TROUBLESHOOTING
29.
ALTERNATOR WHINE & OTHER DISTRACTING
NOISES
Because of the level of ambient noise present with the apparatus motor running, alternator
whine and other noises may not be noticed in the communications systems until an intercom
is added. A noisy system will always be more apparent, once an intercom is installed.
COMMON CAUSES OF NOISE ON THE COMMUNICATION CIRCUIT
• Improper installation
• Intercom adjusted improperly
• Radio Interface not connected properly
• Intercom power connections dirty, loose or connected to the wrong location
• Battery terminals corroded
• A faulty alternator
Generally, the problem is not caused by the alternator. It is usually the result of a difference
in potential between the apparatus radio signal ground and the intercom signal ground.
Additional sources may also exist in the apparatus electrical system.
TO REDUCE OR ELIMINATE ALTERNATOR WHINE
• Connect the apparatus radio to the cleanest power source possible: a source with-
out motors (e.g. heaters, windshield wipers, etc.), sirens, strobes or flashers.
• Use the same precautions when connecting the intercom power.
• Ensure that the power and ground connections for the radio and the intercom are
clean and tight.
• Ensure that the power and ground wires for the radio and the intercom are no
smaller in diameter than 18 AWG.
• Keep all battery connections clean and free from dirt and corrosion.
• Use separate noise filters on radio and/or intercom power as needed.
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