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Re: New alternator - No AM radio?

On Sat, 17 Jan 1998 17:51:38 -0600, Matt <matjen@xsite.net> wrote:

>On 1/17/98 at 5:26 p.m. Rich wrote:
>>Don't see any connection with the alternator change out, but my experience
>>with radio reception is that even the smallest break in
>>antenna/cable/connector continuity will destroy AM reception but FM will
>>"jump" this incontinuity. The only other thing I can think of is the new
>>alternator is generating too much RF interference (which happens to also
>>up AM reception). Did you try listening to AM with the engine not running?
>>That would eliminate at least one possibility.
>Great suggestion Rich.  Can't believe I didn't think of it myself.  It turns
>out that the AM is fine when the car is turned off.  When the engine is
>running it is almost all static.  So now the question is - How do I stop the
>RF interference.  Are there any commonly used tricks?  Should I just
>exchange the alternator?

The alternator could, indeed, be bad. So many rebuilds are.  But there is
also some chance that the noise suppression capacitor - normally mounted
on the rear of the alternator case - was not transferred to the new alternator
during the swap.  A suppressor cap would not overcome the noise
produced by an alternator with a blown diode but it often will make a
difference. By the way, alternator noise generally manifests itself as
a "whine" which changes pitch with engine rpm.  If your noise is more
like between-channel static, look to the antenna/cable - something
may have come unplugged - or to radio itself.

DeWitt Harrison    de@aztek-eng.com
Boulder, CO
88 5kcstq