VHF interference (w/ outboard). Help please!

[ANDYCOHO]

OK, I've tried everything that I know of.

My VHF is just about useless while running my main motor (150hp Merc. outboard w/ new regulators). I've tried noise filter capacitors, wiring through my main power panel and wiring directly to the battery (Perko switch) and combo's off all 3.

But, still the interference noise continues.

HELP! PLEASE!!!

[StickFish]

First off how is you coax connector attached? Has the SWR on the antenna been checked? A broken coax shield connection will turn your narrow VHF antenna into a broadband receive antenna which means it will hear and pass everything to your radio

Next, describe the noise cause there are two types of noise that come from your ignition and several ways to deal with it.

Did you try atorroid choke on everything except the coax coming into the radio?

radio shack part number 273-104

http://www.ifish.net/gallery/data/500/Catalog273-104.jpg

[ANDYCOHO]

First off how is you coax connector attached?

Brand new "Crimped" on connection.

Has the SWR on the antenna been checked?

No, how do I check that?

A broken coax shield connection will turn your narrow VHF antenna into a broadband receive antenna which means it will hear and pass everything to your radio

Makes sense, how do I check that?

Next, describe the noise cause there are two types of noise that come from your ignition and several ways to deal with it.

At idle there is very little noise (a scratchy whining that increases in pitch), but as the RMP's increase, so does the interference noise. Until all incoming radio transmissions are just about totally broken and unreadable. Turn the motor off and instantly: "All Clear".

Did you try atorroid choke on everything except the coax coming into the radio?

Didn't try this one, but will order it right away.

Thanks!

[StickFish]

If the noise was a staccato spark type noise you would have a hard time getting rid of that one. The whine you describe sounds like alternator whine which increases in pitch as you increase engine RPM - sometimes the two will be in there together.

Crimped on connector - like a factory crimped connector from Digital Antenna, or one someone else crimped on? Connectors should be soldered.

As far as SWR I can check that for you or the place that crimped on the connector should have been able to. If the antenna shows HIGH SWR most likely its due to the coax shield not being connected to the coax connector.

Another option is a filter capacitor across the speaker connections inside the radio.

What brand radio is it and what brand and model antenna?

Brand new "Crimped" on connection.



No, how do I check that?



Makes sense, how do I check that?



At idle there is very little noise (a scratchy whining that increases in pitch), but as the RMP's increase, so does the interference noise. Until all incoming radio transmissions are just about totally broken and unreadable. Turn the motor off and instantly: "All Clear".



Didn't try this one, but will order it right away.

Thanks!

[ANDYCOHO]

Crimped on connector - like a factory crimped connector from Digital Antenna, or one someone else crimped on? Connectors should be soldered.

Shakespeare Crimped on. But just went to the Crimped on when I moved my antenna to the top of my tower. I had a soldered connection and the noise was there as well.

As far as SWR I can check that for you or the place that crimped on the connector should have been able to. If the antenna shows HIGH SWR most likely its due to the coax shield not being connected to the coax connector.

Another option is a filter capacitor across the speaker connections inside the radio.

What brand radio is it and what brand and model antenna?

It's a Icom IC-M304 w/ a Shakespeare Galaxy antenna.

I have another IC-304 w/ the same antenna on my Alumaweld w/ the power through my main panel and I don't get any noise.

Though the antenna that I'm having "issues" with is 1 (+/-) year older and I'm not the original purchaser of the antenna.

I bought both radios at the same time.

The way your describing everything, it's sounding like a bad antenna. Am I right to assume this?

Thanks for all your help!

[StickFish]

Should be tested before that assumption is made. I live in Tigard - if you wanted to drag the boat over I could take a look Sunday afternoon is best.

[SOL]

If the power to your radio is running parallel (for more than 2ft) with your engine wiring you will get 'engine whine'. Is the power to your radio ran down the opposite side of the engine wiring?


Im no expert on this like StickFish but I have had that problem with car stereos. Hope you get it figured out.