Cobra Electronics 148 NW ST Antennas Ignition Noise Interference, CB Antenna, Marine Installation

148 NW ST manual 3.3 6/15/99 3:12 PM Page 6

Antennas Ignition Noise Interference

CB Antenna

Note

For optimum performance in passenger cars the ideal anten- na location is on the center of the roof. Second choice is on the center of the trunk.

Note

Because many newer trucks feature fiberglass door skins, the outside mirror must be ground- ed to the chassis via a ground strap if the antenna is mounted on mirror bracket.

Note

3-way Combination Antennas are also available which allow operation of all three bands (AM-FM & CB),using a single antenna. However, this type of antenna usually results in less than normal transmit and receive range when compared to a standard-type “Single Band” CB antenna. Call 773- 889-3087 for further informa- tion.

CB Antenna

Since the maximum allowable power output of the transmitter is limited by the FCC,the antenna is critical in affecting transmission distance. Only a properly matched antenna system will allow maximum power output. Cobra loaded type antenna models are highly recommended for most installations. Consult your Cobra dealer for further details, or call 773.889.3087 and speak to a Cobra representative.

1A standard antenna connector is provided on the transceiver for easy connection.

Marine Installation

The transceiver will not operate at maximum effi- ciency in a boat without a ground plate, (unless it has a steel hull). Before attempting installation , consult your dealer for information regarding an adequate grounding system and prevention of electrolysis between fittings in the hull and water.

Use of a mobile receiver at low signal levels is normally limited by the presence of electrical noise. The primary source of noise in automobiles is from the alternator and ignition system. Typically, when signal level is adequate, the back- ground noise does not present a serious problem. Also, when extremely low level signals are being received, the transceiver may be operated with the vehicle’s engine turned off. The unit requires very little current and therefore will not signifi- cantly discharge the vehicle’s battery.

Even though the Cobra 148 NW ST has an auto- matic noise limiter, in some installations ignition interference may be high enough to make good communications impossible. Many possibilities exist and variations between vehicles require different solutions. Consult your COBRA dealer or a 2-way radio technician for help in locating the source of a severe noise.

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