[Amps] stability of amps

[Peter Chadwick]

Peter said:
>That design has nothing to do with neutralization, there is none.
It´s just passive grid, <


Passive grid relies on the fact that the external impedance from grid to ground is less (more?) than any negative real input impedance produced by feedback. I'll not go into the argument as to what is a 'negative impedance' - it's taken pages of learned magazines without producing any firm definition. For our purposes, I'm going to assume that we talk about negative real parts of the input impedance. 
Putting it very simply, neutralisation relies on a balance of phase and amplitude between the plate to grid impedance and the grid to cathode impedance.  Not always easy to get over a wide band
73
Peter G3RZP