Well, just some comments from an old electronics tech, ham, sailor, pilot, stereo nut, etc. who has had lots of experience with &^%#$@! noise sources... First, ICOM makes world class radios... As was pointed out by another person on the list, putting a half deaf, consumer grade, radio in place of a sensitive receiver from ICOM, VERTEX, KENWOOD, FURUNO, SITEX, etc. is a poor solution... Next, filtering the power line noise at the radio is the least effective place to do it... Put your filters at the noise source... This means the alternator and the inverter... Radio Shack, or just about any truck stop that sells CB radios will have them on the shelf... The only reason for a filter at the radio is if pumps or other gear on the boat is generating noise, and putting a filter on them is not feasible... Next, run a dedicated +(power) and -(return) line for the radio directly from the battery terminals... Notice the dedicated ground, isolated from everything but the battery terminal and the radio - don't ground the radio or it's mount to the metal of the boat... Most important... In autos, where taming noise from the electric fuel pumps is a real bear because the entire metal skin of the vehicle becomes saturated with electrical noise, the isolated negative DC line all the way back to the battery terminal is one of the key ingredients in the solution... And tape, or bind the + & - wires together, or get one of the molded red and black wire pairs... Don't let the two wires separate helter skelter all over the boat as that increases noise pickup on the wires... Finally, at each end of the new power line solder a 0.1 MFD capacitor across the + and - wires - a 0.01 will work also.. They can be had at radio shack for a few cents...... This will cure 99% of noise problems... denny / k8do

"ICOM makes world class radios" I agree This thread?was about bad support which is what I got when I told them about the problem of noise in the 502 Which wasn't in the 127 and isn't in the 504. They left something out and wouldn't admit it. To me that's bad support. Giving me possible remedies, chokes and filters which didn't help, then in the end?blaming the inverter. To me that's bad support. Telling me they left something out or maybe swapping my 502 for a 504 To me that would be good support. Rodger

Thanks Denny, Tom and Arild for your suggestions and explanations! I've got a better understanding of this black magic now, and I'm on a mission! Ted Sequin, GB32-126 Cape Elizabeth, ME > -----Original Message----- > From: trawlers-and-trawlering-bounces@lists.samurai.com > [mailto:trawlers-and-trawlering-bounces@lists.samurai.com] On > Behalf Of Dennis OConnor > Sent: Wednesday, July 23, 2008 7:46 AM > To: trawlers-and-trawlering@lists.samurai.com > Subject: Re: T&T: Icom - bad support > > Well, just some comments from an old electronics tech, ham, > sailor, pilot, stereo nut, etc. who has had lots of > experience with &^%#$@! noise sources... > > First, ICOM makes world class radios... As was pointed out > by another person on the list, putting a half deaf, consumer > grade, radio in place of a sensitive receiver from ICOM, > VERTEX, KENWOOD, FURUNO, SITEX, etc. is a poor solution... > > Next, filtering the power line noise at the radio is the > least effective place to do it... Put your filters at the > noise source... This means the alternator and the inverter... > Radio Shack, or just about any truck stop that sells CB > radios will have them on the shelf... The only reason for a > filter at the radio is if pumps or other gear on the boat is > generating noise, and putting a filter on them is not feasible... > > Next, run a dedicated +(power) and -(return) line for the > radio directly from the battery terminals... Notice the > dedicated ground, isolated from everything but the battery > terminal and the radio - don't ground the radio or it's mount > to the metal of the boat... Most important... In autos, where > taming noise from the electric fuel pumps is a real bear > because the entire metal skin of the vehicle becomes > saturated with electrical noise, the isolated negative DC > line all the way back to the battery terminal is one of the > key ingredients in the solution... And tape, or bind the + & > - wires together, or get one of the molded red and black wire > pairs... Don't let the two wires separate helter skelter all > over the boat as that increases noise pickup on the wires... > > Finally, at each end of the new power line solder a 0.1 MFD > capacitor across the + and - wires - a 0.01 will work also.. > They can be had at radio shack for a few cents...... > > This will cure 99% of noise problems... > > denny / k8do > _______________________________________________ > http://lists.samurai.com/mailman/listinfo/trawlers-and-trawlering > > To unsubscribe or modify your subscription options (get > password, change email address, etc) go to: > http://lists.samurai.com/mailman/options/trawlers-and-trawlering > > Trawlers & Trawlering and T&T are trademarks of Water World > Productions. Unauthorized use is prohibited.