INSTALLATION
MOBILE STATIONS
ENVOY™ TRANSCEIVER REFERENCE MANUAL 403
Radio frequency interference (mobile stations only)
Types of noise
Engine noise and electrical accessories often cause RF interference.
Noise interference can be:
• induced into and carried along the cables to the transceiver
• radiated from the noise source and picked up at the antenna
Noise from the battery-charging system
Alternator/generator-to-battery wiring
A low-pass filter, such as a Marine Technology type MAR-60A (up to 60 A), should
be fitted to the main battery lead at the alternator to minimise noise. The filter must be
rated for the maximum current available from the charging system. The earth lug of
the filter should attach to the alternator body or the engine block.
Table 36: Noise source and type
System Noise source Noise type
Ignition Ignition Spark plug leads
Battery charging Alternators Diode switching and
brushes
Other Brakes and bearings Static discharge
Oil pressure sender Contact arcing
Tachometer Impulse
Winches Motor brushes
Wipers and fan motors Motor brushes
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