[Amps] parasitic oscillation techniques

[Phil Clements]

If you will recall, in the mid-1980's, there was a massive recall of all
8877's by Eimac. The explanation was that they had a "heat-dam" problem,
whatever that is. An undetermined number of the defective tubes never made
it back to the factory. They appeared at ham fests, and all over the
internet sales sites. We had to go by the date codes on the tubes to protect
ourselves. A trick by sellers was to remove the code from the tube.

I will not bore you any further; many posts about this event are in the
"Amps" archives, if you want more details.

My guess is that hundreds, if not thousands, of 8877's were blown by
customers prior to the recall, and factory and dealer stock had to be pulled
and destroyed, or rebuilt.

A thousand hams could not even come close to the loss to the Eimac 8877
program, even if they had all built and botched amplifiers! The record for
blowing 8877's is held by Eimac, and has not been broken since; even after
1988.

(((73)))
Phil, k5PC