Rick Stealey wrote:
>
> If your amp used to be stable why do you think it would suddenly start
> arcing, or go into
> parasitic osc.? It IS possible the resistors in the parasitic chokes changed
> value, and that
> should be easy to change if so. Expect them to have increased in value but
> see how much.
> But you should also look carefully at the bandswitch because that is a
> troublesome item
> in that amp. Also make sure your output relay is clean. And look down in
> there carefully
> when it is spitting and see where it is occurring- you might just need to
> clean or burnish
> a plate on one of the variable caps (where it might have arc'd once when not
> tuned properly
> and a little burr developed.)
> The issue of replacing parasitic chokes with those of a "new" design has been
> debated
> on this list through 1000's of postings. I happen to be in the camp that
> says, "If it used
> to work, just find out what changed over the years, don't redesign it."
I would agree with all of the above and add that the arc could be
occurring in the tube, if it is gassy.
Parasitic oscillations rarely (if ever?) cause arcs anyway, so this is
probably the least likely scenario.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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