Roger, and all,
Without a lot of compression and clipping the duty cycle for SSB is only
20%. Given 100W out at 60% efficiency, we are looking at roughly 167W
input at the 20% duty cycle or roughly 34 watts.
Small but important correction: If you have a 100W amp that has 60%
efficiency, then this efficiency is valid ONLY at 100W. At any lower
power the efficiency is lower too. Used in SSB at an average output of
20W, its input power will be far more than 34W. More like 80W, in fact.
Instead a high efficiency amplifier like an EER design will largely
maintain efficiency over the entire power range. So that a 100W EER
amplifier might need 120W input for 100W carrier output, and maybe 25W
average input for 20W average output on SSB.
That's the biggest advantage of using high efficiency amplifiers. Not
going from 60% to 80% efficiency at full carrier output, but going from
25% to 80% average efficiency on SSB!
Manfred
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