My ARSG had a melt-down

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Original poster: "Daniel Hess by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dhess1-at-us.ibm-dot-com>





I was running with my original ARSG last night. A 12" diameter disk with 12
flying brass electrodes, driven by a 1/20th HP Robbins induction motor. I'm
surprised the little motor had the mojo to spin up to speed but it could.
This thing was built in the early nineties back when I didn't know what I
was doing. No Tesla list, only Lindsey's reprints from the twenties. Since
I planted my new RF ground recently, I've been fine tuning this coil,
trying to shoot for the magic K values. As it was night, the only light in
my shop was coming from the coil itself and the gap.

The output was really going great; I'd started with thin purple sparks and
as the tuning progressed I was achieving fatter, white sparks when
suddenly, the output became sporadic and the tone from the gap became
inconsistent. The blue/white light from the gap revealed smoke billowing
from the gap itself. Shut down, shop lights on; I'd used a plank of 1/4"
hard PVC to mount the fixed electrodes. These electrodes were mounted with
1.25" fender washers (to help dissipate heat, haha!) and these had gotten
so hot they pulled through the PVC. More like they boiled their way out.
Funny thing is, I had lots of run time on this gap before but was using it
with my old glass & foil cap. This time I was using a MMC. I hated that it
was destroyed but then again, the way it went out was so cool. I could
replace the PVC panels with either phenolic or G10 but the entire rotor was
also made from 1/2" PVC. So maybe I will conclude that this incident was a
friendly warning from God not to use PVC for construction of a RSG and just
retire the whole thing.

One interesting side note; I never noticed this before but as I'd raise or
lower the rotor speed, I could hear a combination or beat tone (where two
different frequencies partially coincide creating a perceived third tone
caused by the incidence of the two frequencies adding positively and/or
negatively). I would slowly change the rotor speed, attempting to
synchronize the two pitches. When this happened, (synchronize the two
frequencies and the beat tone goes away) even though it would only last a
few seconds, the coils output would increase dramatically, then decrease as
the two frequencies moved apart. Even the fluorescent tubes (which were
turned off but would still glow in the field of the coil) would get
brighter in step with the coil's output. Conversely, when the two
frequencies were at their maximum difference, the coil and the fluorescent
tubes were at their lowest output.

This effect was the most noticeable at the lower rotor speeds, in the
neighborhood of 60 - 80 bps. I know that one of the two frequencies I heard
was the sound of the RSG electrodes presenting and thus, firing, but am
unclear what the other sound was. Perhaps the output sparks from the toroid
itself?

Comments welcome,

Daniel