Cobra 18WXST User Guide

Installation

Location

Plan the location of the transceiver and microphone bracket
before starting the installation. Select a location that is conve­nient for operation and does not interfere with the driver or
passengers in the vehicle. In automobiles, the transceiver is
usually mounted to the underneath of the dash panel, with the
microphone bracket beside it.

Mounting and Connections

The transceiver is held in the universal mounting bracket by
two thumb screws, permitting adjustment at the most conve­nient angle.

A universal mounting bracket is supplied along with self tap­ping screws and star washers. The mounting must be mechan­ically strong and also provide a good electrical connection to
the chassis of the vehicle. To mount the transceiver:

1. Determine the most con-

venient location in your
vehicle. Hold the COBRA
radio with mounting
bracket in the exact loca­tion desired. If nothing
will interfere with mount­ing it in the desired posi­tion, remove the mounting
bracket and use it as a tem­plate to mark the location
for the mounting screws.

2. Drill necessary holes and secure mounting bracket in

location.

Operating Instructions for Your

CITIZENS BAND

2-WAY MOBILE RADIO

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WITH INSTANT EMERGENCY CHANNEL 9

Welcome to the Cobra Family of 2-way communications.
Cobra has dedicated over 30 years of research and develop­ment to the technology that made Cobra #1 in CB Radios.
Please take some time to read this booklet. Although this CB
is simple to operate, we want you to be aware of all the
unique features your new CB Radio offers.

THE CB STORY

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 communications service was
opened in 1959. (CB also includes a Class A citizens band
and Class A remote control frequencies.)

FCC regulations permit only "transmissions" (one-party to
another) rather than" broadcast" (to a wide audience). Thus,
advertising is not allowed on CB channels because that is
"broadcasting".

“Cuts Static coming in, adds Punch going out!”

Cobra proudly introduces the first Patent Pending technolo­gy that dramatically improves the transmission and recep­tion of CB radio signals.

This revolutionary system reconfigures the transmission sig­nal which allows it to be transferred more effectively through
cluttered airwaves. It literally ÒpunchesÓ your message
through the hundreds of thousands of signals that are in the
air. At the same time, SoundTracker system dynamically
adjusts the relationship between the signal and static com­monly referred to as noise. This allows CobraÕs SoundTracker
system to significantly reduce the amount of static on all
incoming CB signals. The system can be further optimized
when two SoundTracker CBÕs are used to talk to each other.

The end result is a clearer, cleaner sounding reception of sig­nals and more powerful transmission which

dramatically

improve CB Communications

WARNING
Replacement or substitution of transistors, regular diodes or
other parts of a unique nature, with parts other than those
recommended by Cobra, may cause violation of the techni­cal regulations of Part 95 of the FCC Rules, or violation of
Type Acceptance requirements of Part 2 of the Rules.

LICENSING
Citizens Band (CB) Radio operators are no longer re­quired to obtain an FCC license to operate their CB
equipment or provide station identification.
Nevertheless, an operator of a CB radio station is still re­quired to comply with the communications act and with
the rules of CB Radio Operation.

Model

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Mobile whip antennas utilize the metal body of the vehicle as
a ground plane. When mounted at a corner of the vehicle they
are slightly directional, in the direction of the body of the vehi­cle. For all practical purposes, however, the radiation pattern is
non-directional. The slight directional characteristic will be
observed only at extreme distances. A standard antenna con­nector (Type SO-239) is provided on the transceiver for easy
connection to a standard PL-259 cable termination. Cobra load­ed-type antenna models AT-35, AT-60 and AT-70 are highly rec­ommended for most installations. Consult your Cobra dealer
for further details (or see order form at the back of this book).

When installed in a boat, the transceiver will not operate at
maximum efficiency without a ground plate unless the vessel
has a steel hull. Before installing the transceiver in a boat, con­sult your dealer for information regarding an adequate
grounding system and prevention of electrolysis between fit­tings in the hull and water.

3-Way Combination Antennas are available which allow op ­eration of all three bands (AM-FM & CB), using a single
antenna. However, use of this type of antenna usually
results in less than normal transmit and receive range when
compared to a standard-type "Single Band" antenna
designed for CB only.

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 serious problem. Also, when extremely low level signals are
being received, the transceiver may be operated with vehicle
engine turned off. The unit requires very little current and
therefore will not significantly discharge the vehicle battery.

Even though this COBRA radio has an automatic noise limiter, in
some installations ignition interference may be high enough to
make good communications impossible. The electrical noise may
come from several sources. Many possibilities exist, and varia­tions between vehicles require different solutions to reduce the
noise. Consult your COBRA dealer or a 2-way radio technician
for help in locating and correcting the source of severe noise.

3. Connect the antenna cable plug to the standard recep-

tacle 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 installations, +13.8VDC is usually ob­tained from the accessory contact in the fuse box. This
prevents the set being left on accidentally and also per­mits operating the unit without the vehicle's engine
running.

Before installing the CB radio, visually check the ve­hicle battery connections to determine which battery
terminal, positive or negative (positive is the larger of
the two) is grounded to the engine block (or chassis).

5. Connect the black lead to the negative side of the auto-

mobile. This is usually the chassis of the car. Any con­venient location with good electrical contact (remove
paint) may be used.

6. Mount the microphone bracket on right side of the

transceiver or near it using two screws supplied. When
mounting in an automobile, place the bracket under
the dash so the microphone is readily accessible.

CB Antenna

Since the maximum allowable power output to the trans­mitter is limited by the FCC, the antenna is one important
factor affecting transmission distance. Only a properly
matched antenna system will allow maximum power trans­fer from a 50-ohm transmission line to the radiating ele­ment. In mobile installations (cars, trucks, boats, etc.), an
antenna system that is non-directional should be used.

A vertically polarized quarter-length whip antenna pro­vides the most reliable operation and the greatest range.
The shorter loaded-type whip antennas are more attractive,
compact and adequate for applications where the maxi­mum possible range is not required. Also the loaded whips
do not present the problems of height imposed by the full
quarter-wavelength whip.

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Temporary Mobile Operation

To operate your COBRA transceiver from a car on a tempo­rary basis, you may want to purchase an additional ciga­rette lighter adapter from your COBRA dealer. This adapter
and a magnetic mount antenna allow you to quickly
"install" your transceiver for temporary use.

Operation

Controls and Indicators

Refer to controls, indicators and connectors as illustrated
below:

A. Front Panel

1. Microphone Connector. Allows for convenient

removal of the microphone plug when storage is
required. The microphone MUST be connected to the
unit at all times when in use, for proper operation.

2. Off/On/Volume. Turn clockwise to turn power on and

set the desired listening volume.

3. Squelch. This control is used to cut off or eliminate

receiver background noise in the absence of an incom­ing signal. For maximum receiver sensitivity, it is
desired that the control be adjusted only to the point
where the receiver background noise or ambient back­ground noise is eliminated. Adjust until the receiver
noise disappears. This will require the incoming signal
to be slightly stronger than average receiver noise.
Further clockwise rotation will increase the threshold
level which a signal must overcome in order to be
heard. Only strong signals will be heard at a maximum
clockwise setting.

4. CB,WX1, WX2, WX3. CB mode is for normal CB opera-

tion. Switch to WX1, or WX2, or WX3 to find the
Weather VHF Radio Station active in your area.

5. Channel Up/Down Buttons. When depressed, these

buttons are used to select any one of the forty citizens
band channels desired.

For a "RAPID" change of channels, depress and hold the
desired button (up or down). This allows all 40 channels
to be covered in about 6 seconds.

6. LED Channel Display. The selected channel will be dis-

played.

7. S/RF Power Meter. Shows relative transmitter RF out-

put power and input signal strength when receiving.
The LED (Light Emitting Diode) segments glow green to
amber to red...this indicates receive or transmit activity.

8. RX/TX Indicator LED. 4 red indicator will light when in

the receive mode. A green indicator lights when in receive
mode. When weather channel is selected, the channel
display will be turned off.

9. SoundTracker™LED. A red indicator will illuminate

when the SoundTracker system is engaged on your CB.

10. Channel 9 Button. Depressing this button provides

instant access to emergency Channel 9. Channel 9 on
display will flash to remind you that the function is acti­vated.

11. SoundTracker™ Switch. Depressing this button turns

on the SoundTracker system in your radio.

¥

Automatic Noise Limiter. This is a non-switchable
feature that is always "on" to reduce background noise.

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