On Sat, 28 Aug 2004 10:56:03 +0100, Ian Jackson
wrote:

Don't forget that you cannot really modulate a 'linear' amplifier by
varying the supply rail (which is what 'plate & screen' mod does). The
modulated stage has to be non-linear (eg Class C) where the power output
varies as the square of the supply volts. If the PA was biassed in Class
A, there wouldn't be any modulation.

Certainly there would be no *amplitude* modulation, but that doesn't
preclude FM and various other schemes.
--

"What is now proved was once only imagin'd." - William Blake, 1793.