I gather John's idea is to always have maximum plate voltage swing,
regardless of power level. One way of doing this is to vary the B+ supply
with the amplitude of the signal. A system doing this, albeit with a solid
state linear and a switching regulator, was done by Collins in the early
70's. Varying the B+ so that the plate swing is always the maximum
percentage of the possible swing keeps up the efficiency, and always runs at
the same plate load impedance.
You can imagine the amp having a modulator to vary the B+ - just like plate
modulation in the good ol' days. You could even expect 400 watts out of a
pair of 6146B's - after all, they gave 400 watts PEP in the AM days. But you
have an extra amp and PSU to do it. Guess there still ain't no free lunch.
73
Peter G3RZP
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