hi rich et al.,
rich wrote:
> If the cathode is not at RF-gnd potential, the resultant feedback
> decreases amplification.
not always! it depends on the phase of the feedback that results.
in fact, it is very easy to build an oscillator that has the cathode
away from (RF) ground!
but... rich and i both like the idea of putting a non-inductive
resistor in the cathode return to ground (in a grid driven tetrode)
to get some negative feedback at the desired operating frequencies;
it helps to stabilize the amp; it makes the amp harder to
overdrive, and it reduces the zero-signal plate dissipation.
furthermore, (depending on the tube) it can make the amplifier more
linear. (i.e. it can reduce the odd-order IMD products at a given
output power level.)
73,
George T. Daughters, K6GT
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