[Amps] Super Cathode Circuit

[Peter Chadwick]

To add to what Tom said, Pappenfus recommends the circuit for high gain tubes, and specifically mentions the 4CX250B and 4CX1000. There is also a caveat against grid current, but a suggestion that IM3 of -50dB can be obtained. If you don't have that virtual ground for RF between plate and grid which the screen supplies, I don't see it working.
I can see how you could do it with triodes: you'd need two of them in series in a cascode arragement. Why you would ever consider doing so other than a purely academic exercise is another matter, unless maybe, you wanted to grid modulate the top one for AM. It would have to be a contender for most useles circuit idea ever, though.
73
Peter G3RZP