturated. It cannot be made any stronger regardless of how much you try to
magnetise it.
In a magnetic bar, there are two poles: North and South. They are marked as
‘North’ and ‘South’ poles because, when the magnetic bar is suspended horizontally,
one of the ends will always point towards the Earth’s geographical north and the other
pole towards the Earth’s geographical south. This is because of the fact that the Earth
itself behaves like a huge magnet. In a magnet, the like poles repel and the unlike
poles attract-a reason for the specific alignment of the magnetic bar. The magnetic bar
is surrounded by the invisible lines of forces which originate from the ‘North’ pole
and terminate in the ‘South’ pole.

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Ferro-magnet
Iron, nickel and cobalt (including the alloy mentioned above) are considered
ferromagnetic. Ferro-magnetic materials are difficult to be converted to magnet but
once magnetized under the influence of another magnetic field, they cannot be
completely demagnetized. Ferromagnetic materials are used to make permanent
magnets. One of the strongest permanent magnetic materials is a combination of
iron, aluminum, nickel and cobalt called “Alnico”.

Paramagnet
Materials which get demagnetized once the external magnetic field is removed are
paramagnetic.

Use of Permanent magnets in Electronics

Electricity and electronics cannot be discussed by leaving apart ‘magnetism’
separately. Permanent magnets are used in electronics to make electric meters,
headphones, loudspeakers, radar transmitting tubes etc. Temporary magnetic
materials are also equally important in electricity and electronics to make devices
which may be quickly changed from being magnetic to non-magnetic.

Electromagnets
The flow of an electric current through a wire creates a circular magnetic field around
the wire. This magnetic field has the highest intensity near the conducting wire and
the intensity gradually decreases as the distance from the wire increases. The
direction of these magnetic flux lines can be found by the ‘left hand rule’. If the
conducting wire shown below is grasped by the left hand, the curled fingers point to
the direction of magnetic flux lines and the thumb shows the direction of current flow.

52
 If a straight conducting wire is made into a loop giving it a ‘coil’ shape, the
small magnetic loops around the wire overlap each other resulting in a more stronger
magnetic field around the whole coil. The strength of the magnetic field depends on
the number of turns in the coil, amount of current in the coil and the permeability of
the core material. Air has a permeability of 1. But iron is more permeable than air and
is capable of transferring the magnetic flux line more efficiently. Based on this
principle, electromagnets can be made. An electromagnet consists of a coil
surrounding a soft iron core. The core remains magnetized so long as there is flow of
current in the coil. The direction of the magnetic field in a coil can also be found by
the ‘left hand rule’. If a coil is grasped in left hand, the curled fingers point to the
direction of current flow, the thumb shows the direction of magnetic flux and N pole
of the coil.
Electromagnets have many applications in electronics. Two of the most
important uses of electromagnetism are in transformers and motors.
Electromagnetic relays, electric bells, buzzers are commonly used electromagnets.
Electromagnetic relays are used as switching devices in electrical and electronic
circuits.

53
Transformers
Transformer is a device which consists of two coils arranged in a way so as to
generate a magnetic coupling effect (the coupling effect is enhanced by winding the
two coils on a common iron core) and thereby transfer electrical energy (AC voltage)
from one coil (called the primary coil) to the another coil (called the secondary coil).
A transformer works on the principle of ‘mutual inductance’ (see page). One of the
most useful characteristics of a transformer is its ability to step-up or step-down of
AC voltages. The step-up or step-down ratio will be proportional to the turns in each
coil, i.e.,,

VS = NS/NP X VP

Where, VS = Secondary voltage

NS = Number of turns on secondary
NP = Number of turns on primary
VP= Primary voltage
The currents flowing in the primary and secondary follow a similar relationship, but
in opposite ratio, i.e.

IS = NP/NS X IP

Where, IS = Secondary current

IP =Primary current

In other words, a step-up in voltage produces a step-down in current and vice versa.

54
Transformers as Coupling Device

Transformers are very useful to use in radio or audio frequency circuits as coupling
devices. As well as providing coupling, they can act as ‘amplifiers’ to step up an
audio or radio frequency voltage (but not as power amplifiers); and even more
important for impedance (see page ) matching. By choosing the proper turns ratio the
impedance of a fixed load can be transformed to any desired higher or lower
impedance, within practical limits. This can be a particularly important requirement
when coupling transistor radio stages.
For impedance matching, the following relationship applies:

Where,
ZP=Impedance of the transformer looking into the primary terminals
ZS=Impedance of the load connected to the secondary of the transformer

Resistors

What are resistors?

A resistor is a device designed to have a definite amount of resistance-used in circuit
to limit current flow or to provide a voltage. Resistance (R) is the retarding force in a
material that impedes the flow of current. The potential (E) needed to achieve a
current (I) through a material that behaves linearly, e.g. conductors and resistors, is
given by Ohm’s law:
E=IR
Where, E=emf (in volts, V)
I=intensity of current (in amperes, A)
R=Resistance (in ohms, Ω )
So, if we know any two values, we can find out the other value. The above formula
can rearranged as shown below:

55
 E
I= /R or Current in amperes= volts/ohms

From this formula, it is evident that-“Current varies directly as the voltage and
inversely as the resistance”.
The formula can also be arranged to find out the resistance in a circuit if the
voltage and current are known.
E
R= /I or Resistance in ohms= volts/amperes

Practical Resistors
The resistance of a material depends on four physical factors:
(1) The type of material from which it is made. For example copper and silver are
very good conductors of electric current, but iron is six times lesser in its conductivity
than them.
(2) The length (greater the length greater is the resistance).
(3) Cross-sectional area (greater the cross-sectional area larger the amount of free
electron implying lesser resistance).
(4) Temperature (except for carbon and other semiconductor materials).
So each material has a specific resistance inherent in them. The specific
resistance of a material is the number of ohms in a 1 foot long 0.001 inch
diameter round wire of that material at room temperature. Silver has the least
specific resistance, i.e. 9.75 Ω and nichrome is an alloy, which has specific
resistance as high as 660 Ω.

Wire-wound resistor
Nicrome or german silver wires are wound on a tubular ceramic form to make wire-
wound resistor. Wire-wound resistors are generally available in values from 1 ohms to
300 kiloohms. Power ratings of this type of resistors vary from 1 to 50 watts.

Carbon resistor
Powedered carbon is mixed with a binding material and baked into small, hard tubes
with wire attached to each end to make carbon resistors. The percentage of carbon in
the mixture determines the resistance value in ohms. Carbon resistors are generally
available in values from 10 ohms to 22 megaohms. Power ratings of this type of
resistors vary from 1/8 watt to 2 watts.

Colour codes of resistors

Carbon resistors are colour coded to indicate their values. Each resistor has four
colour bands on its body. The first band (the band which is nearest to the end of the
resistor) is the first number. The second band is the second number. The third band is
the multiplier, i.e. number of zeros following the second number.

Colour Band 1 Band 2 Band 3

56
 Black 0 0
Brown 1 1 0
Red 2 2 00
Orange 3 3 000
Yellow 4 4 0000
Green 5 5 00000
Blue 6 6 000000
Violet 7 7 0000000
Gray 8 8 00000000
White 9 9 000000000

Resistors having values lower than 10 Ω have three colour bands. The third
band is either golden or silver in colour. A golden band indicates that the first two
numbers are to be multiplied by 0.1. A silver band indicates multiplication by 0.01.
The tolerance of three band resistors is 20%. If the golden or silver band is the fourth
band respectively, then they indicate a tolerance of 5% and 10% respectively.

Questions:
1. A circuit has a resistance of 100 ohms and voltage applied across the circuit is 20
volts. What is the amount of current flowing through it?
E
We have, I= /R or I=20/100=0.2 A (ampere) or 200 mA (milliampere)

2. Find out the voltage required to produce 3 A of current through a 50 Ω (ohms)

resistor.

We have, IR=E or 3 x 50 = 150 V (volts)

Power and Energy

As mentioned above, heat is developed in the load resistor as a result of current
flowing through it. In absence of the load, a battery despite having the electromotive
force (EMF), cannot produce movement of electrons and no electrical work is
accomplished. When there is a load across the battery, movement of electrons take
place. The product of the EMF (in volts) and movement of electrons (in amperes)
gives us the amount of electrical work accomplished whose unit is watt (W).

P=EI

Where P=power (in watts, W)

57
 E=emf (in volts, V)
I=current (in amperes, A)
So, 1 V causing 1 A to flow through a 1 Ω resistor produces 1 W of power.

The above formula can also be expressed as

P=EI=(IR)I =I2R (because the ohm’s law states: E=IR)

Or

P=EI=E(E/R)=E2/R (because the ohm’s law states: I= E/R)

Questions:

1. Find out the heat dissipated by a 50 Ω resistor when 0.25 A of current flow pass
through it.

We have, P=I2R or P=0.252 x 50=0.0625 x 50=3.125 W

2. Find out the power dissipated by a 10,000 Ω resistor connected across a voltage
source of 250 V.

We have P=E2/R=2502/10,000=6.25 W

3. Find out the maximum voltage that may be connected across a 20 W, 2000 Ω
resistor.

We have, P= E2/R

Or , E2=PR

Or,

Or,

E= 200 V

4. Find out the maximum current that can flow through a 100 Ω 1 W resistor.

58
 We have,

Or,

What are conductors?

Materials which allow the flow of electric current through them are called conductors.
Metals are known to be good conductors, with copper and silver among the best. The
conductivity of a particular material depends on the number of free electrons present
in it. A conductor may be a very good conductor, a fairly good conductor or a poor
conductor. So, a greater conductivity or conductance implies lesser resistance and a
lesser conductivity implies greater resistance. So, conductance (conductance is
expressed in siemens, S) and resistance (R) are the same thing but from opposite
viewpoints. They are said to be reciprocal of each other, i.e.

R=1/S or S=1/R

So the Ohm’s law can be expressed in terms of conductance by using 1/S in place of
R in the three foremulas:

E=IR=I(1/S) or E=I/S

Resistance in series and parallel

The circuit shown here is a simple circuit with one load or resistor across a voltage
source (e.g. a battery).

59
 The circuit shown below is a series circuit where three resistors are connected
one after another. It is evident from the diagram that there is only path through which
current flows.

The circuit shown below is a parallel circuit where each resistor has its
independent path for the flow of current from the same source of voltage.

The circuit shown below consists of two batteries and three resistors in series.
In a series circuit the same amount of current flows through all parts of each circuit.
The resistors are connected in series to obtain a greater resistance and it is equal to the
sum of the values of each resistor, i.e. 40 Ω. Two batteries are connected in series in
this circuit to obtain the highest possible voltage which is the sum of the values of
each battery, i.e. 20 V.

60
From the Ohm’s law, the current flowing through this circuit will be:
E
I= /R or I=20/40=0.5 A

Precaution
We should be careful while connecting batteries in series, because, the maximum
current possible through the circuit is no greater than the greatest current that the
weakest battery can deliver. If one of the batteries in the above example is weaker
than the other and capable of passing only, say, 0.2 A, it will be overworked, may
overheat and the voltage across the terminal will drop.
In this type of circuit, the voltage that can be obtained across each resistor is
called the ‘Voltage drop’. From the Ohm’s law, the voltage across each resistor can
be calculated. The voltage drop across the 30Ω resistor is 15 V (0.5 x 30) and the
voltage drop across the 5Ω resistor (each) is 2.5 V. Thus the sum of the voltage-drops
is equal to the source voltage (2.5+2.5+15=20V).

Internal Resistance of batteries

The battery might possess an internal resistance which is to be considered while
calculating the various quantities in a circuit. If a 10 V battery has 1Ω internal
resistance and connected across a 9Ω load resistor, the amount of current flowing
through the circuit would be 1 A. A voltage drop of 1 V will take place inside the
battery and hence the 10 V battery will produce only 9 V across its terminals when
connected to the 9Ω load. When the circuit is open (no currents flowing through it),
the voltage across the battery would be 10 V.

Resistors in parallel circuit

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The circuit shown above is a circuit where two resistors are connected in parallel
across the voltage source. Obviously, there are two paths for the flow of current. One
part of the current flows through R1 and the other part flows through R2. Since total
conductance St of a circuit is equal to the sum of all the conductances connected in
parallel, the formula can be expressed as:

St=S1+S2

Or St=1/R1+1/R2

Or 1/Rt=1/R1+1/R2

The above equation is made into a pair of fractions by placing a 1 over both sides,

Calculation in a complex circuit

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The circuit shown above seems to be a complex circuit. By looking at the
arrangement of the resistors, their values can be computed in simple steps. As
indicated above, calculate as per the steps shown [e.g. step (a), step (b)…..]

Step (a): 15Ω & 5Ω resistors are arranged in parallel imparting a value equivalent to
3.75 Ω

Step (b): 3.75Ω+ 20Ω=23.75 Ω (arranged in series)

Step (c): 6.67 Ω (arranged in parallel)

Step (d): 23.75Ω & 6.67Ω are arranged in parallel. The equivalent value is 5.20 Ω

Step (e): 5.20Ω + 10Ω in series, i.e. 15.20Ω

Step (f): 10Ω and 15.20Ω are in parallel, i.e. 6.03Ω and

finally, 10Ω + 6.03Ω are in series. The equivalent value is 16.03Ω.

What are insulators?

The materials which do not allow the flow of electric current through them are called
insulators. Glass, porcelain, dry air and dry wood are well known insulators.

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Inductors

Self-Inductance
Self inductance is the property of a circuit whereby a change in current causes a
change in voltage. Self-inductance is also more simply known as inductance. If ‘L’ is
the inductance, then increasing the value of ‘L’ increases the amount of voltage that is
induced in response to a change in current. Decreasing the value of ‘L’ decreases the
amount of voltage that is induced in response to a change in current.
Inductance is measured in units of henries (h). Commonly used engineering
units for inductance are- henry (1 h), millihenry (1mh=1 x 10-3 h) and microhenry (1
µh=1x 10-6 h).
One henry is the amount of inductance that is required for generating one
volt of induced voltage when the current is changing at the rate of one ampere
per second.
Inductance is the property of a coil when it is subjected to AC voltage. It
results from the fluctuation of the current flowing through the circuit. When the
current through the coil builds up, an expanding magnetic field also builds up cutting
the turns of the coil resulting in the formation of a counter voltage in the coil which
opposes the flow of the original current. This property of the coil is known as
inductance. Since DC voltage remains constant (except for the instant when the
circuit is closed, i.e. the instant when the switch is made on), there is no fluctuation in
the magnetic lines of force produced across the turns of the coil and counter voltage is
not generated. So a coil offers very negligible resistance (that due to the physical
resistance) to the flow of DC current.

Inductive reactance
Inductive reactance is the opposition to AC current flow that is caused by the
presence of an inductor in the circuit. The symbol for inductive reactance is XL. The
unit of measure for inductive reactance is ohms (Ω). The amount of inductive
reactance in a circuit is proportional to the applied frequency (f) and the value of the
inductor(L).

The equation for calculating the amount of inductive reactance in an ac circuit

is given by:

XL=2πfL

64
 where,
f is the frequency of AC voltage and L is the inductance

The total inductive reactance of a series XL circuit is equal to the sum of the
individual reactance.

Inductive reactance in series

XLT=XL1+XL2+XL3+…XLn

Where XLT is the total inductive reactance and XL1, XL2,…. XLn etc. are the
values of individual reactance.

Inductive reactance in parallel

XLT=1/(1/XL1+1/XL2+1/XL3+1/XLn)

Inductive reactance is an AC version of resistance. In fact, you can use Ohm's

Law by substituting XL for R:

VL = ILXL

where:

VL is the voltage across the inductor in volts

ILis the current through the inductor in amperes
XL is the amount of inductive reactance in ohms

The amount of inductive reactance (XL) changes proportionally with

the applied frequency (f):

65
-Increasing the value of f causes XL to increase.
-Decreasing the value of f causes XL to decrease.

The amount of inductive reactance (XL) changes proportionally with the value
of inductance (L):

-Increasing the value of L causes XL to increase.

-Decreasing the value of L causes XL to decrease.

Questions:
1. What is the value of inductive reactance for an 0.1 H coil that is operating at 1
kHz?

Ans: 628 Ω

Use the basic equation: XL=2πfL

3. What value inductor is required for producing an inductive reactance of 10 Ω at

1.8 kHz?

Ans: 88.5 µH.

Use this form of the basic equation:

4. At what frequency will a 150 mH inductor have an inductive reactance of

150 Ω ?

Ans: 159 Hz

Use this form of the basic equation:

4. What is the total inductive reactance of a circuit when XL1 = 150 Ω and XL2 = 75
Ω are in series?

Ans: 225 Ω

66
Equation to find out inductive reactance in a circuit with a number of
inductors in parallel

Use one of these inverse equations to determine the total inductive reactance of a
parallel inductor circuit:

where:

XLT = total inductive reactance

XL1 , XL2 , XL3 , XLn = values of the individual reactance

The procedure for finding the total inductive reactance of a parallel inductor
circuit is identical to finding the total resistance of a parallel resistor circuit.
The total reactance of two inductors in parallel can be found by applying the
product-over-sum formula:

Capacitor
Capacitor is a device used to store electrical energy and then release it as current into
the circuit. Its property is just the reverse of an inductor. The capacitance of a
capacitor is measured in Farad.
A capacitor has a capacitance of 1 farad if a 1 Volt difference in potential
results in the storage of 1 coulomb of charge.

1 coulomb = 6.28 x 1018 electrons

The capacitance is, C=Q/E,

Where, C is capacitance in farads,

Q is the charge in coulombs,
E is the voltage in volts.

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Practically farad is a large unit. The smaller units are micro farads (µf) and pico
farads (pf).

When two metallic plates or conductors are separated by an insulator, also

known as a dielectric, they behave like a capacitor. The conductors can be long or
short piece of metal plate or any other conducting material. The insulator between the
two conductors which is known as dielectric can be air, mica, wax-impregnated paper
ceramic etc. The properties of a capacitor:
1. It stores energy in the form of electrical field
2. Capacitance is the property of an electric circuit that tends to oppose a change
in voltage.
3. It passes A.C. and blocks D.C.

Functioning of a capacitor
A capacitor when connected across a voltage source, an electrostatic field builds up
between the metallic plates. The field builds up due to the accumulation of electrons
on the negative plate and release of electrons from the positive plate until the
capacitor voltage reaches its maximum. The capacitor will be in this charged state as
long as it is connected to the voltage source. After removal of the voltage source, the
capacitor can not loose its charge (theoretically, a perfect capacitor would hold the
charge forever, but in practice, some of the charge leaks out), unless both the plates
are connected with the help of a conducting path. When there is a conducting path,
electrons from the negatively charged plate flows to the positive plate until both the
plates are neutralized.

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Capacitor in a DC Circuit
In DC circuits, the capacitor will allow current to flow till it becomes fully charged,
however since no current can flow through the dielectric material of the capacitor, no
current flows after the capacitor gets fully charged.

Capacitor in an AC Circuit
The AC voltage or current is fluctuating in nature. It is not only fluctuating but also
changing the direction of flow, i.e. the polarity of the AC voltage source keeps on
changing resulting in a charging and discharging of the capacitor. Unlike a DC
circuit, here, current will continue to flow in the circuit (though the electrons don’t
cross the dielectric material of the capacitor).

Capacitor in a varying DC circuit

If the voltage source is a varying DC, then also there is continual charging and partial
discharging of the capacitor resulting in an AC current flowing through the circuit. In
fact, the capacitor blocks the DC, but pass the AC component.

Factors that affect capacitance

1. Area of plates : The larger the plates, the higher its capacity to store charges,
i.e. capacitance is directly proportional to the plate areas.
2. Space between the plates: The closer the plates, higher is the capacity to hold
charges, because, the electrostatic pull on the electrons collected at the
negative side of the voltage source will be more. Capacitance is inversely
proportional to the spacing between plates.
3. Type of dielectric used: Some materials are more dielectric than the others.
Vacuum is the basic dielectric with which other materials are compared. It is
said to be having a dielectric constant of 1. The dielectric constant of air is
slightly more than this (1.0006). Dielectric constant is the ability of a material
to permit the establishment of electric lines of force between oppositely
charged plates. A dielectric (other than air) makes the positively charged
surface of a capacitor repel more free electrons and negatively charged surface
accept more electrons than when air is dielectric, thus increasing the
capacitance. The dielectric constant of mica ranges from 5 to 9. Dielectric

69
 constant of glass is 4.2.Capacitance is directly proportional to the
dielectric constant.
A formula to determine the capacitance of a two-plate capacitor is:

Where

C= Capacitance in pF
K= dielectric constant
A= area of one of the plates, in inch2
S= spacing between plates, in inches

The above formula is valid for a two plate capacitor. For a multiplate capacitor,
the formula is:

Where N=number of plates in the capacitor

It is seen that a 3-plate capacitor has twice the plate area exposed and thus
twice the capacitance.

Quantity of charge in a capacitor

The quantity of charge in a capacitor can be found from the formula:

Q=CE

Where,
Q = charge, in coulombs (C)
C = capacitance, in F
E = voltage, in V

If a 0.1µF capacitor is charged by a 10 V source, the electron difference will be:

Q=0.0000001 x 10 = 0.000001 C or 10-6 C

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10-6 C = 6.25 x 1018 x 10-6 = 6.25 x 1012 electrons

If the charged capacitor is disconnected from the voltage source, it will still
retain the electron difference on its plates (assuming that there is no leakage). Now, if
a similar uncharged capacitor is connected across the charged capacitor, electrons
flow from the charged to the uncharged capacitor and it will get charged to 5 V as a
result of distribution of half amount of electrons into it. Since the other capacitor lost
half of its electrons, its voltage will be reduced to 5 V (now, both the capacitors will
be having a voltage of 5 V each) from 10 V. If both the capacitors are reconnected in
series, the total voltage-drop across them would become 10 V.

Capacitive Reactance
Capacitive reactance is the resistance offered by a capacitor to the flow of AC through
it. It is measured in ohms (Ω). The formula to calculate capacitive reactance in a
circuit is:

Where Xc = reactance, in Ω
f = frequency, in Hz
C = capacitance, in F
Questions:
1. Find out the reactance of a 0.002 µF capacitor to a frequency of 2,000 kHz.

Solution:

Capacitors in parallel

Capacitors can be connected in parallel to obtain a greater value. The formula is:

Total capacitance of capacitors in parallel, Ct= C1+C2+C3+…..Cn

While connecting the capacitors in parallel, it should be noticed that the

voltage applied on them does not exceed the voltage rating of the capacitor with
the minimum voltage rating.

71
Capacitors in series

As shown above, when two capacitors are connected in series, the bottom & top
plates of the respective capacitors are ignored and consequently combined effect of
two capacitors of equal value is to simulate a single capacitor with half the value of a
single capacitor, i.e. if two 10 µF capacitors are connected in series as shown above,
we will get an effective capacitance of 5 µF. This is because the circuit sees only two
plates (plate a & b) with a dielectric distance of twice that of a single capacitor
(capacitance decreases when distance between plate increases). It is to be noted that
when capacitors of different voltage ratings are connected in series, the voltage that
can be applied to them can be equal or less than the total voltage obtained by adding
voltages of each capacitor, alternatively, we can say that when capacitors in series are
connected across voltage source, the sum of the voltage-drops across each of them
will always equal the source voltage.
The formula to calculate the total capacitance of a number of capacitors
connected in series is:

Types of capacitors
There are fixed value capacitor as well as variable value capacitors available for
electronics work. Paper, mica, ceramic and polyester capacitors have fixed values.

Paper capacitor
Paper capacitors are made by rolling two metal foils with a strip of paper and then
impregnating with a dielectric between them. For high voltage applications, several
layers of papers are used to separate the metallic foils. They are not suitable for use at
frequencies above 1 MHz, which virtually restricts their application to audio
frequency (AF) circuits. They are available in capacities from 0.05 µ F up to 1 or 2 µ
F with working voltages from 200 to 1000 volts.

Mica capacitor
Mica is used as a dielectric between the metallic plates in this type of capacitors.

72
These capacitors have excellent high frequency response.

Ceramic capacitor
In this type of capacitor, ceramic is used as a dielectric which has a high dielectric
constant. Ceramic capacitors have good stability with regards to temperature and
voltage changes. They are widely used in miniaturized audio frequency (AF) and
radio frequency (RF) circuits. Their capacities ranges from 1pF to 1 µ F with high
working voltage.

A Disc ceramic capacitor A Tubular Ceramic capacitor

Polyester film capacitor

In this type of capacitors polyester is used as a dielectric to impart a high breakdown
voltage. Their capacities ranges from 0.01 µF up to 2.2 µ F. Their low inherent
inductance makes them suitable for coupling and decoupling applications.

Polystyrene capacitor
These capacitors are made from metallic foil interleaved with polystyrene film,
usually with fused polystyrene enclosure to provide high insulation resistance. They
provide good stability and reliability at high radio frequencies because of their low
inherent inductance and low series resistance. Their values range from from 10 pF to
100,000 pF, but working voltage generally falls substantially with increasing capacity
(as low as 60 volts for a 100,000 pF polystyrene capacitor).

Electrolytic capacitor
An electrolytic capacitor consists of an aluminum-foil positive plate immersed in a
solution called an electrolyte (ionizable solution capable of carrying current). The
aluminum foil is the positive plate, and the electrolyte is the negative plate, if a liquid
can be called a plate. To make an electrical connection to the liquid, another
aluminum foil is placed in the solution. To prevent the two foils from touching each
other, a piece of gauze is placed between them. The +ve foil is surrounded by a thin
oxidized film formed due to application of a particular voltage which acts as the
dielectric. Electrolytic capacitors can not be used in AC circuits. Their values range
from 1 µ F to 4700 µ F or more with working voltage ranging from 10 volts dc up to
500 volts.

73
Variable capacitors
Variable capacitors are widely used in radio frequency work where it is required to
change the value of the capacitor in order to tune the circuit to a particular frequency.
Usually, air is used as a dielectric in this type of capacitor. The capacitance is made to
vary either by changing the distance between the plates or by changing the plate area
exposed. This type of capacitor may consist of two plate or more than two plates.
Metallic gang capacitors and button trimmers are the most common example of
variable capacitors. In a trimmer the two metallic plates are made to vary in their
distance with the use of a screw.

Electrical Impedance
Electrical impedance is the total opposition to current flow in an AC circuit. It takes
into account all sources of opposition. Since it is the total opposition, impedance is
measured in ohms, just as resistance and reactances are. If an inductor and resistance
are connected in series with a source of A.C., the impedance of the circuit is:

If XL=4Ω and R=3 Ω

Therefore,

=5 Ω

The impedance of a series R-L circuit can never be equal to or greater than the

74
sum of XL and R, nor can it be equal to or less than either XL or R.

Inductance and Capacitance in Series

When an inductor and a capacitor are connected end to end, a series L-C circuit is
formed. If the inductor is a pure inductor and capacitor, a pure capacitor, then the
circuit has no D.C. resistance which is practically impossible. There is always some
resistance present in the circuit. Inductor has inductive reactance, XL and capacitor
has the capacitive reactance, XC. The net resistance present in the circuit is negligible.
If the circuit has an inductance L of 1 henry in series with a capacitor C of 10
µF and the applied voltage E is 100 volts and frequency is 50 Hertz.

Then,

Inductive reactance XL=2πfL= 6.28 x 50 x 1 = 314 Ω

Capacitive reactance,

The impedance of such circuit is the difference of inductive reactance and

capacitive reactance.

Z=XC-XL=318.5-314 = 4.5 Ω

If XL is greater than XC then the impedance is XL - XC.

Resonant frequency
Resonant circuits make it possible to select one frequency from all others. For
example, there are hundreds of radio stations that broadcast signals strong enough to
be received by your radio receiver. The tuning circuit of the radio receiver
accomplishes the task of discarding all other signals but to allow only the desired
signal to be processed. The single frequency at which the circuit responds best is
called the resonant frequency of the circuit. Resonance occurs when the inductive
reactance becomes equal to capacitive reactance or XL = XC.
It can be achieved by either varying capacitance or inductance. In a radio
receiver, it is achieved by varying the value of the variable capacitor. A series
resonant circuit offers very little resistance when the circuit operates at the resonant
frequency. High current is permitted to flow through the circuit.

Parallel Resonant Circuit

In the circuit diagram shown below, the part of the circuit between the points ‘a’ and
‘b’ is called a ‘tank’ because the resonant frequency will be captured and held there
while all other frequencies are allowed to flow through it. So if the AC source is
producing AC current at the resonant frequency, that current is blocked by the tank.
The current is not permitted to travel from ‘a’ to ‘b’ through the tank. But when the

75
AC source is producing current at any other frequency, the current can flow from ‘a’
to ‘b’ with little opposition.

Tuning Circuit
In a radio receiver, the selection of the desired frequency out of hundreds of other
frequencies is achieved by the use of resonant circuit. The resonant circuit basically
consists of an inductor and a capacitor. The frequency of resonance is usually
achieved by changing the capacitance of the variable capacitor.

In the tuning circuit shown above, all the frequencies captured by the antenna
are passed to ground through the primary coil L1. They will try to cause current flow
in the tank circuit, but only the resonant frequency will be successful in creating a
current flow. The information it carries will be sent to the other radio circuits while
the non-resonant frequencies are practically ignored.
In the circuit shown above, the condition of series resonance is present but is
not apparent. In this circuit the transformer secondary coil has a capacitor across it
with a reactance of the secondary, forming a resonant circuit. At first glance it appears
to be a parallel-resonant circuit. The primary coil, however, is inducing an AC voltage
into each turn of the secondary coil. Theoretically, the secondary may be considered

76
to have a source of AC inserted in series with its turns.

Filtering
Resonant circuits are used to filter out the desired frequency. A series resonant circuit
allows to pass its resonant frequency while the parallel resonant circuit (called the
tank circuit) blocks the flow of its resonant frequency

‘Q’ of a circuit
The term ‘Q’ is applied to AC circuits in which inductance and capacitance are
involved. It in fact express the ‘quality’ of the inductor or capacitor and since lesser
the ohmic resistance of the coil (inductor), more perfect inductor the coil is, with little
loss. ‘Q’ can be found from the formula:

Q = Xi / R (in case of coil); where Xi = inductive reactance, R = Ohmic resistance.

Again,

Xi = 2πfL

Where,

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f = frequency,
L = inductance

Therefore, Q = 2π f L / R ; this shows that the same coil or inductor possesses high
‘Q’ at higher frequency.

Skin effect
A phenomenon called ‘Skin effect’ also causes loss of efficiency of a coil or inductor.
It is observed that at higher frequencies, electrons flow nearer to the surface of the
conducting wire; since the usable cross-sectional area lessens, the ohmic resistance
increases resulting in a lower ‘Q’.

Prevention of ‘Skin effect’

(i) By using large diameter wire.

(ii) By silver-plating of the wire used.
(iii) Using fewer turns while making the coil, but increasing the core
permeability; e.g. using powdered iron core.
(iv) By using ‘Litzendraht wire’, an insulated multistrand wire. Several thin
strands have more surface for a given wire diameter than does a solid wire
(Litz wire is effective only up to about 1 MHz)

B. Thermionic Emission & Valves

An electric current can also flow in a gas. A voltage applied across a gas-filled tube
causes ionization of the gas: free electrons stream towards the plate with the positive
potential, colliding with the atoms in their way and detaching electrons from their
orbits. The positive ions move toward the opposite end of the tube.
The most common material used in the construction of a vacuum tube
envelope is glass. The electrode leads pass through a glass bead sealed into an eyelet.
The electrodes in a vacuum tube are supported by insulators such as mica and a
variety of ceramics. The electrodes themselves are commonly made from metals such
as nickel, copper, aluminum, molybdenum, and tungsten.
In thermionic valves the electrons move in a vacuum. An example of such a
device is the diode. The envelope of a diode houses two main parts which are also
called the anode (or plate) and the cathode. Near the cathode there is a filament or
miniature electric heater which heats the cathode. Most tubes employ heater-cathodes.
A heater-cathode consists of a metal cylinder coated with special oxides that liberate
great quantities of electrons when heated to a relatively low temperature. In this case
an "electron liquid", consisting of electrons that move chaotically in the very body of
the cathode, between its atoms, begin to "boil". This phenomenon is known as
'electronic emission’. As a result of this emission, a cloud of "electron gas" is formed
round the cathode. If the cathode is now connected to the negative terminal of a
voltage source and the anode, to the positive terminal, the anode will begin attracting
electrons from the cloud, "drawing" them away from the cathode, and a current will
flow inside the diode. Freedom for the electron proves very short-lived: no sooner

78
does it escape from the cathode it is immediately attracted by the anode.
A diode is in fact a one-way valve. When the negative terminal of the voltage
source is connected to the anode and the positive terminal to the cathode, the
electrons will not be able to escape the cathode, because it attracts them. But even
those that do escape have nowhere to fly in particular: previously they were attracted
by the anode, now it forces them back to the cathode. With such a connection no
current flows through the diode. This property of the diode is employed for
converting the alternating current to direct current which is called rectification. The
current flowing through a diode is called the plate current. The flow of plate current
can be controlled by two ways: by varying cathode temperature; and by changing the
applied voltage (called the plate voltage). But cathodes are designed to operate most
efficiently at one particular temperature. An increase in plate voltage results in an
increase in plate current. But after a certain point, further increase in plate voltage will
not cause any corresponding increase in the plate current. This point is called the
saturation point.

Diode valve as a rectifier

As shown in the circuit given below, the source of plate voltage in the plate circuit is
a transformer providing an alternating voltage to the plate. During one half cycle, the
plate end of the transformer-secondary winding may be positive and the cathode end
negative. On the next half cycle the plate end will be negative and the cathode end
positive. As described above, the diode allows only one half cycle of the emf to
produce current in the circuit. With ac plate voltage the plate current is pulsating dc.
This one-way-gate effect is a main use of diodes. A diode is also called a rectifier.

Triode Valve
The introduction of a third electrode (control grid) between the cathode and the anode
of a diode makes it a triode. In the triode, current is controlled by means of a voltage
applied between the cathode and the grid. With a high negative grid potential (with
respect to the cathode), the grid becomes a barrier for the electrons. They will
"crowd" in the space between the cathode and the grid; the valve will be cut off, since

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no current will flow from the cathode to the anode. With a positive grid potential, the
grid will help the anode, since its positive potential will be added to that of the anode.
A heavy current will flow through the valve. However, with too high a positive grid
potential the grid may turn from a helper of the anode into its competitor: some
electrons will be drawn to it and will not reach the anode. In this case a harmful grid
current appears in the valve. That is why in normal operation the grid is made to vary
only more or less negatively.

Amplification factor of a triode valve

In the circuit shown below, the voltage (-Eg) in the grid circuit is –8 V. Plate voltage
(+Ep) is 200 V. Plate current is 3mA. By increasing +Ep by 40 V it is found that
plate current increases from 3 to 7 mA. Returning to the original values, Grid voltage
(-Eg) is –8 V, +Ep=200 V, and Ip=3mA, it is found that if the –Eg value is reduced by
2 V, from –8 to –6 V, the Ip will again rise from 3 to 7 mA. This indicates that the
same Ip change can be produced either by changing the Ep by 40 V or by changing
the –Eg by 2 V. This controlling ratio of 40:2 is equal to 20. The tube is said to have a
µ (mu) or amplification factor of 20. Thus the grid is found to be 20 times more
effective in changing plate current than the plate voltage.

Triode as an amplifier

In a theoretical circuit comprising a microphone, a transformer, a triode valve with a

load resistance, the microphone induces a small ac voltage into the secondary of the
transformer and between grid and cathode. With no signal applied to the grid and with
100 V from the plate supply, the dc voltage-drop across the load resistor Rl might be
75 V. As the input signal reaches a peak of 1V negative, the current in the plate
circuit will decrease. The voltage drop across the plate-load resistor might decrease
by 12 V, to 63 V across the Rl. As the grid voltage swings to 1 V positive, the plate
current will increase, until there is a voltage drop of perhaps 87 V across the load
resistor. As grid voltage varies from –1 V to +1 V (a 2 V peak to peak variation), the
voltage across the load resistor varies between 87 and 63, i.e. 24 V. The voltage ratio
of 2:24 indicates that across the plate load resistor, the voltage variation is 12 times
more than the variation between the grid and the cathode.

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Bias voltage

In the circuit described above, the grid was driven negative and positive alternately.
But this creates distortion. To avoid the distortion, in a practical circuit, the grid may
never be allowed to become positive and thus there is no grid current (Ig) from the
cathode. This is accomplished by adding a dc voltage source in series with the grid-
cathode circuit. The negative potential is applied to the grid through the transformer,
and the positive potential to the cathode. The negative dc voltage added in series with
the grid circuit is known as the bias voltage. If a negative 10 V bias is enough to
produce plate-current cutoff with a given plate voltage, then a possible bias voltage
would be half of this, i.e. 5 V for a class A amplifier. It can accommodate a peak ac
emf of 5 V from the secondary of the grid-circuit transformer and neither cutoff the
plate current nor drive the grid into positive region.

C. Semiconductors: Diodes & Transistors

In the early days of electricity there were only two groups of material: insulators and
conductors. Insulators are materials which do not allow the flow of electric current
through them. Glass, porcelain, dry air and dry wood are well-known insulators.
Metals are known to be good conductors, with copper and silver among the best. The
conductivity of a particular material depends on the number of free electrons
present in it.
There is another group of material known as semiconductors. Semiconductors
like germanium and silicon are bad conductors of electricity in their purest form. But
when certain impurities (iridium or arsenic, which have a slightly different atomic
structure from that of germanium or silicon) are added in the form of carefully
controlled quantities, either an increase of free electrons or deficiency of electrons
results. A semiconductor is called an n-type semiconductor where conduction takes
place by reason of excess free electrons. A semiconductor is called a p-type
semiconductor where conduction takes place due to freely moving ‘holes’ (positively
charged) which replace electrons displaced by random electron movement in the
material.

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 When pieces of p-type and n-type semiconductors are joined together, a p-n
junction results. Flow of electric current through such a junction is possible only
when the positive pole of the battery (voltage source) is connected to the p-type
semiconductor and the negative pole to the n-type semiconductor. This is called the
“forward biased” condition.

In this condition, positively charged holes are repelled by the battery voltage
towards the junction between p and n type material. Simultaneously, the electrons in
the n-type material are repelled by the negative battery voltage toward the p-n
junction. Despite the presence of a potential barrier at the p-n junction, which
prevents electrons and holes from moving across and combining, under the influence
of the electric field of the battery the holes move to the right across the junction and
the electrons move to the left. As a result, electrons and holes combine and for each
combination of that takes place near the junction, a covalent bond near the positive
battery terminal breaks down, an electron is liberated and enters the positive terminal.
This action creates a new hole which moves to the right toward the p-n junction. At
the opposite end, in the N-region near the negative terminal, more electrons arrive
from the negative battery terminal and enter the n-region to replace the electrons lost
by combination with holes near the junction. These electrons move toward the
junction at the left, where they again combine with new holes arriving there. As a
consequence, a relatively large current flows through the junction. The current

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through the external connecting wires and battery is due to that of the flow of
electrons. If, however, the polarity of the battery is reversed, i.e., the positive terminal
is connected to n-type semiconductor and the negative terminal of the battery to the p-
type semiconductor, the p-n junction will block the electron flow by building up a
voltage barrier at the junction. The holes are now attracted to the negative battery
terminal and move away from the junction because of the attraction of the positive
terminal. Since there are effectively no hole and electron carriers in the vicinity of the
junction, current flow stops almost completely. The diode is now in reverse biased
condition. This type of device is called a “solid state diode” or a semiconductor.

Use of Semiconductor diode

By exploiting their property of one way flow of electric current, they can be utilized
to convert alternating current to direct current (known as rectification). Without
adequate filtering, the resultant d.c. is pulsating in nature. However, it will be
appreciated that a diode will work in both a dc and an ac circuit. An example of the
use of a diode in a dc circuit (say output side of a dc power supply) to eliminate any
possibility of reverse polarity voltage surges occurring which could damage
transistors in the same circuit.

The circuit shown above is a basic half-wave rectifier circuit passing one half
of each AC cycle as DC and suppressing the other half cycle. The purpose of the
capacitor is to maintain the DC voltage output as far as possible by discharging on
each ‘suppressed’ half cycle. The DC output in this type of circuit is not smooth
having a ‘ripple’ at the AC frequency.

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 The circuit shown above is that of a simple full wave rectifier whose
secondary voltage is halved (because of the center tapping), but the current that can
be drawn is doubled. The capacitor charges and discharges alternately to produce a
smoother DC supply. The ‘ripple’ will still be there which will be equal to twice the
AC frequency.
The usual form of full-wave rectifier circuit is the bridge rectifier shown
below. This gives approximately the same no-load voltage as a half-wave rectifier
with the advantage of full-wave rectification and better smoothing. A single high
value electrolytic capacitor is used for smoothing.

Transistors
The simplest of the transistors are of two types-either p-n-p or n-p-n. Two p-n
junction diodes can be sandwiched back to back to form a p-n-p or n-p-n junction
transistor. But in a practical transistor, the center or n-type portion of the sandwich is
extremely thin in comparison to the p-regions. In the 1st illustration, both the p-n

84
junctions are reverse biased.

In this type of connection, holes in the each of p-region are attracted towards
the negative battery terminal and the mobile electrons in the n-region are initially
moved away from both junctions in the direction of the positive battery terminal. Due
to the displacement of holes and electrons, there will be no current flow in the
external circuit.
In the 2nd illustration, one of the p-n junctions is forward biased, while the
other is reversed biased. In a transistor, the middle layer (here n-region) is called the
base, the forward biased p-n junction is called the emitter junction and the reverse
biased p-n junction is called collector junction. Due to the positive potential at the
emitter junction, the holes in the p-region cross into the n-region (the base). But this
region is very thin and there are very few electrons with which holes can combine. So,
majority of the holes drift across the base into the collector junction. About 5 per cent
of them are lost in the base region as they combine with electrons. For each hole that
is lost by combination with an electron in the base and collector areas, a covalent
bond near the emitter electrode breaks down and a liberated electron leaves the
emitter electrode and enters the positive battery terminal. The new hole that is formed
then moves immediately toward the emitter junction, and the process is repeated.
Thus, a continuous supply of holes are injected into the emitter junction, which flow
across the base region and collector junction, where they are gathered up by the
negative collector voltage. The flow of current within the p-n-p transistor thus takes
place by hole conduction from emitter to collector, while conduction in the external
circuit is due to the flow of electrons.

Because of the reverse bias no current can flow in the collector circuit,
unless current is introduced into the emitter. Since a small emitter voltage of about

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0.1 to 0.5 volt permits the flow of an appreciable emitter current, the input power to
the emitter circuit is quite small. As we have seen, the collector current due to the
diffusion of holes is almost as large as the emitter current. Moreover, the collector
voltage can be as high as 45 volts, thus permitting relatively large output powers. A
large amount of power in the collector circuit may be controlled by a small
amount of power in the emitter circuit. The power gain in a transistor (power
out/power in) thus may be quite high, reaching values in the order of 1000.

Current gain of transistor (α)

The ratio of collector current to emitter current is known as alpha (α), i.e.

It cannot be higher than 1. It is the measure of possible current amplification

in a transistor.
Beta (β) is another constant defined as ratio of collector current to base
current. If IE is the emitter current, and IC/IE = ∝, then IB=base current= 1-∝ , i.e.,

Transistor Symbols and Connection

When transistors are operated as amplifier, three different basic circuit connections
are possible: (a) Common-base, emitter input; (b) common-emitter, base input; and
(c) common-collector, base-input.
Regardless of the circuit connection the emitter is always forward biased
and collector is always reverse biased.

Described below is a ‘common emitter, base-input’ basic transistor amplifier

circuit using a PNP transistor. The transistor is in common-emitter configuration. It
needs two separate supply voltages--one for base bias and the other for the
collector. In the first diagram, two separate batteries are used. But the voltages can
also be provided by a single supply (as shown in the second diagram) taken to the
common connection (the emitter) and the collector; and tapping the collector side to
apply the necessary forward bias voltage to the base dropped a bias resistor.

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 In this type of amplifier circuit, the collector current is fed through an output
load (R2). The biasing voltage to the base is provided through the resistor R1 is of the
order of 0.1 to 0.2 volts for germanium transistors; and about 0.6 to 0.7 volts for
silicon transistors. This type of biasing is called as current biasing. A relatively small
base current can instigate a very much larger collector current (or, more correctly, a
small input power is capable of producing a much larger output power). In other
words, the transistor works as an amplifier. However, this type of circuit is not very
stable. To provide stability, another type of base biasing is used, which is called
voltage biasing. In the amplifier circuit shown below, with voltage bias, two resistors
(R1&R2) are used as a potential divider. A resistor R3 is also added in the emitter line
to provide emitter feedback automatically to control the bias voltage under varying
working conditions. This resistor is usually paralleled with a capacitor to provide
further stabilization.

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D. Radio Receiver
A radio receiver is a device, which is used to receive radio frequency transmission
from a radio transmitter. A radio transmitter transmits radio frequency (RF) signal
generated at a particular frequency , on which the intelligence (e.g. any type of audio)
is superimposed. Transmission of this audio information or audio frequency (AF) is
possible only through the use of radio frequency. However, in reality the audio
frequency (AF) does not get transmitted; instead, the sound content is literally carried
on the back of the RF signal, the two together forming what is called a modulated
signal.
Modulated radio frequency can be produced in two different ways--amplitude
or ‘up-and-down’ modulation, known as AM; and frequency modulation (FM). In
FM broadcast, actually a very small variation in the RF signal frequency takes place
about the station frequency. FM technique is usually followed in very high frequency
(VHF) transmissions.
Amplitude modulation technique is easier and hence widely used for
medium wave and short wave broadcasts. There are hundreds and thousands of
broadcasts that take place in different radio frequencies or wavelengths. The
relationship between wavelength and frequency is:

Radio frequency (RF) generation

A basic oscillator which can produce oscillations at a particular frequency consists of
a capacitor, a coil (inductor) and a DC voltage source along with a switch as shown
below.

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 By making the switch ‘ON’ instantly and then releasing it to make ‘OFF’, a
pulse of current finds it path to the capacitor as well through the inductor resulting in
an expanding magnetic filed across the inductor while charging the capacitor
simultaneously. The instant when the switch is made ‘OFF’, the capacitor discharges
releasing the extra electrons on the top plate through the inductor to reach the other
plate. The current thus produced is in the same direction as when the switch was made
‘ON’. Thus it aids to maintains the expanding magnetic field produced during the
instant when the switch was made ‘ON’. The capacitor will reach a neutral state after
the electron from the top plate neutralizes the bottom plate (the positively charged
plate), i.e. the capacitor will be getting discharged in the process. As there is no
supply of electrons from the DC voltage source (because the ‘switch’ is ‘OFF’), and
the capacitor is also fully discharged, so, the magnetic field around the inductor will
now collapse resulting in a self-induced voltage. This self-induced voltage will make
enough current to flow through the inductor to charge the capacitor in opposite
direction. A similar process described above will now start and repeat over and over
again producing damped oscillating currents until all of the energy is wasted by
circuit resistance and other losses. This is called the ‘flywheel effect’. It is similar to
what happens when a pendulum is started in motion. It tries to continue swinging at
the same frequency until all of the starting energy is used up. The unique thing to
notice here is that oscillations will maintain a particular frequency despite loosing
their amplitude. This frequency is called the resonant frequency and the circuit
described above is called a tank circuit. The frequency of resonance can be found
from the formula:

In the electronic circuitry, a damped oscillation is not at all desirable from the
practical utility point of view. So, the objective is to use a transistor or triode valve to
provide the necessary gain (and not loss!) and feedback (the energy) to sustain the
oscillations or to produce perfect sine wave frequency. Described below are two
practical oscillator.

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Hartley Oscillator

In the Hartley oscillator circuit shown above, the frequency of oscillation is

determined by the resonant frequency of the tank circuit consisting of C1 and L1. L1 is
tapped at its center to form two inductors : L1a and L1b. L1a is effective in the base
circuit of the PNP transistor and L1b is in the collector circuit of the transistor. When
B+ is applied to the collector through a RF choke, collector current begins to flow.
The resulting drop in collector voltage is coupled through C3 and developed across
L1b. This serves as the initial excitation for the tank and causes circulating current to
begin to flow in the tank. The circulating current produces a voltage across L1a, which
is coupled by capacitor C2 to the base of the transistor. The amplified signal at the
collector is coupled back to the tank circuit by capacitor C3, and developed across L1b.
The feedback voltage developed across L1b is in phase with the input voltage across
L1a, and so maintains the tank circuit oscillations.

Colpitts oscillator

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The Colpitts oscillator is similar to the Hartley oscillator, except that two capacitors
are used in the tank circuit instead of a tapped coil.The output frequency of a
Colpitts oscillator is determined by the value of the tank inductance and the total
capacitance of the two series capacitors. Capacitor C1 is in the base circuit and C2 is
in the collector circuit. The AC tank voltage produced by the circulating current
divides between the two capacitors. The voltage across C1 is applied to the base of the
transistor by coupling capacitor C3 and base resistor R1. The resulting collector signal
is coupled back to the tank circuit by capacitor C4 and developed across tank
capacitor C2. The feedback is in phase with the base voltage as a result of the 180-
degrees phase shift introduced by the transistor, and the 180-degree shift caused by
the ground tap between C1 and C2.

Tuning circuit of radio receiver

The job of a radio receiver is to receive only a particular radio frequency at a single
time. For this, a sorting device known as the ‘tuning circuit’ (see page 76) is used at
the ‘front end’ of a radio receiver.

Detection
After sorting out the desired frequency, a diode is used at the ‘detector’ or
‘demodulator’ stage of the receiver, where it rectifies out one half of the RF signal
containing the audio information. This half cycle of the RF is still imposed with the
AF content. So the next step is to filter out the RF to receive or detect an undulating
AF signal. These undulations follow exactly the same variations as the AF signal
originally imposed on the transmitter RF signal at the transmitting station by a
microphone.
A resistor and a capacitor acts as a filter for a specified frequency. So, a diode
detector is to match a load (resistor) with the capacitor so as to form the required filter
circuit, so that only the varying dc (undulating AF portion of the signal) is passed at
the output from the detector stage. A basic diode detector circuit is shown here.

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AF Amplification
The audio signal thus obtained is then amplified in the audio amplifier stage of the
receiver. There may be more than one stages of amplification but with the limitation
of using only a certain number of stages of amplification after which distortion in the
audio takes place.
The radio receiver described above is a very simple radio receiver which
has a limitation in its detector stage. This type of receiver is called Tuned Radio
Frequency receiver (TRF). The detector works most effectively with an RF input
voltage of 1 volt or more. Signal obtained directly from an aerial circuit are most of
the time more than a few millivolts in strength, and weaker the signal the less
effectively they will be detected. So, the range of stations that can be picked up is
limited, and no amount of amplification after detection can make up for this
limitation.
This limitation or lack of sensitivity can be overcome by amplifying the
incoming signal before detection, so that the detector is always working with good
signal strength. This is accomplished by the use of an amplifier stage right at the
beginning of the circuit or by super-heterodyne circuitry. By comparing and
contrasting a ‘Tuned Radio Frequency (TRF) receiver’ with a ‘Super-heterodyne
receiver’, we can better understand the advantages as well as functioning of a super-
heterodyne receiver.

Difference between a Tuned Radio Frequency (TRF) receiver and a

Super-heterodyne receiver.

A TRF receiver consists of the following stages:

(i) Antenna input stage
(ii) A few stages for RF-amplification
(iii) A detector stage for demodulation
(iv) One or more stages of AF amplifier

On the contrary, a super-heterodyne receiver consists of :

(i) RF Amplifier
(ii) Mixer or Converter
(iii) Local Oscillator
(iv) IF Amplifier

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(v) Detector
(vi) Automatic Gain Control (AGC) Circuit.
(vii) AF Amplifiers
1. In a TRF receiver a series of loosely coupled tuned circuits are used to increase
selectivity and each circuit are ganged (interconnected) so that they resonate at the
same frequency. But in a super-heterodyne receiver, this principle is not followed,
instead, the RF amplifier, mixer and local oscillator are ganged to produce an
intermediate frequency (IF).
2. In a TRF receiver the high amplitude original frequency is demodulated at the
detector stage. But in Super-heterodyne sets, the IF is demodulated.
3. In a TRF Receiver, no image frequency is produced. But image frequency is
produced in super-heterodyne receiver.
4. In a TRF receiver, selectivity is not constant; the receiver is more selective at the
low frequency bands, while less selective at the high frequency end. Because the
detector and amplifiers of a super-heterodyne receiver can be designed to amplify
only intermediate frequency (IF), this type of receiver is more selective and offer
high fidelity (exact reproduction quality of the transmitted signal).
5. In TRF receiver, amplification is not constant over the tuning range. In super-
heterodyne receiver amplification is constant since all the time it amplifies a
constant frequency at the IF stages.

Functioning of a Super-heterodyne Receiver

The main objective of the super-heterodyne receiver is to produce an intermediate
frequency (IF) by the process of heterodyning or beating. This can be accomplished
when two frequencies are mixed to produce the beat frequency. In super-heterodyne
receivers, the IF is usually 455 kHz which is selected because the broadcast band
begins above that frequency. So, if we imagine a situation when the RF amplifier is
tuned to receive a 800 kHz broadcast signal, the local oscillator must be tuned to 1255
kHz, which will result in an IF of 455 kHz (1255-800 kHz=455 kHz).
Since we have to tune the RF amplifier section throughout the entire broadcast
band, the frequency of the local oscillator must also vary in a manner that it always
maintains a gap of 455 kHz. To achieve this condition, the Local Oscillator and RF
Amplifier section are 'ganged', i.e. their tuning condensers are connected/ganged
mechanically in such a way that when we tune the variable capacitor in the RF
section, the variable capacitor in the local oscillator also changes its value, it 'tracks'
the frequency to which the 'Aerial Circuit' is tuned and remain separated from the
tuned frequency by 455 kHz up.
The Intermediate Frequency (IF), which is a considerably low frequency
is being used, because-
(i) it is a suitable frequency to achieve amplifying efficiency.
(ii) It provides better selectivity.
(iii) It provides better sensitivity throughout the broadcast band.
(iv) It provides uniform sensitivity as well as uniform selectivity.

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Radio Frequency (RF) Amplifier section

This section performs two major tasks:

(i) it couples the antenna voltage to the converter of the receiver;
(ii) By selectivity, it accepts only the desired frequency and all others are rejected.
(iii) By amplifying the desired signal, the Signal-to-Noise ratio is increased in the
converter stage for efficient operation.

Converter or Mixer Section

The main objective of the super-heterodyne receiver is to produce a constant
Intermediate Frequency (most commonly used frequency being 455 kHz in
commercial broadcast band radio sets). In the mixer stage, the local oscillator
frequency and the selected station frequency is or combined, where, by the process of
'heterodyning', i.e. 'beating', the 'Intermediate Frequency (IF)' is obtained. If the RF
Amplifier section selects and amplify a signal of 800 kHz, then the local oscillator
produces a frequency of 1255 kHz. By mixing both the frequency at the mixer stage, a
difference of frequency of the value 455 kHz is obtained (1255-800=455 kHz).

Intermediate Frequency (IF) Amplifier

The 455 kHz IF is fed to the IF amplifier through an IF transformer. The circuitry of
the IF section is so designed and tuned so that it gives the optimum gain at that
particular IF frequency.

Detector/Demodulator and 1st Audio Frequency Amplifier stage

The Amplitude Modulated (AM) IF is demodulated and detected. A diode working as
rectifier solves this purpose (see page 92). The triode/transistor amplifies the audio
signal and the volume control potentiometer system controls the intensity of sound.

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AF Power Amplifier
This section further amplifies the audio signals which is finally fed to an output
transformer which matches the impedance of output stage with the speaker (in modern
transistor receivers, the necessity of output transformer is eliminated).

AGC or AVC in a super-heterodyne radio set

Automatic Gain Control is a most needed part of super-heterodyne circuitry. A
disadvantage of manual gain control (volume control) with a receiver is that it can't
provide constant output under all conditions. If a receiver is tuned from a weak signal
to strong signal, its output must increase intolerably. This would then require
readjustment of the volume control. Similarly, when a receiver is tuned to particular
signal the output level can vary widely if the input signal strength fluctuates as a
result of fading and adjustments of the volume control has to be done. Since such
signal fluctuations are rapid, constant readjustment of volume control would be
necessary which is impractical. This is where AGC or AVC comes into picture and is
used in addition to the manual control.
All AGC or AVC (Automatic Volume Control) circuits perform two basic
functions;
(i) The first of these is to develop a DC (Direct Current) which is
proportional to the receiver input signal all the time.
(ii) The AGC voltage is applied to the RF and IF stage of the receiver
where it serves as a Bias voltage.
In this way the AGC voltage controls the gain of RF and IF stages, and
therefore the overall gain of the receiver. When the signal level at the receiver input
increases, the AGC voltage increases proportionately. Consequently, a larger bias is
applied to the IF and RF stages and their gain is applied to the IF and RF stages and
their gain is reduced.
The receiver output thus remains relatively constant instead of increasing in
accordance with the input signal strength and vice-versa.
In valve type RX (receiver), the grids of RF and IF portions valves are biases
by negative voltage. While in a transistor it depends on transistor type.

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Squelch circuit
The squelch circuit or Q (Quieting) circuit is a circuit which is controlled by AGC or
AVC voltage. The modern high gain receivers shows a disadvantage without it, that
is, without a squelch circuit, annoying buzzing and cracking sounds are heard over the
loudspeaker in absence of input signal. So a circuitry is arranged in such a way that
AF gain is kept reduced in absence of input signal from the antenna.
With no signal there is no Negative AGC voltage, and the squelch tube allows
current to flow through it then passing through R3 to the +250 V point. Thus R3
produces a DC voltage drop across it which is more negative at midpoint than at the
bottom being in series with the amplifier grid circuit, tube past cutoff, preventing it
from functioning.
When a signal is received, AGC or AVC voltage biases the squelch tube to
'cutoff', stopping plate current flow. Consequently, the voltage drop across R3 ceases,
allowing the AF amplifier tube to act in a normal manner.

Image Frequency in a super-heterodyne receiver set

The intermediate stage (mixer + local oscillator) of a super-heterodyne radio set
produces an Intermediate Frequency (IF) due to the beating of RF input frequency and
Local Oscillator Frequency. This frequency is obtained by deducting the RF input
from the tuned circuit from that of Local Oscillator Frequency. So, while
receiving a 800 kHz RF signal, the Local Oscillator is made to oscillate at a frequency
of 1255 kHz which results in an Intermediate Frequency (IF) of 455 kHz (which is
accepted as a standard in almost all the Broadcast band receiver circuits); but it is
found that in case of comparatively less selective receiver, if a broadcast
frequency 455 kHz up, from the 1255 kHz local oscillator frequency manages to
intrude the RF tuned circuit even to a little extent, then another difference of
frequency equal to intermediate frequency results; viz. 1710-1255=455 kHz. But
this '455 kHz' being generated from a signal frequency having different audio
information causes adverse effect at the audio end of the receiver. The
intelligence of both would be present in the speaker at the same time making the
sound reproduction is unintelligible.

Prevention of Image Frequency

(i) By highly selective RF tuned amplifier;

(ii) By using an IF which is convenient to use and at the same time separation
between desired and image signals is made large. Possibility of image
frequency generation is greater in a receiver designed for an IF of 175 kHz
than a receiver using an IF of 455 kHz.

'Selectivity' of a radio receiver

Selectivity is the measure of the ability of a radio receiver to select a particular
frequency or particular band of frequencies and rejecting all other unwanted
frequencies. But higher selectivity does not necessarily make a better receiver. For
instance, a 'broadcast signal' consists of the carrier frequency and its two side bands.

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In a situation where a carrier frequency of 800 kHz is modulated with a 5 kHz (5000
Hz) tone, the sum of the carrier and the audio frequency results in the Upper Side
Band (USB) of 805 kHz. The difference of carrier and audio frequency results in a
Lower Side Band (LSB) of 795 kHz. So, for proper reproduction of the broadcast
signal at a particular carrier frequency, the receiver must receive (select frequencies
from 795 to 805 kHz. A receiver more selective than this would reject a part of the
frequencies thus proper reproduction would be hindered.

Sensitivity of a receiver
It is the ability of a radio receiver to respond to the desired radio frequency signal
effectively. Higher the ability of the receiver to respond to a weak signal, greater is its
sensitivity.

What is a S-meter?
A S-meter is a visual indicator of signal strength. A simple S meter consists of a
milliammeter in series with an RF or IF amplifier plate/collector circuit. With no
signal, there is no AGC bias voltage and maximum plate current flows. With a signal,
the AGC biases the tube, reducing the plate current and the indication on the meter.
The stronger the signal, the lower the meter indication, signifying a strong strength.

What is a Beat Frequency Oscillator?

To change the second detector from a rectifying or envelope detector to a heterodyne
detector to receive A1A (Continuous Wave Morse Code), A2A (Modulated CW
Morse Code), J3E (Single Side Band), the Beat Frequency Oscillator is turned on. It
is a variable frequency oscillator using a Hartley, Colpitts or Armstrong circuit. It is
tunable to the Intermediate Frequency and one or two kilohertz higher and lower. It
heterodynes with any signal coming through the IF strip, producing an audible beat
frequency in the detector. Both the BFO and LO (Local Oscillator) must have good

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frequency stability.

Why ham radio transmissions are not heard in ordinary radio receiver
sets?

The radio sets available in the market for general public are designed to receive
Amplitude Modulated (AM) or Frequency Modulated (FM) broadcasts only. But the
ham radio operators use a very efficient mode of transmission called Single Side Band
(SSB) transmission. The power of a ham radio station is also very low ( usually not
more than 100 watts) in comparison to the broadcast station (which use power in the
kilowatts range). In fact many of the broadcast band radio receivers available in the
market also covers some of the frequencies which are allotted to the ham radio
stations. A 4 band radio set (inclusive of the Medium Wave band) can be expected to
cover some popular ham radio frequencies like 7 to 7.1 MHz (i.e. 7000 to 7100 kHz),
14 to 14.350 MHz (i.e. 14,000 to 14,350 kHz) and 21 to 21.450 MHz (i.e. 21,000 to
21,450 kHz). This kind of receiver can be improvised to receive ham radio
transmissions with very little effort.
First, we will need an outdoor aerial. Because, these radio sets are not
sensitive to receive low power transmissions. Majority of the hams use power below
100 watts (a broadcast station may use 4000 or 5000 watts of power or even more
than that!). A novice ham radio operator may be found to be operating with a power
as low as 0.5 watt!
Ham radio conversation if heard on an ordinary radio set sounds like the 'Duck
quacking'. There is no intelligibility in the audio. As already mentioned, our ordinary
radio sets are meant to receive AM signals only and not to receive SSB signals-a
separate unit is required at the 'Detector' stage of the AM receiver, which is nothing
but a stable 'Frequency Generator' (RF Oscillator), called the 'Beat Frequency
Oscillator' (BFO). The BFO is used to introduce a 'Local Carrier Frequency'
(frequency of the carrier is 10 to 20 Hertz within that of the transmitter carrier
frequency which is suppressed at the transmitter of the ham radio station willingly in
order to save power). A BFO can also be used to make the un-modulated Continuous
Carrier Wave (CW) transmissions (e.g. in Morse Code transmission) intelligible.

E. Radio Transmitters
Amplitude Modulation and %ge of modulation
Amplitude Modulation (AM) is a process in which the amplitude of a radio frequency
current is made to vary and modify by impressing an audio frequency current on it.
A radio frequency current has a constant amplitude in absence of modulation
and this constant amplitude RF carries no information, i.e. no audio intelligence and is
of no use to radio telephone (voice communication), but has application in morse
code communication.
So, to give intelligence to the RF current, audio signal is
impressed/superimposed on the RF current in a non-linear modulator circuit; as a
result of which carrier current amplitude begins to rise to a maximum value above and
below its original amplitude during the positive cycle of the audio signal and during

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the negative cycle of the audio signal, it falls to a minimum value.

Unmodulated 50% Amplitude of 100%

RF Carrier Audio signal modulated audio signal modulated
Carrier is increased carrier

This results in the carrier having two outlines of the audio signal, this is
because the variation at instant in the amplitude of the carrier wave is directly
proportional to the value of the modulating signal.
During amplitude modulation, two side band frequencies are also produced.
Upper sideband frequencies equal to the carrier frequency plus audio frequency and
lower side band frequency is equal to carrier frequency minus audio frequency. So the
amplitude modulated carrier occupies a space in frequency spectrum, the width of
which is equal to twice the highest modulating frequency.

Percentage of modulation
The degree of modulation in an AM wave is expressed by %ge of maximum deviation
from the normal amplitude of the carrier RF wave.
The effect of such modulated wave is measured by a receiver's ability to
reproduce the signal in distorted or undistorted manner.

Percentage of modulation=(VoltageMax-VoltageMin)/(VoltageMax+VoltageMin) x
100

Where VoltageMax is the maximum instantaneous value of the modulation and

VoltageMin is the minimum value of the RF carrier.

Why over modulation is not desirable?

Over modulation is not desirable, i.e. modulation should not exceed 100 %, because if
modulation exceeds 100 % there is an interval during the audio cycle when the RF
carrier is removed completely from the air thus producing distortion in the

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transmission.

What are the Side-bands of an AM signal?

Side bands are the sum and difference frequencies produced at the transmitter by the
modulating frequencies. For instance a 5 kHz (5,000 Hz) Audio tone might be used to
modulate an 800 kHz carrier frequency. This would produce frequencies of 800 kHz,
805 kHz and 795 kHz. 800 kHz is the carrier and 795 and 805 kHz are the two side
band frequencies.

What is Single Side Band (SSB) transmission?

At full modulation the carrier in an AM signal requires two thirds of the power but
conveys no information. The second side band can be viewed as redundant
(overlooking frequency-selective fading in an ionospheric transmission path, that may
distort one side band at times). Interference between several carrier frequencies,
resulting in steady audio whistles or 'beats' is another disadvantage of AM.
Power may be saved and the band occupied by an AM signal in the frequency
spectrum can be halved if only one side band is transmitted without carrier. The result
is single side band suppressed carrier signal, called simply single side band signal
(SSB) transmission.
The carrier must be reintroduced at the receiver in such systems and closely
adjusted to the original carrier frequency to avoid signal distortion. The introduced
carrier carrier must be within 10 or 20 Hertz of the original carrier frequency for
adequate intelligibility of voice signals, and stable oscillators are needed for
generation of the local carrier.
For SSB the transmitter does not need to generate carrier power, and ratings
are in terms of peak-envelope-power (PEP), the power capability at the peak of the
modulating signal with linearity of the amplifier is maintained. For equal information
content, and 100% modulation, the SSB signal requires only 1/6 th power of the
double side band signal. However, the situation is even more favourable to SSB when
speech is transmitted. Speech is not a continuous sine wave, and its average power is
low with respect to its peak requirements. A peak-to-average power ratio of 10:1 is
often assumed for speech, and under that condition, a Double Side Band (DSB) AM
signal would require 1.05 times carrier power, whereas for equal intelligibility the

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SSB signal would require only 0.05 units of power or 1/21 as much.

Because of the lower power rating, circuit components designed for SSB
equipment can be smaller and lower in cost.
For generation of a modulated signal without carrier, a balanced modulator
is used. A filter then discards one side band.

Why 100% modulation should be aimed in voice transmission?

The power of a modulated wave is found from the formula:

Pmod=(1+m2/2) x Pcarr

Where Pmod=Power of the modulated wave,

M=degree of modulation,
Pcarr=power in the carrier frequency.

The power in an amplitude modulated wave is divided between the carrier and
the two side bands. The carrier power is constant, and so, the side band power is the
difference between the carrier power and the total power in the modulated wave. The
above formula is to find the power of the modulated wave when carrier is modulated
by single sinusoidal tone.

If the carrier power=50 watts

%ge of modulation=100 or 1
degree of modulation=1

Then the power of the modulated wave,

Pmod=(1+m2/2) x 50=3/2 x 50 = 75 watts

Since the carrier power = 50 watts; the two side bands have 25 watts in them, i.e.

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25
/75 x 100% = 33.3% of the total power with 100% modulation.

In case of 50% modulation with same carrier power we have,

Pmod=(1+0.52/2) x 50 = 2.25/2 x 50 = 56.25 watts

Now the side bands have only 6.25 watts (since 56.25-50 = 6.25)
Since all the intelligence being transmitted is contained in the side bands, the
desirability of a high percentage of modulation is crystal clear. A comparatively low
powered, but well modulated transmitter often produces a stronger signal at a given
point than does a much higher powered, but poorly modulated, transmitted the same
distance from the receiver.

Schematic diagram of our intended transmitter and its function in brief

RF Oscillator
This is the stage where the carrier frequency intended to be used is generated by
means of Crystal Oscillator Circuitry or capacitance-inductance based Variable
Frequency Oscillator (VFO). The RF oscillator is designed to have frequency stability
and power delivered from it is of little importance, hence can be operated with low
voltage power supply with little dissipation of heat.

Buffer Amplifier
The low power RF carrier output from the RF oscillator is amplified in this portion
and it also keeps the RF oscillator and power amplifier circuits separate electrically
imparting frequency as desired by the amateur can be done in this stage, when the
carrier frequency multiplication technique is applied here. In it the Morse key for
keying out carrier continuous wave can be accommodated.

Modulator

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Audio information is impressed upon the carrier frequency at this stage.

Balanced Modulator
In this type of modulator, while the audio information (voice) is impressed upon the
carrier frequency, at the same time its output gives a signal without carrier frequency
but yet with the two side band frequencies carrying the voice/audio information.

Side-band filter
It discards out any one of the side band.

RF linear Amplifier
RF power amplification is done here and this stage is coupled to the antenna system
through antenna impedance matching circuitry. Care is taken at this stage so that no
harmonic frequency is generated which will cause interference in adjacent band
(splatter) on other bands.

Crystal oscillators
Crystal oscillators are used in most modern commercial radio transmitters, either
telegraph or telephone. Quartz crystal oscillators are used because they do not drift
more than a few hertz from the frequency for which they are ground. A variable
Frequency Oscillator (VFO) tends to drift considerably more.
Crystals made from quartz are used in radio frequency oscillator circuits in
order to impart stability to the frequency of oscillation. The function of the quartz
crystals are based on the piezoelectric effect, i.e. generation of electricity by
compressing or stretching the quartz. Conversely the quartz crystal can be made to
expand or contract physically by applying a voltage across it (e.g. by placing it
between two metallic plates where the voltage is applied).

Expansion and contraction of a crystal

At its resonant frequency a crystal behaves exactly like a tuned circuit. If a

crystal between metal plates is shock-excited by either a physical stress or an electric
charge, it will vibrate mechanically at its natural frequency for a short while and at the
same time produce an ac emf between the plates. This is somewhat similar to the
damped electron oscillation of a shock excited LC circuit.
The circuit shown in the next page is a TPTG (Tuned Plate Tuned Grid)
circuit. When the switch is closed, the LC (Inductance-Capacitance) tank in the plate
circuit is shock-excited into oscillation by the sudden surge of plate current. The ac
developed across this LC circuit is fed back to the top crystal plate through inter-
electrode capacitance, and to the bottom plate of the crystal through the bypass

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capacitor from the LC circuit. The crystal starts vibrating and working as an ac
generator on its own. The emf generated by the crystal, applied to the grid and
cathode, produces plate current (Ip) variations in the plate LC circuit.

With both crystal and LC circuit oscillating and feeding each other in proper
phase, the whole circuit oscillates as a very stable ac source. The plate LC circuit
must be tuned slightly higher in frequency than the crystal to produce the required
phase relationship between the two circuits to sustain oscillations.

F. Radio Wave Propagation

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The Role of Ionosphere in Radio Wave Propagation
Long distance propagation of radio waves depends on an invisible layer of charged
particles, which envelops the Earth. This layer of charged particles known as the
ionosphere has been in existence for millions of years. For those, who pioneered the
long distance radio communication during the early part of the twentieth century, the
ionosphere came as a boon. During the formative days of radio communication, radio
scientists could not come to a definite conclusion about how radio waves propagated
round the world. The father of radio, Gug1ielmo Marconi himself was at a loss to
explain how, on 12th December, 1901, he established the first real long distance
wireless communication between St. Johns, New Foundland, USA (now in Canada)
and Poldhu in the Southern Tip of England, a distance of more than 3,000 kms across
the Atlantic Ocean. At that time, it was known that except for very short distances, the
radio waves did not follow the natural curvature of the earth. Earth's curvature is a
direct block to line-of-sight communication. When enough distance separates the two
radio stations so that their antennas fall behind the curvature, the Earth itself blocks
the transmitted signals from the receiver, because, electromagnetic waves travel in
straight lines until they are deflected by something.

Oliver Heaviside in England and A.E. Kennally in America, in 1902,

suggested that there must be some kind of reflecting medium in the upper atmosphere
that caused the radio waves to be returned to Earth at considerable distances from the
transmitter. Under the action of solar radiation and the hail of meteorites, an ionised
layer is formed in the upper part of the Earth's atmosphere. In this layer, the neutral
air molecules are decomposed into ions and electrons and the whole layer presents a
chaos of charged particles. Short wave radio signals (radio signals which fall in the
range of 1.5 MHz to 30 MHz) are reflected from this layer just as light rays are
reflected from the surface of a mirror, or sound wave from a barrier. likewise, this

105
layer can be compared to the edge of a billiard table. Communication specialists use
this layer like the edge of a billiard table: if the ball does not go straight into the
pocket, it can be directed on the rebound! In the same way, the short wave signals
radiated by distant radio stations get to our receiver on the rebound. They can
continue traveling to several places round the world, for the Earth is also like the edge
of a billiard-table.
The ionosphere is located above the troposphere, starting at an altitude of 50
kms above the surface of the earth and extending up to an altitude of 400 kms or
more. The troposphere is the region of the earth's atmosphere immediately adjacent to
the earth's surface and extending upward for some tens of kilometres. Radio waves
are refracted or bent slightly, when traveling from one medium to another. Refraction
is caused by a change in the velocity of a wave when it crosses the boundary
between one propagating medium and another. If this transition is made at an
angle, one portion of the wave-front slows down or speeds up before the other, thus
bending the wave slightly. Radio waves are commonly refracted when they travel
through different layers of the atmosphere, whether it is highly charged ionospheric
layers 100 km and higher, or weather-sensitive area near the Earth surface. When the
ratio of the refractive indices of two media is great enough, radio waves can be
reflected, just like light waves striking a mirror.
The role of ionosphere in radio wave propagation can be discussed only in
terms of the different radio frequencies available for communication and in the light
of the existence of different ionospheric layers. Although the various methods used
confirmed the theories of Heaviside and Kennally, there were differences between the
results obtained by Professor Appleton and other investigators. It was discovered that
there was not one, but more than one reflecting layers in the ionosphere. The first
trials with pulse waves in 1925 by Breit and Tuve in America were successful in
that the method proved to be much more practicable. Since radio waves take 1
millisecond to travel 300 km, the height of the layer established from the first echo
in this case was found to be 300 km. The ionised layers were designated with letters
of the alphabet by E. V. Appleton.
The lowest layer known at a height of about 50 to 90 km being called the D
region because this is not strictly a layer but a relatively dense part of the
atmosphere where atoms are broken up into ions by sunlight that recombine
very quickly. The amount of ionisation therefore depends on the amount of sunlight
and the region has the effect of absorbing the energy from a radio wave, particularly
at frequencies in the band of 3 to 4 MHz and frequently as high as 7 MHz. High
frequencies (1.5-30 MHz) penetrate this layer, while low frequency (LF: 30-300
kHz) and medium waves are absorbed by this layer. To some extent LF and Very Low
Frequency (VLF: 3 to 30 kHz) are reflected during daytime.
The E-layer extends from an altitude of 100 km. Though sunlight is an
important factor for its existence, after sunset also it exists for some time. This layer
is responsible for evening and early night time propagation of medium waves (500
kHz to 1500 kHz) up to a distance of about 250 km. Propagation of lower short wave
frequencies, e.g. 2 MHz , up to distance of 2000 km at daylight time is due to this
layer. It has little effect at night.
F1 layer exists at an altitude of 200 km during daytime and its characteristics
are very similar to E-layer which merges into F2 layer at night. HF frequencies in the

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range of 1500 kHz to 30 MHz (i.e. 30,000 kHz) propagates through this layer during
daytime.
F2 layer is the most important layer, which exists at altitudes ranging from
250 to 400 km and HF long distance propagation round the clock is due to this layer.
The behaviour of this layer is influenced by the time of the day, by season and by
sunspot activity. F2 layer was formerly known as Appleton layer. This layer has a
high ionization gradient. This layer exists both in the daytime and nighttime. Since at
such an altitude air density is extremely low, the free ions and electrons (due to the
action of ultraviolet radiation from the Sun) cannot recombine readily and so can
store energy received from the Sun for many hours; that is the reason the refractive
property of this layer changes only to a negligible extent during day and night.
The path which the short wave signal follows through the F2 layer is in reality a
curved one. Degree of the curve depends on the angle of incidence of the wave,
ionization gradient of the layer and frequency of the signal. Maximum distance for F2
layer reflection is about 4000 km.

Radio wave propagation by multiple reflection

A strong enough radio signal can propagate by multiple reflections. Having
returned to Earth from the ionosphere, the Earth’s surface acts as a reflector and
returns the signal back to the ionosphere, where it is reflected back to Earth yet again.
In this way radio signals can travel around the globe almost instantly! Because, radio
wave travels at a velocity of 3,00000 km per second in vacuum. Its velocity gets
changed very negligibly in a different medium, which is insignificant, because the
earth is a very small place with a radius of only 6000-km. Communication between
any two points on the earth is thus almost instantaneous.

Propagation characteristics of different ham radio bands

The problem of variable propagation conditions can be partially overcome by using
frequency diversity, in which an allotted wireless communication network is provided
with several frequency assignments spanning the high frequency (short wave) band of
frequencies. The radio operator can thus choose the channel that gives the best results
at any given time. The 1800 kHz (1.8 MHz or 160 metre band) band suffers from
extreme daytime D-layer absorption. Even at high radiation angles, virtually no signal
can pass through the F layer and daytime communication is limited to ground-wave
coverage. At night, the D layer quickly disappears and world-wide 160m
communication becomes possible via F2-layer skip. Atmospheric and man-made
noise limit propagation of this band. Tropical and mid-latitude thunderstorms
cause high levels of static in summer, making winter evenings the best time to
work long distance at 1.8 MHz.
The 3500 kHz (3.5 MHz or 80 metre band) is the lowest HF ham band, which
is similar to 160 m in many respects. Daytime absorption is significant, but not quite
as extreme as at 1.8 MHz. High-angle signals may penetrate to the E and F layers.
Daytime communication range is typically limited to 400 km, primarily via
ground-wave propagation. At night, signals are often propagated halfway around
the world. As at 1.8 MHz, atmospheric noise is a nuisance, making winter the most
attractive season for the 80 m. The 7000 kHz (7 MHz or 40 metre) band is useful for

107
daytime communication up to a distance of 800 km via E and F layers. Long
distance world-wide communication takes place in this band through F2 layer. The 10
MHz or 30 metre band is unique because it shares characteristics of both daytime and
night-time bands. Communication up to 3000 km is typical during daytime, and this
extends halfway around the world. The band is generally open via F2 on a 24-hour
basis. Unfortunately, the 10 MHz band is not yet released to the Indian ham radio
operators.

Skip distance, skip zone and dead zone

Skip distance, skip zone and dead zone are importantly associated with ionospheric
propagation. If we take a simple case, where a radio receiver located at a distance of
200 kilometres away from the wireless transmitting station is unable to receive the
radio signal, but another receiving station (the intended station) at a greater distance
(say 1000 km) is able to receive the radio signal perfectly, then distance of the
intended receiver from the transmitter is termed as 'skip distance'.
Despite being located closer to the radio transmitter, one of the receiving
stations is not able to receive the radio signal. This is because of the fact that this
receiving station is located in a skip zone or dead zone. The ground waves
transmitted from the transmitter are unable to reach this receiving station
because of signal attenuation by the earth or are stopped by the Earth's
curvature and the sky wave will not reach the receiver, because it bounces again
more than 200 kilometers way. So some 'blind zones' are formed and if the receiver
is located in that blind zone it will receive no signal or very weak signal.
The above situations are particularly pronounced in high frequency (HF)
signals where ground waves fade away and skip distances may be a thousand
kilometers or more. In such a situation, another station (who is not in skip with the
station in blind zone) can relay the message to the receiving station located in the
blind zone.

How do the hams overcome the variable propagation conditions of the

ionosphere and the problem of skip?
The problem of variable propagation conditions can be partially overcome by using
frequency diversity, in which an allotted communication network is provided with
several frequency assignments spanning the High Frequency (HF) band of
frequencies. The ham can choose the frequency that gives the best results at any given
time. Similarly if a station is in skip at a particular frequency, another workable
frequency can be found out.

What is line-of-sight propagation?

The radio frequencies above 30 MHz has the tendency to penetrate the ionosphere
making them unsuitable for long distance propagation. So, the range of frequencies
from 30 to 300 MHz (also 300 MHz and above), which are placed under the Very
High Frequency (VHF) category are mainly used for line-of-sight communication.
The most common example of line-of-sight communication is the TV Telecast. Ham
radio operators use VHF frequencies in the range of 144-148 MHz (as well as 50
MHz in some countries) for line of sight communication.

108
 A TV transmission tower is made as tall as possible so that its signals can have
a wide area of coverage. To receive a TV telecast, we have to turn our TV antenna
(known as a Yagi antenna) towards the TV transmission tower. In areas where the TV
transmission tower is located at a far away place from a viewer, the viewer has to
increase the height of his TV receiving antenna. This means that both the transmitting
and receiving antenna should literally see each other to make the communication
effective. Otherwise there should be some means to redirect the signal back to the
receiver. Artificial Satellites in space (which houses active electronic relaying
device), terrestrial relay station and passive reflectors (the metallic plates we see
above the hills) are employed to extend the VHF coverage. Line-of-sight
communication is considered reliable within a short distance (or even for long
distance communication if artificial communication satellites are employed), because
instead of relying on the ionosphere (whose propagation conditions are not under
human control), relay stations (known as repeater station) can be set up on tall towers.
The relay station can cover a certain area most reliably round the clock. Different
services employing VHF for communication also have their own repeater station.
Another advantage of VHF is that the size of the VHF equipment is very small
(because of its low power as well as miniaturization in the circuit design). A VHF
communication set is also popularly known as a Walkie-Talkie. We are certain that
the above description is sufficient to clear any doubt about the range of a Walkie-
Talkie !

A Passive reflector

What are the two phenomenae significant in line-of-sight reception?

In case of line-of-sight reception, sometimes there may be two components of the
signal. One is the direct signal and other may be the signal reflected from the
ionosphere (e.g. in case of a 50 MHz signal, which rarely gets reflected by the
ionosphere). Both the signals leave the antenna with the same signal phase, but travel
different paths to the receiving antenna. These paths may be of different length.
Because the reflected signal suffers 180 degree phase reversal at the point of
reflection, the two signals may aid or oppose each other in the receiving antenna. The

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resultant signal may be stronger or weaker than the direct path signal alone, which is
not desirable.
The problem arising out of the undesirable phase reversal phenomenon
can be overcome by varying the height of the antenna.

What is the temperature inversion phenomenon as applicable to the line-

of-sight communication?
The line-of-sight propagation is limited to the optical horizon and it is only about 75
km for frequencies above 30 MHz; but it is found that in the spring, or sometimes in
summer, this line-of-sight propagation extends to about 500 kms. This is due to the
presence of layer of hot, dry air above a layer of cool, moist air. The direct waves are
bent back which otherwise pass over the receiving antenna.

What is 'Grey line' propagation as applicable to line-of-sight

communication?
It has been observed that around sunspot maximum years at about 11-years intervals,
the daytime F2 layer, roughly 250-400 kms above the surface of the Earth, can often
open long distance paths of frequencies up to and beyond 50 MHz. In periods of low
sunspot activity very few long-distance paths are open above 25 MHz. Radio
amateurs, whose transmitters are so much less powerful than those used for
broadcasting, have come to recognise the importance of what is called 'grey line'
propagation. This takes the form of reliable but brief long-distance paths that open
between places where the times of dawn and dusk, dawn and dawn or dusk and dusk
roughly coincide, giving rise to the possibility of extended 'one-hop' propagation due
to layer entrapment brought about by tilts in the F-layer, as the lower F1 and higher F2
layers combine or separate.

What is a critical frequency?

The whole spectrum of radio frequencies suffer various degrees of refraction by the
ionosphere. Waves which are very slightly refracted can not return back to the Earth
and if not having adequate power, get absorbed into the ionosphere. Those having
sufficient power can penetrate the ionosphere depending upon the degree of
refraction. The amount of refraction is inversely proportional to the frequency of
the wave. Obviously, lower the frequency, greater is the refraction and higher the
frequency, lower is the refraction. Though a greater refraction should cause the
frequency to be returned back to Earth, it does not happen always. During day time,
the D layer (It is the lowest region of the ionosphere at a height of about 50 to 90 km.
It is not strictly a layer but a relatively dense part of the atmosphere where atoms are
broken up into ions by sunlight that recombine very quickly) absorbs most of these
waves prohibiting their entry into the E and F layers and hence does not get reflected.
If the frequency of a wave transmitted directly upward is steadily increased, a
point would be reached where the wave would pass right through the ionosphere.
The frequency at which this occurs is called the critical frequency. All frequencies
higher than this will not be returned to Earth.

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What is a beacon?
The beacon is nothing but a radio signal, usually in coded form transmitted from a
particular station to identify itself. The usefulness of the beacons is that they provide
indication of propagation conditions between any two locations worldwide. They also
act as in-band frequency reference for wireless experiments experimenting with
transmitters. They also provide reliable checking facility for beam antennae.

What are differences between fade-out and fading?

Fade-out
It is the gradual phenomenon, that take place with the change of time of the day.
Fadeout of radio signal is related to the ionization gradient of the ionosphere, which
decreases in absence of sunlight. Since ionization is intense during day light hours,
higher frequencies of the short wave spectrum can be used during daylight hours. As
the night approaches, signal strength at that higher frequency decreases. Using a
frequency at the lower edge of the HF spectrum will yield satisfactory result against
this fadeout.

Fading
As distinct from fade-out, fading is the constant variation of the received strength of
radio wave. To the listener it appears as gradual rising and falling of the volume. The
signal waxes and wanes and at times even drops below usable values. This
phenomenon is manifested chiefly in long-distance transmission. It is caused by
multiple reflections from the ionosphere which cause two or more waves from the
same transmitter travel over different paths of different lengths and hence differ in
phase and amplitude when they arrive at the receiving aerial.

G. Aerials
A General Note on Aerials
Aerial or antenna is a device, which acts as the mouth and ear of a radio transmitter or
receiver respectively. Though we don't notice any external aerial in many of the
commercial radio sets, they in fact, have aerials in built within the cabinets holding
their electronic circuitry. But a ham radio operator is mainly concerned with an
external outdoor antenna without which he can't expect to radiate radio energy into
space from his radio transmitter. Similarly, without an external outdoor antenna, his
radio receiver will not be able to pick up the radio waves speeding across the sky. A
radio receiver might not need an external outdoor aerial to receive high power radio
transmissions. But most of the ham radio transmitters use considerably low power
(compared to the broadcast radio stations) which necessitates the use of outdoor
aerials. A low power transmitter with an efficient antennae system or a less sensitive
receiver with efficient antennae system can be made to work beyond imagination!
The aerials are usually made out of metallic rods or wires which are cut into
specific lengths. The aerial should not be placed behind any obstruction, conducting
materials such as tin-roof, ferro-concrete and to lesser extent foliage when wet. The

111
aerial should be as high as practical above the ground and grounded objects such as
metal roofs, power or telephone wires etc.

Different types of antenna system used by ham radio operators:

(1) Horizontal Dipole,

(2) Inverted -V dipole,
(3) Yagi beam,
(4) Ground plan vertical,
(5) Cubical quad

Horizontal dipole is a very popular antenna, which is also easier to construct

and erect. Two supporting structures are (e.g. two bamboo poles) required to erect a
simple horizontal dipole antenna, whereas an inverted ‘V’ dipole antenna requires
only a single pole which supports the feed-point of the dipole.

Working function of a horizontal dipole antenna

A horizontal dipole antenna is a resonant antenna, which is half-wavelength long.
Resonant circuits are well-known in radio engineering as combination of coils and
capacitors, which cause a signal gain at certain frequencies. The same is applied to a
half-wave dipole antenna.

It consists of two straight wire or rod sections, each 1/4 wave long and
positioned in one line (collinear). The antenna is fed in the centre by a coaxial cable
having a characteristics impedance of 50 Ohms or 75 Ohms.
The maximum radiation direction is perpendicular to the axis from the middle
point. The cause of directional radiation by a resonant 1/2 wave dipole antenna is that
the radiation intensity is proportional to the square of the current in the antenna, and
in the dipole current is maximum at the middle; hence the maximum radiation line
passes through the middle of the antenna perpendicularly.

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Why half-wave dipoles are fed at the centre?
Most half-wave dipoles are fed at the centre, because in a half-wave resonant dipole,
maximum current point is at the centre of the antenna and this is the minimum voltage
point. It is easier to construct transmission lines for low voltage than for high voltage.
The other reason is that in a 1/2 wave dipole, the capacitive reactance and
inductive reactance cancel each other (the antenna being resonant), leaving resistance
only as net impedance. Under this condition, the antenna impedance is the resistance
between any two points equidistant from the centre along the antenna length making it
easier to match the transmission line impedance with the antenna impedance.

What is VSWR (Voltage Standing Wave Ratio) ?

When the transmission line does not match the load impedance (antenna impedance),
maximum transference of energy to the antenna is not possible. The energy fed down
the line is transferred to the antenna only partially; in fact, some is reflected back,
forming standing waves on the line. Every half-wave along the line, high-E (Voltage)
and Low-I (Current) points appear. Halfway between these two points will be Low-E
and High-I points.
The ratio of voltage across the transmission line at the high-E point to that at
Low-E points is called the VSWR.

E E
VSWR= max/ min

Or,
I I
SWR= max/ min

The SWR is also equal to the ratio of the characteristic impedance of the
transmission line to the impedance of the antenna (load), or vice versa. For example,
if the line has a characteristic impedance of 300 ohms and antenna impedance is 50
ohms, the SWR is 300/50, or 6. A higher SWR indicates a greater mismatch between
the transmission line and the antenna.

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 When the load (antenna) impedance matches the transmission line impedance,
there will be no standing waves.

SWR=1:1 or 1

VSWR is greater than one for a mismatched system and equal to one for a perfectly
matched system.
VSWR on a transmission line is caused by power being reflected back to the
transmitter from the antenna. If PF is the forward power and PR is the reflected power
measured in watts by a directional wattmeter, then VSWR can also be calculated by
the formula:

What is 'radiation resistance'?

When an antenna is excited into oscillation by a RF source, it radiates energy into
space acting as a source of power. The antenna, which is the source of power must
have an internal resistance or impedance.
We have-
Power, P=I2R,
Where I=current, R=resistance
P 2
Or, R= /I
So in case of the antenna, radiation resistance is the ratio of the radiated
power to the square of the centre current in the antenna.
Radiation resistance is also defined as a fictitious resistance, which when
substituted for the antenna would consume as much power as the antenna radiates.
Radiation resistance is also called 'Feed-point' impedance; in case of a
dipole antenna feed point impedance is nearly 73 Ohms.

Why impedance matching is necessary in an antenna and transmission

line system?
Impedance matching is of utmost importance so far as energy transference from the
transmitter to the antenna through the transmission line is concerned; because,
mismatching will prevent maximum output being radiated, i.e. if the transmission line
impedance doesn't match the antenna feed-point impedance, a part of the energy fed
down the line will be reflected back from the antenna causing standing waves on the
line; it makes the system inefficient.
Mismatching a transmission line to an antenna results in the line at the
transmitter end appearing to have either inductive reactance (Xi) or capacitive
reactance (Xc), which will detune the inductance-capacitance (LC) circuit to which it

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is coupled; mismatching should be avoided so that final stage of the RF amplifier is
not detuned.
In many of the commercial wireless equipment, mismatching should be
strictly avoided to prevent damage of the circuitry.

What is a current fed antenna?

There are many methods of feeding energy to an antenna. The antenna is said to be
current fed when excitation energy from the RF-generator is introduced to the antenna
at the point of high circulating currents. The example is a 1/2 wave dipole antenna. In
this case, the 1/2 wave antenna is cut in two parts at the midpoint and energy is fed by
co-axial transmission line.
In a dipole antenna maximum current flows through the middle point,
hence it is current fed antenna with a characteristic feed point impedance of about
73 ohms, which is considerably small as compared to end point impedance of the
antenna. Midpoint is the low-voltage point.

What is a voltage fed antenna?

When the excitation energy from the RF source is introduced at the point of maximum
voltage, the antenna is said to be voltage fed antenna. The example is the 1/2 wave
unsplitted antenna excited by a resonant R-F line. Voltage changes at this point excite
the antenna into oscillation. The impedance at the end of the antenna is high or it is
the high impedance point.
Any multiple of a 1/2 wave resonant antenna may be end-fed by using a tuned
feeder system leaving one end of the feed-line unconnected. This antenna is also
called Zepp (used earlier on Zeppelins) antenna.

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Different types of antenna system impedance matching procedure
(a) Using the proper transmission line for each particular antenna is a way of
achieving impedance matching. For example, a 1/2 wave dipole has a midpoint
impedance of 73 ohms, so coaxial cable transmission line which has a
characteristic impedance of 75 ohms is used to feed the R-F energy into the
antenna.

(b) Delta match: This type of matching procedure is used with an unsplitted 1/2
wave dipole antenna; the dipole being resonant, its capacitive reactance (Xc)
and inductive reactance (XL) cancel each other, leaving resistance only as net
impedance. Under this condition, the antenna impedance is the resistance
between any two points equidistant from the centre and thus transmission lines
having characteristic impedance of 300 to 600 ohms be used by getting two
points of the antenna to feed where it offers a feed point impedance equal to
transmission line impedance.
To do so, it is essential to spread out the feeders at the antenna end.
The formula used to make this type of matching are :
B= (0.25 x Wavelength)/2; where B is the distance between the two feed point
which will offer 600 ohms impedance.
And C=(0.32 x wavelength)/2, where C is the vertical distance upto which
spreader should be spread (the inclination).

(c) Stub Match : A shorted stub of 1/2 wave length or open stub of 1/4 wave can
be connected to the splitted dipole. Here the low midpoint impedance of 73
ohms of the dipole is repeated at the close end of the stub; but there are cetain
points on the stub which would offer as high as 600 ohms impedance yet
matching with 73 ohms feed point.

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(d) Gamma Match: Here outer sheath of the 75 ohms coaxial cable is connected
to the middle point of the unsplitted dipole, while the inner conductor is
connected to a point through a capacitor to cancel inductive reactance, so that
antenna impedance at feed point is 75 ohms. Gamma match is slightly
unbalanced.

(e) T-Match: In this type of impedance matching, two coaxial cables are held
side by side and both their outer sheaths are connected to the midpoint of the
unsplitted dipole, while two points are chosen on the dipole where inner
conductors going parallel to each other (of the coaxial) are connected.

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(f) 1/4 wave transmission line impedance matching device: A 1/4 wave line
can act as an impedance matching device between high and low impedance
circuits if it has the proper intermediate impedance found from the formula: Z
= /Z1.Z2
Where Z1 = antenna feedpoint impedance; Z2 main transmission line
impedance. When we want to match a 300 ohms transmission line to a 70
ohms feed point impedance dipole antenna, then the 1/4 wave transmission
line connected between both the system should have
Z= / 300 x 70 = 145 ohms

What is a Yagi antenna?

When a half wave dipole antenna consists of one or more parasitic arrays, the antenna
becomes parasitic beam antenna, named as "Yagi" after its designer Proff. Yagi,
Japan.
The antenna consists of mainly three elements, the 1/2 wave splitted dipole
driven element (either folded or straight), in front of this driven element is the 5%
shorter director element, back of the driven element is the 5% longer reflector. All
the elements can be assembled on a single conducting boom. This antenna beams
radio signals in the direction of the director and theoretically no signals to the
backward direction. Yagi antenna is most commonly used for very high frequency
(VHF) work. Because of shorter wavelengths, it is easier to construct a Yagi antenna
for VHF work than the HF work. Instead of using a folded dipole (the driven
element), as shown below in the diagram, the driven element can be kept unfolded
(straight). In that case, the feed-point impedance of the antenna would be around 75
Ω.

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 Part-IV

Study material to learn Morse Code

The International Morse Code

The telegraphic code used for amateur radio telegraphic communication is the
International Morse Code consisting of dot (.) and dashes (-). In Morse Code a dot (.)
is made by pressing the telegraph key down and allowing it to spring back up again
rapidly; and for making a dash (-), the key is held down for a bit longer period. It is
said that a dash(-) unit is three time longer than a dot(.) unit. The Morse Code in fact
consists of combinations of aurally distinguishable tones. A tone produced for short
duration is a dot tone and a tone three times longer than this tone is a dash tone.

A Morse Key

To practice Morse Code sending, a novice can use a small device called the
'Code Practice Oscillator' (CPO). This is a small electronic circuit capable of
generating a sinusoidal audio tone when a key (or switch) is made 'on' or 'off'
manually. The circuit of a CPO shown below can be easily assembled by a novice.

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 A Code Practice Oscillator (CPO) circuit

It is advisable not to start practice sending the Morse code until the novice is
proficient in receiving Morse code. For receiving practice, you have to rely on a ham
radio operator who can send/generate Morse code using a CPO or you can try to find
out Morse Code transmissions over your radio receiver. Morse code practice cassettes
and multimedia computer software are nowadays available. Mere gaining confidence
in sending does not qualify you to be an expert receiver! In fact you may not be able
to receive a single letter in Morse code even if you gained a sending proficiency of 12
words Per Minute (WPM)! Remembering the Morse codes is an art by itself. It
involves a rhythmic response in your mind. Try to remember the combination of dot
(.) and dashes (-) by their sound and not as a group of printed symbols. For this
purpose, a dot (.) is referred to as a 'di' and a dash (-) as a 'dah'. A 'di' coming at the
end of the combination is pronounced as 'dit'
The letter 'R' is represented by '. - .' (di dah dit) in Morse code. The time taken
to produce the sound equivalent to one 'di' or 'dit' (dot) is taken as unit time and called
a dot unit. A 'dah' is approximately of three dot units length and the space between
two sound elements of a letter is one dot unit, i.e. silence period is one dot unit. The
space between two letters or characters is equal to three dot units. The space between
two words is equal to five dot units. The word 'cat' can be represented as -.-. .- - (dah
di dah dit di dah dah)

Morse Code speed

The minimum speed to qualify for a Grade II licence is 5 words per minute (5 wpm).
5 letters/characters constitute a word. A message containing 125 letters when sent in 5
minutes or when received in 5 minutes makes your speed 5 wpm.

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125
/5=25 words in 5 minute; i.e. 5 words per minute.

In fact Morse code devised by Samuel F.B. Morse (1791-1872) is a primitive

type of digital communication which still works efficiently in this era of
microprocessors and computers.
Morse code is also called CW, i.e. Continuous Wave, in the sense that a
constant amplitude interrupted radio frequency wave is transmitted; interruption being
made in conformity with the code.

Analog and Digital methods

The electrical telephone and telegraph are very simple examples which illustrates the
difference between the analog and digital methods. In the telephone, the information
is transmitted from one end to the other via a current which varies continuously as
direct equivalent of sound waves striking the microphone-the analog approach. In the
telegraph, the information is encoded (cyphered) and sent as a sequence of current/no
current pulses illustrating the digital approach.

Why Morse code is still in use?

It was deemed important that ham radio operators prove an ability to transmit and
receive in Morse Code signals. In the last 50 years, however, the International
Telecommunication Union (ITU) has reviewed and modified the amateur Morse
Code requirement at every international conference capable of changing it. In 1947
(Atlantic City) the ITU agreed that Morse proficiency should only be required when
the operation took place on frequencies below 1000 MHz (1 GHz). At WARC-59
(The 1959 World Administrative Radio Conference) this level was dropped to144
MHz. A further reduction was made at WARC-79 to its presents 30 MHz.
Despite the capability of voice communication, Morse code is still in use. One
important reason is that a vast group of the radio amateurs still adore Morse code. A
ham radio operator employing digital communication techniques (like Packet
Radio, Radio Tele Typing-RTTY or AMateur Tele-printing Over Radio-
AMTOR) in his ham radio operation treats Morse code with much the same
affection he has for those modern innovations!
A ham radio operator wearing his headphone and the Morse Key in hand can
send messages silently without disturbing his family members who might be sleeping
comfortably!
Another reason is that short wave radio telephone (voice) signals often suffer
very rapid and deep fading; two frequencies separated by only a few hertz, fade at
different times. To overcome this, modulated code tones are transmitted. The situation
is now that under severe conditions of fading, the carrier frequency may fade out
completely but one or the other side band may remain strong as a result a
continuously readable signal is received. This is the reason that we hear a band full of
exotic sounding CW call-signs at any time of day or night. When the a band appears
to be dead, and we can barely copy phone signals, the band remains alive with many
CW signals.

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Why this be so?
(i) The answer is that to communicate human speech, a wider bandwidth is required
than that of the CW signal. With a smaller bandwidth the 'signal to noise ratio' of
the receiver is significantly improved, and the threshold at which signals can still
be received above the noise level is therefore extended.
(ii) Also, it is possible for the human ear to be able to resolve CW signals which are
only marginally above the noise level, whereas SSB signals of the same signal
level could not be copied. It has been suggested that CW has an advantage of
approximately 20dB over SSB signals. A narrow band-pass filter improves the CW
reception.

How to learn Morse Code?

Many newcomers seek exemption from 'tiresome' Morse test for Short wave
operation. This is unfortunate as the Morse code is the key to enter into the world of
ham radio with a very little monetary investment. A novice can assemble a simple
Morse code transmitter with lesser technical hurdles than that of a SSB Voice
transmitter. Morse code can be learnt easily if we use certain techniques to remember
the codes. Learning the Morse code can also be considered as an entirely personal
venture embarked upon by alone. Following points should be kept in mind while
learning the Morse code-
(1) Try to remember the codes from their sound.
(2) Don’t begin with a practice to send. Sending is much easier compared to
receiving.
(3) During receiving of a message, don’t write down the ‘dot’ and ‘dash’
combinations. Directly write down the letters in running hand. Don’t bother to
know the content of the message. Just continue writing the letters one by one
and leave a space when you are not sure about the letter. If you wait
wondering about what the letter was, you would get stuck and in the process
many letters would pass by you, which you would not be able to jot down.

THE INTERNATIONAL MORSE CODE

A ._ J .___ S ... 1 .____

B _... K _._ T _ 2 ..___
C _._. L ._.. U .._ 3 ...__
D _.. M __ V ..._ 4 ...._
E . N _. W .__ 5 .....
F .._. O ___ X _.._ 6 _....
G __. P .__. Y _.__ 7 __...
H .... Q __._ Z __.. 8 ___..
I .. R ._. 9 ____.
0 _____

PUNCTUATIONS

. (Period) ._._._ (AAA)

, (Comma) __..__ (MIM)
? (Question mark) ..__.. (IMI)
; (Semicolon) _._._. (NNN)

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- (Hyphen) _...._ (BA)
Error sign ........ (8 dots)
Sentence separation indicator _..._ (BT)
End of transmission of a message ._._. (AR)
Invitation to transmit _._ (K)
Wait ._... (AS)
End of work ..._._ (VA)

Almost all the letters/characters and punctuation marks can be arranged in

certain groups which can used to show the resemblance between/among the
combination of dot and dashes. For example the letter 'A' (. _ ) is the opposite of 'N'
(_ .). Similarly, the letters A, U, V and the character 4 can be made into a group
which shows a definite sequence. Given below is a table of such combinations.

A . _ T _ N _ . E .
U . ._ M __ D _ .. I ..
V . .._ O ___ B _... S ...
4 . ..._ H ....
5 .....
W .__ Y _.__ K _._ P .__.
G __. Q __._ R ._. X _.._
L ._.. A ._ D _.. B _...
F .._. N _. U .._ V ..._

Part-V

Safety Measures in a Ham Radio Shack

Electricity is one of the most magnificent discoveries that the mankind has achieved
since the dawn of civilization. We are now wholly dependent on this wonder of
science. Without electricity our life will become miserable and probably the life will
come to a standstill. It is the backbone of an industrialized society without which
progress of a society can't even be dreamt of. Functioning of all the fields of science
are wholly dependant on the availability of electricity including your ham radio!
While electricity has made our life full of comfort and ease, it has also the potentiality
to create heavy destruction if we do not take adequate precautions against its potential
ills. A casual attitude towards the electricity should always be avoided.

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 The ham should keep his wireless equipment in a protected place, so that, it
can not be operated by any unauthorized person in his absence. All the equipment
should be properly installed and precaution should be taken so that they don't create
electrical hazards. For this and the safety of the other people in the house, equipment
should have proper ground connection (an alternative path to the Earth). Though the
switch board sockets have the facility to insert a three pin electrical plug (the male
plug from our equipment), the wire connecting to the ground from the third hole of
the socket may remain disconnected somewhere without our knowledge. This may
create a risk to your life because the electrical equipment's current carrying wires are
vulnerable to insulation breakdown due to many reasons.

Under such circumstances, if a current carrying wire touches the metallic

portion of the equipment, current will start flowing in that portion also. Under such a
situation, if we touch an electrical gadget housed in a metallic enclosure, we may get
electrocuted as well! In fact electrical currents seek for the paths of low resistance. In
the above situation, if we are bare footed, then these electrical currents will find their
easiest path to the Earth (Ground) through our body and simulate a close circuit
situation. Our body will heat up (because the human body too offers resistance to the

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flow of current) and we will die! In a different situation where the metallic portion of
the electrical gadget is properly grounded with the help of a good conducting wire
(e.g. copper), even if we touch the current carrying metallic portion, most of the
current will flow through that grounded copper wire only causing less damage to our
body. A part of the current will still find their path to the ground through our body
because we are still bare footed! So the highest safety measure is to wear shoes made
of insulated material (which do not conduct electricity) and keep us separated from
the ground (the Earth). In this situation, even if we accidentally touch the current
carrying metallic portion of the electrical gadget, current will not able to find their
path in to the ground through our body and we shall remain safe. In no case, the
'phase' (current carrying) and 'neutral' wires should be touched by your hand
simultaneously. Doing so will create the most potential risk to your life, because,
current from 'phase' to 'neutral' will now flow from one hand to the other hand (if you
use both your hands to touch the 'phase' and 'neutral' !) through your body and you
will be getting killed in the process!
So, always:
1. Check for proper ground connection in the electrical wiring of the house.
2. If possible connect an extra conducting wire to the ground (you can tightly tie
the wire on to a water pipe) from the metallic enclosure of the electrical gadget.
3. Don't touch electrical gadgets with wet hand. Water reduces the resistance of
the skin of our body and as a result electrical currents find their easy entry into our
body!
4. Always wear insulated shoes (rubber, plastic etc.)
5. A dry wooden board can be kept on the floor which will provide additional
insulation.
6. The electrical device should have a 'fuse' as per the current rating of the device.
For example, if the equipment is designed to allow a current of 5 ampere, the 'fuse'
should also be rated 5 ampere. Any more current due to short circuit will blow the
fuse and inactivate the equipment. This will prevent further damage of the
equipment and other electrical wiring will remain safe.
7. There should be a main switch (called the "Big Switch"!) at your easy reach.
While closing down your ham radio operation, this switch should be pulled to
disconnect all the equipment at the same time. That is why, in ham terminology,
many operator's use the phrase "Pulling the Big Switch" to indicate that he is
closing down his station!
8. Now-a-days, miniature circuit breaker switches (MCB) are also available. This
type of switches provide safety to the electrical gadgets connected to the electrical
sockets by automatically disconnecting them from the current in the event of a
short circuit in the electrical wiring.
9. The fuses in the electrical meter box should not be tempered with. A blowing
fuse indicates that an electrical gadget is drawing more current than its
specification. Alternatively, you may be using too much of electrical gadgets in
your house resulting in a current flow which exceeds your allotted rating. In such
a situation, if you increase the thickness of the fuse wire to prevent it from
frequently burning down, the whole electrical wiring of your house will at the risk
of burning down.

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 AMATEUR RADIO EXAM QUESTION PAPER SAMPLE
RULES & REGULATIONS -Operating procedures
1. Which emission mode must be used to obtain assistance during a disaster?
a) Only SSB
b) Only SSB and CW
c) Any mode
d) Only CW
2. What should you do if a CW station sends "QRS" when using Morse code?
a) Send slower
b) Change frequency
c) Increase your power
d) Repeat everything twice
3. What is the recommended way to break into a conversation when using phone?
a) Say "QRZ" several times followed by your call sign
b) Say your call sign during a break between transmissions from the other stations
c) Say "Break" "Break" "Break" and wait for a response
d) Say "CQ" followed by the call sign of either station
4. Which of the following 20 meter band segments is most often used for most data transmissions?
a) 14.000 – 14.050 MHz
b) 14.070 - 14.100 MHz
c) 14.150 - 14.225 MHz
d) 14.275 - 14.350 MHz
5. What action should be taken if the frequency on which a net normally meets is in use just before the net begins?
a) Reduce your output power and start the net as usual
b) Increase your power output so that net participants will be able to hear you
c) Ask the stations if the net may use the frequency, or move the net to a nearby clear frequency if necessary
d) Cancel the net for that day
6. Which of the following is an advantage when using single sideband as compared to other voice modes on the HF
amateur bands?
a) Very high fidelity voice modulation
b) Less bandwidth used and high power efficiency
c) Ease of tuning on receive
d) Less subject to static crashes (atmospherics)
7. What is an azimuthal projection map?
a) A world map projection centered on the North Pole
b) A world map projection centered on a particular location
c) A world map that shows the angle at which an amateur satellite crosses the equator
d) A world map that shows the number of degrees longitude that an amateur satellite appears to move westward
at the equator with each orbit
8. How do you call another station on a repeater if you know the station\'s call sign?
a) Say "break, break" then say the station's call sign
b) Say the station's call sign then identify your own station
c) Say "CQ" three times then the other station's call sign
d) Wait for the station to call "CQ" then answer it
9. The frequency of 40 Meter band in MHz is
a) 14 - 14.350
b) 7 - 7.2
c) 21 - 21.450
d) 15 - 15.400
10. Which sideband is commonly used in the VHF and UHF bands?
a) Upper Side Band
b) Lower side band
c) Vestigial side band
d) Double side band
11. When are you prohibited from helping a station in distress?
 a) When that station is not transmitting on amateur frequencies
b) When the station in distress offers no call sign
c) You are never prohibited from helping any station in distress
d) When the station is not another amateur station
12. What is a practical way to avoid harmful interference when calling CQ using Morse code or CW?
a) Send the letter "V" 12 times and then listen for a response
b) Keep your CQ to less than 2 minutes in length to avoid interference with contacts already in progress
c) Send "QRL? de" followed by your call sign and listen for a response
d) Call CQ at low power first; if there is no indication of interference then increase power as necessary
13. What does it mean when a CW operator sends "KN" at the end of a transmission?
a) Listening for novice stations
b) Operating full break-in
c) Listening only for a specific station or stations
d) Closing station now
14. Who is accountable if a repeater station inadvertently retransmits communications that violate WPC
rules?
a) The repeater trustee
b) The repeater control operator
c) The transmitting station
d) All of these answers are correct
15. Which of the following statements is true of the single sideband (SSB) voice mode?
a) Only one sideband and the carrier are transmitted; the other sideband is suppressed
b) Only one sideband is transmitted; the other sideband and carrier are suppressed
c) SSB voice transmissions have higher average power than any other mode
d) SSB is the only mode that is authorized on the 160, 75 and 40 meter amateur bands
16. Which layer of ionosphere disappears during night time?
a) F
b) E
c) D
d) C
17. When sending CW, what does a “C” mean when added to the RST report?
a) Chirpy or unstable signal
b) Report was read from S meter reading rather than estimated
c) 100 percent copy
d) Key clicks
18. How do you call another station on a repeater if you know the station\'s call sign?
a) Say "break, break" then say the station's call sign
b) Say the station's call sign then identify your own station
c) Say "CQ" three times then the other station's call sign
d) Wait for the station to call "CQ" then answer it
19. What does the Q signal "QSL" mean when operating CW?
a) We have already confirmed by card
b) I acknowledge receipt
c) We have worked before
d) Send slower
20. What is the first thing you should do if you are communicating with another amateur station and
hear a station in distress break in?
a) Continue your communication because you were on frequency first
b) Acknowledge the station in distress and determine what assistance may be needed
c) Change to a different frequency
d) Immediately cease all transmissions
21. How do you indicate you are looking for any station with which to make contact?
a) CQ followed by your call sign
b) RST followed by your call sign
c) QST followed by your call sign
 d) SK followed by your call sign
22. What should you transmit when responding to a call of CQ?
a) Your own CQ followed by the other station’s call sign
b) Your call sign followed by the other station’s call sign
c) The other station’s call sign followed by your call sign
d) A signal report followed by your call sign
23. What must an amateur do when making a transmission to test equipment or antennas?
a) Properly identify the station
b) Make test transmissions only after 10:00 PM local time
c) Notify the WPC of the test transmission
d) State the purpose of the test during the test procedure
24. What is the meaning of the procedural signal "CQ"?
a) Call on the quarter hour
b) New antenna is being tested (no station should answer)
c) Only the called station should transmit
d) Calling any station
25. What brief statement is often used in place of "CQ" to indicate that you are listening for calls on a repeater?
a) Say "Hello test" followed by your call sign
b) Say your call sign
c) Say the repeater call sign followed by your call sign
d) Say the letters "QSY" followed by your call sign
26. Why should you use the International Telecommunication Union (ITU) phonetic alphabet when identifying your
station?
a) The words are internationally recognized substitutes for letters
b) There is no advantage
c) The words have been chosen to represent amateur radio terms
d) It preserves traditions begun in the early days of amateur radio
27. Who is in charge of the repeater frequency band plan in your local area?
a) The local WPC monitoring office
b) Only WPC HO New Delhi
c) The recognized frequency coordination body
d) Amateur Radio society of India
28. What is the main purpose of repeater coordination?
a) To reduce interference and promote proper use of spectrum
b) To coordinate as many repeaters as possible in a small area
c) To coordinate all possible frequencies available for repeater use
d) To promote and encourage use of simplex frequencies
29. Which of these statements is true about legal power levels on the amateur bands?
a) Always use the maximum power allowed to ensure that you complete the contact
b) An amateur may use no more than 200 Watts PEP to make an amateur contact
c) An amateur may use up to 1500 Watts PEP on any amateur frequency
d) An amateur must use the minimum transmitter power necessary to carry out the desired communication
30. What is the proper way to break into a conversation between two stations that are using the frequency?
a) Say your call sign between their transmissions
b) Wait for them to finish and then call CQ
c) Say "Break-break" between their transmissions
d) Call one of the operators on the telephone to interrupt the conversation
31. Amateurs are forbidden to transmit about
a) Equipments
b) weather
c) Antennas
d) Third party messages
32. Standard time and frequency is transmitted on
a) 7050 KHz
 b) 14050 KHz
c) 21050 KHz
d) 10000 Khz

33. What is considered to be proper repeater operating practice?

a) Monitor before transmitting and keep transmissions short
b) Identify legally
c) Use the minimum amount of transmitter power necessary
d) All of these answers are correct
34. What rule applies if two amateur stations want to use the same frequency?
a) The station operator with a Restricted Grade license must yield the frequency to an General Grade licensee
b) The station operator with a lower power output must yield the frequency to the station with a higher power
output
c) No frequency will be assigned for the exclusive use of any station and neither has priority
d) Station operators in ITU Regions 1 and 3 must yield the frequency to stations in ITU Region 2
35. What should you do if you hear a newly licensed operator that is having trouble with their station?
a) Tell them to get off the air until they learn how operate properly
b) Report them to the WPC HO.
c) Contact them and offer to help with the problem
d) Move to another frequency
36. A3E indicates
a) SSB
b) AM-DSB voice
c) FM Voice
d) FSK
37. Line of sight propagation is the mode of communication in
a) LF
b) HF
c) MF
d) VHF
38. The wavelength of 300 MHz is in Meters is
a) 1
b) .1
c) 1.1
d) 0.01
39. Squelch control is used to eliminate
a) static interference
b) electrical disturbance
c) receiver noise
d) unwanted carrier
40. 4th harmonic of 2.5 MHz is
a) 10 MHz
b) 15 MHz
c) 8 MHz
d) 7.5 MHz
41 The UHF range is
a) 30 to 300 KHz
b) 300 to 3000 KHz
c) 3 to 30 GHz
d) 300 to 3000 MHz
42. Indian amateurs can communicate with other amateurs in
a) All countries
b) Countries permitted by ITU
c) Countries permitted by Indian Government
d) Countries permitted by Indian Amateur society
43. Restricted grade amateurs can communicate on 7 MHz in
a) A1
b) A3
c) F3
d) A3E
44. Lady amateurs are known as
a) XL
b) XYL
c) YL
d) LY
45. Minimum age to become an amateur is
a) 18 years
b) 14 years
c) 12 years
d) 16 years
46. All timing in the Log book should be in
a) IST
b) UTC
c) GMT
d) Local time
47. Amateurs should preserve their log for a period of
a) 6 months
b) 1 year
c) 2 years
d) 9 months from the date of the last entry
48. Q code to indicate time is
a) QRG
b) QRX
c) QTR
d) QSA
49. Test signal shall not be continued more than
a) 30 seconds
b) 1 minute
c) 2 minutes
d) 3 minutes
50. In India the standard time signal is broadcast by
a) ISRO
b) WPC
c) OCS
d) NPL
51. PANPAN transmitted thrice indicates
a) Distress
b) Emergency
 c) Urgency
d) Distress and emergency
52. The broadcast of music is allowed in amateur service
a) on request
b) when channel is free
c) never
d) only for testing
53. The abbreviation VA means
a) End of transmission
b) End of message
c) End of working
d) End of schedule
54. Swl's are permitted to transmit in the frequency band of
a) 7-7.1 MHz
b) 3.89-3.9 MHz
c) 144-146 MHz
d) None of these
55. The amateur license is renewed by
a) P & T
b) Ministry of communication
c) Monitoring stations
d) None of these
56. FM Broadcasting station emission is
a) A1E
b) A3E
c) J3E
d) F3E
57. Q code to indicate the location of a station is
a) QTL
b) QTH
c) QTN
d) None of these
58. Amateur station on a ship can contact another amateur on land on a frequency authorized to
a) the ship
b) amateur stations
c) by the ministry of communication
d) ships calling frequency
59. SOS transmitted three times indicates
a) urgency
b) distress
c) safety
d) none of these
60. All timings in logbook should be in
a) IST
b) GMT
c) UTC
d) Local time
ANSWER:-
1.c, 2.a, 3.c, 4.b, 5.c, 6.b, 7.b, 8.b, 9.b, 10.d, 11.a, 12.d, 13.c, 14.c, 15.b, 16.c, 17.a, 18.b, 19.b, 20.b, 21.a, 22.c, 23.a,
24.d, 25.b, 26.a, 27.b, 28.b, 29.d, 30.c, 31.d, 32.d, 33.a, 34.c, 35.c, 36.b, 37.d, 38.a, 39.c, 40.a, 41.d, 42.a, 43.d, 44.c,
45.a, 46.a, 47.b, 48.c, 49.a, 50.d, 51.c, 52.c, 53.c, 54.d, 55.b, 56.d, 57.b, 58.b, 59.b, 60.a,
BASIC ELECTRONICS
1. What is the name of a current that flows only in one direction?
a) An alternating current
b) A direct current
c) A normal current
d) A smooth current
2. What is the standard unit of frequency?
a) The megacycle
b) The Hertz
c) One thousand cycles per second
d) The electromagnetic force
3. How much voltage does an automobile battery usually supply?
a) About 12 volts
b) About 30 volts
c) About 120 volts
d) About 240 volts
4. What is the name of a current that reverses direction on a regular basis?
a) An alternating current
b) A direct current
c) A circular current
d) A vertical current
5. What is the term used to describe opposition to current flow in ordinary conductors such as wires?
a) Inductance
b) Resistance
c) Counter EMF
d) Magnetism
6. What instrument is used to measure the flow of current in an electrical circuit?
a) Frequency meter
b) SWR meter
c) Ammeter
d) Voltmeter
7. What instrument is used to measure Electromotive Force (EMF) between two points such as the poles of a battery?
a) Magnetometer
b) Voltmeter
c) Ammeter
d) Ohmmeter
8. What is the name for the distance a radio wave travels during one complete cycle?
a) Wave speed
b) Waveform
c) Wavelength
d) Wave spread
9. What term describes the number of times that an alternating current flows back and forth per second?
a) Pulse rate
b) Speed
c) Wavelength
d) Frequency
10. What does 50 hertz (Hz) mean?
a) 5000 cycles per second
b) 50 cycles per second
c) 5000 meters per second
d) 50 meters per second
11. Electromagnetic waves that oscillate more than 20,000 times per second as they travel through space are generally
referred to as what?
a) Gravity waves
b) Sound waves
c) Radio waves
d) Gamma radiation
12. How fast does a radio wave travel through space?
a) At the speed of light
b) At the speed of sound
c) Its speed is inversely proportional to its wavelength
d) Its speed increases as the frequency increases
13. How does the wavelength of a radio wave relate to its frequency?
a) The wavelength gets longer as the frequency increases
b) The wavelength gets shorter as the frequency increases
c) There is no relationship between wavelength and frequency
d) The wavelength depends on the bandwidth of the signal
14. What is the formula for converting frequency to wavelength in meters?
a) Wavelength in meters equals frequency in Hertz multiplied by 300
b) Wavelength in meters equals frequency in Hertz divided by 300
c) Wavelength in meters equals frequency in megahertz divided by 300
d) Wavelength in meters equals 300 divided by frequency in megahertz
15. What are sound waves in the range between 300 and 3000 Hertz called?
a) Test signals
b) Ultrasonic waves
c) Voice frequencies
d) Radio frequencies
16. What property of a radio wave is often used to identify the different bands amateur radio operators use?
a) The physical length of the wave
b) The magnetic intensity of the wave
c) The time it takes for the wave to travel one mile
d) The voltage standing wave ratio of the wave
17. What is the frequency range of the 2 meter band in the India?
a) 144 to 146 MHz
b) 222 to 225 MHz
c) 434 to 438 MHz
d) 50 to 54 MHz
18. What is used to convert radio signals into sounds we can hear?
a) Transmitter
b) Receiver
c) Microphone
d) Antenna
19. What is used to convert sounds from our voice into radio signals?
a) Transmitter
b) Receiver
c) Speaker
d) Antenna
20. What two devices are combined into one unit in a transceiver?
a) Receiver, transmitter
b) Receiver, transformer
c) Receiver, transistor
d) Transmitter, deceiver
21. What device is used to convert the alternating current from a wall outlet into low-voltage direct current?
a) Inverter
b) Compressor
c) Power Supply
 d) Demodulator
22. What device is used to increase the output of a 10 watt radio to 100 watts?
a) Amplifier
b) Power supply
c) Antenna
d) Attenuator
23. Which of the battery types listed below offers the longest life when used with a hand-held radio, assuming each
battery is the same physical size?
a) Lead-acid
b) Alkaline
c) Nickel-cadmium
d) Lithium-ion
24. What is the nominal voltage per cell of a fully charged nickel-cadmium battery?
a) 1.0 volts
b) 1.2 volts
c) 1.5 volts
d) 2.2 volts
25. What battery type on this list is not designed to be re-charged?
a) Nickel-cadmium
b) Carbon-zinc
c) Lead-acid
d) Lithium-ion
26. What is required to keep rechargeable batteries in good condition and ready for emergencies?
a) They must be inspected for physical damage and replaced if necessary
b) They should be stored in a cool and dry location
c) They must be given a maintenance recharge at least every 6 months
d) All of these answers are correct
27. What is the best way to get the most amount of energy from a battery?
a) Draw current from the battery as rapidly as possible
b) Draw current from the battery at the slowest rate needed
c) Reverse the leads when the battery reaches the 1/2 charge level
d) Charge the battery as frequently as possible
28. What formula is used to calculate current in a circuit?
a) Current (I) equals voltage (E) multiplied by resistance (R)
b) Current (I) equals voltage (E) divided by resistance (R) [I=E/R Ohm's Law]
c) Current (I) equals voltage (E) added to resistance (R)
d) Current (I) equals voltage (E) minus resistance (R)
29. What formula is used to calculate voltage in a circuit?
a) Voltage (E) equals current (I) multiplied by resistance (R) [E=I*R Ohm's Law]
b) Voltage (E) equals current (I) divided by resistance (R)
c) Voltage (E) equals current (I) added to resistance (R)
d) Voltage (E) equals current (I) minus resistance (R)
30. What formula is used to calculate resistance in a circuit?
a) Resistance (R) equals voltage (E) multiplied by current (I)
b) Resistance (R) equals voltage (E) divided by current (I) [R=E/I Ohm's Law]
c) Resistance (R) equals voltage (E) added to current (I)
d) Resistance (R) equals voltage (E) minus current (I)
31. What is the resistance of a circuit when a current of 3 amperes flows through a resistor connected to 90 volts?
a) 3 ohms
b) 30 ohms (As per ohm's law R=E/I, Thus R = 90 Volts / 3 Ampere)
c) 93 ohms
d) 270 ohms
32. What is the resistance in a circuit where the applied voltage is 12 volts and the current flow is 1.5 amperes?
a) 18 ohms
b) 0.125 ohms
 c) 8 ohms
d) 13.5 ohms
33. What is the current flow in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms?
a) 9600 amperes
b) 200 amperes
c) 0.667 amperes
d) 1.5 amperes
34. What is the voltage across the resistor if a current of 0.5 amperes flows through a 2 ohm resistor?
a) 1 volt
b) 0.25 volts
c) 2.5 volts
d) 1.5 volts
35. What is the voltage across the resistor if a current of 1 ampere flows through a 10 ohm resistor?
a) 10 volts
b) 1 volt
c) 11 volts
d) 9 volts
36. What is the voltage across the resistor if a current of 2 amperes flows through a 10 ohm resistor?
a) 20 volts
b) 0.2 volts
c) 12 volts
d) 8 volts
37. What is the current flowing through a 100 ohm resistor connected across 200 volts?
a) 20,000 amperes
b) 0.5 amperes
c) 2 amperes
d) 100 amperes
38. What is the current flowing through a 24 ohm resistor connected across 240 volts?
a) 24,000 amperes
b) 0.1 amperes
c) 10 amperes
d) 216 amperes
39. What is the formula used to calculate electrical power in a DC circuit?
a) Power (P) equals voltage (E) multiplied by current (I)
b) Power (P) equals voltage (E) divided by current (I)
c) Power (P) equals voltage (E) minus current (I)
d) Power (P) equals voltage (E) plus current (I)
40. How much power is represented by a voltage of 13.8 volts DC and a current of 10 amperes?
a) 138 watts
b) 0.7 watts
c) 23.8 watts
d) 3.8 watts
41. How much power is being used in a circuit when the voltage is 120 volts DC and the current is 2.5 amperes?
a) 1440 watts
b) 300 watts
c) 48 watts
d) 30 watts
42. How can you determine how many watts are being drawn by your transceiver when you are transmitting?
a) Measure the DC voltage and divide it by 60 Hz
b) Check the fuse in the power leads to see what size it is
c) Look in the Radio Amateur's Handbook
d) Measure the DC voltage at the transceiver and multiply by the current drawn when you transmit
43. How many amperes are flowing in a circuit when the applied voltage is 120 volts DC and the load is 1200 watts?
a) 20 amperes
b) 10 amperes
 c) 120 amperes
d) 5 amperes
44. How many milliamperes is the same as 1.5 amperes?
a) 15 milliamperes
b) 150 milliamperes
c) 1500 milliamperes
d) 15000 mill amperes
45. What is another way to specify the frequency of a radio signal that is oscillating at 1,500,000 Hertz?
a) 1500 kHz
b) 1500 MHz
c) 15 GHz
d) 150 kHz
46. How many volts are equal to one kilovolt?
a) One one-thousandth of a volt
b) one hundred volts
c) one thousand volts
d) one million volts
47. How many volts are equal to one microvolt?
a) one one-millionth of a volt
b) one million volts
c) one thousand kilovolts
d) one one-thousandth of a volt
48. How many watts does a hand-held transceiver put out if the output power is 500 mill watts?
a) 0.02 watts
b) 0.5 watts
c) 5 watts
d) 50 watts
49. What will happen to the resistance if the temperature of a carbon resistor is increased?
a) It will increase by 20% for every 10 degrees centigrade
b) It will stay the same
c) It will change depending on the resistor's temperature coefficient rating
d) It will become time dependent
50. What type of capacitor is often used in power-supply circuits to filter the rectified AC?
a) Disc ceramic
b) Vacuum variable
c) Mica
d) Electrolytic
51. Which of the following is the primary advantage of ceramic capacitors?
a) Tight tolerance
b) High stability
c) High capacitance for given volume
d) Comparatively low cost
52. Which of the following is an advantage of an electrolytic capacitor?
a) Tight tolerance
b) Non-polarized
c) High capacitance for given volume
d) Inexpensive RF capacitor
53. Which of the following is one effect of lead inductance in a capacitor used at VHF and above?
a) Effective capacitance may be reduced
b) Voltage rating may be reduced
c) ESR may be reduced
d) The polarity of the capacitor might become reversed
54. What is the main disadvantage of using a conventional wire-wound resistor in a resonant circuit?
a) The resistor's tolerance value would not be adequate for such a circuit
b) The resistor's inductance could detune the circuit
 c) The resistor could overheat
d) The resistor's internal capacitance would detune the circuit
55. What is an advantage of using a ferrite core with a toroidal inductor?
a) Large values of inductance may be obtained
b) The magnetic properties of the core may be optimized for a specific range of frequencies
c) Most of the magnetic field is contained in the core
d) All of these choices are correct
56. How should two solenoid inductors be placed so as to minimize their mutual inductance?
a) In line with their winding axis
b) With their winding axes parallel to each other
c) With their winding axes at right angles to each another
d) Within the same shielded enclosure
57. Why might it be important to minimize the mutual inductance between two inductors?
a) To increase the energy transfer between both circuits
b) To reduce or eliminate unwanted coupling
c) To reduce conducted emissions
d) To increase the self-resonant frequency of both inductors
58. What is an effect of inter-turn capacitance in an inductor?
a) The magnetic field may become inverted
b) The inductor may become self resonant at some frequencies
c) The permeability will increase
d) The voltage rating may be exceeded
59. What is the common name for a capacitor connected across a transformer secondary that is used to absorb transient
voltage spikes?
a) Clipper capacitor
b) Trimmer capacitor
c) Feedback capacitor
d) Suppressor capacitor
60. What is the common name for an inductor used to help smooth the DC output from the rectifier in a conventional
power supply?
a) Back EMF choke
b) Repulsion coil
c) Charging inductor
d) Filter choke
61. What type of component is a thermistor?
a) A resistor that is resistant to changes in value with temperature variations
b) A device having a controlled change in resistance with temperature variations
c) A special type of transistor for use at very cold temperatures
d) A capacitor that changes value with temperature
62. What is the peak-inverse-voltage rating of a rectifier?
a) The maximum voltage the rectifier will handle in the conducting direction
b) 1.4 times the AC frequency
c) The maximum voltage the rectifier will handle in the non-conducting direction
d) 2.8 times the AC frequency
63. What are the two major ratings that must not be exceeded for silicon-diode rectifiers?
a) Peak inverse voltage; average forward current
b) Average power; average voltage
c) Capacitive reactance; avalanche voltage
d) Peak load impedance; peak voltage
64. What is the approximate junction threshold voltage of a germanium diode?
a) 0.1 volt
b) 0.3 volts
c) 0.7 volts
d) 1.0 volts
65. When two or more diodes are connected in parallel to increase current handling capacity, what is the purpose of the
resistor connected in series with each diode?
a) The resistors ensure the thermal stability of the power supply
b) The resistors regulate the power supply output voltage
c) The resistors ensure that one diode doesn't carry most of the current
d) The resistors act as swamping resistors in the circuit
66. What is the approximate junction threshold voltage of a silicon diode?
a) 0.1 volt
b) 0.3 volts
c) 0.7 volts
d) 1.0 volts
67. Which of the following is an advantage of using a Schottky diode in an RF switching circuit as compared to a
standard silicon diode?
a) Lower capacitance
b) Lower inductance
c) Longer switching times
d) Higher breakdown voltage
68. What are the stable operating points for a bipolar transistor that is used as a switch in a logic circuit?
a) Its saturation and cut-off regions
b) Its active region (between the cut-off and saturation regions)
c) Between its peak and valley current points
d) Between its enhancement and deletion modes
69. Why is it often necessary to insulate the case of a large power transistor?
a) To increase the beta of the transistor
b) To improve the power dissipation capability
c) To reduce stray capacitance
d) To avoid shorting the collector or drain voltage to ground
70. Which of the following describes the construction of a MOSFET?
a) The gate is formed by a back-biased junction
b) The gate is separated from the channel with a thin insulating layer
c) The source is separated from the drain by a thin insulating later
d) The source is formed by depositing metal on silicon
71. Which element of a triode vacuum tube is used to regulate the flow of electrons between cathode and plate?
a) Control grid
b) Heater
c) Screen Grid
d) Suppressor grid
72. Which of the following solid state devices is most like a vacuum tube in its general characteristics?
a) A bipolar transistor
b) An FET
c) A Tunnel diode
d) A varistor
73. What is the primary purpose of a screen grid in a vacuum tube?
a) To reduce grid-to-plate capacitance
b) To increase efficiency
c) To increase the high frequency response
d) To decrease plate resistance
74. What is an advantage of the low internal resistance of Nickel Cadmium batteries?
a) Long life
b) High discharge current
c) High voltage
d) Rapid recharge
75. What is the minimum allowable discharge voltage for maximum life of a standard 12 volt lead acid battery?
a) 6 volts
b) 8.5 volts
 c) 10.5 volts
d) 12 volts
76. When is it acceptable to recharge a carbon-zinc primary cell?
a) As long as the voltage has not been allowed to drop below 1.0 volt
b) When the cell is kept warm during the recharging period
c) When a constant current charger is used
d) Never
77. Which of the following is a rechargeable battery?
a) Carbon-zinc
b) Silver oxide
c) Nickel Metal Hydride
d) Mercury
78. What is impedance?
a) The electric charge stored by a capacitor
b) The inverse of resistance
c) The opposition to the flow of current in an AC circuit
d) The force of repulsion between two similar electric fields
79. What is reactance?
a) Opposition to the flow of direct current caused by resistance
b) Opposition to the flow of alternating current caused by capacitance or inductance
c) A property of ideal resistors in AC circuits
d) A large spark produced at switch contacts when an inductor is de-energized
80. Which of the following causes opposition to the flow of alternating current in an inductor?
a) Conductance
b) Reluctance
c) Admittance
d) Reactance
81. Which of the following causes opposition to the flow of alternating current in a capacitor?
a) Conductance
b) Reluctance
c) Reactance
d) Admittance
82. How does a coil react to AC?
a) As the frequency of the applied AC increases, the reactance decreases
b) As the amplitude of the applied AC increases, the reactance increases
c) As the amplitude of the applied AC increases, the reactance decreases
d) As the frequency of the applied AC increases, the reactance increases
83. How does a capacitor react to AC?
a) As the frequency of the applied AC increases, the reactance decreases
b) As the frequency of the applied AC increases, the reactance increases
c) As the amplitude of the applied AC increases, the reactance increases
d) As the amplitude of the applied AC increases, the reactance decreases
84. What happens when the impedance of an electrical load is equal to the internal impedance of the power source?
a) The source delivers minimum power to the load
b) The electrical load is shorted
c) No current can flow through the circuit
d) The source can deliver maximum power to the load
85. Why is impedance matching important?
a) So the source can deliver maximum power to the load
b) So the load will draw minimum power from the source
c) To ensure that there is less resistance than reactance in the circuit
d) To ensure that the resistance and reactance in the circuit are equal
86. What unit is used to measure reactance?
a) Farad
b) Ohm
 c) Ampere
d) Siemens
87. What unit is used to measure impedance?
a) Volt
b) Ohm
c) Ampere
d) Watt
88. Why should core saturation of a conventional impedance matching transformer be avoided?
a) Harmonics and distortion could result
b) Magnetic flux would increase with frequency
c) RF susceptance would increase
d) Temporary changes of the core permeability could result
89. What is one reason to use an impedance matching transformer?
a) To reduce power dissipation in the transmitter
b) To maximize the transfer of power
c) To minimize SWR at the antenna
d) To minimize SWR in the transmission line
90. Which of the following devices can be used for impedance matching at radio frequencies?
a) A transformer
b) A Pi-network
c) A length of transmission line
d) All of these choices are correct
91. Which of the following describes one method of impedance matching between two AC circuits?
a) Insert an LC network between the two circuits
b) Reduce the power output of the first circuit
c) Increase the power output of the first circuit
d) Insert a circulator between the two circuits
92. A two-times increase or decrease in power results in a change of how many dB?
a) 2 dB
b) 3 dB
c) 6 dB
d) 12 dB
93. How does the total current relate to the individual currents in each branch of a parallel circuit?
a) It equals the average of each branch current
b) It decreases as more parallel branches are added to the circuit
c) It equals the sum of the currents through each branch (Kirchhoff’s Current Law)
d) It is the sum of the reciprocal of each individual voltage drop
94. Capacitance is measured in
a) Amperes
b) watt
c) Farad
d) Coulombs
95. Frequency is
a) cycles per second
b) Kilo cycles per second
c) Cycles per minute
d) cycles per hour
96. Resonant frequency in a tuned circuit is equal to
a) 1/2piLC
b) 1/2pi√LC
c) 2pi√LC
d) 2pi√L+C
97. Power dissipated in a 400 Ohm resistor at 1 Amp is
 a) 40 Watts
b) 400 KW
c) 4 Watts
d) 400 Watts
98. Zener diode is used for
a) Rectification
b) Voltage regulation
c) Current regulation
d) Switching
99. Plate current in a diode flows only when the plate is
a) Negative with respect to cathode
b) positive with respect to cathode
c) when plate is at a lower voltage than cathode
d) both at same potential
100. 3 resistors of 2,3 & 4 ohms are connected in series. The voltage across the circuit is 9 V , the current drawn by 3
ohms resistor is
a) 1.5 Amps
b) 27 Amps
c) 1 Amp
d) 3 Amps
101. A superhetrodyne receiver is tuned to 555 KHz and its local oscillator at 1010 KHz . The image frequency will be
a) 1565 KHz
b) 455 KHz
c) 1465 KHz
d) none of these
102. 3 to 30 MHz band is known as
a) MF
b) LF
c) VHF
d) HF
103. The wavelength of a broadcast station at 1000 KHz is
a) 30 Meters
b) 300 Meters
c) 0.3 Meteors
d) none of these
104. The core of power supply transformer is laminated to
a) decrease impedance
b) increase impedance
c) decrease eddy current losses
d) none of these
105. In a resonant circuit
a) Xl = Xc
b) Xl > Xc
c) Xl < Xc
d) none of these
106. When frequency of a carrier is varied according to modulation the result is
a) frequency modulation
b) amplitude modulation
 c) product detection
d) none of these
107. The phase relationship between the input and output of a common emitter circuit in degrees is
a) 90
b) 180
c) 270
d) 0
108. The quartz crystal oscillator is known for its
a) linearity
b) stability
c) high output
d) flexibility
109. The effect of inter electrode capacitance of a triode is more predominant at
a) HF
b) VHF
c) LF
d) none of these
110. Which of the following is a characteristic of a liquid crystal display?
a) It requires ambient or back lighting
b) It offers a wide dynamic range
c) It has a wide viewing angle
d) All of these choices are correct
111. What is meant by the term MMIC?
a) Multi Megabyte Integrated Circuit
b) Monolithic Microwave Integrated Circuit
c) Military-specification Manufactured Integrated Circuit
d) Mode Modulated Integrated Circuit
112. What is a microprocessor?
a) A low powered analog signal processor used as a microwave detector
b) A miniature computer on a single integrated circuit chip
c) A microwave detector, amplifier, and local oscillator on a chip
d) A low voltage amplifier used in a microwave transmitter modulator stage
113. What safety feature does a power-supply bleeder resistor provide?
a) It acts as a fuse for excess voltage
b) It discharges the filter capacitors
c) It removes shock hazards from the induction coils
d) It eliminates ground-loop current
114. What components are used in a power-supply filter network?
a) Diodes
b) Transformers and transistors
c) Quartz crystals
d) Capacitors and inductors
115. What should be the minimum peak-inverse-voltage rating of the rectifier in a full-wave power supply?
a) One-quarter the normal output voltage of the power supply
b) Half the normal output voltage of the power supply
c) Double the normal peak output voltage of the power supply
d) Equal to the normal output voltage of the power supply
116. What should be the approximate minimum peak-inverse-voltage rating of the rectifier in a half-wave power
supply?
a) One-half the normal peak output voltage of the power supply
b) Half the normal output voltage of the power supply
c) Equal to the normal output voltage of the power supply
d) Two times the normal peak output voltage of the power supply
117. What should be the impedance of a low-pass filter as compared to the impedance of the transmission line into
which it is inserted?
a) Substantially higher
b) About the same
c) Substantially lower
d) Twice the transmission line impedance
118. What is an advantage of a crystal controlled transmitter?
a) Stable output frequency
b) Excellent modulation clarity
c) Ease of switching between bands
d) Ease of changing frequency
119. What type of receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier?
a) A super-regenerative receiver
b) A TRF receiver
c) A super-heterodyne receiver
d) A direct conversion receiver
120. What type of circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio?
a) Product detector
b) Phase inverter
c) Mixer
d) Discriminator
121. What portion of the AC cycle is converted to DC by a half-wave rectifier?
a) 90 degrees
b) 180 degrees
c) 270 degrees
d) 360 degrees
122. What portion of the AC cycle is converted to DC by a full-wave rectifier?
a) 90 degrees
b) 180 degrees
c) 270 degrees
d) 360 degrees
123. What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load?
a) A series of DC pulses at twice the frequency of the AC input
b) A series of DC pulses at the same frequency as the AC input
c) A sine wave at half the frequency of the AC input
d) A steady DC voltage
124. Which of the following is a characteristic of a Class A amplifier?
a) Low standby power
b) High Efficiency
c) No need for bias
d) Low distortion
125. For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal?
 a) SSB
b) CW
c) AM
d) All of these answers are correct
126. Which of the following is an advantage of a Class C amplifier?
a) High efficiency
b) Linear operation
c) No need for tuned circuits
d) All of these answers are correct
127. How is the efficiency of an RF power amplifier determined?
a) Divide the DC input power by the DC output power
b) Divide the RF output power by the DC input power
c) Multiply the RF input power by the reciprocal of the RF output power
d) Add the RF input power to the DC output power
128. Which of the following describes a linear amplifier?
a) Any RF power amplifier used in conjunction with an amateur transceiver
b) An amplifier whose output preserves the input waveform
c) A Class C high efficiency amplifier
d) An amplifier used as a frequency multiplier

ANSWER:-
1.c, 2.b, 3.a, 4.b, 5.b, 6.c, 7.b, 8.c, 9.d, 10.b, 11.c, 12.a, 13.b, 14.d, 15.c, 16.a, 17.a, 18.b, 19.a, 20.a, 21.c, 22.a, 23.d,
24.b, 25.b, 26.d, 27.b, 28.b, 29.a, 30.b, 31.b, 32.c, 33.d, 34.a, 35.a, 36.a, 37.c, 38.c, 39.a, 40.a, 41.b, 42.d, 43.b, 44.c,
45.a, 46.c, 47.a, 48.b, 49.c, 50.d, 51.d, 52.c, 53.a, 54.b, 55.d, 56.c, 57.b, 58.b, 59.d, 60.d, 61.b, 62.c, 63.a, 64.b, 65.c,
66.c, 67.a, 68.a, 69.d, 70.b, 71.a, 72.b, 73.a, 74.b, 75.c, 76.d, 77.c, 78.c, 79.b, 80.d, 81.c, 82.d, 83.a, 84.d, 85.a, 86.b,
87.b, 88.a, 89.b, 90.d, 91.a, 92.b, 93.c, 94.c, 95.a, 96.b, 97.d, 98.b, 99.d, 100.c, 101.a, 102.d, 103.b, 104.c, 105.a, 106.a,
107.d, 108.b, 109.d, 110.d, 111.b, 112.b, 113.b, 114.d, 115.c, 116.d, 117.b, 118.a, 119.d, 120.d, 121.b, 122.d, 123.a,
124.d, 125.b, 126.a, 127.b, 128.b.
 SAMPLE ASOC EXAM QUESTION PAPER
Time for General Grade : 2 hours
Time for Restricted Grade : 1 hour
Max marks for both grades : 100

Instructions
1. There will be 2 sections in the question paper. Each section contains 50 questions. All
questions carry equal marks. All the candidates are required to write the answers for the
questions in the box provided for each of the respective questions.
2. Candidates appearing for General grade should answer all the questions.
3. Candidates appearing for Restricted grade should answer only first 25 questions from each
of the section.

SECTION-A
1) Parameter that determines lowest signal reception capability of a receiver is
a) Sensitivity
b) Fidelity
c) Selectivity
d) Squelch

2) TRF stands for

a) Turning radio frequency
b) Turning rod frequency
c) Tuned radio feed
d) Tuned radio frequency

3) If a super hetero dyne radio receiver is tuned to 1255 KHz & the IF frequency is
455KHz, then the frequency of the local oscillator of the receiver is
a) 1255 KHz
b) 800 KHz
c) 1710 KHz
d) 455 KHz

4) Kirchhoff’s voltage Law states that

a) The sum of voltages in a loop is zero
b) The algebraic sum of voltages in a loop is zero
c) The sum of currents at a junction is zero
d) The algebraic sum of currents at a junction is zero

5) Among all these materials, which one has poor conductivity ?

a) Copper
b) Aluminum
c) Silicon
d) Silver
6) A magnet does not attract which one in the following
a) Nickel
b) Aluminum
c) Iron
d) Cobalt

7) The unit of resistance is

a) Mho b) Volts c) Ampere d) Ohm

8) The expanded form for ‘LDR’ is

a) Light Emitting Display
b) Low Dependent Reading
c) Light Emitting Diode
d) Light Dependent Resistor

9) The three leads of a common transistor are

a) Base Collector Case
b) Emitter Collector Bias
c) Collector Base Omitter
d) Collector Base Emitter

10) If R is resistance, I is current and V is voltage, then Ohms law states that
a) R=V/I
b) I=R/V
c) V=R/I
d) V/(R/I)=1

11) If two capacitors are placed in series, is the final capacitance will be:
a) Higher than the sum of the two capacitors
b) Lower than the least of the two capacitors
c) The sum of the two capacitors
d) Cannot be determined the given data.

12) Which is the unit of energy in electronics?

a) Ohm
b) Ampere
c) Joules
d) Watt

13) The high frequency band (HF) is

a) 3KHz to 30KHz b) 3MHz to 30MHz
c) 30KHz to 300KHz d) 30MHz to300MHz
14) Among the following which is not a directional antenna
a) Whip antenna

b) Yagi-Uda antenna
c) Loop antenna
d) Dish antenna

15) The unit of current is

a) Volts
b) Ampere
c) Watt
d) Hertz

16) If a small value of inductance is connected in parallel with a large value, the
combined inductance will be
a) The same
b) Higher
c) Lower
d) Cannot be determined with the given data.

17) The equivalent capacitance when three capacitors of 150 micro farad are connected
in series is
a) 450 micro farad capacitor
b) 300 micro farad capacitor
c) 150 micro farad capacitor
d) 50 micro farad capacitor

18) A resistor with color bands: Red-Violet-Orange-Silver, has the value of

a) 23 kilo Ohm , 5% tolerance
b) 27 kilo Ohm , 5% tolerance
c) 2.7 kilo Ohm , l0%tolerance
d) 27 kilo Ohm , 10% tolerance

19) The abbreviation of RMS voltage is

a) Railway Mail Service voltage
b) Real Mean Square voltage
c) Root Mean Square voltage
d) Root Mean Service voltage

20) If the peak voltage of a sinusoidal ac supply is 150 volts, the RMS value is
a) Less than peak value
b) More than peak value
c) Equal to peak value
d) Not related to peak value of the voltage
21) A capacitor and inductor in series is called a
a) Tuned Circuit
b) Timing Circuit
c) Delay Circuit
d) Schmitt Circuit

22) A domestic inverter

a) Converts ac to ac

b) Converts ac to dc
c) Converts dc to ac
d) Converts dc to dc

23) The current in a circuit is 25mA, then the equivalent value is

a) 0.00025 Ampere
b) 0.0025 Ampere
c) 0.025 Ampere
d) 0.25 Ampere

24) If 2 mA current flows through a 100 Kohm resistor, then the voltage across it is
a) 2 volts
b) 20 volts
c) 200 volts
d) 0.2 volts

25) The tolerance bands with colors gold, silver & brown represent
a) 5%, 10%, 2%
b) 5%, 10%, 1%
c) 10%, 5%, 1%
d) 10%, 5%, 2%

26) India uses which encoding technique for commercial TV broad cast
a) NTSC
b) SECAM
c) PAL
d) None of the above

27) The video bandwidth in a TV transmission in India is

a) 455 KHz
b) 10.7 MHz
c) 4.2 MHz
d) 5.5 MHz
28) Sky wave propagation utilizes
a) Troposphere
b) Stratosphere
c) Ionosphere
d) Exosphere

29) Ionosphere does not have _______ layer.

a) C
b) D
c) E
d) F

30) Which layer of ionosphere disappears during night time?

a) C
b) D
c) E

d) F

31) In dealing with sky/ground wave propagation, the area of silence where no signals
are received is the
a) dead zone
b) skip distance
c) skip zone
d) propagation distance.

32) Frequencies lesser than the critical frequency are

a) passed into space
b) the most desirable
c) returned to earth
d) refracted by the F2 layer

33) For mobile communications, the up-link frequency is _____ down link frequency .
a) Less than
b) More than
c) Equal to
d) Less or more than the

34) All India Radio (AIR) does not broadcast

a) Amplitude Modulation transmission
b) Frequency Modulation transmission
c) Pulse Modulation transmission
d) Both a and b
35) A diode can be used in the following stages of a radio receiver
a) Detector
b) Mixer
c) Rectification
d) All of the above

36) Geo stationary orbit is ___ km away from the earth

a) 3100
b) 32786
c) 36786
d) 39000

37) Which antenna is used for direction finding purpose?

a) Loop antenna
b) Active Whip antenna
c) Whip antenna
d) Dipole antenna

38) A transformer converts

a) AC voltage into DC voltage
b) DC voltage into AC voltage
c) AC voltage into different AC voltage

d) DC voltage into different DC voltage

39) A matching transformer (10:1 turns ratio) is used to match 200 ohms into ___ ohms.

a) 2
b) 20
c) 200
d) 5

40) The following are transformer losses

a) Hysteresis losses
b) Eddy current losses
c) Copper losses
d) All of the above

41) Digital modulation techniques are

a) Amplitude modulation
b) Frequency modulation
c) Phase shift keying
d) Phase modulation

42) The following idle component dissipates energy

a) Capacitor
b) Inductor
c) Resistor
d) All of the above

43) The most common stage used for amplifying an electrical signal is
a) Common Base
b) Common collector
c) Common emitter
d) Emitter follower

44) The biasing of a transistor is to

a) To avoid thermal run away
b) To provide stable operation
c) To have a stable quiescent point
d) All of the above

45) The ideal value of ripple factor should be

a) 0
b) 1
c) 0.707
d) 1.414

46) The full wave rectifier employs

a) 1 diode
b) 2 diodes
c) 3 diodes d) 4 diodes

47) The following is used as a Voltage smoothing device

a) Resistor
b) Capacitor
c) Inductor
d) Both a and b

48) The following modulation is used for audio transmission in TV broadcast

a) Amplitude modulation
b) Frequency modulation
c) Pulse modulation
d) None of the above
49) NICAM technique is used in TV broadcast
a) For transmitting video
b) For transmitting mono aural audio
c) For transmitting stereo audio
d) For transmitting timing signals

50) Conventional Facsimile machine sends ______ data over _____ media
a) Analog, air
b) Digital, air
c) Analog, telephone
d) Digital, telephone

SECTION-B

51) Under Indian Wireless Telegraph rules, 1973, the minimum age to work on a radio
transmitting apparatus is ______ years
a) 12
b) 15
c) 18
d) 21

52) An amateur is forbidden to transmit

a) communications of business
b) transmissions of entertainment value or music
c) advertisements
d) all the above

53) Log containing chronological record of all transmissions should be preserved for
a) 1 day
b) 1 month
c) 6 months
d) 12 months

54) Log containing chronological record of all transmissions should contain

a) Date and time of all transmissions
b) Call sings intercepted

c) Summary of communications
d) All of the above
55) Which of the following should be given top priority?
a) Safety signal
b) Routine communication signal
c) Distress signal
d) Urgency signal

56) The following is not an amateur call sign of India

a) VU2XYZ
b) VU3ABC
c) VU44AB
d) VU3RS

57) The standard time & frequency signal in India is

a) 5 MHz
b) 10 MHz
c) 20 MHz
d) 100 MHz

58) The standard time & frequency signal in India call sign is
a) VU2
b) VU3
c) ATA
d) ATU

59) The abbreviation for end of message in Morse code is

a) AA
b) AR
c) ED
d) EN

60) QTR stands for ?

a) What is the correct time?
b) What is your position in latitude and longitude?
c) Thank you for sending
d) What is Time and Hour?

61) The standard emission designation consists of

a) 8 letters/numerals
b) 3 letters/numerals
c) 6 letters/numerals
d) 2 letters/numerals

62) Metric waves means

a) 3-30 MHz
b) 3-30 KHz
c) 30-300 KHz
d) 30-300 MHz

63) The standard bandwidth designation consistsof

a) 5 letters/numerals
b) 3 letters/numerals
c) 4 letters/numerals
d) 2 letters/numerals

64) Which should be used as a suffix in call sign for mobile amateur stations
a) ME
b) MB
c) MO
d) ML

65) The Q code for “What is the correct time” is

a) QCT
b) QTM
c) QRT
d) QTR

66) The Q code for “ Are my signals fading? ” is

a) QSB
b) QAM
c) QSI
d) QSF

67) The Q code QRQ represents

a) Shall I stop slowing?
b) Shall I increasepower?
c) Shall I send faster?
d) Shall I decreasepower?

68) The Phonetic alphabet for L is

a) Lilly
b) Lima
c) Limca
d) Lisa
69) The Phonetic for ‘3’ is
a) Terra Three
b) Tele Three
c) Tango Three
d) Tango Tree

70) The expanded from for AA in Morse code is

a) End of line
b) End of message
c) End of transmission
d) End of signal

11) The expanded form for TU in Morse code is

a) Thank u
b) Thank you
c) Thank everyone
d) None of the above

72) The expanded form for CQ in Morse code is

a) Calling you
b) Calling any station
c) Calling Quebec
d) Calling none

73) The abbreviation for ‘stand by’ in Morse code is

a) SY
b) AS
c) SB
d) AD

74) The Q code for “What is the name of your station ?” is

a) QNS
b) QRA
c) QYS
d) QNA

75) The Q code for “Are you ready?” is

a) QRY
b) QRV
c) QAR
d) QRE
76) The expanded from of SOS is
a) Save our selves
b) Save one self
c) Save one souls
d) Save our souls

77) The distress signal in radio telephony is

a) Help, Help, Help
b) May day. May day, May day
c) Save, Save, Save
d) Save our souls

78) The phonetic for alphabet ‘Y’ is

a) Yardly
b) Yankee
c) Yan
d) Yarn

79) The phonetic for ‘9’ is

a) New Nine
b) Nove Nine
c) Novel Nine
d) Nine

80) Which one of this is not a standard frequency signal

a) l5 MHz
b) l0 MHz
c) 5 MHz
d) 1 MHz

81) The renewal fee for General Grade Amateur license under new rules is
a) Rs 1000
b) Rs 2000
c) Rs. 100
d) Rs.200

82) The fee for mobile endorsement under new rules is

a) Rs 100
b) Rs. 200
c) Rs. 1000
d) Rs. 2000
83) The maximum DC power permitted under new rules for Restricted grade amateurs

under 144-146 MHz band is

a) 10 watts
b) 25 watts
c) 50 watts
d) 100 watts

84) The maximum DC power permitted under new rules for General grade amateurs
under 7000-7100 KHz band is
a) 50 watts
b) 100 watts
c) 200 watts
d) 400 watts

85) The permitted emission under new rules for Restricted grade amateurs under
144-l46 MHz band is
a) A3E
b) J3E
c) F3E
d) AlA

86) The first symbol in the designation for classification of emission represents
a) Nature of signals modulating the main carrier
b) Type of modulation of the main carrier
c) Type of information to be transmitted

d) None of the above

87) Emission designation of commercial FM broadcast transmission in India is

a) ME
b) J3E
c) F3E
d) R3E

88) Conventional Morse code transmission can be represented by

a) J3E
b) F3E
c) ME
d) AlA
89) The second symbol in the designation of emission represents
a) Nature of signals modulating the main earner
b) Type of modulation of the main carrier
c) Type of information to be transmitted
d) None of the above

90) The following frequency band is permitted for general grade amateurs only
a) 1820 - 1860 KHz
b) 3500 - 3700 KHz
c) 5725 - 5840 MHz
d) 21000 - 21450 KHz

91) The fee for change of location new rules is

a) Rs. 100
b) Rs. 200
c) Rs. 500
d) Rs. 1000

92) The maximum DC power permitted under new rules for General grade amateurs
under 144-146 MHz band is
a) 10 watts
b) 25 watts
c) 50 watts
d) 100 watts

93) The standard designation for a bandwidth of 4.8 KHz is

a) 4800 Hz
b) 4K8
c) 4K80
d) 4800

94) A bandwidth of 402 M represents

a) 4000 MHz
b) 402 MHz
c) 4.2 MHz
d) 420 MHz

95) The emission C3F denotes

a) Single side band analog audio emission

b) Common analog radio emission
c) Vestigial sideband analog TV emission
d) Vestigial sideband digital TV emission

96) The expanded form for RST is

a) Readability signal tone
b) Readability strength tone
c) Readability strength testing
d) Readability signal strength tone

97) The phonetic for ‘W’ is

a) Wine
b) White
c) Whiskey
d) Wheel

98) The UHF band extends from

a) 3-30 KHz
b) 30-300 MHz
c) 3-30 MHz
d) 300-3000 MHz

99) Which of the frequency bands was not allocated for Amateur service
a) 7000 - 7100 KHz
b) 7100 - 7200 KHz
c) 10120 - 10240 KHZ
d) 28000 - 29700 KHz

100) ‘WPC’ stands for

a) Wireless Planning and Coordination
b) Wireless Placement cell
c) Wireless Planning cell
d) Wireless Placement and Coordination

****** * * * * * * * * * * * * * * * * * * *
 Annexure-I

List of Wireless Monitoring Stations conducting

amateur radio licencing examination

Ahmedabad: Delhi: Mangalore:

Officer-in-Charge, Engineer-in-Charge, Officer-in-Charge,
Wireless Monitoring Station, Regional Headquarter (N), Wireless Monitoring Station, 3-1-41,
A/101, Amarkunj Aparrtments, E-315, Pushpa Bhavan, Madangir Bijai,
Opp. Gurukul, Road, Swarna Niketan,
Ahmedabad-380052 New Delhi-110 062 Mangalore-575004
Ajmer: Gorakhpur: Mumbai:
Officer-in-Charge, Officer-in-Charge, Officer-in-Charge,
Wireless Monitoring Station, Wireless Monitoring Station, Avas Wireless Monitoring Station, Gorai
Christianganj, Shantipura, Vikas Colony, Surajkund, Road, Borivili (W),
Ajmer-305 001 Gorakhpur-273001 Mumbai 4000092
Bangalore: Goa: Nagpur:
Officer-in-Charge, Officer-in-Charge, Officer-in-Charge,
Wireless Monitoring Station, 18, Wireless Monitoring Station, Near Wireless Monitoring Station,
Padmanabha Nagar, Teachers' Training College, P.O. Chindwara Road, P.O. Koradi T.P.S.,
Banashakari,2nd Stage, Bangalore- Alto Betim, Nagpur 441111
560070 Goa- 403112
Bhopal: Hyderabad: Ranchi:
Officer-in-Charge, Officer-in-Charge, Officer-in-Charge,
Wireless Monitoring Station, Wireless Monitoring Station, 1-1- Wireless Monitoring Station, P.O.
E-1/149, 648/4 Harmo Housing Colony,
Arera Colony, Gandhi Nagar, Ranchi-834012
Bhopal-462003 Secunderabad-500380
Calcutta: Jalandher City: Shillong:
Officer-in-Charge, Officer-in-Charge, Engineer Inspection,
Wireless Monitoring Station, Wireless Monitoring Station, 327, Wireless Monitoring Station,
Village-Gopalpur, P.O. Sarkarpool, Mota Singh Nagar, Jullander City Lapalang, Rynjah,
24-Parganas, 144001 Shillong-793006
Calcutta- 743352
Darjeeling: Jalna: Srinagar:
Officer-in-Charge, Engineer-in-Charge Officer-in-Charge,
Wireless Monitoring Station, 7, International Satellite Monitoring Wireless Monitoring Station, Kursu,
Oak's Rose Bank Building, Earth Station, Indewadi Village, Rajbagh,
Holding No. 560, Ambad Road, Srinagar-190008
Darjeeling 734101 Jalna-431203
Dibrugarh: Madras: Trivandrum:
Officer-in-Charge, Officer-in-Charge, Officer-in-Charge,
Wireless Monitoring Station, Wireless Monitoring Station, Wireless Monitoring Station,
Girdharilal Sardarmall’s Building, Perungudi, T.C. 9/951-1, Panicker's Lane,
Mancotta Road, Madras-600096 Sasthamangalam,
Dibrugarh-786001 Trivandrum- 695010
Schedule of licencing examination:
Place Month of Examination
Delhi, Mumbai, Calcutta & Madras Every month Visakhapatnam:
Ahmedabad, Hyderabad & Nagpur January, March, June, August, Officer-in-Charge,
October & December
Wireless Monitoring Station,
Ajmer, Bangalore, Bhopal, Darjeeling, January, April, July & October
Dibrugarh, Gorakhpur, Goa, 6-20-9,
Jalandhar, Jalna, Mangalore, Ranchi, Chinna Waltair,
Shillong, Srinagar, Trivandrum, Visakhapatnam- 530023
Visakhapatnam
 Annexure-II
Call-sign Prefixes of Amateur Radio Stations of different
countries allotted by the
International Telecommunication Union (ITU)
Prefix Country CQ Zone
1AO Sovereign Military Order of Malta 15
1S Spratly Is. 36
1X Chechnya (erstwhile USSR)
2A-2Z United Kingdom 14
3A Monaco 14
3B6,7 Agalega & St. Brandon 39
3B8 Mauritius 39
3B9 Rodriguez Is. 39
3C Equatorial Guinea 36
3C0 Annobon 36
3D2 Fiji, Conway Reef, Rotuma Is. 32
3DA Swaziland 38
3DN Fiji 32
3K3 European Islands between 30 Deg. E long. To 170 Deg. W long
3V Tunisia 33
3W, XV Vietnam 26
3X Guinea 35
3Y Bouvet 38
3Y Peter Is. 12
3Z Poland 15
4F Philippines 27
4JA-4JZ, 4KA-4KZ Azerbaidjan 21
4J1, R1MV Malyj Vysotskij Island 16
4K0 Drifting Ice Station (Russian Polar Stations)
4K1 Antarctica (Russian Polar Stations)
4K4 Asian Islands between 65 Deg E long. To 170 Deg. W long
4K2 Franz Josef Land (Russian Polar Stations) 40
4LA-4LZ Georgia 21
4P-4S Sri Lanka 22
4U ITU Geneva 14
4U United Nations Headquarters 05
4X, 4Z Isreal 20
5A Libya 34
5B, P3, H2 Cyprus 20
5H, 5I Tanzania 37
5N, 5O Nigeria 35
5R, 5S Madagascar 39

2
Prefix Country CQ Zone
5T Mauritania 35
5U Niger 35
5V Togo 35
5W Western Sarnova 32
5X Uganda 37
5Y, 5Z Kenya 37
6O Somalia 37
6V, 6W Senegal 35
6Y Jamaica 08
7J-7N Japan 25
7O Yemen 21, 37
7P Lesotho 38
7Q Malawi 37
7S Sweden 14
7T-7Y Algeria 33
7Z Saudi Arabia 21
8J Japan 25
8P Barbados 08
8Q Maldive Is 22
8R Guyana 09
8S Sweden 14
8Z Saudi Arabia 21
9A Croatia 15
9G Ghana 35
9H Malta 15
9I, 9J Zambia 36
9K Kuwait 21
9L Sierra Leone 35
9M2, 4 West Malaysia 28
9M6, 8 East Malaysia 28
9N Nepal 22
9O-9T Zaire 36
9U Burundi 36
9V Singapore 28
9X Rwanda 36
9Y, 9Z Trinidad and Tobago 09
A2 Botswana 38
A3 Tonga 32
A4 Oman 21
A5 Bhutan 22

3
Prefix Country CQ Zone
A6 United Arab Emirates 21
A7 Qatar 21
A8 Liberia 35
A9 Bahrain 21
AA-AL USA 3, 4, 5
AM-AO Spain 14
AT-AW India 22
AP-AS Pakistan 21
BS7 Scarborough Reef 27
BM, BO, BU, BV Taiwan 24
BA, BD, BG, BT, BY China 23, 34
C2 Nauru 31
C3 Andorra 14
C5 Gambia 35
C6 Bahamas 08
C8-C9 Mozambique 37
CA-CE Chile 12
CE0 Easter Island, San Felix and San Ambrosia, Juan Fernandez Island 12
CE9 Antarctica
CF-CK Canada 1-5
CM, CO Cuba 08
CN Morocco 33
CP Bolivia 10
CT Portugal 14
CT3 Madeira Is. 14
CU Azores 33
CV-CX Uruguay 13
CY9 St. Paul Island 05
CY0 Sable Island 05
D2-3 Angola 36
D4 Cape Verde 35
D5 Liberia 35
D6 Comoros 39
DA-DM Germany 14
DU-DZ Philippines 27
E2 Thailand 26
E3 Eritrea 37
E4 Palestine
EA-EH Spain 14
EA6-EH6 Balearic Is. 14

4
Prefix Country CQ Zone
EA8-EH8 Canary Is. 33
EA9-EH9 Ceuta and Melilla 33
EI-EJ Ireland 14
EK Armenia 21
EL Liberia 35
EP-EQ Iran 21
ER Maldova 16
ES Estonia 15
ET Ethiopia 37
EU, EV, EW Byelorussia 16
EX Kyrgyzstan 17
EY Tajikistan 17
EZ Turkmenistan 17
F, TM, TO-TQ France 14
FG Guadeloupe 08
FH Mayotte 39
FJ, FS Saint Martin 08
FK New Caledonia 32
FM Martinique 08
FO Clipperton Is. 07
FO French Polynesia 32
FP St. Pierre & Miquelon Is. 05
FR, FG Glorioso Is. 39
FR, FJ, FE Juan de Nova (Europe) 39
FR, FT Tromelin Is. 39
FR Reunion Is. 39
FT8W Crozet Is. 39
FT8X Kerguelen Is. 39
FT8Z Amsterdam & St. Paul Is. 39
FW Wallis & Futuna Is. 32
FY French Guiana 09
G, GX England 14
GD, GT, MD Isle of Man 14
GH, GJ Jersey 14
GI, GN Northern Ireland (UK) 14
GM, GS Scotland (UK) 14
GU, GP Guernsey 14
GW, GC Wale (UK) 14
H4 Solomon Is. 28
HA, HG Hungary 15

5
Prefix Country CQ Zone
HB Switzerland 14
HB0 Liechtenstein 14
HC, HD Equador 10
HC8, HD8 Galapagos Is. 10
HH Haiti 08
HI Dominican Republic 08
HJ, HK Colombia 09
HK0 Malpelo Is 09
HK0 San Andres & Providencia 07
HL, DS, DT South Korea 25
HO, HP, 3E, 3F Panama 07
HQ, HR Honduras 07
HS Thailand 26
HV Vetican 15
HZ Saudi Arabia 21
IA-IZ Italy 15, 33
IS0, IM0 Sardinia 15
J2 Djibouti 37
J3 Grenada 08
J4 Greece 20
J5 Guinea-Bissau 35
J6 St. Lucia 08
J7 Dominica 08
J8 St. Vincent & Grenadlines 08
JA-JS Japan 25
JD1 Minami-Tori-Shima 27
JD1 Ogasawara Is. 27
JT-JV Mongolia 23
JW Svalbard Is. 40
JX Jan Mayen Is. 40
JY Jordan 20
K, W, NA-NZ, AA-AK United States of America 3, 4, 5
KC6 Belau (Western Caroline Is.) 27
KG4 Guatanamo Bay 08
KH0 Manana Is. 27
KH1 Baker & Howland Is. 31
KH2 Guam 27
KH3 Johnston Is. 31
KH4 Midway Is. 31
KH5 Palmyra Jarvis Is. 31

6
Prefix Country CQ Zone
KH5K Kingman Reef 31
KH6 Hawaii 31
KH7 Kure Is. 31
KH8 American Samao 32
KH9 Wake Is. 31
KL7 Alaska 1
KP1 Navassa Is. 08
KP2 Virgin Is. 08
KP3, KP4, WP Puerto Rico 08
KP5 Desecheo Is. 08
LA-LN Norway 14
LO-LW, AY, AZ Argentina 13
LX Luxembourg 14
LY Lithuania 15
LZ Bulgaria 20
M1, M0 United Kingdom 14
OA-OC Peru 10
OD Lebanon 20
OE Austria 15
OF-OI Finland 15
OH0 Aland Is. 15
OJ0 Market Reef 15
OK, OL Czeck Republic 15
OM Slovak Republic 15
ON-OT Belgium 14
OX Greenland 40
OY Faroes 14
OZ Denmark 14
P2 Papua New Guinea 28
P4 Aruba 09
P5 North Korea 25
PA-PI Netherlands 14
PJ2, 4, 9 Bonaire, Curacao (Neth Antilles) 09
PJ5-8 St. Maarten, Saba & St. Eustatius Is. 08
PP-PY Brazil 11
PP0-PY0 Fernando de Noronha, St. Peters & St. Paul Rocks, Trinidad & Martin Vaz 11
PZ Surinam 09
S0 Western Sahara 33
S2 Bangladesh 22
S4 South Africa 38

7
Prefix Country CQ Zone
S5 Slovenia 15
S7 Seychelles 39
S9 Sao Tome & Principe 36
SA-SM Sweden 14
SN-SR Poland 15
ST Sudan 34
ST0 Southern Sudan 34
SU Egypt 34
SV-SZ Greece 20
SV/A Mount Athos 20
SV5 Dodecanese 20
SV9 Crete 20
T2 Tuvalu 31
T30 W. Kiribati (Gilbert Is.) 31
T31 Central Kiribati (British Phoenix Is.) 31
T32 East Kiribati (Line Is) 31
T33 Banaba Is. (Ocean Is.) 31
T5 Somalia 37
T7 San Marino 15
T9, 4N4, 4O4 Bosnia-Herzegovina 15
TA-TC Turkey 20
TF Iceland 40
TG, TD Guatemala 07
TI, TE Costa Rica 07
T19 Cocos Is 07
TJ Cameroon 36
TK Corsica 15
TL Central Africa 36
TN Congo 36
TR Gabon 36
TT Chad 36
TU Ivory Coast 35
TY Benin 35
TZ Mali 35
UA-UI1, 3, 6, RA-RZ European Russia 16
UA2 Kaliningrad 15
UA-UI8, 9, 0 RA-RZ Asiatic Russia
UJ-UM Uzbekistan 17
UN-UQ Kazakhstan 17
UR-UZ, EM-EO Ukraine 16

8
Prefix Country CQ Zone
V2 Antigua Barbuda 08
V3 Belize 07
V4 St. Kitts & Nevis 08
V5 Namibia 38
V6 Micronesia (East Caroline Is.) 27
V7 Marshall Is. 31
V8 Brunei 28
VA, VE, VF, VO, VY Canada 1-5
VK, VI, AX Australia 29, 30
VK0 Heard Is. 39
VK0 Macquarie Is. 30
VK9C Cocos-Keeling Is. 29
VK9L Lord Howe Is. 30
VK9M Mellish Reef 30
VK9N Norfolk Is. 32
VK9W Willis Is. 30
VK9X Christmas Is. 29
VP2E Anguilla 08
VP2M Montserrat 08
VP2V British Virgin Is. 08
VP5 Turks & Caicos Is. 08
VP8 Falkland Is. 13
VP8, LU South Georgia Is. South Orkney Is., South Sandwich Is. 13
VP8, CE9, HF0, LU, RA1 South Shetland Is. 13
VP9 Bermuda Is. 05
VQ9 Chagos Is. 39
VR6 Pitcairn Is. 32
VS6, VR2 Hong Kong 24
VU2, VU3 India 22
VU7 Andaman & Nicobar Is. (India) 26
VU4 Laccadive Is. (India) 22
XA-XI, 4A-4C Mexico 06
XA4-X14 Revilla Gigedo 06
XJ Canada 1-5
XT Burkina Faso 35
XU Cambodia 26
XW Laos 26
XX9 Macao 24
XY-XZ Myanmar 26
YA, T6 Afghanistan 21

9
Prefix Country CQ Zone
YB-YH Indonesia 28
YI Iraq 21
YJ Vanuatu 32
YK Syria 20
YL Latvia 15
YN Nicaragua 07
YT, YU, YZ, 4N Yugoslavia 15
YV-YY, 4M Venezuela 09
YV0 Ares Is. 08
Z2 Zimbabwe 38
Z3, 4N5 Macedonia 15
ZA Albania 15
ZB2 Gibraltar 14
ZC4 Cyprus (United Kingdom Sovereign Bases) 20
ZD7 St. Helena 36
ZD8 Ascension Is. 36
ZD9 Tristan de Cunha & Gough Is. 38
ZF Cayman Is. 08
ZK1 North & South Cook Is. 32
ZK2 Niue 32
ZK3 Tokelau Is. 31
ZL, ZM New Zealand 32
ZL7 Chatham Is. 32
ZL8 Kermadec Is. 32
ZL9 Auckland & Campbell Is. 32
ZP Paraguay 11
ZR-ZU Republic of South Africa 38
ZS0, 1 Penguin Is. 38
ZS8 Prince Edward & Marion Is. 38

List of Call-sign Blocks allotted by ITU

Prefix Country Prefix Country Prefix Country

AAA-ALZ USA AMA-AOZ SPAIN APA-ASZ PAKISTAN
ATA-AWZ INDIA AXA-AXZ AUSTRALIA AYA-AZZ ARGENTINE
A2A-A2Z BOTSWANA A3A-A3Z TONGA A4A-A4Z OMAN
A5A-A5Z BHUTAN A6A-A6Z U.A.E. A7A-A7Z QATAR
A8A-A8Z LIBERIA A9A-A9Z BAHRAIN BAA-BZZ CHINA
CAA-CEZ CHILE CFA-CKZ CANADA CLA-CMZ CUBA
CNA-CNZ MOROCCO COA-COZ CUBA CPA-CPZ BOLIVIA
CQA-CUZ PORTUGAL CVA-CXZ URUGUAY CYA-CZZ CANADA
C2A-C2Z NAURU C3A-C3Z ANDORRA C4A-C4Z CYPRUS
C5A-C5Z GAMBIA C6A-C6Z BAHAMAS C7A-C7Z World Meteorological
Organisation
C8A-C9Z MOZAMBIQUE DAA-DRZ GERMANY DSA-DTZ SOUTH KOREA
Prefix Country Prefix Country Prefix Country
DUA-DZZ PHILIPPINES D2A-D3Z ANGOLA D4A-D4Z CAPE VERDE
D5A-D5Z LIBERIA D6A-D6Z COMOROS D7A-D7Z SOUTH KOREA
D7A-D9Z SOUTH KOREA EAA-EHZ SPAIN EIA-EJZ IRELAND
EKA-EKZ ARMENIA ELA-ELZ LIBERIA EMA-EOZ UKRAINE

10
EPA-EQZ IRAN ERA-ERZ MOLDOVA ESA-ESZ ESTONIA
ETA-ETZ ETHIOPIA EUA-EWZ BELARUS EXA-EXZ KYRGYZ
EYA-EYZ TAJIKISTAN EZA-EZZ TURKMENISTAN E2A-E2Z THAILAND
E3A-E3Z ERITREA E4A-E9Z UNALLOTTED HAA-HAZ HUNGARY
HBA-HBZ SWITZERLAND HCA-HDZ ECUADOR HEA-HEZ SWITZERLAND
HFA-HFZ POLAND HGA-HGZ HUNGARY HHA-HHZ HAITI
HIA-HIZ DOMINIC REP. HJA-HKZ COLOMBIA HLA-HLZ SOUTH KOREA
HMA-HMZ NORTH KOREA HNA-HNZ IRAQ HOA-HPZ PANAMA
HQA-HRZ HONDURAS HAS-HSZ THAILAND HTA-HTZ NICARAGUA
HUA-HUZ EL SALVADOR HVA-HVZ VETICAN HWA-HYZ FRANCE
HZA-HZZ SAUDI ARABIA H2A-H2Z CYPRUS H3A-H3Z PANAMA
H4A-H4Z SOLOMON IS. H5A-H5Z UNALLOTTED H6A-H7Z NICARAGUA
H8A-H9Z PANAMA IAA-IZZ ITALY JAA-JSZ JAPAN
JTA-JVZ MONGOLIA JWA-JXZ NORWAY JYA-JYZ JORDAN
JZA-JZZ INDONESIA J2A-J2Z DJIBOUTI J3A-J3Z GRENADA
J4A-J4Z GREECE J5A-J5Z GUINEABISSAU J6A-J6Z ST. LUCIA
J7A-J7Z DOMINICA J8A-J8Z ST.VINCENT/GRE J9A-J9Z UNALLOTTED
NADINES
KAA-KZZ U.S.A. LAA-LNZ NORWAY LOA-LWZ ARGENTINA
LXA-LXZ LUXEMBOURG LYA-LYZ LITHUANIA LZA-LZZ BULGARIA
L2A-L9Z ARGENTINA MAA-MZZ UNITED NAA-NZZ U.S.A.
KINGDOM
OAA-OCZ PERU ODA-ODZ LEBANON OEA-OEZ AUSTRIA
OFA-OJZ FINLAND OKA-OLZ CZECH OMA-OMZ SLOVAK REPUBLIC
REPUBLIC
ONA-OTZ BELGIUM OUA-OZZ DENMARK PAA-PIZ NETHERLANDS
PJA-PJZ NETHERLAND PKA-POZ INDONESIA PPA-PYZ BRAZIL
ANTILLES
PZA-PZZ SURINAME P2A-P2Z PAPUA/NEW P3A-P3Z CYPRUS
GUINEA
P4A-P4Z ARUBA P5A-P9Z NORTH KOREA RAA-RZZ RUSSIAN
FEDERATIONS
SAA-SMZ SWEDEN SNA-SRZ POLAND SSA-SSM EGYPT
SSN-STZ SUDAN SUA-SUZ EGYPT SVA-SZZ GREECE
S2A-S3Z BANGLADESH S4A-S4Z UNALLOTTED S5A-S5Z SLOVENIA
S6A-S6Z SINGAPORE S7A-S7Z SEYCHELLES S8A-S8Z SOUTH AFRICA
S9A-S9Z SAO TOME & TAA-TCZ TURKEYALA TDA-TDZ GUATEMALA
PRINCIPE
TEA-TEZ COSTA RICA TFA-TFZ ICELAND TGA-TGZ GUATEMALA
THA-THZ FRANCE TIA-TIZ COSTA RICA TJA-TJZ CAMEROON
TKA-TKZ FRANCE TLA-TLZ CENTRAL TMA-TMZ FRANCE
AFRICAN
REPUBLIC
TNA-TNZ CONGO TOA-TQZ FRANCE TRA-TRZ GABON
TSA-TSZ TUNISIA TTA-TTZ CHAD TUA-TUZ IVORY COAST
TVA-TXZ FRANCE TYA-TYZ BENIN TZA-TZZ MALI
T2A-T2Z TUVALU T3A-T3Z KIRIBATI T4A-T4Z CUBA
Prefix Country Prefix Country Prefix Country
T5A-T5Z SOMALIA T6A-T6Z AFGANISTAN T7A-T7Z SAN MARINO
T8A-T8Z PALAU REP. T9A-T9Z BOSNIA & UAA-UIZ RUSSIAN FED.
HERZEGOVINA
UJA-UMZ UZBEKISTAN UNA-UQZ KAZAKSTAN URA-UZZ UKRAINE
VAA-VGZ CANADA VHA-VNZ AUSTRALIA VOA-VOZ CANADA
VPA-VQZ U.K. VRA-VRZ HONGKONG VSA-VSZ U.K.
VTA-VWZ INDIA VXA-VYZ CANADA VZA-VZZ AUSTRALIA
V2A-V2Z ANTIGUA V3A-V3Z BELIZE V4A-V4Z ST. KITTS & NEVIS
V5A-V5Z NAMIBIA V6A-V6Z MICRONESIA V7A-V7Z MARSHALL IS.

11
V8A-V8Z BRUNEI V9A-V9Z UNALLOTTED WAA-WZZ U.S.A.
XAA-XIZ MEXICO XJA-XOZ CANADA XPA-XP7 DENMARK
XQA-XRZ CHILE XSA-XSZ CHINA XTA-XTZ BURKINAFASO
XUA-XUZ CAMBODIA XVA-XVZ VIETNAM XWA-XWZ LAO
XXA-XXZ PORTUGAL XYA-XZZ MYANMAR YAA-YAZ AFGANISTAN
YBA-YHZ INDONASIA YOKA-YIZ IRAQ YJA-YJZ VANUATU
YKA-YKZ SYRIA YLA-YLZ LATVIA YMA-YMZ TURKEY
YNR-YNZ NICARAGUA YOA-YRZ ROMANIA YSA-YSZ EL SALVADOR
YTA-YUZ YUGOSLAVIA YVA-YYZ VENEZUELA YZA-YZZ YUGOSLAVIA
Y2A-Y9Z GERMANY ZAA-ZAZ ALBANIA ZBA-ZJZ U.K.
ZKA-ZMZ NEW ZEALAND ZNA-ZOZ U.K. ZPA-ZPZ PARAGUAY
ZQA-ZQZ U.K. ZRA-ZUZ SOUTH AFRICA ZVA-ZZZ BRAZIL
Z2A-Z2Z ZIMBABWE 23A-23Z MACEDONIA Z4A-Z9Z UNALLOTTED
2AA-2ZZ U.K. 3AA-3AZ MONACO 3BA-3BZ MAURITIUS
3CA-3CZ EQUATORIAL 3DA-3DM SWAZILAND 3DN-3DZ FIJI
GUINEA
3EA-3FZ PANAMA 3GA-3GZ CHILE 3HA-3UZ CHINA
3VA-3VZ TUNISIA 3WA-3WZ VIETNAM 3XA-3XZ GUINEA
3YA-3YZ NORWAY 3ZA-3ZZ POLAND 4AA-4CZ MEXICO
4DA-4IZ PHILIPPINES 4JA-4KZ AZERBAIJAN 4LA-4LZ GEORGIA
4MA-4MZ VENEZUELA 4NA-4OZ YUGOSLAVIA 4PA-4SZ SRILANKA
4TA-4TZ PERU 4UA-4UZ UNITED NATIONS 4VA-4VZ HAITI
4WA-4WZ UNALLOTTED 4XA-4XZ ISREAL 4YA-4ZZ UNALLOTTED
5AA-5AZ LIBYA 5BA-5BZ CYPRUS 5CA-5GZ MOROCCO
5HA-5IZ TANZANIA 5JA-5KZ COLOMBIA 5LA-5MZ LIBERIA
5NA-5OZ NIGERIA 5PA-5QZ DENMARK 5RA-5SZ MADAGASCAR
5TA-5TZ MAURITANIA 5UA-5UZ NIGER 5VA-5VZ TOGOLESE
REPUBLIC
5WA-5WZ WEST SAMOA 5XA-5XZ UGANDA 5YA-5ZZ KENYA
6AA-6BZ EGYPT 6CA-6CZ SYRIA 6DA-6JZ MEXICO
6KA-6NZ S. KOREA 60A-6OZ SOMALI 6PA-6SZ PAKISTAN
6TA-6UZ SUDAN 6VA-6WZ SENEGAL 6XA-6XZ MADAGASCAR
6YA-6YZ JAMAICA 6ZA-6ZZ LIBERIA 7AA-7IZ INDONESIA
7JA-7NZ JAPAN 7OA-7OZ YEMEN 7PA-7PZ LESOTHO
7QA-7QZ MALAWI 7RA-7RZ ALGERIA 7SA-7SZ SWEDEN
7TA-7YZ ALGERIA 7ZA-7ZZ SAUDI ARABIA 8AA-8IZ INDONESIA
8JA-8NZ JAPAN 8OA-8OZ BOTSWANA 8PA-8PZ BARBADOS
8QA-8QZ MALDIVES 8RA-8RZ GUYANA 8SA-8SZ SWEDEN
8TA-8YZ INDIA 8ZA-8ZZ SAUDI ARABIA 9AA-9AZ CROATIA
9BA-9DZ IRAN 9EA-9FZ ETHIOPIA 9GA-9GZ GHANA
Prefix Country Prefix Country Prefix Country
9HA-9HZ MALTA 9IA-9JZ ZAMBIA 9KA-9KZ KUWAIT
9LA-9LZ SIERALEONE 9MA-9MZ MALAYSIA 9NA-9NZ NEPAL
9OA-9TZ CONGO 9UA-9UZ BURUNDI 9VA-9VZ SINGAPORE
9WA-9WZ MALAYSIA 9XA-9XZ RWANDA 9VA-9ZZ TRINIDAD & TOBAGO

12
 ANNEXURE-III

A Sample Question Paper for Amateur Radio Licencing Examination

SECTION-A

Radio Theory and Practice

1. What is Ohm’s law? A resistor has the following colour bands: RED, RED, ORANGE
& GOLD respectively. What is the value of this resistor?
2. State whether ‘TRUE’ or ‘FALSE’ and correct the ‘FALSE’ statements:
(a) When two resistors are connected in parallel, their resistance increases.
(b) A capacitor allows DC current to pass through it.
(c) When two capacitors are connected in parallel, their capacitance decreases.
(d) In a P-N junction diode, flow of current is possible only when the negative pole
of the battery is connected to the p-type semiconductor and positive pole to n-
type semiconductor.
(e) Centre tapped transformer secondary is not essential for a bridge rectifier
circuit.
(f) In a transistor amplifier circuit, the ‘emitter’ is always reverse biased and
‘collector is always forward biased.
(g) In a PNP transistor, the ‘collector’ is applied with a negative voltage.
(h) SWR value is more than one for a matched system.
(i) The fourth band in a resistor is silver coloured. The tolerance of this resistor is
10%.
(j) Two capacitors with the values 5 mFd & 10 mFd are connected in parallel. The
5 mFd capacitor has a voltage rating of 10 volts and the 10 mFd capacitor has
a voltage rating of 6 volts. We can apply 9 volts to this circuit without
damaging the 10 mFd capacitor.
3. Draw the schematic diagram of the transmitter you intend to build for ham radio
operation and explain the function of each stage in brief.
4. Explain the working function of the antenna you intend to use for ham radio
transmissions.
5. Draw the block diagram of a super-heterodyne receiver. What are superiorities of this
type of receiver over the TRF receivers?
6. Write short notes on:
(a) Image frequency in a super-heterodyne receiver.
(b) Ionosphere.
(c) Single Side Band transmission.
(d) Percentage of modulation.
(e) Selectivity & sensitivity of receiver.
(f) Colpitts oscillator.
(g) Skip distance.

13
 (h) Differences between ‘fadeout’ and ‘fading’.
(i) A.G.C.
(j) B.F.O.

SECTION-B

Rules & Regulations

1. What is a distress message? What action would you take if you receive a distress
message?
2. Explain the meaning of the following:
QRX 10 minutes, QSY 14.155 MHz, QRU?, QRV, QRL, KN, VA, AS, QSB, QRS.
3. Describe the procedure of establishing a contact with another amateur station using
radiotelephony and radiotelegraphy.
4. What do you mean by ‘Amateur Radio Service’?
5. State whether ‘TRUE’ or ‘FALSE’. Correct the ‘FALSE’ statements.
(a) In India, a Grade-I licence holder is allowed to use 400 watts of power in
certain sub-bands.
(b) In India, A Grade-II licence holder can directly use radiotelephony after getting
his licence.
(c) In India, ham radio operators are allowed to use the frequency band 7000 kHz
to 7300 kHz.
(d) In India, an amateur radio operator can handle third party messages.
(e) Amateur radio operators are allowed to use secret language for
communication.
(f) 4S7VK is a call-sign of USA.
(g) An amateur radio operator should maintain the secrecy of communication.
(h) An amateur radio operator is allowed to communicate with the Military during
emergency.
(i) A message passed on by an amateur radio operator to a third party by taking
money is called ‘QSP’.
(j) Third party messages can be handled by an amateur radio operator during a
disaster.
6. What are the amateur radio bands of frequencies? Can a Restricted Grade Licence
holder use High Frequencies (HF) for communication?
7. What is the condition to get a ‘Voice endorsement’ by a Grade-II licence holder?

14
 Annexure-IV

Nomenclature of the Frequency and Wavelength Bands used in Radio

Communication

As per the International Radio Regulations, the radio spectrum is subdivided into nine
frequency bands, which are designated by progressive whole numbers in accordance
with the following table. As the unit of frequency is the hertz (Hz , frequencies shall
be expressed:
- in Kilohertz kHz, upto and including 3000 kHz;
- in megahertz MHz , above MHz, up to and including 3000 MHz;
- in gigahertz GHz, above 3 GHz, up to and including 3000 GHz.
For bands above 3000 GHz, i.e. centimillimetric waves, micrometric waves and
decimicrometric waves, it would be appropriate to use terahertz THz.
However, where adherence to these provisions would introduce serious
difficulties, for example in connection with the notification and registration of
frequencies, the lists of frequencies and related matters, reasonable departures may be
made.
Band Symbols Frequency Range Corresponding Metric Metric
Number lower limit exclusive, Subdivision Abbreviations
upper limit inclusive for the bands
4 VLF 3 to 30 kHz Myriametric waves B.Mam
5 LF 30 to 300 kHz Kilometric waves B.km
6 MF 300 to 3000 kHz Hectometric waves B.hm
7 HF 3 to 30 MHz Decametric waves B.dam
8 VHF 30 to 300 MHz Metric waves B.m
9 UHF 300 to 3000 MHz Decimetric waves B.dm
10 SHF 3 to 30 GHz Centimetric waves B.cm
11 EHF 30 to 300 GHz Millimetric waves B.mm
12 300 to 3000 GHz Decimillimetric
waves

Note 1:
“Band Number N” extends from 0.3 x 10N to 3 x 10N Hz, e.g., Band No. 7 is the HF
(High Frequency) band ranging from 0.3 x 107 to 3 x 107 Hz, i.e. 3000000 Hz (3
MHz) to 30000000 Hz (30 MHz)

Note 2:
Symbols and prefixes: Hz=hertz, k=kilo 103, M=mega 106, G=giga 109, T=tetra 1012