[Amps] Neutralising a tetrode amplifier with a broadband input

[Alan Ibbetson]

Grid driven tetrode linear amplifiers lend themselves to broadband input
circuits using a swamping resistor and, say, a pi section low pass filter
that absorbs the grid-cathode capacitance. Svetlana suggests that if the
passive grid resistance is small enough there is no need for neutralisation
but that seems like a bandaid to discard gain in exchange for stability.

How do you extract a signal from the anode when there is no tuned circuit
at the grid for the necessary phase reversal needed for conventional bridge
neutralisation? Would a bifilar ferrite loaded phase reversing transformer
across the grid resistor work? Or is there a better way?

73, Alan G3XAQ
-- 
Alan Ibbetson
alan at g3xaq.net