[AMPS] TL-922 Filament Transformer Protection

[Tom Rauch]

Hi Jon,

> Oh, sure.  But my question is not wether or not it happens.  But as Tom
> pointed out, the filter action of the input pi-network will limit the
> response of the spark pulse.  Plus how large an amplitude is generated? 
> Is it enough of a voltage spike to drive the amplifier into conduction? 
> And even if it is the output signal on the anode still won't be all that
> large.  And any anode ringing will be even less of an amplitude.  Could
> that ringing of small amplitude be large enough to start an oscillation? 
> I doubt it except for in perhaps the most instable of all amplifiers.  I
> have no proof, but neither do you.

If an amplifier is unstable, in other words if feedback exceeds loss 
and the phase is correct, it will oscillate no matter what the 
perturbance is.

Even shot noise from the normal process of electron emission will 
make the PA oscillate if it is biased into conduction.

It would be a design challenge, if not totally impossible, to build an 
amplifier that oscillates only when hit with a sharp pulse and yet 
behaves normally with a normal signal.

Rich's theories rest on the very shaky foundation that the PA is an 
uncontrolled oscillator with feedback levels high enough to send it 
into meltdown only on "rare occasions", when hit by cosmic bullets 
or disturbed by a relay closure.

73, Tom W8JI
w8ji@contesting.com

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