Usually a lurker, I can't help but jump in here with an "amen" to your
comments about arcs vs. parasitics. The big "bangs" in my experience
had to do with blocking caps letting go, HV connectors breaking down,
etc. My first and really most frustrating effort at amp building was 4
811As. I had managed to collect 16 of the bottles and thought I had a
lifetime supply. I foolishly watched while the plates turned white hot
and melted in a matter of a few seconds with no noise and no drive.
What was this demon that was destroying my tubes? After sacrificing all
16 on the alter of the demon parasitic, I gave up on 811s and moved on
to 813s. No problems there with parasitics, but there were a few bangs
before I got the right components in place. I'm not saying that
parasitic activity can't be accomponied by sound and fury, just that in
my experience it was a silent killer.
Ken K4XL
km1h@juno.com wrote:
<a bunch of stuff snipped>
> Even an out of control parasitic will not cause a bang initially. The
> tube will run away, the plate current will soar and the tube may fail but
> this takes several seconds from start to finish and is usually a silent
> process in the vacuum of the tube. The bang in this case is usually a PS
> path failure.
>
> 73 Carl KM1H
--
Ken K4XL
grimm@lynchburg.net
Boatanchor Manual Archive - ftp://198.28.36.115/pub
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