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COVER
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Contents

Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Elimination of Licensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Controls and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Mobile Station Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Mobile Station Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Marine Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Connecting the Power Cords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Ground Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Negative Ground System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Positive Ground System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
To Receive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Weather Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
To Transmit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Multi-Function Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Servicing Your Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Radio Code Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Two-Year Extended Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Unpacking

Carefully unpack your PC78LTW and check the contents against this list:
n PC78LTW CB 2-way mobile radio
n Microphone
n Mounting Bracket Kit
n DC Power Cord
n Reference Guide
n Part 95 Subpart D (FCC Rules)
n Product Registration Card

If any items are missing or damaged, contact your place of purchase immediately.

Please be sure to complete and mail your

Product Registration Card.
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Description
Your Uniden PC78LTW represents the highest quality communications device
designed for use in the Citizens Band Radio Service. It will operate on any of the
40 AM frequencies authorized by the Federal Communications Commission (FCC).

The Citizens Band Radio Service is under the jurisdiction of the

Federal Communications Commission (FCC). Any adjustments or
alterations which would alter the performance of the transceiver's
original FCC type acceptance, or which would change the
frequency determining method, are strictly prohibited.
Replacement or substitution of crystal, transistors, ICs, regulator
diodes, or any other part of a unique nature, with parts other than
those recommend by Uniden, may cause violations of the
technical regulations in Part 95 of the FCC Rules or in violation of
type acceptance requirements in Part 2 of the rules.

Elimination of Licensing
The FCC has ruled that CB Radio Service operators are no longer required to
obtain an FCC License to operate their CB equipment. In doing so, the FCC also
decided to permit CB station operation without station identification.
Elimination of individual station licenses does not reduce the operating
privileges or responsibilities of CB users. An operator of a CB radio station is still
required to comply with the Communications Act and with the rules of Citizens
Band Radio Service.
Uniden is a registered trademark of Uniden America Corporation.

Features, Specifications, and availability of Optional

Accessories are subject to change without notice.

Emergency Operation
1. Set the switch to CH9 or turn Channel Selector knob to Channel 9.
2. Press the microphone PTT switch and speak clearly.
3. If there is no response, select an active channel and ask that party to
relay your emergency broadcast on Channel 9.

All channels, except Channel 9 may be used for normal

communication. Channel 9 is reserved by the FCC for emergency
communication involving the immediate safety of individuals or
protection of property. Channel 9 may also be used to render
assistance to a motorist.
This is an FCC rule and applies to all operators of CB radios.

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Controls and Functions

FRONT VIEW - PC78LTW BACKLIGHTED PANEL

1. Microphone Jack
2. ON OFF - VOLUME: Turns radio on or off; adjusts speaker volume.
3. SQUELCH: Reduces background noise when there is no
incoming signal.
4. RF GAIN: Improves reception in strong signal areas.
5. MIC GAIN: Adjusts microphone sensitivity.
6. DELTA TUNE: Fine tunes the receiver.
7. SWR: Calibrates the meter for Standing Wave Ratio
(SWR) measurements.
8. Weather Channel Knob: Selects weather channel.
9. Channel Knob: Selects channel.
10. Channel Display: Displays current channel selection.
11. RX/TX Indicator: Red-transmitting; green-receiving.
12. ANT: Indicates a high SWR condition in antenna system. Check
antenna, cable and connections.
13. Dynamic Squelch Control (DSC): Automatically sets Squelch to
optimal level for stronger signals.
14. CH9/OFF: Turns Channel 9 on or off.
15. BRT/DIM: Adjusts the brightness of LED Channel Display, RX/TX
Indicator, and RF Signal Meter.
16. NB/ANL: Reduces external noise and interference from vehicle
ignition systems.

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17. CB/WX/PA Switch: Selects PA (Public Address) WX (Weather

Radio) or CB.

Do not use PA function unless an

external speaker is connected.

18. S/RF/SWR/CAL: Selects meter function. S/RF - normal;

SWR and CAL are for SWR measurements only. See page 8
for calibration procedures.
19. Multi-function Meter: Measures SWR, RF and S signal strength.

REAR VIEW

20. POWER: Connects DC power to transceiver.

21. EXT. SP.: Connects optional 8-ohm 4-watt speaker to remotely
monitor receiver.

When the external speaker is plugged in, the

internal speaker is off.

22. PA SP.: Connects external 8-ohm, 4-watt speaker.

To prevent acoustic feedback, separate the

microphone from the speaker when operating
the PA at high output levels.

23. ANT.: Connects antenna cable to transceiver.

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Installation

MOBILE STATION INSTALLATION

Plan the location of the transceiver and
microphone bracket before beginning installation.

1. Select a location that is convenient for operating the radio, but

does not interfere with the driver or passenger.
2. Install bracket with self-tapping screws provided.
3. Connect wiring. (See instructions for Connecting the Power Cords).
4. Attach the microphone bracket to the side of the radio.
5. Attach radio to bracket.

MOBILE STATION ANTENNA

Because the maximum power output of the transmitter is limited by the
FCC, the quality of your antenna is very important. To achieve the
maximum transmission distance, we strongly recommend that you install
only a high quality antenna. You have just purchased a superior transceiver
- don't diminish its performance by installing an inferior antenna.
Only a properly matched antenna system will allow maximum power
transfer from the 50 ohm transmission line to the radiating element.
Your Uniden dealer is qualified to help you select the proper antenna
for your requirements. A whip style antenna may be used for
automobile installation.
A short ‘loaded’ whip antenna is easier to install on
an automobile. However, the efficiency of the short
whip antenna is less than that of a full quarter-wave
whip antenna.

MARINE INSTALLATION
Consult your dealer for information regarding marine installation. It is
important to adequately ground the system and to prevent electrolysis
between the fittings in the hull and the water.

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CONNECTING THE POWER CORDS

We recommend connecting the power lead to the Ignition Switch
Accessory Terminal. This way, the transceiver is automatically turned off
when the ignition switch is turned off.
Or, the power cord may be connected to an available terminal on the
fuse block, or, to a point in the wiring harness. However, caution must
be taken to prevent a short circuit. If in doubt, contact your vehicle dealer
for information.

This transceiver may be installed and used in any 12-volt

DC negative or positive ground system vehicle.

GROUND INFORMATION
Note: This transceiver may be installed and used in any 12-volt DC negative
or positive ground system vehicle.
Most newer U.S. and foreign made cars, and small trucks, use a negative
ground system. Some older cars, and some new large trucks, use a positive
ground system.
With a negative ground system, the negative (-) battery terminal is usually
connected to the vehicle motor block. If you cannot determine the polarity
system of your vehicle, contact your vehicle dealer for information.

Negative Ground System

If you have a negative ground system,
connect the red DC power cord from the
transceiver to the positive (+) battery
terminal or other convenient point.
Then connect the black power cord
to the vehicle chassis or negative (-)
battery terminal.

Positive Ground System

If you have a positive ground system,
connect the black DC power cord from the
transceiver to the negative (-) battery
terminal or other convenient point. Then,
connect the red power cord to the vehicle
chassis or the positive (+) battery terminal.

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To Receive

Be sure that the power source, antenna, and microphone

are properly connected before proceeding.

1. Turn unit ON and set

VOLUME Control to a
comfortable level.

2. Select CHANNEL.

3. Set switch to NB/ANL.

Dynamic Squelch Control automatically sets Squelch to the optimal level

for stronger transmission and signal clarity. To scan for weaker signals,
turn Dynamic Squelch Control off and perform the following steps:

4a. Turn SQUELCH fully clockwise

so only strong signals
can get through.

4b. Turn SQUELCH fully counter-

clockwise until you hear a hiss.
Everything gets through - noise, weak
signals, and strong signals.

4c. Turn SQUELCH back clockwise until

the hiss stops. Only clearer signals get
through.

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Set SQUELCH only when

the radio is not receiving a
strong signal.

5. Adjust RF GAIN knob (small)

to optimize reception in strong
signal areas.

6. Adjust DELTA knob to

reduce or eliminate adjacent
channel interference.

7. Set meter switch to S/RF.

Weather Information

Your PC78LTW combines a CB Radio with a Weather Radio and a

Weather Alert System. The Weather Radio continually broadcasts
weather conditions. The Weather Alert System sounds a seven-second
signal in the event of severe weather.
To configure your CB radio to receive
weather alerts while using your CB radio:

1. Set the switch to WX.

2. Turn the Weather Channel knob to

the channel with best reception.

Left at this setting, you will hear only

weather broadcasts and Weather Alert Signals.

To use your CB radio normally while monitoring

for weather alerts, set the switch to CB.

When you hear a Weather Alert Signal, and desire to

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To Transmit

Perform a voltage Standing Wave Ratio (SWR) measurement

prior to using the transmitter. A SWR ratio in excess
of 2:1 may damage the transmitter.

Be sure to read and understand Part 95, FCC Rules and

Regulations before operating your transmitter.

1. Select a channel.
2. Adjust MIC GAIN.

3. When the channel is clear, press

the microphone PTT switch
and speak.

Multi-Function Meter
SWR Meter: Measures SWR (standing wave ratio) of antenna. Use to check
antenna system or to adjust your antenna to the proper length.

To measure SWR:
1. Position meter switch
to CAL.
2. Press microphone PTT
switch. (Transmit)
3. Calibrate meter with
SWR CAL knob by adjusting
the needle to the t mark.

4. Move the meter switch to

the SWR position while pressing
the microphone PTT switch.

A reading below 2 is acceptable. Higher readings indicate a problem in the

antenna system. Problems may be caused by humidity, vibration, or
corrosion. Check both ends of the coaxial cable connector. Also check for
damage to the cable or antenna.
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RF Meter: Measures RF Output Power for transmitter. To use, position

the meter switch at S/RF. Press microphone PTT switch to read
transmitting power.
S-Meter: Measures incoming signal strength. To use, position the meter
switch at S/RF. The meter swings to indicate signal strength.
i.e. S 3, S 5, S 7 . . .

Preventive Maintenance
Every six months:

1. Check the Standing Wave Ratio (SWR).

2. Be sure all electrical connections are tight.
3. Inspect antenna coaxial cable for wear or breaks in shielding.
4. Be sure all screws and mounting hardware are tight.

Maintenance
The PC78LTW is designed to give you years of trouble-free service. There
are no user-serviceable parts inside. Except for the fuse in the DC power
cord, no maintenance is required.
To replace a blown fuse:

1. Press ends of the fuse holder

together. Twist to open.
Carefully separate the
two pieces.

2. Remove the fuse and inspect.

If blown, replace with the same
type fuse.

Use only the fuse specified for your PC78LTW.

Failure to do so may void your warranty.

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Troubleshooting
Problem Suggestion
Unit does not power up q Check the ignition key position.
q Check power cord connections.
q Check fuse.
q Check vehicle electrical system.
No reception q Check microphone connection.
q Set CB/WX/PA switch to CB.
q Check VOLUME and SQUELCH.
q Check antenna.
q Check antenna connection.
q Set RF GAIN to MAX.
Poor Reception q Check VOLUME and SQUELCH.
q Be sure antenna SWR is normal.
q Set RF GAIN to MAX.
q Check and adjust DELTA TUNE.
No Transmission q Set CB/WXPA switch to CB.
q Check microphone connection.
q Check MIC GAIN and adjust to MAX.
Low Transmission q Be sure antenna SWR is normal.
q Check MIC GAIN and adjust to MAX.

If you do not get satisfactory results after performing the above checks,
call the Uniden Customer Service Center at 1-800-297-1023, 8:00 a.m. to
5:00 p.m. CST, Monday through Friday.

Servicing Your Transceiver

Technical information, diagrams, and charts are provided on request. It is
the user's responsibility to see that this radio is operating at all times in
accordance with the FCC Citizens Radio Service regulations. We highly
recommend that you consult a qualified radio/telephone technician for
servicing and aligning this CB radio product. Please read the Warning
information on page 1 of this Guide.

When ordering parts, be sure to specify the correct

model number and serial number of the unit.

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Radio Code Definitions

The following list contains common “10-Codes” used by CB radio

operators for faster communication and better understanding.

Code Meaning Code Meaning

10-1 Received poorly 10-35 Confidential information
10-2 Receiving well 10-36 Correct time is
10-3 Stop transmitting 10-37 Wrecker needed at
10-4 OK, message received 10-38 Ambulance needed at
10-5 Relay message 10-39 Your message is delivered
10-6 Busy, stand by 10-41 Please turn to channel
10-7 Out of service, leaving air 10-42 Traffic accident at
10-8 In service, subject to call 10-43 Traffic tie up at
10-9 Repeat message 10-44 I have a message for you
10-10 Transmission completed, 10-45 All units within range
standing by please report
10-11 Talking too rapidly 10-50 Break channel
10-12 Visitors present 10-60 What is next
10-13 Advise Weather/ message number
Road conditions 10-62 Unable to copy, use phone
10-16 Make pickup at 10-63 Net directed to
10-17 Urgent business 10-64 Net clear
10-18 Anything for us? 10-65 Awaiting your next
10-19 Nothing for you, return message/assignment
to base 10-67 All units comply
10-20 My location is 10-70 Fire at
10-21 Call by telephone 10-71 Proceed with transmission
10-22 Report in person to in sequence
10-23 Stand by 10-77 Negative contact
10-24 Completed last assignment 10-81 Reserve hotel room for
10-25 Can you contact 10-82 Reserve room for
10-26 Disregard last information 10-84 My telephone number is
10-27 I am moving to channel 10-85 My address is
10-28 Identify your station 10-91 Talk closer to microphone
10-29 Time is up for contact 10-93 Check my frequency on
10-30 Does not conform to this channel
FCC rules 10-94 Please give me a
10-32 I will give you a long count
radio check 10-99 Mission completed, all
10-33 EMERGENCY TRAFFIC units secure
10-34 Trouble at this station 10-200 Police needed at

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Specifications
General
Channels: 40
CB Frequency Range: 26.965 to 27.405 MHz
Weather Frequency Range: 162.400MHz (WX CH1)
162.425MHz (WX CH2)
162.450MHz (WX CH3)
162.475MHz (WX CH4)
162.500MHz (WX CH5)
162.525MHz (WX CH6)
162.550MHz (WX CH7)
Frequency Control: Phase Locked Loop (PLL) synthesizer
Frequency Tolerance: ±0.002%
Operating Temperature: -30°C to +60°C
-10°C to +60°C (DSC on)
Microphone: Plug-in type; 600 ohms dynamic
Input Voltage: 13.8 VDC nominal (positive or negative ground)
Current Drain: TX: AM full modulation, 2.2 A (max.)
RX: Squelched, 0.25 A; with maximum audio output,
1.2A (nominal)
Size: 7-9/32” W x 8-57/64” D x 2-13/64” H
Weight: 4 lbs. 3 oz. with microphone
Antenna Connector: UHF, SQ-239
Meter: Illuminated; indicates relative power output and received
signal strength SWR.
Transmitter
Power Output: 4 watts
Modulation: High- and low-level, Class B amplitude modulation
Frequency Response: 300 to 3000 Hz
Output Impedance: 50 ohm, unbalanced
Receiver
Sensitivity: Less than 1 µV for 10 dB, (S+N)/N
Selectivity: 6 dB @ 7 kHz, 60 dB; @10 kHz
Image Rejection: 80 dB typical
Adjacent-Ch. Rejection: 60 dB typical
IF Frequencies: Double Conversion: 1st: 10,695 MHz; 2nd: 455 kHz
Automatic Gain Control (AGC): Less than 10 dB change in audio output for inputs from
10 to 50,000 µV
RF Gain Control: Adjustable for optimum signal reception
Delta Tune Range: ±1.5 kHz, continuously adjustable
Noise Blanker: RF type
Squelch: Adjustable; threshold less than 1 µV
Audio Output Power: 4 watts
Frequency Response: 300 to 3000 Hz
Distortion: Less than 7% at 3 watts, 1000 Hz
Internal Speaker: 16 ohms, round
External Speaker: 8 ohms, disables internal speaker when connected
(not supplied)
PA System
Power Output: 4 watts into external speaker
External Speaker for PA
speaker: 8 ohms when CB/PA switch is in PA. The PA
(not supplied) also monitors the receiver; separate jack provided.

Specifications shown are typical and subject to change without notification.

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Two-Year Extended Warranty

Important: Evidence of original purchase is required for warranty service.
WARRANTOR: UNIDEN AMERICA CORPORATION (“Uniden”)
ELEMENTS OF WARRANTY: Uniden warrants, for two years, to the original retail
owner, this Uniden Product to be free from defects in materials and craftsmanship
with only the limitations or exclusions set out below.
WARRANTY DURATION: This warranty to the original user shall terminate and be of
no further effect two years after the date of original retail sale. The warranty is invalid
if the Product is (A) damaged or not maintained as reasonable or necessary, (B)
modified, altered, or used as part of any conversion kits, subassemblies, or any
configurations not sold by Uniden, (C) improperly installed, (D) serviced or repaired
by someone other than an authorized Uniden service center for a defect or
malfunction covered by this warranty, (E) used in any conjunction with equipment or
parts or as part of any system not manufactured by Uniden, or (F) installed or
programmed by anyone other than as detailed by the owner’s manual for this product.
STATEMENT OF REMEDY: In the event that the product does not conform to this
warranty at any time while this warranty is in effect, warrantor will either, at its option,
repair or replace the defective unit and return it to you without charge for parts,
service, or any other cost (except shipping and handling) incurred by warrantor or its
representatives in connection with the performance of this warranty. Warrantor, at its
option, may replace the unit with a new or refurbished unit. THE LIMITED
WARRANTY SET FORTH ABOVE IS THE SOLE AND ENTIRE WARRANTY
PERTAINING TO THE PRODUCT AND IS IN LIEU OF AND EXCLUDES ALL OTHER
WARRANTIES OF ANY NATURE WHATSOEVER, WHETHER EXPRESS, IMPLIED OR
ARISING BY OPERATION OF LAW, INCLUDING, BUT NOT LIMITED TO ANY
IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE. THIS WARRANTY DOES NOT COVER OR PROVIDE FOR THE
REIMBURSEMENT OR PAYMENT OF INCIDENTAL OR CONSEQUENTIAL DAMAGES.
Some states do not allow this exclusion or limitation of incidental or consequential
damages so the above limitation or exclusion may not apply to you.
LEGAL REMEDIES: This warranty gives you specific legal rights, and you may also
have other rights which vary from state to state. This warranty is void outside the
United States of America.
PROCEDURE FOR OBTAINING PERFORMANCE OF WARRANTY: If, after
following the instructions in the owner’s manual you are certain that the Product is
defective, pack the Product carefully (preferably in its original packaging). The
Product should include all parts and accessories originally packaged with the Product.
Include evidence of original purchase and a note describing the defect that has
caused you to return it. The Product should be shipped freight prepaid, by traceable
means, to warrantor at:
Uniden America Corporation
Parts and Service Division
4700 Amon Carter Blvd
Fort Worth, TX 76155
(800) 297-1023, 8 a.m. to 5 p.m., Central,
Monday through Friday

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