TRC-55 (210-0151) Installation Faxback Doc. # 16736 The TRC-55 Citizens Band Transceiver can be used either as a Base or Mobile unit -- powered from 120 volts AC, or 12 volts DC negative ground. For Base station use, no special installation procedures are required except for normal precautions relating to excessive dirt, moisture and extremely hot temperatures. Avoid installation and use in areas of high dust and dirt concentrations. For Mobile use, the primary installation considerations are safety and convenience for the driver and passengers. Always mount in a position where normal operation, and connecting cables, will not interfere with either the driver (especially when operating the brake, clutch, shift lever and accelerator) or the comfort of the passengers. The typical installation is under the dash just over the drive-shaft hump. Carefully plan the installation and cable routing. Mount the transceiver using the mounting brackets supplied. At first, to mount the transceiver, attach the mounting brackets to the sides of the Transceiver. Then use it as a template to mark mounting holes in the under side of the dash (don't drill into existing wires or trim). Drill 7/32" (5.5 mm) holes. Mount The Transceiver with the hardware supplied. You can fasten the Mic Clip to either side of the Transceiver; mount as shown, with hardware supplied. Connect the 12 volts DC power cable between chassis ground (black wire) and the Accessory terminal on the vehicles ignition switch (red wire with in- line fuse). The Transceiver is designed for use only with 12 volts, negative ground electrical systems. Plug the cable into the rear panel DC power receptacle. Connect The coaxial cable from the antenna system to the ANTENNA connector on the rear of the unit. If desired, connect an External speaker or PA speaker to the jack(s) on the rear of the unit. 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 the coaxial type and should have an impedance equal to the antenna impedance. Since the 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 line losses increase with length. Use foam- insulation coax for best results. If the transmission line must be long, keep it to exact multiples of a half wavelength. That is, multiples of 14 feet. This will assure a proper impedance match and thus maximum transfer of signal between antenna and transceiver. 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 will be defeated. FIXED STATION ANTENNAS The most popular fixed station antenna is a ground plane. An improved form of the ground plane is the coaxial or collinear antenna. 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 is a problem. GROUND PLANE DUAL 6-ELEMENT BEAM VERTICAL BEAM BASE STATION ANTENNAS The Radio Shack store carries a complete line of base station CB antennas and accessories. MOBILE STATION ANTENNAS Mobile CB antennas are one of two types: a full length or a loaded whip. Your Radio Shack store carries a complete line of both types of mobile antennas. The location of the antenna has a great effect on the antenna efficiency and directivity. Antennas mounted in the center of the roof radiate equally in all directions. A bumper mounted 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. ROOF MOUNT FRONT COWL MOUNT REAR DECK BUMPER MOUNT Since the normal 1/4 wavelength whip antenna is too long (102") for roof mounting on a vehicle, the antenna is shortened and a loading coil is utilized to provide the proper electrical length. As a result, the over- all efficiency is reduced and the non-directional advantage is defeated. Thus, a bumper mounted full-length whip antenna will normally give the best results. A few general rules should be followed for proper installation of any mobile antenna. 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 maintain a vertical position when the vehicle or boat is in motion. 4. Mount it as far as possible from sources of noise (ignition system, gauges, etc.) and convenient for transmission line routing away from these noise sources. Unless specifically designed for use without a separate ground, an antenna mounted in a boat requires a ground. This can be either the metal hull or a ground made of tin-foil or copper sheeting. This ground should cover an area of 12 square feet or more. Be sure the transceiver has an adequate ground as well. NOISE Your vehicle or boat can be the cause of much noise interference. Remember, the transceiver has a very sensitive receiver and it will pick up even the smallest trace of ignition noise. Any noise that you hear in the transceiver is almost totally from external sources. The receiver itself is exceptionally quiet. Steady, high noise levels can not be eliminated by internal circuits (such as the ANL and Noise Blanker circuits). When the level of the noise approaches the level of an incoming signal, switching in the ANL and /or NB will reduce the level of the signal, along with the level of the noise. Noise problems can not be solved internally (in the transceiver); they must be solved at the source of the noise. This interfering noise can be generated anywhere in the electrical system of the vehicle or boat. The first step in reducing or eliminating this noise is to locate the source of the noise. If you wonder if the noise is from your ignition system, the transceiver or an external source, try this simple test. Turn your ignition switch off and set it to ACC (accessories). This turns off the ignition, but supplies power to the transceiver. Most of the noise will disappear - indicating that the source of noise is your ignition system. IGNITION SYSTEM The most common source of noise is the ignition system. This noise can be identified by the fact that it varies with the speed of the engine. It consists of a series of popping sounds occurring at a regular rate that will vary with the speed of the engine and stop when the ignition is turned off. There are a number of things that can be done to reduce this type of noise: 1. Use only the "radio suppression type" high voltage ignition wire. Most new cars come already equipped with this type of wire. 2. Inspect the high voltage ignition wire and all connections made with this wire. Old ignition wire may develop leakage resulting in hash. 3. If noise still persists, replace the spark plugs with spark plugs that have suppressor resistors built-in. Be sure to use the correct type for your vehicle. Other sources of noise are: generator/alternator, regulator, gauges and static discharge. Most of these types of noise can be effectively reduced or eliminated by using bypass capacitors at the various output voltage points. Once again, we suggest you check your Radio Shack store for a wide selection of noise reduction accessories. (br/all-08/29/95)