Best chance is an open diode in the rectifier bridge. There are a thousand
more automobile electrical repair shops than there are aviation electrical
repair shops, and the replacement parts are mostly the same.

I would NEVER suggest having an automobile shop work on an airplane part,
but I've got this friend Ernie ...

JIm

"Dave Anderer" wrote in message
news:2007031113571416807-danderer@udeledu...
I'm looking for advice to help shorten the trouble-shooting process here.

My Arrow has developed an alternator whine over the past few hours. It is
*barely, barely" noticable on both radios when receiving, but loud and
obnoxious (both to me and other aircraft) when transmitting. No doubt it
is the alternator - switching the alternator off fixes the problem.