[Amps] Parasitics & Filament Sag

[Harold Mandel]

Gentlemen,

A previous post mentions a phenomenon wherein is written 
"parasitic oscillation" and what I deduce as filament sag.

Is it possible that these two conditions are related?

It is understood how a strong magnetic field within the tube envelope
can perhaps alter the filament geometry, but can this happen as a result
of a VHF "excursion?"

Respectfully,

  Hal Mandel
W4HBM


[SNIP]
> Hundreds of empirical observations from all makes of amplifiers must be
> wrong. Clearly, the problems must be the mysterious parasitic
> oscillation, which obviously is pushing the filament sideways.
[SNIP]