am radio whine....850

i poised this problem a few months ago and received a number of fellow
owners expressing the same problem but no suggestion as what
specifically to do to solve the problem.
very early mornings, while attempting to listen to one of the clear
channel 50,000 watt clear channel am stations in the usa. i am bothered
by a constant whine which appears to be produced by the alternator as it
is engine rpm related. there has to be a tech out there that knows
exactly what to do to solve this problem. way back when, i recall, a
capacitor being hooked to the distributor was the way to solve this,
along with a trim on the antenna. i don't recall the exact positioning
or where the wire attached and the rear of my oem cd am fm radio has no
visible trim screw.
anyone know the answer to the above problem?

regards

 

The capacitor went on the alternator - and the secondary side (high
voltage) of the ignition had some resistance added. You can see if the
noise is caused by the alternator by removing the drive belt and seeing
if the noise disappears. If all your ignition parts are original, and
the alternator is not the problem, then you need to look for resistance
in ground connections.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

Check for a bad ground on your antenna.

 

I have the exact same problem. Somewhat weaker AM stations have a loud
annoying whine when I'm driving.

I've tried all sorts of things, but no luck so far:

1. Put ferrite toroids around both wads of wires coming out the rear of the
radio unit.
2. Replaced the antenna with a regular, non-retracting one.
3. Checked the coax ground on the antenna cable between the radio and the
antenna, with an ohmmeter. It's grounded fine.
4. Verified I'm using resistor spark plugs. I am.
5. Put an ignition noise suppression thingy on the coil (engine stalled, so
much for that idea).

I have not tried the alternator trick someone mentioned though. Is there a
specific brand for that part?

Thanks,

Mike

 

The whine can sometimes be caused by loss of a good common ground back where
the antenna is located. Might try running a braided ground strap under the
car from the engine block back to the antenna grounding point. You can also
connect the strap to several points between these locations, like the body
or frame, to keep it from drooping and also further improve the grounding
throughout the car. This has worked for me on Ham Radio equipment in the
past.

Good luck