I have been working on a tetrode amp which was slow to generate power
and varying
input swr and signs of negative grid current.
Last nite, I removed all input circuit components and then started
over. The first component reinstalled was the 50 ohm input resistor. I
was working with no voltages applied and continued building the circuit
one component at a time. Everyting was stable. I changed the value of
the coupling/dc blocking capacitor to a 1200pf mica.
The circuit now consists of first feeding the resistor, then coupling
the resisual voltage to the grid. The negative bias is fed directly to
the grid via a 50uh inductor. All is well.
As far as the original problem? I really cant say, except I suspect
the coupling/blocking capacitor was the culprit...
I still have to bypass the meters, but the operation is now stable.
Thanks to all who have helped with their input.
73, Lynn NO9Z
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