Re: audio modulated SSTC

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 


 > Original poster: Finn Hammer <f-h-at-c.dk>
 > snip
 >
 >
 > >Plasma tweeters use capacitive feedback mostly and  produce a very
 > >good audio quality. However the operating frequency is much higher
 > >than in our TC systems. And the output power is relatively small. Is
 > >the a.m. statement wrong in principle?
 > >Any answers and comments are very welcome.
 >
 > There are a couple of vacuum tube based plasma tweeters, U. Haumann`s
being
 > one of them for the self made "person".
 > The oscillator is based on a pentode, where there are more than one grid
in
 > the path btwn. kathode and anode. One grid can be used to set up the
 > oscillation, another grid can be used to modulate the output with audio.
 >
 > I think this could be done by varying the supply voltage to the H-bridge:
 > Oscillate with the bridge, audio modulate a big industrial IGBT in the
 > supply rail. It will have to burn up at least 50% of the delivered power,
 > so Therefore a big industrial type is needed, one that is good for
 > dissipating those 1-2 kW`s loss.
 > In this case, a self tuning oscillator would be ideal. (I think)
 > I`l try it out some time, unless someone else does it first, and maby even
 > then.
 >
Essentially, what you are describing is classic AM modulation, so any of the
traditional techniques would work (including using a big old modulation
transformer).  You can also generate the varying "plate voltage" by
modulating a PWM type power supply, in classic Class D audio amplifier.