[Amps] Tuned Input

[Peter Chadwick]

Has anyone ever come up with an equation for the input impedance of a GG stage in Class AB2?
I guess the problem is that it's a variable with drive level - at very low level, where the stage is Class A, it's the classical 1/gm, but it should be possible to simulate at higher power levels if someone has time (and the interest) to produce a suitable model.

It would answer a lot of questions posed here. Similalry, has anyone ever measured the input impedance at various power levels? The best way would be a dual directional coupler and notwork analyser or vector voltmeter.
73
Peter G3RZP