Alternator Whine

[647jc]

I have a basic Vans 60 amp alternator with the built in regulator. I also have a stereo intercom with several music sources. I get the typical alternator whine in my headsets most noticeable when listening to music but also present on COM and just plain intercom. The strength of the whine depends on how much the battery is being charged or how much current the alternator is generating. It is loudest immediately after engine start or when I turn on ALL my lights, strobe, nav, landing and taxi. The battery is new and this is really a fairly typical problem in aircraft but it is annoying and I would sure like to eliminate it if possible.

What I?m looking for is advice from someone who has personally experienced and SOLVED this problem. I appreciate suggestions but I really don?t want to try this and try that, etc. I suspect a filter on the alternator output may be the solution but there are many types, capacitors, inline filters (chokes/capacitors) etc. I?ve dealt with similar problems on old cars and I know you can spend a LOT of time trying different solutions and sometimes never really solve the problem therefore I?m asking for someone with firsthand experience to share their solution.

[vic syracuse]

Joe, you didn't mention the type of intercom. I have seen this many times in the past, and it can be solved in a couple of ways. First, make sure all of your sources for music input are properly shielded. Then, there are a number of alternator noise eliminators that do work, and you can find them on all of the supply house websites. They are less than $100 and do work. The other apporach I have used is to put RF chokes and coils on the input power to the intercomm. Radio Shack usually carries them as CB noise eliminators.

Vic

[647jc]

Hi Vic,

Thanks for the information. My intercom is a Flightcom 403d. Yes, all the audio lines are shielded and my grounds are as they should be. I?m pretty sure the noise in coming in on the power lines to the audio devices. I bought a 12 volt power filter and installed it on the intercom power line which helped significantly but there is still a faint whine. It?s not practical for me to put filters on ALL of the audio components (COM, intercom, mixer, CD player, EFIS and EMS) so I think the most practical solution would be to filter it at it?s source. I know the battery is supposed to filter most of the alternator whine but it doesn?t take care of all of it. I know there are quite a few alternator filters available but I really don?t want to experiment with all the different types and vendors, that?s why I?m hoping to find someone who has solved this problem first hand and can provide vendor and part number for something that will have a high probability of solving my problem.

[CJK]

You're right, the noise is coming in through the power feed to your panel. Add an RF choke as Vic suggests and you should see a big improvement.

-- Chris

[RV Jerry]

A COMMON PROBLEM IS WHEN INSTALLING INTERCOM JACKS THE INSULTED STEP WASHERS ARE NOT PUT IN ..THE JACKS SHOULD NOT BE GROUNDED HAVE SEEN ITENTCAL PROBLEM BEFORE GOOD LUCK