VHF Radio or Antenna Issue ??

Don S/V ILLusion · Sep 18, 2014

The receiver section of all radios won't appear voltage sensitive but as soon as you key the mic, the voltage can drop significantly if you have a bad connection causing your problem. That isn't to say I think it is the only possible cause. Rather, it is the easiest to check and you should always start with the easy stuff.

By 'check', I don't mean visually. You need to measure voltage both at the source and at the radio terminals while keying the mic.

If it's not a voltage problem and the coax and coax connectors are old, a bad connection tor, bad coax or moisture intrusion in either could cause the problem you describe.

Obviously, it could also be the radio itself or the antenna but that can be easily diagnosed by simply using a different antenna and coax or different radio connected to the existing antenna system.

Sailgunner · Sep 19, 2014

I had a similar problem and had to replace the antenna.

Bill Roosa · Sep 19, 2014

If you are in a marina see if somebody has a hand held VHF and buy him some beer to take it a mile or so away and hail you on the freq of your choice and see if you are getting any signal out. It is not at all apparent that you even have a problem. Automated radio checks are not at all 100%.

Kings Gambit · Sep 19, 2014

jeff356 said:
Went to the boat today and was not able to get a response from the automated radio check via channel 27 but did raise someone close by on channel 16 (i know, bad form). Looking for ideas on best way to proceed, try to find a loose antenna and test, replace the VHF (Icom IC-M422)

Automated radio checks may not respond or give a weak play back if there is response. I have gotten barely audible play backs of my transmission on automated while live voice replies from similar or greater distance tell me I'm coming in "loud and clear." Use VHF 9 for radio checks; might raise the Coast Guard Aux on VHF 9 if anyone is operating at that time. Otherwise, try raising Vessel Assist on their working channel if you're a member [BOAT US]. Radio technicians can, I believe, conduct a certain test to diagnose your problem, if you have one.

RHUMB RUNNER · Sep 19, 2014

I had a problem with the same Icom IC-M422, turns out they have a component that goes bad in the receive section. The Icom repair station repaired it for free and it was out of warranty. I would start there.

Forrest15112 · Sep 20, 2014

Do you know what kind of antenna you have? You can do a simple open/short test across the center conductor and shield of your antenna connector to possibly rule out a broken or shorted feedline. Some antennas will show a short at DC and some will show wide open, so this test is only good if you are supposed to see a short and are seeing an open. A basic multimeter should have a continuity setting where it will measure the resistance of whatever is connected between the test leads. My meter gives an audible beep if there is a short. Disconnect the antenna cable at the back of the radio and hold one test lead to the outer housing of the connector and the other to the center pin of the connector. Make sure they don't touch and don't hold both with your fingers touching the metal test lead tips. You may read the resistance through your body from one hand to the other. It's not dangerous and won't shock you, but may confuse the readings you get.

Common antennas will be described as 1/4, 1/2, or 5/8 wave. This is the length of the radiator at the frequency it is designed for. It's basically the distance a full radio wave travels at the frequency. 1/4 wave and 1/2 wave antennas do not need loading coils and such to match up with the radio and cabling. 5/8 wave antennas do need a circuit to match up and these will usually indicate a short circuit at dc when measured with a multimeter. The obvious problem is that you can have a shorted cable and not really be able to tell without disconnecting the cable at the antenna, but if you read an open, you know you have a problem. The opposite is true with antennas that are not shorted to ground.

From my experience, if you have any exposed connectors, that's most likely where the trouble is. You can test the radio on a neighbor's boat or with a temporary antenna to rule out the radio itself. I saw a boat once where the owner ran a coax jumper from the radio under the sole and made a connection in the bilge. The connectors eventually got wet and corroded.

ISABELLA5 · Sep 20, 2014

Locate a ham radio operator with an antenna analyzer and presto the antenna/lead will be confirmed. Most hams are pretty agreeable to help other radio users. Try calling the local club near your boat.

Forrest15112 · Sep 21, 2014

ISABELLA5 said:
Locate a ham radio operator with an antenna analyzer and presto the antenna/lead will be confirmed. Most hams are pretty agreeable to help other radio users. Try calling the local club near your boat.

Mention the fridge is full of cold adult beverages, works every time. Seriously, here's a link to a local club in Baltimore. They even have a phone number at the bottom of the page to contact them. Most hams are nice folks who enjoy helping others. A small donation to their club would be appreciated or, they may have someone who is willing to test and FIX your trouble for a smaller than professional fee. Explain your problem and ask if they can help. If you were in the New Orleans area, I'd check it out for ya. I suppose most others are wanting to help like that too.

http://w3ft.com/

Xaris · Sep 22, 2014

I had the same problem on my Hunter 41 VHF. In my case, the inside connector element at the base of the antenna (on top of the mast) a corroded out. So, from the outside, it looked fine, the connector inside the base was not making contact with the cable pin coming up the mast. I simply replaced the antenna. Immediately, got a five by five response across the bay. (Getting up the mast is the hard part

)

seadaddler · Sep 22, 2014

Check

Have you checked the ant connection in the headliner where the mast
is deck stepped.
The ant cable comes out the bottom of mast and than down into cabin
and usually have removable wood plate up on headliner is another connection for
for when removing mast.
nick

Schatzi · Sep 23, 2014

Jeff:
I have a 2003 Hunter in Middle River as well. If you need help don't hesitate to ask! I have had to replace my antenna (missing), connector at the mast, and replaced the radio over the last several years. ICOM will go over the radio for a reasonable fee and return it in just a couple of weeks. I may have my old radio to test if you would like. We also have a very active Hunter Owners Club with a wealth of knowledge. Many of them are in the Middle River area (www.nshsa.org).