Technical Issues

Power

Radios normally operate on 12V. Some radios can also operate on 24V. The radio has to be connected to a power supply of the voltage that it is rated for.

The power supply has to be able to supply sufficient current for the radio to be able to operate. If it can't then the voltage can drop when a transmission is ocurring. Also a fuse (usually inline) can blow or a circuit breaker (usually on a panel) can be tripped.

The power supply connection must be good - must have a low resistance. There must not be a short circuit between the active connection and the ground - this will blow the fuse \ trip the breaker. If there is leakage on a battery connection that will drain the battery. Water conducts electricity. Connections need to be dry - use insulation, tape, heatshrink, vaselene.

Antennas

Antennas used for transmission usually have a 50 ohm impedance. The antenna must match the transceiver. This can be measured by using a SWR (Standing Wave Ratio) meter. The SWR should be around 1:1.2 and should not be more than 1:1.5. The higher the SWR the more RF (Radio Frequency) energy that is reflected from the antenna back down the transmission line hence the less efficient the antenna is.

In normal operation a marine transceiver will be connected to a matching antenna and will, hence, have a low SWR. If the transmission line (usually a RG58 cable) that connects the transceiver to the antenna is damaged or if the cable is not cleanly connected at each end - eg to the connector (usually BNC or PL259) - then the SWR can be adversely effected.

The transmission line and connections can be 'buzzed' using a multimeter. With the transmission line disconnected from the transceiver and the antenna the meter should show :-
i) an open circuit (infinite resistance) between the active and ground connections
and
ii) a short circuit (zero resistance) for each of the lines end to end.

Most antennas have infinite resistance between the active and ground connections. Some have zero resistance between the active and ground connections. At operating frequencies they should present a 50 ohm impedance.

Generally speaking off-the-shelf antennas and transmission lines should be ready to go.

Volume

Make sure that you turn your volume up sufficiently high so that you can hear incoming transmissions.

Squelches

The squelch is used to block out background noise. It is opened by strong signals. It will block weak signals. If you have a high local noise level - eg electrical noise - and if you turn your squelch up high that will block out all signals. On some equipment it won't be adjustable - if so - don't worry.

CTCSS & DCS Squelches - Tone Operated Squelches

CTCSS & DCS squelches are not being used. They are generally not used on marine radios. If you have a radio that has a CTCSS & DCS squelch ensure that it is switched off.

Testing

Test your radio - make sure that your transceiver can transmit and receive ok. Make sure that your volume is adjusted ok and that you can clearly hear other transmissions.