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Re: Character Revisited
11/26/96
Forwarded post
>>>>
Rick,
Sure, no problem. Please be sure to state that this was very informal
testing. I was really trying to prove that tube and transistors could
each do the job well to an old, die hard tube fan, and just screwing
about in general.
Were I going to publish any of this, I'd want to revisit some of the
testing, and have learned a bit more about how the RF wattmeter acted
to less spectrally pure signals, etc.
I would not describe these results as definitive, but they did show
that for the one secondary coil tested, the spectral content had more
to do with delivered arc length than did the driver technology.
In all this messing about, there were two specific drivers that might
be exceptions, but I suspect this probably had more to do with
impedance matching than anything else.
An argon thyratron made a really frighteningly good driver. One cold
winter night we had corona everywhere, while angry masses of plasma
danced inside the tube. St. Elmo's fire oozed along the plate
electrode and the ozone grew so thick we pulled the plug for fear of
damaging the secondary insulation.
No attempt was made to measure of control the spectral content, but
the DC input power was rather low for the display we received. (I
would not have brought my test equipment NEAR that thing!)
A similar display was given by an old diathermy machine that was given
to me by Bob (Mr. Tesla coil) Golka himself. This ancient example of
state of the art electronic snake oil uses a pair of self oscillating
triodes with exceptionally thick plate structures.
While these oscillate at a frequency quite a bit above the self
resonant frequency of the coil we used, it was quite spectrally broad,
being a sort of odd, square wave multivibrator circuit.
This drivers shows that indeed, the higher the frequency, the longer
the arc for a given power level. You know, I was just cleaning up in
the basement, and I ran across that old diathermy machine chassis. I
wonder what ever became of that thyratron?
This is a guess, but if you were to drive a given coil at it's
fundamental, and push the even harmonics was up (dV/Dt?) so that there
were lots of higher frequency harmonics, I think you would find
greater arc lengths for the same input power. That's how I recall
things acting. It makes some sense on conventional, and less
conventional levels.
snip . . .
Oh yes, the die hard tube fan grumbled a lot, and pointed out that the
thyratron and diathermy machines both made more impressive displays,
with less circuitry than did ganged solid state amps. The primary
power levels were a different story, so we agreed to disagree. He
forever did gain a respect for Phase Linear power amps though, even of
here chock full of bipolar transistors!
>>>>>>
______________________________ Reply Separator
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Subject: Re: Got your emails.
Author: rwall-at-ix-dot-netcom-dot-com (Richard Wayne Wall) at SMTP
Date: 11/23/96 7:18 AM
11/22/96
May I forward portions of your posts to the Tesla List. I think they
would be extremely intereted in your experiments mimicing gap
discharges with solid state drivers in TCs and getting similar outputs
from the secondary.
This is original research and you might consider publishing. But, I
know your time constraints.
RWW