I drive a 1995 del Sol Si with an EH6 engine (that's possibly redundant) and I'm experiencing what I believe to be alternator whine. I've tried everything I can think of to solve the problem and nothing makes it better.

I've pulled power from the engine compartment (black from the battery terminal, red from the fuse box where it connects to the battery terminal) to the passenger-side rear box. The cable connects to a power distribution unit (WMR RIGRunner 4005) and from there to a number of things in the driver-side rear box including the ham radio (Kenwood TM-732A) and an FM transmitter ("Songbird", made in China). The ham radio chassis is grounded to the car chassis with a foot-long length of 14 gauge wire which connects to the metal directly under the driver-side rear box. Continuity checks out on the ground connection.

When I use the in-dash radio for normal radio purposes, it sounds fine and has no whine regardless of whether the car is turned on or not. I can transmit and receive just fine when the car is turned off. Turning on the car, however, causes a horrible whine to come over the speakers from the FM transmitter. When I power the FM transmitter via AAA batteries, the whine goes away -- but the ham radio whines on transmit which is bad. :-) I was able to measure a very small (0.01-0.02 mA) current between the ground of the FM transmitter's power connector and the ham radio's ground only while the car was running.

I built and installed a filter as per http://n4maa.us/alternator.htm and it didn't work. I bought a professional-made filter in case I screwed up somehow and it didn't work either. I replaced the plugs and wires with no improvement. I'm at a loss. Any suggestions?

 

i know this isnt relevant but..why the ham radio?
anyhow.. have u tried connecting the positive to another location?

 

Ham radio is one of my two hobbies -- the other is brewing mead, the consumption of which doesn't combine well with cars. ;-)

I haven't tried connecting the positive to another location, but I don't know where would be better than actually connected to the battery. I'm going to try connecting the ham radio's ground directly to the battery instead of to the chassis in the hopes of removing the possibility of a ground loop, but that's the only idea I've heard that I haven't yet tried...

 

i'd change the ground position(s) for everything and see if that helps. it sounds like your normal ground loop. how is the audio signal transmitted to everything? ham radio transmits via transmitter to a channel on the radio? how is the signal sent from the ham to the transmitter? at any rate you might be able to plug in a ground loop isolator inline.

 

Ham radio audio out is wired to the FM transmitter, which transmits at low power on broadcast FM frequencies (107.1 is the frequency I use). I tune the in-dash radio to 107.1, and I hear the ham radio output. When the engine is on, I hear a huge ground loop sound even when I use my cell phone as an audio source so it's not just the ham radio having trouble.

 

what i meant is what kind of cable physically connects the transmitter to the ham radio? a coaxial or RCA, etc.

i'd still move the grounds to other spots on the chassis and/or beef them up, but you can probably put a ground loop isolator inline between the ham radio and fm transmitter.

 

Here's a picture of the device. The white wire plugs into the ham radio or my cell phone. I would think the ground loop isolator would work if I weren't seeing that troubling current on the power connector...