Assessments - 3, GPA: 3.3
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Facilidade de uso
From its high tech detachable control panel to finned cast almuinum transmitter heatsink it incorporates features found on no other CB. These features include full surface mount technoloy, fiberglass printed circuit board, dual power output stage, and a digital information screen using a black matrix LCD (liquid crystal display). All the features are under microprocessor control for increased function and reliability. Your Midland 79-290 assures you of having the ultimate technology in a CB radio. 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. The units location must not interfere with airbag operation. In automobiles, the transceiver is usually mounted below the dash panel, with the microphone bracket beside it. MOUNTING THE RADIO The transceiver is supplied with a universal mounting bracket. When mounting the bracket and radio to your car, make sure it is mechanically strong. Also provide a good electrical connection to the chassis of the vehicle. Proceed as follows to mount the transceiver: 1. After you have determined the most convenient location in your vehicle, hold the transceiver with mounting bracket in the exact location desired. If nothing will interfere with mounting it in the desired position, remove the mounting bolts. Before drilling the holes, make sure nothing will interfere or be damaged by the installation of the mounting bolts. 2. Connect the antenna cable plug to the standard receptacle on the rear panel. Most CB antennas are terminated with a type PL 259 plug and mate with the receptacle. 3. Connect the red DC power input wire (with the fuse) to +13.8 Vdc. This wire extends from the rear panel. In automobile installation, +13.8 Vdc is usually obtained from the accessory contact on the ignition switch. This prevents the set being left on accidentally when the driver leaves the car, and also permits operating the unit without the engine running. Locate the accessory contact on most ignition switches by tracing the power wire from the AM/FM radio in the car. The AM/FM radio power circuit generally has noise filtering built-in, making it a good place to connect your CB. 4. Connect the black lead to +13.8 Vdc. This is usually the chassis of the car. Any convenient location with good electrical contact (remove paint) may be used. 5. Mount the microphone bracket on the right side of the transceiver or near the transceiver, using two screws supplied. When mounting in an automobile, place the bracket under the dash so the microphone is readily accessible. IGNITION NOISE INTERFERENCE 4 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 vehicle itself. If the CB operates quietly with the car motor turned off it’s most likely that the car electrical system is generating noise. 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. ANTENNA 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 pratical purposes, however, the radiation pattern is nondirectional. 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. If the transceiver is not mounted on a metal surface, it is necessary to run a separate ground wire from the unit to a good metal electrical ground in the vehicle. When installed in a boat, the transceiver will not operate at maximum efficiently 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. TUNING THE ANTENNA FOR OPTIMUM SWR Since there is such a wide variety of base and mobile antennas, this section will strictly concern itself to the various types of mobile adjustable antennas. Because the antenna length is directly related to the channel frequency, it must be tuned to resonate optimally all 40 channels of the transceiver. Channel 1 requires a longer antenna than Channel 40 because it is lower in frequency. Due to the various methods of adjusting antennas for proper SWR we have chosen what we think is the optimum method: A. Antennas with adjustment screws (set screws). 1.Start with the antenna extended and tighten the set screw lightly enough so that the antenna can be easily s...