Distributed amplifiers are a totally different ballgame to putting tubes in
parallel. They're not efficient - one, done in the early 1960's used 2
amplifiers in push-pull, each using eight 4CX250Bs. It had 1100 volts on the
plates, and a forced air cooled wideband transformer at the output, delivered 1
kW PEP from 2 - 27MHz (and caught fire at 28!) and drew 5kW from a 3 phase line
at 0.9PF. That would push anyone's electricity bill!
The technique has been used in GaASFET amps at low power, running from 20 to
50GHz from memory.
Half the power is dumped in the laod at teh sending end: I seem to recall some
porposals of using a second transmission line as a delay line and a hybrid
coupler to get that power out.
73
Peter G3RZP
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