Cobra 25ltd St Cb Tranciever Manual

OPERATING INSTRUCTIONS FOR YOUR
40 CHANNEL
CITIZENS BAND 
2-WAY MOBILE RADIO
Model
25 LTD ST
Cobra Electronics Corporation
6500 W. Cortland Street
Chicago, IL 60707
PRINTED IN HONG KONG ©COBRA ELECTRONICS CORP. 1997 480-205-P-001 

The Citizens Band lies between the shortwave broadcast and 10-meter Amateur
radio bands, and was established by law in 1949. The Class D two-way commu-
nications service was opened in 1959. (CB also includes a Class Acitizens band
and Class C remote control frequencies.)
FCC regulations permit only ÒtransmissionsÓ (one party to another) rather than
ÒbroadcastsÓ (to a wide audience). Thus, advertising is not allowed on CB
Channels because that is Òbroadcasting.Ó
“Cuts Static coming in, adds Punch going...

Specifications (cont.)
GENERALChannels40 
Frequency Range26.965 to 27.405 MHz.
Frequency ControlPhase Lock Loop (PLL) synthesizer.
Frequency Tolerance0.005%.
Operating Temperature Range-30¡C to + 50¡C.
MicrophonePlug-in dynamic.
Input Voltage13.8VDC nom.(positive or negative ground).
Current DrainTransmit: AM full mod., 1.5A(maximum)
Receive: Squelched, 0.3A; full audio output, 1.2A
(nominal).
Size8 5
/
8Ó D  x 7 9
/
32Ó W  x 2 13
/
64Ó H .
Weight4 lbs.
Antenna ConnectorUHF, SO-239.
Semiconductors26...

5
Installation (Cont.)
3.
Connect the antenna cable plug to the standard receptacle on the unit. Most
CB antennas are terminated with a type PL-259 plug which mates with the
receptacle marked ANT.
4.
Connect the red lead of DC power cord to +13.8 VDC. In automobile instal-
lations, +13.8 VDC is usually obtained from the accessory contact in the fuse
box. This prevents the set being left on accidentally and also permits oper-
ating the unit without the vehicles engine running.
Before installing the CB...

7
Installation (Cont.)
Ignition Noise Interference
Use of a mobile receiver at low signal levels is normally limited by the presence
of electrical noise. The primary source of noise in automobile installations is from
the alternator and ignition system in the vehicle. Under most operating conditions,when signal level is adequate, the background noise does not present a seriousproblem. Also, when extremely low level signals are being received, the transceivermay be operated with vehicle engine turned off....

Operation (Cont.)
9
5.
RF GAIN.Adjust as required to optimize signal. This control is used 
primarily to optimize reception in strong signal areas. Gain is reduced by
counterclockwise rotation of the control. 
6.CHANNELSELECTOR SWITCH.This switch selects any one of forty
Citizens Band channels desired. The selected channel is indicated by the
LED readout, directly above the channel selector knob.7.
S-METER. Swings proportionally to the strength of the incoming signal
during receiving.
RF-METER. Swings...

11
3.
ANTENNACONNECTOR:This SO-239 connector permits connection
of the transmission line cable PL-259 connector to the transceiver.
4.
POWER. This jack permits connection of the DC power to the transceiver.Apower cord with polarized plug is supplied with the radio. The polar-
ized plug ensures that the power will always be connected properly.
Operating Procedure to Receive
1.
Be sure that the power cord, antenna and microphone  are connected to the
proper connectors before proceeding further. The PA/CB...

13 12
Operation (Cont.)Operating Procedure to Transmit
1.
Be sure the operator has read and understands part 95, F.C.C. Rules and
Regulations prior to operating the transmitter.
2.
Select the desired channel.
3.
Set the DYNAMIKE control fully clockwise.
4.
The receiver and transmitter are controlled by the pr
ess-to-talk switch
on the
microphone. Press the switch and the transmitter is activated; release switch
to receive. When transmitting (on a clear channel), hold the microphone two
inches from the...

1415
The COBRACB transceiver is specifically designed for the environment encoun-
tered in mobile installations. The use of all solid state circuitry and its light weight
result in high reliability. Should a failure occur, however, review the following,
then if necessary, replace parts only with identical parts. Do not substitute. Refer
to the schematic diagram and parts. 1.
Check connections to the source of power and make sure it is the 13.8 VDC
required to operate your radio.
2.
Check the fuse in the...

Appendix (Cont.)If You Think  You Need Service 
If  You Think  You Need Service, Call 773-889-3087