VHF-Transceiver

AR 3201 - ( )

Installation and Operation

Manual DV 28110.03
Issue 1 April 1992

B E C K E R F L U G F U N K W E R K G M B H • Baden Airpark • B 108

D-77836 Rheinmünster • Telephon +49 (0) 7229 / 305-0
E-Mail info@ becker-avionics.de or support@becker-avionics.de
 FIRST ISSUE AND CHANGES

Issue . . . . . 1 . . . . . April 1992

LIST OF EFFECTIVE PAGES

Page No.: Issue : Page No.: Issue :

Title 04/92

1-I - 1-II 04/92

1-1 - 1-8 04/92

2-I - 2-II 04/92

2-1 - 2-8 04/92

3-I - 3-II 04/92

3-1 - 3-6 04/92

8-I - 8-II 04/92

Annex 1 to 27 04/92

Copyright by Becker Flugfunkwerk,

All rights reserved

 AR 3201 - ( )

Table of contents

Section 1 GENERAL INFORMATION Page

1.1 Introduction 1-1

1.2 Purpose of equipment 1-1
1.3 General description 1-2
1.4 Variants survey 1-3
1.5 Specifications 1-5
1.5.1 General data Transceiver 1-5
1.5.2 Receiver specifications 1-5
1.5.3 Transmitter specifications 1-6
1.5.4 Optional functions 1-7
1.6 Certification 1-7
1.7 Accessories 1-7
1.8 Scope of delivery 1-8
1.9 Software 1-8

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Section 1 GENERAL INFORMATION

1.1 Introduction

The following Handbooks describe the VHF-communications transceiver AR 3201 - ( ).

The Handbooks DV 28110.03 (,, Installation and Operation ‘‘) and DV 28110.04 (,,Maintenance and
Repair‘‘) contain the following sections :

Section DV 28110.03 DV 28110.04

1 General Information X X

2 Installation X X

3 Operation X X

4 Theory of Operation X

5 Maintenance and Repair X

6 Illustrated Parts List X

7 Modification and Changes X

8 Circuit Diagrams X X

1.2 Purpose of equipment

The VHF transceiver permits transceiver communication on 760 channels in the frequency range
118.000 MHz to 136.975 MHz with a channel spacing of 25 kHz. It can also be limited to 135.975 MHz
= 720 channels by incorporating a different PROM. Extensions for additional modes such as
temperature and operating voltage measurements, etc. are provided for.

The VHF transceiver is physically designed for unrestricted application in category II aircraft. In the
environmental categories there is no limitation for application in the instrument panel and for use in

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rigid fuselage mounting in all aircraft. The VHF transceiver is designed for compliance with RTCA and
EUROCAE airworthiness requirements.

1.3 General description

The VHF transceiver is designed as a single-block unit with dimensions in keeping with 58 mm diameter
standard instrument size. Mounting is by means of four screws (behind-panel fitting). AII controls and
indicators are located on the front panel. The rear panel locates the connector for connecting the
transceiver to aircraft wiring, the antenna socket and a test connector.

The transceiver features a single superhet receiver. A squelch circuit suppresses noise and input
signals below a specific field strength. The switching threshold is adjustable from without through the
case. The squelch can be defeated with the squelch switch.

The transmitter has wideband tuning over the range 118.000 MHz to 136.975 MHz. Transmitter output
power is greater than 5 watt. In transmitter operation sidetone is automatically on. In transceiver with
serial No. of 4000 and above, an arrow flashes on and off in the upper left side of the LCD during
transmission

The injection frequency of the receiver and the transmit frequency of the transmitter are generated by
a voltage-controlled oscillator (VCO) which is signalled by a digital frequencysynthesizer in conjunction
with a microprocessor.

The microphone input is designed for a dynamic microphone or for a standard microphone, the
transceiver being infactory-set for a dynamic microphone. Conversion to a standard microphone is
done in transceivers up to serial No. 86 by resoldering a jumper on the soldering side of the audio
module. As of serial number No. 86 the conversion is made by reconnecting a wire jumper on the
component side of the audio module. The microphone input is connected to a dynamic compressor
which maintains the modulation depth constant over a microphone input voltage range of approx.
40 dB.

The frequency indication is a liquid crystal display ( LCD). The MHz and kHz frequency selectors permit
selection of the desired channel frequency. The MHz frequency selector indexes in steps of 1 MHz,
the kHz frequency selector in 25 kHz steps.

The transceiver also contains a memory for storing four different channel frequencies, even when the
transceiver is OFF. The stored frequencies are called up by the channel selector switch in positions
1 - 4. In switch position A a further channel frequency can be set which is, however, lost when the
transceiver is switched off. In transceiver with serial No. fo 4000 or above, the channel frequency set
in position A is also stored and not deleted when the unit is powerd down.

In addition, when the VHF transceiver is powered up, a self-test function is automatically activated to
test the LCD. For a period of a few secounds, all of the segments in the LCD flash on (188.88).
Aterwards, either the frequency 121.5 MHz appears (channel selector switch in position A), or one of
the 4 stored frequencies (depending on the position of the channel selector switch). The VHF
transceiver is now ready for operation.

In Transceiver with serial No. of 4000 or above, either the most recently set frequency in channel A
appears, or one of four stored frequencies (depending on the position of the channel celector switch).
When the self-test function is activated, an arrow flashes on and off in addition to the digits 188.88
(⇐ 188.88).

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The transceiver also contains a stage for monitoring the aircraft supply voltage. This stage is ON as
soon as the transceiver is switched on. Should the aircraft supply voltage drop to 11 V - 10.5 V, the
readout will commence flashing.

For operation on an 28 V aircraft system a voltage regulator (VR 2011 ) is necessary. In aircraft with
no power circuit (gliders) the battery box (BK 5) is provided.

When using the emergency power unit EPU 400 the transceiver can be continued to be operated at
reduced output power (12 V operating voltage) even when aircraft power is down.

When operating the IC mode, the transceiver can be used for intercommunications.

The auxiliary audio input permits input of audio signals from other equipment in the aircraft, however,
these auxiliary audio input is standard as of module No. 471 . Up to module No. 470 this feature was
only available as an option.

If LCD illumination is required, it can be connected either directly to the operating voltage or to a
dimmer.

The standard version can be extened by optional voltage and temperature measuring facilities without
affecting the airworthiness of the transceiver.

An optional voltage and temperature measurement circuit permits measurement of either two different
voltages or two different temperatures or a single voltage and a single temperature with the aid of two
corresponding sensors and two external pushbuttons. The LCD provides indication on pressing the
external pushbuttons for approx. 4 seconds. Temperature can be indicated in Fahrenheit or Celsius.

1.4 Variants survey

Table 1 -1 surveys the variants of transceiver AR 3201 - ( ). The various variants are not different in
appearance, i.e. dimensions, case depth, etc. being the same for all variants. The necessary
accessories are given in the List of Accessories at the end of Section 1 for the various variants, all of
which have no effect on airworthiness of the transceiver.

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Transceiver AR 3201-( )

Drawing No./ Type Voltage Tamperature Temperature 760 720

Order No measurement measurement measurement channel channel
in deg Celsius in deg.
Fahrenheit

28110-00000.000 AR 3201-( ) no no no yes

389.528-910

28111 -00000.000 AR 3201-(1) yes yes no yes

397.156-910

28112-00000.000 AR 3201-(2) yes no yes yes

397.164-910

28113-00000.000 AR 3201-(3) no yes no yes

397.172-910 two different
temperatures

28114-00000.000 AR 3201-(4) no no yes yes

397.180-910 two different
temperatures

28120-00000.000 AR 3201-(10) no no no yes

767.018-910

28121 -00000.000 AR 3201-(11) yes yes no yes

767.026-910

28122-00000.000 AR 3201-(12) yes no yes yes

767.034-910

28123-00000.000 AR 3201-(13) no yes no yes

767.042-910 two different
temperatures

28124-00000.000 AR 3201-(14) no no yes yes

767.050-910 two different
temperatures

Table 1-1

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1.5 Specifications

1.5.1 General data Transceiver

Operating voltage 12,4 V . . . 15,1 V

Emergency operation (10,0 V) Intelligible communication

Current consumption 14 V without

Panel illumination
Receive ,, stand by ‘‘ typ. 70 mA
Receive ,, stand by ‘‘ with auxiliary input typ. 90 mA
Transmit typ. 1 .8 A

Panel illumination 13,8 V / 40 mA DC

Fuse 5A

Operating temperature range D1 - 20° . . .+ 55°C,

Env. Cat. RTCA DO - 160A shorttime temperature + 70°C

Altitude max. D1 50000 ft

Env. Cat. RTCA DO - 160A

Vibration MNO
Env. Cat. RTCA DO - 160A

Dimensions
Panel 60.6 mm x 60.6 mm
Mounting depth 212.5 mm

Weight 0.9 kg

1.5.2 Receiver specifications

Type Receiver Single superhet

Frequency range 118.000 MHz . . . 136.975 MHz

Channels 760

Channel spacing 25 kHz

Sensitivity (mod. 1000 Hz/30%) ≤ 5µV emf for 6 dB S+N

N

Bandwidth ≥ ± 8 kHz at 6 dB down

Selectivity ≥40 dB at ± 17 kHz

≥60 dB at ± 25 kHz

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Squelch fixed in unit, defeatable with squelch switch

AGC characteristic from 5µV . . . 100 mV emf ≤ 6 dB

Undesired radiation ≤ 4 x 10-10watt

Distortion / m = 85% ≤ 10 %

Frequency response audio channel relative

to 1000 Hz / 0 dB ≤ 6 dB 350 Hz . . . 2500 Hz
≥ 18 dB at 5000 Hz

Intermediate frequency 21.4 MHz

Rated audio output

Speaker at 13.8 V operating voltage
≥ 2.5 watt into 4 Ω typ. 3 watt
at 10.0 V operating voltage
≥ 1.5 watt into 4 Ω
Headphone at 13.8 V operating voltage
≥ 40 mW into 300 Ω
at 10.0 V operating voltage
≥ 30 mW into 300 Ω

Audio power output unregulated 100 mV/30% mod. Ri ≥ 10kΩ

Auxiliary input 1 V eff. / 600 Ω

1.5.3 Transmitter specifications

Transmitter output at 13.8 V operating voltage

≥ 5 watt

at 10.0 V operating voltage

(Emergency operation)
≥ 2 watt

Mode of modulation amplitude modulation A3E

Modulation depth ≥ 85%

≤ 100 % (dynamic compressing)

Input voltage for m = 85 %

no overmoduIation at input voltages
dyn. mike ca. 2mV Dynamic-Compressor
Standard mike ca. 200 mV Dynamic-Compressor

Frequency deviation ≤ 0.002%

Undesired radiation ≤ 2.5 x 10 - 5 watts

Spurious emissions within the 108 - 117.95 MHz range ≤ 2 x 10 - 7 watts

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Frequency response ≤ 6 dB 350 Hz . . . 2500 Hz

Distortion / m = 85% / 1000 Hz ≤ 10%

m = 85% / 350 - 1000 Hz ≤ 20%

Carrier noise level ≥ 35 dB

1.5.4 Optional functions

Digital voltmeter (operating voltage indication) 7 V . . . 35 V DC ± 0.1 V

Ditial thermometer - 20°C . . . +100°C

Temperature sensor Linear tolerance ± 1,5°C

NOTE

The VHF transceiver is designed for the frequency range 118 to 137 MHz. The frequency
range between 136 MHz and 137 MHz may not be used for mobile aircraft radio
communications until after January 1990, in accordance with the relevant regulations.

1.6 Certification

FTZ certification LB 393/83

LBA certification 10.911/76

Specification
RTCA DO - 156
RTCA DO - 157
RTCA DO - 160A
EUROCAE ED 23 / ED 24 / ED 14A

Performance classification D1 / A/MNO/XXXXXXABABA

1.7 Accessories

The following connectors are necessary for connecting the transceiver without options :

1 Cable connector plug for transceiver Order No. 430.722-277

Antenna connector plug UG 88/U for transceiver Order No. 725.706-277
IC-Switch Order No. 213.055-278

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When the transceiver incorporates the temperature or voltage measurement option, the following items
are required :

1 Cable connector complete Order No. 431.036-950

Detail parts
1 Cable connector plug for option Order No. 710.687-277
Temperature sensor - 65°C . . . 150°C Order No. 431.044-955
Bounceless pushbuttons Order No. 724.742-278

1.8 Scope of delivery

Screw block Order No. 472.875-203

Spring washer Order No. 213.126-213

1.9 Software

Frequency synthesizer, frequency storage and frequency display of the AR 3201 - ( ) are controlled
by a microprocessor. The software used has been categorized to Function Criticality Category

,,ESSENTIAL‘‘

accordirig to the guide,lines of RTCA DO - 178.

Uses elass was determined to be

,,CLASS X‘‘

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Table of contents

Section 2 INSTALLATION Page

2.1 General 2-1

2.2 Pre-instailation check 2-1
2.2.1 General 2-1
2.2.2 Visual inspection 2-1
2.3 Mechanical installation 2-1
2.3.1 Mechanical installation VHF transceiver 2-1
2.3.2 Mechanical installation of a temperature sensor 2-1
2.4 Installation wiring 2-2
2.4.1 General 2-2
2.4.2 Microphone connection 2-2
2.4.3 Speaker/headphones connection 2-3
2.4.4 IC connection 2-3
2.4.5 Panel lighting 2-3
2.5 Auxiliary audio input (optional) (standard as of module No. 471) 2-4
2.6 Testing after installation 2-8
2.6.1 Ground testing with engine OFF 2-8
2.6.2 Ground testing with engine ON 2-8

Fig. 2-1 Jumpers location for charging the microphone input from dynamic to
standard microphone 2-3
Fig. 2-2 Panel connection 2-4
Fig. 2-3 Auxiliary audio input 2-4
Fig. 2-4 Dimensions of VHF transceiver 2-5
Fig. 2-5 Aircraft wiring 2-6
Fig. 2-6 Wiring diagram AR 3201 - ( ) with Speaker - Junction 2-7
Fig. 2-7 Location of IC control 2-8

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Section 2 INSTALLATION

2.1 General

Installation of the VHF communication transceiver and the battery box depends on the type of aircraft
and equipment involved, the instructions given in this section thus being only generally applicable.

2.2 Pre-instailation check

2.2.1 General

Prior to fitting the new system in the aircraft, the units must be checked according to the following
procedure to establish whether they have been damaged in transit.

2.2.2 Visual inspection

Prior to commissioning the equipment, carry out a visual inspection to establish any of the following
deficiencies.

1. Soilage, dents, scratches, corrosion, broken fasteners, damaged paintwork on enclosures and
parts thereof.

2. Soilage and scratches on the nameplate, front panel and markings.

3. Soilage, bends or broken-off pins, cracked plug and socket inserts.

4. Soilage and mechanical damage to rotary switches, LCD elements, knobs and pushbutton.

2.3 Mechanical installation

2.3.1 Mechanical installation VHF transceiver

The VHF transceiver is designed for incorporating in an aircraft instrument panel in behind panel
installation. The circular cutout and the fastener holes must be drilled in accordance with the standard
for small size instruments. Location must be min. 30 cm away from the magnetic compass of the
aircraft to avoid the compass being affected by the transceiver. Dimensional requirements are shown
in Fig. 2-4. Four DUZ fasteners (supply) are used to secure the unit.

2.3.2 Mechanical installation of a temperature sensor

The VHF transceiver permits indication of temperatures in the range - 20° C to +100° C with the aid
of an integral measuring circuit and a connected remote temperature sensor. The latter is located in
accordance with the particular requirements and local conditions. The wiring can be seen from Fig. 2-5.
Only use shielded flexed leads, noting the color coding of the connecting cables. The red lead must
be connected to J 3101/8, the blue lead to J 3101/2. The shielding must be connected to pin 4 of
J 3101.

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The temperature measuring circuit in the VHF transceiver and the temperature sensor are calibrated
in the factory together for optimum temperature measuring accuracy. Should the device or the
temperature sensor develop a fault or should the transceiver need replacing, the device will need
recalibrating according to the instructions as given in Section 5, Item 5.7.

2.4 Installation wiring

2.4.1 General

Fig. 2-5 illustrates the installation wiring of the VHF transceiver. In wiring the VHF transceiver the
battery voltage feeder cable should be AWG 20.

NOTE
a) Only use airworthy cable, i.e. self-extinquishing in suitable AWG for power supply and the other
lines.

b) Pull rubber sleeves over the solder juctions on the instrument connector.

c) A 3 A fuse or circuit breaker must be incorporated in the power supply.

d) Prior to switching on the unit, carefully check the wiring, particularly making sure that +ve and -ve
are not confused.

CAUTION
The AR 3201 - ( ) is only protected against wrong polarity when a fuse is incorporated
in the power supply, i.e. so that the fuse blows, leaving the unit undamaged. If no fuse is
provided, the unit can be ruined. In this case, the unit is not covered by our guarantee.

Suitable type cable sets are available for aircraft wiring (contact manufacturer).

CAUTION
Never tie any aircraft wiring into the connecting lines. In addition, the connecting cable
must not be put down together with line carrying pulsed information (IFC’s, DME, XPR,
SLAVED GYRO) the same applying to autopilot supply and control lines.

2.4.2 Microphone connection

The VHF-transceiver features a microphone amplifier as standard which is compatible with both a
dynamic microphone and a standard microphone. Unless stated otherwise, the transceiver is set in
the factory for a dynamic microphone connection. By resoldering jumper Br 4001 on the audio module
the microphone input can be changed from a dynamic microphone to a standard microphone. This
jumper is accessible after unscrewing the case and removing the audio module. As of serial No. 86,
conversion from dynamic to standard microphone has been simplified, jumper 4401 then no longer
requiring resoldering but merely reconnecting, without requiring removal of the audio module.

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View showing components side of audio module

Standard Mike

Dyn. Mike

Fig. 2-1 Jumpers location for charging the microphone input from dynamic to standard microphone

2.4.3 Speaker/headphones connection

The audio output of the transceiver is compatible with a 4Ω speaker or headphone with an impedance
of 300Ω - 600Ω or both in parallel without having to switch the transceiver over.

CAUTION
The magnetic field of the speaker will affect the compass, therefore, minimum spacing
between speaker and compass must be 1.3 m when selecting speaker location.

2.4.4 IC connection

The IC connection is provided for aircraft with high ambient noise and requires use of the headset
together with an IC switch in the unit connector for the additioning wiring (see aircraft wiring Fig. 2-4).
The normal communications position is the OFF position of the IC-switch, i.e. in the ON position
communications operation is the same as before, however, with intercommunication between the two
crew members without having to press the (PTT) button.

2.4.5 Panel lighting

The transceiver features a panel lighting circuit which must be connected to the + 14 V supply voltage
by connection P 4101/7 or to a dimmer control. It is good practice to provide the lighting externally via
a separate lighting switch to save current in aircraft having no power system, e.g. gliders.

CAUTION
The lighting is not switched off on operation of the ON/OFF switch.

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Fig. 2-2 Panel connection

2.5 Auxiliary audio input (optional) (standard as of module No. 471)

The auxiliary audio input permits audio input from other equipment in the aircraft. This input can only
be heard, however, in the RX mode. The possibility of circuiting two units together finds application in
aircraft having, for instance, only one transceiver and one NAV receiver. When using the auxiliary
audio input, a 680Ω resistor must be switched to GND. When circuiting units together, 100Ω decoupling
resistors must be included (see following diagrams). Output of the audio listening amplifier requires
an audio input voltage of approx. 1 V/600Ω .

Fig. 2-3 Auxiliary audio input

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Fig. 2-4 Dimensions of VHF transceiver

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Fig. 2-5 Aircraft wiring

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Fig. 2-6 Wiring diagram AR 3201 - ( ) with Speaker - Junction

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2.6 Testing after installation

2.6.1 Ground testing with engine OFF

After installing the transceiver, measure antenna matching between antenna base and antenna feeder
by means of a VHF reflection meter (voltage/standing-wave meter).
Over the complete frequency range of the transceiver, the voltage/standing-wave ratio must be within
the value 3 : 1. Exceeding this value is an indication of mismatch, which can be due to a wrong or
inadequate counterweight.
After antenna measurement, carry out a voice test with the ground station.

2.6.2 Ground testing with engine ON

With the engine running make sure that the aircraft voltage is within the permissible tolerances at
approx. 14 V. Make the test at engine cruising speed. Carry out speech test at a long distance away
from the ground station. At engine cruising speed the cabin noise of the aircraft must only be heard
muted thus making for clear, intelligible conversation. Hold microphone close to lips when speaking.
Switch on intercommunications by means of the IC switch (when provided) and carry out speech test
at engine cruising speed.

If necessary, correct volume by means of IC control (see Fig. 2-7).

Apply squelch switch and check squelch function. The squelch threshold can be set from without by
means of the squelch control.

CAUTION
In speaker operation no acoustic feedback should occur via the sidetone. If necessary, turn down
sidetone by means of the SIDETONE control.

Fig. 2-7 Location of IC control

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Table of contents

Section 3 Operating Instructions Page

3.1 Control and Indicators 3-1

3.2 Operating instructions for serial no. 0 to serial no. 3999 3-3
3.3 Operating instructions serial no. 4000 upwards 3-3
3.4 Storing frequencies 3-4
3.5 Setting the emergency frequency 3-4
3.5.1 Setting the emergency frequency on models with
serial numbers up to 3999 3-4
3.5.2 Setting the emergency frequency on models with
serial numbers of 4000 or above 3-4
3.6 LC display blinking 3-5
3.7 IC operation 3-5
3.8 Optional temperature, voltage measurement 3-5
3.9 Auxiliary audio input (optional) (standard as of module No. 471) 3-5
3.10 No channel freuency storage 3-5
3.11 Precautions 3-6

Fig. 3-1 Controls and indicators 3-1

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Section 3 Operating Instructions

3.1 Control and Indicators

Fig. 3-1 Controls and indicators

Controls and indicators Description Function

Volume control Potentiometer Turning control clock-wise

increases volume continuously.

ON/OFF switch combined with 3-position rocker switch Postion OFF :

squelch VHF transceiver OFF.
Position ON :
VHF transceiver ON, squelch
OFF
(input noise audible).
Position SQL :
Transceiver ON, Squelch ON.
Input limited to transmitters
having a field strength
exceeding the set squelch
threshold

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Controls and indicators Description Function

Channel selector 5-position rotary switch Position A :

When the transceiver is powerd
up, a brief test routine is
performed for the segments of
the display. Afterwards the
channel frequency 121,500 MHz
appears in the display and the
transceiver is ready for
operation. In models with serial
no. of 4000 or above, the moste
recently set frequency instead of
121,500 MHz.

The setting of channel

frequencies is performed with
the channel selector switch in
position A, regardless of the
units serial number

Position 1 through 4 :
If is wished to store a channel
frequency in any one of the four
memory locations, then channel
frequency to be stored must first
be set with the frequency
selector switch in position A.
Then the desired memory
location is selected using the
channel selector switch, and the
Store button is pressed.
Stored channel frequencies
remain in the memory even,
when the unit is powered down
and can be immediately called
up again after the unit has been
switch on.

MHz frequency selector switch Rotary switch (continuous) Switches the MHz steps
indicated by the frequency
readout.

kHz frequency selector switch Rotary switch (continuous) Switches the 25 kHz steps
indicated in the frequency
readout. The 3rd digit behind the
point is not indicated, e.g.
125.52 = 125.525 MHz.

Frequency indication LC display 5 digits When the unit switched on,

following completion of the self-
test routine the frequency
appers in the display on which
the unit is ready to operate.
During transmission, in models
with serial no. 4000 or above
arrow also flashes on and off.

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Controls and indicators Description Function

Store button Pushbutton Briefly pressing the STORE

button causes the display
frequency to be stored in one of
the four memory locations,
provided that the channel
selector switch is not in position
A, but set to one of the four
memory positions (1 - 4). In
models with serial no. of 4000 or
above the STORE button must
be held depressed for approx. 2
seconds in order for the
displayed channel frequency to
be written into the selected
memory location.

3.2 Operating instructions for serial no. 0 to serial no. 3999

NOTE
Switch off transceiver when engines are started or stopped.

1. Switch on VHF transceiver with ON/OFF switch. For a few seconds the LC display reads 188.88
(display test). The transceiver then automatically switches to 121.500 MHz (emergency frequency)
when the channel selector is in position A. When it is positioned to one of the stored channel
frequencies (switch position 1-4) the display reads the stored channel frequency. To select a
channel frequency other than the stored channel frequencies, position channel selector to A and
then set the desired frequency by means of the MHz and kHz frequency selector switches.

2. Set to frequency of local ground station and position VOL control to center position.

3. Operate PTT key and call ground station. For optimum intelligibility keep microphone almost
touching lips.

4. On response from the ground station adjust for desired volume using VOL control.

5. Position ON/OFF switch to SQL to suppress weak input signals and input noise.

6. The sidetone volume can be adapted to the noise level of the aircraft by means of the sidetone
volume control.

3.3 Operating instructions serial no. 4000 upwards

NOTE
Switch off transceiver when engines are started or stopped.

1. Use the ON/OFF switch to turn on the VHF transceiver. For a few seconds, the digits 188.88 will
appear in the LCD (display test), as well as an arrow to indicate transmission mode. Afterwards
the VHF transmitter automatically switches to the most recently set frequency, if the channel

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selector switch is in position A. If the channel selector switch is set to one of the stored channel
frequencies (any one of switch positions 1 through 4), then the channel frequency stored in that
memory location will appear in that display. If any other channel frequency is desired other than
those channel frequencies stored, then the channel selector switch should be set to position A
whereupon the desired frequency can be set using the MHz and kHz frequency selector dials.

2. Repeat steps 2 through 6 of Section 3.2.

3.4 Storing frequencies

Four memory locations are available for channel frequencies; each of these can be used to store any
channel frequency used for aircraft communications. They can be used in any desired order. To store,
proceed as follows :

a) Switch the channel selector switch to position A.

b) Use the MHz and kHz rotary switches to set the desired channel frequency.

c) Set the channel selector switch to the desired memory location.

d) Press the store button. For models with serial nos. of 4000 or above, the STORE button must be
held depressed for approx. 2 seconds.

NOTE
When overwriting a stored channel frequency, the same procedure as listed in steps a.
through d. should be followed.

3.5 Setting the emergency frequency

3.5.1 Setting the emergency frequency on models with serial numbers up to 3999

As already described in the operating instructions, the transceiver automatically switches to the
emergency frequency 121.500 MHz when the channel selector is positioned to A in switching the
transceiver on. To quickly switch to the emergency frequency in an emergency situation best procedure
is to switch the channel selector to A and to briefly switch the transceiver off/on, after which the
transceiver operates on the emergency frequency of 121.500 MHz. Under normal operating c onditions,
this can be set by means of the frequency selector switches. Another possibility is to store the
emergency frequency directly in one of the four available channels.

3.5.2 Setting the emergency frequency on models with serial numbers of 4000 or above

In models with serial numbers of 4000 or above, the emergency frequency 121.500 MHz does not
automatically appear when the channel selector switch is in position A and the transceiver is powered
up. It is recommended to store the distress frequency in one of the 4 memory locations.
In models with serial numbers of 4000 or above, an arrow flashes on and off in the LCD during
transmission. This is activated by the microprocessor, which outputs the instruction for this along with
the other data for the liquid-crystal display.

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3.6 LC display blinking

As soon as the operating voltage for the transceiver drops to a value of 10.5 V to 11 V, the display
starts blinking to signalize, e.g. in battery operation that the batteries need recharging. The display will
start blinking in transmitter operation since this situation involves the highest current drain.
Since the discharge curves of batteries greatly depend on the type of batteries involved, e.g. lead-acid
or nickel batteries and on the ambient temperature of the batteries, no accurate indication can be given
as to how long the transceiver will remain fully functional on commencement of LC display blinking.
After a few keying cycles, the batteries can be empty in transmitter operation. In receiver operation
the instrument will remain functional for approx. 1-2 hours from commencement of blinking.
At an operating voltage of 10 V, the transceiver remains fully functional, but at reduced output power.

3.7 IC operation

1. Switch on IC switch.

2. Carry out speech test.

3. IC volume can be adapted to the noise Ievel of the aircraft by means of the IC volume control see
(Fig. 2-7).

3.8 Optional temperature, voltage measurement

When the standard version is supplemented by optional temperature and voltage measurement
circuits, note:
Temperature of voltage is measured continuously, whereas display follows only after pressing the
external pushbutton for approx. 4 sec, after which the previously set channel frequency appears.

NOTE
Independent of the temperature or voltage measurement, transceiver operation is
available at the set channel frequency even when the instrument is displaying a tempe-
rature or voltage indication.

3.9 Auxiliary audio input (optional) (standard as of module No. 471)

Via the auxiliary audio input, other radio equipment (e.g.navigation receiver) can be monitored. When
the system is wired up for this application, the volume control of the remote equipment must be set so
that these inputs are intelligible and can be differentiated from each other.
During transmission the auxiliary input from the audio output amplifier is OFF.

3.10 No channel frequency storage

When the stored frequencies are lost when the transceiver is switched off, first measure the battery
voltage at the two button batteries which must be 2.4 V. These batteries are automatically charged
when the transceiver is switched on. When the unit is not switched on for a long time, or in lengthy
storage, the batteries may become discharged. To recharge the battery, it is sufficient to simply connect
the transceiver to the aircraft voltage for a couple of hours. The service life of a new battery is between
3 and 5 years.

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3.11 Precautions

In order to secure a reliable transceiver operation, please note the following precautions:

a) Before running-up the engines, ensure that the transceiver is switched off.

b) Always conduct a verbal pre-flight check. Note that in the vicinity of a flight control, a broken or
shorted antenna cable must not necessarily impair the function. At a distance of 5-10 km from the
ground station, however, the connection will doubtlessly fail.

c) Transceiver communication contact should always be conducted using a clear, loud voice and by
speaking directly into the microphone. Otherwise, cabin background noise could predominate,
making the message inaudible.

d) Use suitable microphones or headset for aircraft only. With certain aircraft types (wood or fibre-glass
aircraft, gliders and helicopters) the signals transmitted by the unit’s antenna may be picked up
and enhanced by the integrated microphone amplifier (feed back). As a result, the signal received
by the flight control will be superimposed by whistles and/or strong distortion. This phenomenon
may not necessarily remain constant for all channels.

e) The PTT button of the microphone or control unit might jam, causing the system to remain in the
transmission mode. In order to rule such cases out, please ensure that the arrow in the frequency
display (from serial no. 4000 onwards) illuminates during the transmission mode, and extinguishes
when the PTT button is released.

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