TRC-424 4-Watt Solid-State
Transceiver (210-1522)     Installation               Faxback Doc. # 48944

ANTENNA SYSTEM

The antenna system includes the transmission line, and it is very important
that you use the correct type of transmission line.  The transmission line
should be of coaxial type and should have an impedance equal to the antenna
impedance.

Since your Transceiver is designed to operate most efficiently into a 50
ohm load, it is best to use a type of coaxial cable with an impedance of 50
ohms.  We suggest type RG-58/U for short lengths and RG-8/U for long
lengths.

Generally speaking, you should keep the length of the transmission line to
a minimum.  Remember that transmission line losses increase with frequency.
Use foam-insulation coax for best results.

The above discussion is as important for reception as it is for
transmission.  If a mismatch exists between the antenna and the receiver,
the excellent sensitivity and signal-to-noise ratio of the receiver
circuitry will be defeated.

MOBILE ANTENNAS

There are two types of mobile CB antennas: a full-length whip or a loaded
whip.  Your local RadioShack store has a complete line of both types and
the salesman can help you to choose the best antenna for your needs.

A vertically polarized whip antenna is best suited for mobile service.  It
is omni-directional and can be the loaded type or a full quarter-wave
(quarter-wave being more efficient).

There are many possible antenna locations on a car.  Four of the most
popular are listed:

      ROOF MOUNT - In this position the antenna radiates equally in all
                   directions.  Since the normal 1/4 wavelength whip
                   antenna is too long (102" [2.6m]) for roof mounting on
                   a vehicle, the antenna is shortened and a loading coil
                   is utilized to provide the proper electrical length.
                   Our Fiberglass Roof-Mount catalog number 21-925 is a
                   good durable antenna.

FRONT COWL MOUNT - The radiation pattern is slightly greater in the
                   direction of the rear fender opposite the side on which
                   the antenna is mounted.  However, this position offers
                   a number of advantages.   The CB antenna can be easily
                   mounted.  It can double as both the CB and the standard
                   auto radio antenna by employing a two-way coupler.  Ask
                   about our catalog number 21-930 Front Cowl Mount
                   antenna which is designed for CB, AM and FM operation.

       REAR DECK - The radiation pattern is strongest in the direction of
                   the front fender opposite the side on which the antenna
                   is mounted.  In this position you can use a full
                   quarter-wave antenna or a shorter, loaded whip.  Here
                   you might consider RadioShack's catalog number 21-926
                   or 21-908, or one of the full 102" (2.6m) whips.

    BUMPER MOUNT - The antenna radiates in a pattern directly in front of
                   and to the rear of the vehicle, with maximum radiation
                   directly away from the vehicle, in a horizontal plane.
                   Despite its fairly irregular pattern, a bumper mounted
                   full-length whip antenna will normally give the best
                   results.  Removing the antenna is simple and will leave
                   no holes in the car.  We suggest you try our
                   bumper-mount fiberglass whip, catalog number 21-927.

A few general rules should help you install any mobile antenna properly.

1.  Keep it as far as possible from the main bulk of the vehicle.

2.  Keep as much of it as possible above the highest point of the vehicle
    or boat.

3.  During operation, it must be vertical.  Thus, it should be
    mechanically rigid so it will remain vertical when the vehicle or boat
    is in motion.

4.  Mount it as far as possible from sources of noise (ignition system,
    gauges, etc.) and keep the transmission line away from these noise
    sources.

An antenna mounted in a boat requires a ground.  This can be either a metal
hull or a ground made of tin foil or copper sheeting.  This ground should
cover an area of 12 square feet (1.1m^2) or more.  Be sure the transceiver
also has an adequate ground.

FIXED STATION ANTENNAS

The most popular fixed-station antenna is a complex colinear or ground
plane.

Beam antennas provide maximum gain and maximum directivity.  The
directivity can be a disadvantage unless a rotor is used.  Since a beam
antenna is directional, it greatly reduces noise and interference from all
other directions.  This can be a decided advantage on the CB bands where
man-made noise and interference from other CB signals is a problem.

Your RadioShack store carries a complete line of base station CB antennas
and accessories.  For maximum efficiency, we strongly recommend using an
SWR meter to aid in the proper matching of your antenna and Transceiver.

The antenna system should be adequately grounded.

Always use a static discharge unit on your antenna system.

(wr 08/04/98)