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VHF problems

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deastburn
Captain

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USA
334 Posts

Initially Posted - 03/31/2004 : 16:25:07

I need halp from all you electronic whizzes out there.

My VHF last season ceased transmitting, and I relied on my handhelds for the rest of the season. Now I need to locate the source of the problem. Is it:

1) A bad antenna lead (the insulation is cracked and dry in some places, and may be better or worse inside the mast;

2) A faulty transmitter in the radio?

3) A bad antenna (the cap insulation is cracked).

How to isolate the problem without replacing everything?

Thanks for your suggestions.

Dave on "Wood Duck" (#2616 - SR, FK)

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 03/31/2004 : 19:22:51

Dave,

I had problems one season with weak signals. I had the Metz mast top antenna, Raytheon VHF, RG-8U up the mast - all of these were new or newer. I thought I'd take the technical approach to the problem:

Purchased a Shakespeare signal tester - antenna was within spec.

Sent radio back to Raytheon - radio was within spec.

Went to Radio Shack to purchase new PL259s - commented on problem to a young lady at the counter who'd just moved back to Pittsburgh from San Diego; she explained that everytime someone had signal problems in CA it was always the antenna (nahhh, she's a girl, what does she know . . . )

Tested antenna coil as per Metz - tested good.

Installed new PL259s - no improvement.

Replaced rubber grommet on antenna base as suggested by dock neighbor - no change.

Replaced antenna - great transmission/reception.

Go figure! Notice the more things I tried the less technical they became.

Good luck and have patience!

Edited by - OJ on 03/31/2004 19:38:41

Bill Holcomb
Admiral

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USA
769 Posts

Response Posted - 04/01/2004 : 08:47:17

Hi Dave

You didn't say if your radio still could receive messages OK. Mine had that problem a few years ago and the problem was corrosion on the microphone key switch. I cleaned the switch and that fixed the problem.

If you are not receiving either, with all the cracked insulation you describe, I'd probably buy a new rail mount antenna. Plug it in and see if that works.

Bill Holcomb - C25 Snickerdoodle #4839

Edited by - on

seastream
Navigator

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USA
242 Posts

Response Posted - 04/01/2004 : 20:43:58

You have most of the basic equipment you need to diagnose the radio. First, use your handheld to transmit and see if your faulty radio can hear it. Second, reverse the process and see if your handheld can hear the faulty radio. If so, you know at least that the faulty radio can key up and transmit, though you won't know the power output. To rule out the antenna, stick one of those handheld 'rubber ducky' antennas on the back of the faulty radio (you'll need an adapter to do this), or better yet, another antenna. This won't tell you how well the faulty radio will hear others that are miles away, though. Since the frequency range for VHF marine is around 156 MHz plus or minus a few MHz, the CB (27 MHz) variety of SWR meters, wattmeters and other antenna testers available at Radio Shack won't work for testing purposes. If you're anywhere near Lake Winnipesaukee, NH, look me up and I might be able to help further. Good Luck!

Edited by - on

deastburn
Captain

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USA
334 Posts

Response Posted - 04/06/2004 : 22:32:03

Thanks for suggestions.

The radio receives fine. The only clue I have that it does not transmit is that no one ever responds to my requests for a radio check. (Transmissions are not picked up on my handhelds either, so I guess that is another clue.)

I never really use the radio for transmission, since I always single hand and use the handhelds (I have two). But I feel the need for a more powerful VHF in case of emergency. The handheld's transmission range is not very good.

I suspect both the antenna and the radio (PO let it get wet on a nymber of occasions--it had water stains on it when I inherited it. But then it continued to work for five seasons. Go figure.)

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 04/07/2004 : 00:49:00

Never underestimate young ladies from San Diego.

By the way, antenna or cable problems are a million times worse transwmitting.

Edited by - JimB517 on 04/07/2004 00:49:51

km0e
1st Mate

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USA
30 Posts

Response Posted - 04/07/2004 : 06:43:29

Dave, You mentioned your handhelds don't hear your radio, I assume you are doing this at very close range. If so, They shouldn't need an antenna to hear the radio, not that I recommend trying that. I wonder if your problem is lack of audio in your transmissions. Being an Amateur Radio Operator since 1976, I might suggest a broken wire in the microphone cord. Do you hear a carrier when your testing? sounds like someone keyed a microphone and said nothing? You may have to un-squelch your test receiver to determine that. If you have a carrier, but no audio, you may have a bad mirophone cord. Or a bad radio. Hopefully this may give you a direction if you have not come up with anything yet. If there is no carrier, It's probably new radio time. Also, Radio Shack used to carry a limited amount of swr/power meters designed for the 144 mhz ham band that should work fine for testing your VHF marine. I am not sure if they still do, they have in the last few years stopped selling ham equipment for that band. Good Luck! Jim

Edited by - on

tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 04/07/2004 : 13:02:09

Dave,

I had similar problems a while ago and found that the Metz antenna couldn't produce a flat swr, blew the finals on the radio. Replaced the antenna with a new Metz and had the same problem. The easy fix was to replace the antenna with a rail mount Shakespeare ($29) flat swr's out of the box. Also with a tall rig wing I prefer reducing any unnecessary weight aloft, the thing is kinda tippy, and if it's broke fix it. The radio,s function is superb even getting over the one hill here about ( 470'). When I need greater distance I'll use SSB.

Val on the hard DAGNABIT

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.