In article ,
Paul Burridge wrote:
On Sun, 29 Aug 2004 00:48:51 +0000 (UTC),
(Ken Smith) wrote:
In article . net,
Ralph Mowery wrote:
[...]
Any class ( A, B , C ) of amp can be plate modulated for AM. It is then
not really an amplifier.
I disagree with this. If the stage puts out more RF than it takes in, it
is an amplifier
By that definition, it could also be an oscillator!
If you are putting RF in and getting RF out at the same frequency, in any
reasonable case the circuit is acting as an amplifier. The circuit may
well oscillate when no input is applied. This sort of amplifier was very
common in the past and still is somewhat common.
A super-regen receiver is the most obvious example. Many tube based FM
receiver designs had a FM detector that would oscillate with no input
signal. The "burst lock oscillator" in a TV is in fact a very narrow pass
filter and amplifier when there is a burst to lock to. With no burst it
oscillates.
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