Rich said;
>I would like to see RCA's diagram of neutralized g-g 811s.
It's in the TT5 Transmitting Tube manual, up at the back in the 'typical
applications' section as we'd call it these days. They feed back to a tertiary
winding on the filament choke.
I've a feeling I've got some reference to neutralising gg stages in some 1950's
text books (not ham radio ones). I'll try to remember to have a look tonight.
Of course, if it's really 'grounded' grid, it doesn't need neutralising. But we
are talking about tubes with large enough grid structures (572s, 811s) that the
inherent inductance means that the grid isn't really grounded anymore - even
more so with 220pF grid bypass caps.
BTW, was it meant to be 220pF? It's not unknown for a 2200pF cap to have had a
'0' left off on the circuit by draftsman's mistake. The mistake doesn't get
picked up, and then the machine gets copied, and before you know what's what, it
becomes a 'standard' circuit.
73
Peter G3RZP
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