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Re: VTTC - audio modulation

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Class B just means that the tube is "on" for half the sine wave and off
(i.e. cutoff) for half the sine wave.
Class A means the tube is on all the time. Class C means the tube is off
most of the time.

If you want a linear amplifier (i.e. amplifies both positive and negative
half cycles) AND you want to run Class B (for better efficiency than class
A), you need two tubes, one essentially amplifying the positive half
cycles, the other the negative.  if you don't care about distortion, or you
are a narrow band application (i.e. AM transmitter, VTTC), you could run a
single tube in class B. The output (if there was no resonant tank) would
look like the output of a half wave rectifier.

Tesla list wrote:
> Original poster: "Herwig Roscher by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <herwig.roscher-at-gmx.de>
> Dr. Duncan Cadd wrote:
> > Linear rf amps for SSB are always class B (or a close variant)
> Duncan, All!
> I'm not familiar with rf amps (certainly you have noticed this
> already), but doesn't "class B" mean, that 2(!) tubes/transistors are
> operated in push pull service? I really want to learn more about the
> theory before I start frying my VTTC  ;-)
> Tomorrow I'll visit a ham fest and hopefully get some (printed)
> information.
> > "Low" loudness is thus very much a relative term :-)
> - What did you say?  :-)
> Regards,
> Herwig