I have an ICOM VHF, model IC-M502, new this past spring, and two
weekends ago, I noticed it was not transmitting properly.

I was "rafting up" with a friend in his boat, and while we were
negotiating the boat hookup, I tried to stay in touch with the VHF. He
could not hear anything at all when I transmitted at the one watt
setting, but could hear me with some signal breakup at the 25 watt
setting. We tried several channels; same results.

It's not the antenna or its fitting, as far as we can tell, because we
hooked up a spare VHF and it did fine.

The friend believes there may be some problem in the M502's mike. My VHF
radio electronics knowledge is minimal. I am going to send the radio
back to ICOM for a look-see and repairs, but I'd like a better
indication from the experts here as to what might be the problem.

Any ideas?

Thanks!



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Email sent to is never read.

On Tue, 11 Nov 2003 17:10:56 -0500, Harry Krause
wrote:
I have an ICOM VHF, model IC-M502, new this past spring, and two
weekends ago, I noticed it was not transmitting properly.

I was "rafting up" with a friend in his boat, and while we were
negotiating the boat hookup, I tried to stay in touch with the VHF. He
could not hear anything at all when I transmitted at the one watt
setting, but could hear me with some signal breakup at the 25 watt
setting. We tried several channels; same results.

It's not the antenna or its fitting, as far as we can tell, because we
hooked up a spare VHF and it did fine.

The friend believes there may be some problem in the M502's mike. My VHF
radio electronics knowledge is minimal. I am going to send the radio
back to ICOM for a look-see and repairs, but I'd like a better
indication from the experts here as to what might be the problem.

Any ideas?
================================================== ======

If you've tried the antenna AND cable with another radio, and all was
OK, then you've ruled out the most common trouble spots. Another easy
check would be to test the voltage at the radio while it is
transmitting at high power. If less than 12.6 volts, you have a bad
connection in the DC suply wiring. If voltage is OK, there's a small
possibility of a bad microphone or connector. Any thing other than
that and you will need test equipment and a licensed technician.



--

Wayne.B wrote:
On Tue, 11 Nov 2003 17:10:56 -0500, Harry Krause
wrote:
I have an ICOM VHF, model IC-M502, new this past spring, and two
weekends ago, I noticed it was not transmitting properly.

I was "rafting up" with a friend in his boat, and while we were
negotiating the boat hookup, I tried to stay in touch with the VHF. He
could not hear anything at all when I transmitted at the one watt
setting, but could hear me with some signal breakup at the 25 watt
setting. We tried several channels; same results.

It's not the antenna or its fitting, as far as we can tell, because we
hooked up a spare VHF and it did fine.

The friend believes there may be some problem in the M502's mike. My VHF
radio electronics knowledge is minimal. I am going to send the radio
back to ICOM for a look-see and repairs, but I'd like a better
indication from the experts here as to what might be the problem.

Any ideas?
================================================== ======

If you've tried the antenna AND cable with another radio, and all was
OK, then you've ruled out the most common trouble spots. Another easy
check would be to test the voltage at the radio while it is
transmitting at high power. If less than 12.6 volts, you have a bad
connection in the DC suply wiring. If voltage is OK, there's a small
possibility of a bad microphone or connector. Any thing other than
that and you will need test equipment and a licensed technician.



--


Thanks. I'm planning to pack it up and ship it off to an ICOM repair
depot this week. I'll let you know what the diagnosis is.

I've had awful luck with VHF radios the last 15 years. I dunno why,
either, because I keep them out of the elements and I'm not a frequent
user.

HK

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Email sent to is never read.

On Tue, 11 Nov 2003 21:27:16 -0500, Harry Krause
wrote:
I've had awful luck with VHF radios the last 15 years. I dunno why,
either, because I keep them out of the elements and I'm not a frequent
user.
================================================== ====

Radios on small power boats get subjected to a lot of shock and
vibration which might explain some of that. I usually have a hand
held VHF onboard as a backup, and for use away from the helm.
You can get a cheap handheld for $100 or less and keep it in a zip
lock bag. I prefer the type that uses ordinary alkaline batts since
they have a long shelf life.

I've got that same model and use it quite a bit. The first thing that
occurred to me after reading your post is that possibly the moisture has
seeped in, causing a bad connection somewhere. Another question, did the
problem recur after you tried the antenna on your spare VHF then switched
back to the M502?

I don't think the microphone could be the culprit, since the mic is doing
exactly the same thing at different power transmit levels.

Dave


"Harry Krause" wrote in message
...
I have an ICOM VHF, model IC-M502, new this past spring, and two
weekends ago, I noticed it was not transmitting properly.

I was "rafting up" with a friend in his boat, and while we were
negotiating the boat hookup, I tried to stay in touch with the VHF. He
could not hear anything at all when I transmitted at the one watt
setting, but could hear me with some signal breakup at the 25 watt
setting. We tried several channels; same results.

It's not the antenna or its fitting, as far as we can tell, because we
hooked up a spare VHF and it did fine.

The friend believes there may be some problem in the M502's mike. My VHF
radio electronics knowledge is minimal. I am going to send the radio
back to ICOM for a look-see and repairs, but I'd like a better
indication from the experts here as to what might be the problem.

Any ideas?

Thanks!



--
--
Email sent to is never read.

Must be the Republicans and George Bush's fault somehow.

"Harry Krause" wrote in message
...
I have an ICOM VHF, model IC-M502, new this past spring, and two
weekends ago, I noticed it was not transmitting properly.

I was "rafting up" with a friend in his boat, and while we were
negotiating the boat hookup, I tried to stay in touch with the VHF. He
could not hear anything at all when I transmitted at the one watt
setting, but could hear me with some signal breakup at the 25 watt
setting. We tried several channels; same results.

It's not the antenna or its fitting, as far as we can tell, because we
hooked up a spare VHF and it did fine.

The friend believes there may be some problem in the M502's mike. My VHF
radio electronics knowledge is minimal. I am going to send the radio
back to ICOM for a look-see and repairs, but I'd like a better
indication from the experts here as to what might be the problem.

Any ideas?

Thanks!



--
--
Email sent to is never read.

I have to ask the question. The man said he was not going to try to fix the
radio himself, that he was going to send it to the service dept, why is
everyone trying to solve the problem? Especially since no one can even look
at the radio.

This ability to solve problems with limited knowledge seems to go beyond
politics to electronics.


"DaveH" wrote in message
...
I've got that same model and use it quite a bit. The first thing that
occurred to me after reading your post is that possibly the moisture has
seeped in, causing a bad connection somewhere. Another question, did the
problem recur after you tried the antenna on your spare VHF then switched
back to the M502?

I don't think the microphone could be the culprit, since the mic is doing
exactly the same thing at different power transmit levels.

Dave


"Harry Krause" wrote in message
...
I have an ICOM VHF, model IC-M502, new this past spring, and two
weekends ago, I noticed it was not transmitting properly.

I was "rafting up" with a friend in his boat, and while we were
negotiating the boat hookup, I tried to stay in touch with the VHF. He
could not hear anything at all when I transmitted at the one watt
setting, but could hear me with some signal breakup at the 25 watt
setting. We tried several channels; same results.

It's not the antenna or its fitting, as far as we can tell, because we
hooked up a spare VHF and it did fine.

The friend believes there may be some problem in the M502's mike. My VHF
radio electronics knowledge is minimal. I am going to send the radio
back to ICOM for a look-see and repairs, but I'd like a better
indication from the experts here as to what might be the problem.

Any ideas?

Thanks!



--
--
Email sent to is never read.

I had the same type of problem , to make matters worse mine was
intermittent. Even sent it back, they found no fault. After some head
scratching, I figured out yhat it must be power supply, it was the little
take apart "bayonet" connectors that ICOM puts in the two power wires (black
and red) that are a couple of inches from the radio. I removed these and
hard spliced the wires and no problems since. I would try that before
sending it back.

--
Ron White
My boatbuilding website is:
www.concentric.net/~knotreel

I might be missing something please help me understand. You stated you
wanted suggestions as to what is wrong, but you are going to be returning it
to Icom anyway. If you are going to send it back to Icom as you stated, why
do you care what people on here think might be wrong with it. If you really
wanted help on solving the problem, why tell people you are going to return
it to Icom anyway.


"Harry Krause" wrote in message
news:c3dhc2g=.99e9fbb540dac4ebb2f430ab099f4c84@106 8647547.cotse.net...
Paul Garcia wrote:

I have to ask the question. The man said he was not going to try to
fix the
radio himself, that he was going to send it to the service dept, why is
everyone trying to solve the problem? Especially since no one can
even look
at the radio.

This ability to solve problems with limited knowledge seems to go beyond
politics to electronics.


That's right, Paul. The radio is under warranty and I am not going to
void that warranty by taking it apart to look for...well, what? I don't
know. But I was hoping that someone here might have been able to shed
some light on the problem, someone who might have had some experience
with the electronics in these devices. I'd like to avoid the bother of
UPSing the radio to a warranty station.

I also have realized I really didn't check for the faults I am able to
check very scientifically. While we did attach another radio to the
existing antenna, we used an outside power supply to power it up. Maybe
I'll take another look at the wiring between the panel and the radio.

What is your area of expertise, Paul? Snotty newsgroup comments? You're
only a third-rater at that.

On Tue, 11 Nov 2003 17:10:56 -0500, Harry Krause
wrote:

I was "rafting up" with a friend in his boat, and while we were
negotiating the boat hookup, I tried to stay in touch with the VHF. He
could not hear anything at all when I transmitted at the one watt
setting, but could hear me with some signal breakup at the 25 watt
setting. We tried several channels; same results.

It's not the antenna or its fitting, as far as we can tell, because we
hooked up a spare VHF and it did fine.

Check the incoming power for oxidation or loose connections, anything
that causes a voltage drop when the TX load kicks in. Common problem
and easy to overlook.


/Marcus

--
Marcus AAkesson
Gothenburg Callsigns: SM6XFN & SB4779
Sweden
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