alternator noise

[Bash]

I have an Icom IC-M402 VHF, using it with a CommandmicII at the helm. The system seems to have developed a new problem. The radio works fine when I'm sailing, but when I'm motoring it has developed a tone that varies with RPMs while receiving. I'm told that while transmitting the radio has a whistle.

This is not a new installation. The radio has worked fine since the boat was set up in 2006, so something that used to work has gone wrong.

But what? Thank you in advance for your suggestions.

[DeepFrz]

Replace the noise suppression capacitors on your alternator. If there aren't any, add some. How old is the alternator? It may be time for service.

[Bash]

Originally Posted by DeepFrz

Replace the noise suppression capacitors on your alternator. If there aren't any, add some. How old is the alternator? It may be time for service.

The alternator is a high capacity Balmar that was installed new on the boat in 2006. The engine has 700 hours on it.

Does that sound about right in terms of time for a service?

[DeepFrz]

Nope, sounds almost new to me.

[Bash]

Originally Posted by DeepFrz

Nope, sounds almost new to me.

I know! We keep thinking of this as "the new boat," but I've already had to replace the water heater and the oil cooler, and now I have to service the heat exchanger on the Yanmar, which is suddenly running warmer than I like.

Sigh. On the other hand, I've still got the OEM sails and they've got great shape. On my previous new boat, I went through the OEM canvass in five years.

Seriously, how old should a Balmar alternator be before it needs servicing?

[Dsanduril]

The most common cause (but by no means only) cause of alternator whine on radios is a poor ground connection. The whine is usually created when there's a voltage difference in the system. So, if any noise suppressors look fine, and the system used to work as installed I'd start looking for connections (particularly ground side) that have become corroded. Unfortunately, that can be a long hunt.

[DeepFrz]

Seriously, how old should a Balmar alternator be before it needs servicing?

I only mentioned the service part because I had no idea how old it was. Time to service really depends on how heavily it is used. I was thinking that maybe the brushes were worn down but they shouldn't be in that period of time. So, as Dsanduril says, check or replace the noise suppressors and check all your power connections. Giving Balmar a call would be a good idea as well.