[Amps] Parasitics & Filament Sag

[Tom W8JI]

> To some extent but what I and I believe others are looking 
> at is a typical L-R-C type of circuit. Not where you have 
> R in the L branch and R in the C branch. This makes it a 
> fish of an entirely different sort!


1.) Every circuit has R in the L and in the C branch. The 
inductor is especially problematic for component Q 
limitations

2.) Resonance has several equally correct or commonly used 
definitions

3.) Resonance has little to do with the long drawn out 
argument

Bypass capacitors and series inductances in the path from 
the bias switching and the tube characteristics limit the 
slew rate of any plate current change caused by opening or 
closing a relay (or any other bias change). The sharpest 
rise time or deltaV/t that could ever occur would be during 
actual operation of the amplifier. It could never be caused 
by a bias change.

When the obviously false notion a bias change can have a 
waveform change so sharp it will "ring" a VHF circuit in the 
anode system of an HF amplifier is coupled with the fact 
that a spectrum analyzer could never capture a dampened 
waveform, the whole theory falls apart. There are far larger 
holes in this idea than a debate about the definition of 
resonance. It sounds like a bad theory brought about through 
improper use or understanding of test equipment.

73 Tom