Troubleshooting the VHF radio

Published on December 5th, 2022

When bad things happen at sea, a communication system to get support is vital, and making sure that system functions well is equally paramount. In this report by Eric Steinberg with Farallon Electronics, he shares his thoughts on troubleshooting the VHF radio:

In our experience, the radio is rarely the problem; maybe 1 out of 100 or of a thousand radios are bad. With VHF radio, receiving is relatively easy, meaning the antenna system can still be pretty bad and receive the usual weather stations. But if the weather stations that are usually crystal clear are now scratchy, there could be a problem.

First is to get out the emergency antenna you have stowed away for many years (you have one, right?) and plug it into the back of the radio eliminating the boats antenna system. If there is marked improvement, we know the antenna system is the issue.

Pro tip, over 80% of failures with marine electronics are connection related.

If we can keep water out (sealed) and connections tight, the connectors are designed to do their job for a lifetime. Always inspect connections for obvious water intrusion, corrosion, oxidation, etc. I have had a connector look okay but the wire going in had a nick in the jacket letting water in and the wire snapped off in my hand as I went to inspect the connector.

Next step, if there is a break in the antenna coax at the mast base, disconnect the mast side antenna and connect your emergency antenna. Is the boat side connector clean and shiny? With this test, the performance should be the same as the test antenna > direct to radio. If there is a marked degrading of performance, assume the radio to mast coax is all or part of the problem.

The likely failure is with the mast side coax, the masthead antenna, or the connection to the antenna. Coax cables can be chafed through, antennas can rot from old age, but the connector is the most likely source of the problem. If the connector wasn’t completely sealed and has had water intrusion, the water can get into the coax, game over. Replace the whole set-up to the mastbase.

Note on emergency antennas: The little flexible ones sold as emergency antennas are only okay, not great. If I am floating around in a situation where I need my emergency antenna, I want something that will perform great.

Our strong suggestion is to have a 3db balanced antenna and a length good quality coax long enough to reach from the back of the radio and out the companionway hatch to a spot the antenna can be clamped/taped/zip tied out of harm’s way (remember, you probably don’t have a mast at this point). A 3db balanced antenna is about 36-inches long and has a “loading coil” at the base; it does not require additional metal for a ground plane.

In the pro world, meters of various types can be used to gain more insight but the outcome is rarely different, meaning one of five things are wrong:
1) A bad coax connector(s)
2) Radio
3) Radio to mastbase coax
4) Coax up the mast
5) Antenna or a combo of these related to water intrusion, corrosion, UV degradation, etc.

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