How does the problem manifest itself, Rich. I have used the
Alpha 78 quite a bit with a Kenwood TS-940, Ten-Tec
Paragon, and Kenwood TS-950SDX. All of these rigs are
solid state, but don't seem to have any trouble driving the
Alpha 78.
BTW, the Paragon uses relay switched low-pass filters (5
pole I believe) to filter the output of their PA. I suspect
Kenwood does similarly. These filters may be providing
the needed energy storage to average out the non-linear
impedance presented by the unfiltered cathode input on the
Alpha 78.
73 de Mike, W4EF.......................................
>> Amplifiers such as the MLA-2500, SB-230, 374, 78, and 76PA have no tuned
>> input. This is not a problem when such a g-g amplifier is driven by a
>> tube-output radio such as the TS-830S. The reason is that although the
>> input Z of a cathode-driven triode fluctuates from roughly 1/3 of the
>> average driving Z on negative peaks to a virtual open circuit on positive
>> peaks, the Pi-network tuned circuit in a tube-output radio acts as a
>> flywheel to smooth out the Z fluctuation at the cathode/s.
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