[Amps] Passive grid stability calculation for a tetrode?

[peter chadwick]

Actually Bill, the formula was derived using tuned circuits, where Rp = QXLp and Rg = QXLg. As you move off resonance, the impedance and gain naturally drops. However, it is worth keeping the value of H around 1 to 1.25 maximum.

The input impedance should be figured as the swamp resistor in shunt with 121pF, although as that is a lower impedance, it will actually increase stability. Whether or not the driver can stand the SWR (and be stable!) is another matter.....

73

Peter G3RZP