> I wholeheartedly agree with John and Tom's points about transmitting
> tubes and how manufacturers can easily loose the formula, sometimes
> they do regain it. In my own 25 years experience in the end use of
> large tubes, it would be difficult to write about all the instances
> of where an Eimac or RCA/Burle tube has suddenly experienced short
> life. Each was traced to a single batch or period of manufactuing
> where a process was changed, a test set was modified, a step was
> missed, a worker retired, or a plant was sold and relocated.
The unfortunate thing is the mass public has been hoodwinked into thinking
tubes are nearly perfect, and little things like tape on cabinets or other
unimportant (from a reliability standpoint) things (like slight mu variation
of tubes) cause oscillations, which destroy tubes and other components.
The false propaganda about parasitics makes it more difficult and time
consuming than it already is to correct **real** problems.
73 Tom
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