[Kenwood] Alternator whine

[Esterson/Pinsky]

I had this headache with my old (1979) Peugot 404 pickup truck and an
Alinco DR-590. I found a few things that helped without doing extensive
testing:

1. Check the quality of the connections to the battery and the alternator -
even a small R can cause enough ac current to make a lot of noise and a bad
connection can rectify (like a diode) and radiate or propagate the ac -
clean the battery posts and cable clamps and smear them with grease, if you
have old battery clamps bolted onto the cables rather than crimped on check
those fittings too, the minus bolt to the chassis or engine, the plus bolt
to the starter and the plus bolt to the plus voltage distribution block,
the connections to the alternator (undo them, sandpaper, fine file, or
emery board to clean the contacts), and of course, any mechanical
connections on the power feed between the battery and the rig (don't forget
the fuses in the in-line fuse holders). I also used a piece of coax shield
as a ground strap between the engine/transmission and the chassis, but this
is usually more of a problem with HF mobile rigs. Finally, and I guess
you've done this by replacing the alternator, make sure the carbon brushes
and the slip-ring in the alternator are in good shape - the sparks are a
real source of the problem. 

2. My truck had a metal dashboard grounded to the chassis. I attempted to
DC-isolate the rig from the chassis through ALL paths. I dc-isolated the
rig from the dash board with a sheet of inner-tube rubber between the
dashboard and mounting bracket, and plastic sleeves for the mounting
screws. the only dc connection to the chassis of the vehicle remaining was
the shield side of the coax at the base of the antenna, which I didn't fix
- but this could be done using a different type of antenna, e.g. magmount -
but check if the magnet base on your magmount is dc isolated from the
shield - if not, a sheet of waxed paper between the magnet and the vehicle
will both dc isolate the coax and protect the finish of the truck. Also,
don't forget any accessories plugged into the rig, like an external speaker
with a metal case (rare).

Your truck is probably in a lot better shape than mine was, and you
probably have a plastic dashboard, but I hope some of these ideas help you
or someone else with this problem - even though the above helped a lot,
folks on the repeaters could always tell how fast I was going, and it drove
me crazy till I replaced the truck with a Vandura diesel former ambulance
with 3 batteries and a fiberglass roof!

-avi 4X6UA

At 16:52 29-06-04 -0400, B Riches wrote:
>Any comments or cures for alternator whine on transmit from fm units?
Truck in question is 2003 Ford 450 diesel with twin batteries.  Alternator
was replaced and noise is less but still there.  Power cables from radio go
directly to the battery that is closest to alternator.  Tried Newmar 10 amp
inline filter in radio power line but made no difference.
>
>73,
>
>Bill Riches, WA2DVU
>Cape May, NJ
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