Galaxy DX-33HP Manuel du propriétaire - Page 4

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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 generator 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 the transceiver has ANL and NB controls, in same 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

A vertically polarized, quarter-wavelength whip antenna provides the most

reliable operation and greatest range. Shorter, loaded-type whip antennas are more

attractive, compact and adequate for applications where the maximum possible

distance is not required. Also, the loaded whips do not present the problems of

height imposed by a full quarter-wavelength whip.

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 purpose, however, the

radiation pattern is nondirectional. The slight directional characteristic will be

observed only at extreme distance. A standard antenna connector (type SO239) 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 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.

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THE PROPER SETTING IS ACHIEVED WHEN THE SWR IS

1.5 OR BELOW, AND WHEN IT HAS THE SAME READING

FOR CHANNELS LOW BAND A1 AND HI BAND D40.

If you are having difficulties in adjusting your antenna, check the following:

A. All doors must be closed when adjusting the antenna.

B. Make sure the antenna base is grounded.

C. Check your coaxial cable routing (it may be pinched when routed into the

car).

D. Try a different location on your car (keeping in mind the radiation pattern

you wish)

E. Is the antenna perfectly vertical?

F. Try a different location in your neighborhood. Stay away from large

metal objects when adjusting (metal telephone or light posts, fences, etc.).

The transceiver will operate into an SWR of 2 to 1 indefinitely

and sustain an SWR of 20:1 for a maximum of 5 minutes at rated

operating conditions.

NOTE

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