[Amps] The maximum amount of 811As and 572Bs in parallel

[Peter Chadwick]

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