Advanced Marine Electrics and Electronics Troubleshooting A Manual for Boatowners and Marine Technicians

144 marine electronics installation and troubleshooting

noise. To help you find the culprit, conduct a

process-of-elimination test, as follows:

1 Set the radio between channels at the low

end of the spectrum (towards the 2 MHz

end).

2 Activate other AC and DC equipment

one at a time.

3 Run all the engines, including AC

generators.

4 Repeat this test sequence at all of the com-

monly used frequencies to be sure that you

haven’t missed an annoying RFI emitter

running at a higher frequency.

Keep in mind that some background noise

is normal and unavoidable. But if, for exam-

ple, audible noise dramatically increases when

you turn on a fluorescent light, you’ve isolated a

culprit. Also keep in mind that some electrical

equipment is cyclical and may only function

intermittently (such as bilge pumps). Check

cycling loads when they’re actually operating,

not just with their power activated.

If you identify a noise source during this

elimination process, it’s best to consult the

radio manufacturer or its local dealer to deter-

mine the best type and rating of filter to install.

Your concerns, as the electrical installer, are

largely limited to those mentioned: the power

supply, cabling, noise, antenna, coaxial cable,

and antenna counterpoise. Any problems not

related to these issues must be addressed by an

electronics technician.

Satellite Communications Systems

Whether they’re used for global telephone con-

nectivity, Internet access, or simply tuning into

a favorite television or satellite radio show,

satellite communications (satcom) systems

battery

laptop

Pactor modem communication port USB hub

to antenna

SSB transceiver

antennatuner

DC power supply

antenna counterpoise

A typical cabling configuration for an SSB radio. On a high-end boat today, you will probably see a Pactor modem connected as

an auxiliary device for sending and receiving e-mail via radio. The boat’s laptop PC will also be linked to the SSB to provide a dis-

play and input device for e-mail, weather charts, and the like. Specific wire terminal identification will vary from one system to

another, but this illustration shows a general layout. The connecting cables shown are all multicable harnesses with the exception of

the antenna coaxial and the wired connection between the antenna tuner and the counterpoise.