RE: audio modulated SSTC

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

Original poster: herwig.roscher-at-gmx.de 


David Trimmell <humanb-at-chaoticuniverse-dot-com> wrote:

 > I would say the problem definatly was not Frequency, as my grid
 > modualted coil ran at around that frequency, also.

David,

I suspect that the key is the form of the discharge/brush:

At the frequencies, our VTTCs run, a hissing sound is generated,
degenerating audio quality. As to SSTCs, somebody (Dan?) wrote: "One
note to add, is that to improve audio quality, it is necessary to
draw-out a continuous white flaming arc from the toroid......" Doing
this, the discharge becomes quite, but *WHY*?

At the frequencies, tweeters run, the discharge looks like the a.m.
modified one and the audio quality is better already.

 > But after building one of Dan's Plasmasonics, I have no interest in
 > messing with VTTC grid modulation.
- I'm playing with such a machine as well, but haven't found the
optimal configuration yet. I am planning on reworking the driver
circuit.

 > And the recent talk of rail and plate modulation has got me real
 > interested, definatly the holy grail of plasma audio!
- Same to me. Thinking of these new ways of modulation, I
unfortunately found out, that I do not fully understand the "old"
classes of operating RF power amplifiers either:

Class A: conduction angle 360 deg - maximum linearity - no tank
               circuit necessary
Class B: conduction angle 180 deg - fully acceptable linearity - tank
              circuit necessary
Class C: conduction angle less than 180 deg - linearity is extremely
               poor, despite a tank circuit is necessary

The latter statement I do not understand: Why is the linearity so
poor? Because of the flywheel effect the correct waveform should be
restored and Class C *oscillators* do this without problems. How is
"linearity" defined? Maybe I am thinking in wrong terms?

Take care,

Herwig



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