• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Horz Sweep amp Pent or screen drive

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Fixed?
 

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Pentode mode (yet still wrapped in a 4th circuit Triode loop).

Emitter resistor for Nervous Nellies (including me). Though plate
coupled DC back through the 4th circuit makes thermal runaway
seem an unlikely thing to be worrying...

If you were to add a switch to defeat 4th circuit plate feedback
back to that first triode. (Perhaps to better hear the Pentode)
you will be glad the emitter resistor was there!

If you needed A2, you'd have to tie the grids higher than ground.
And to a reference that can sink some current. There is no lack
of pull down current available from the BJT beneath the cascode.
Same rule applies for the previous schematic in A2 Triode mode...

I'm not gonna get around to filling in component values any time
soon. I am sorta burned out on schematics for today.
 

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