Jerry Stuckle wrote in news:lras98$ebf$1@dont-
email.me:

As for determining whether it is oscillating or not - I wouldn't trust
anything short of a good spectrum analyzer. The signal could be
anywhere (and changing frequency). A spectrum analyzer will still show
it; a receiver won't necessarily.


No clues at all? I remember when I first set up that little MAR-6 based
preamp, it had some nasty side effects on the sound till I added a springy
ciopper alloy strip to each side on the underside of the board so it bit
gently into the aluminium case when I slid it in to it, finally curing the
local RF oscillations it had before I solved this. I was wondering if similar
audible sounds might be heard as a guide to other, larger scales of local
feedback and oscillation.