Similar support experience with ICOM.  I bought a top of the line
fixed-mount VHF that had all the symptoms of inverter noise.  I borrowed a
friend's $99 Uniden and hooked it up to the same antenna and same power
cable.  There was zero noise on the Uniden.  I then tried another brand
(can't remember which) and it, like the Uniden, was completely noise free.
I plugged the ICOM back in and it was just a noisy as before.

I sent the radio off to ICOM (under warranty).  Many weeks later, I was told
the radio checked out fine.  I was told the problem must be my inverter.
When I explained the troubleshooting I had done, ICOM said they didn't care
what I had done; the problem was not in the radio.  Maybe I do have a noisy
inverter but the noise filters in the cheap Uniden handled it and the ICOM
did not.  I wonder if ICOM's bench testing fails to simulate real install
conditions.

I now have a Standard Horizon that I love - noise free, clear reception, and
clear transmission and no attitude problems with sales/support.  (No
connection to ICOM, Uniden or Standard Horizon - just a dissatisfied ICOM
customer and a happy SH one.)

Bill

"Tapestry"

Bill McLauchlan,
In regards to your complaint with the ICOM. I suspect that ICOM is
correct in that your inverter is the problem. Blaming your ICOM vhf for
being more sensitive than competing equipment is hardly fair. If you
want to desensitize the ICOM until it won't notice the inverter then it
will be about as sensitive as the equipment that you are so happy with.
You did not include the specs from the ICOM and replacement radios but I
suspect you would find that the ICOM is speced to be more sensitive.

You are mistaken in thinking that the difference in the radios is
related to filtering. The $99 Uniden is no where near as good a receiver
as the top of the line ICOM vhfs.

As a practical matter this sort of complaint is fairly routine by people
who upgrade radio receiving equipment but fail to take into the account
the consequences of more sensitive radios.

Regards,
Mike

Capt. Mike Maurice
Tigard Oregon(Near Portland)

Mike,
?I beleive ICOM is the problem. I bought 4 ICOM 502s when they were discontinued. Installed 2 on boats without inverters and 2 on boats with. One was on Rollsdoc. Had the noise problem on the 2 with. ICOM said it was the inverter manufactures fault in that they were building and selling a product that produced RF without a license. Tech support had me jumping through hoops. Filters antennas and so on. I had an ICOM 127 mounted next to the 502. No problem there. In the end we returned the 502s and replaced them, thanks to West Marine not ICOM,with 504s (replacement for 502s) and the problem was gone.
My guess is with the short production run of the 502s and 602s and the bringing out of the 504s and 604s that ICOM might have deleted something from the circutry (like a filter) had a problem and corrected it.

Rodger Wrona
Rollsdoc
MT49PH