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Sync RSG and hot resistors
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From: Gary Lau 06-Feb-1998 2154 [SMTP:lau-at-hdecad.ENET.dec-dot-com]
Sent: Friday, February 06, 1998 9:34 PM
To: tesla-at-pupman-dot-com
Cc: lau-at-hdecad.ENET.dec-dot-com
Subject: Sync RSG and hot resistors
I've completed my conversion to a synchronous RSG for my 15KV/60mA NST
system. So far the results are disappointing. Where I used to get 43"
strikes using a 10 x .03" RQ static gap, I now get only 30" or so. The
RSG uses a modified 1/8 HP motor running at 1800 RPM, four rotating
electrodes, two stationary electrodes, and I've devised a mechanism that
allows me to remotely rotate the motor housing 1/8 turn by pulling on a
pair of strings. The two-gap RSG is in series with a 5 x .03" RQ static
gap. I see no difference if I short out the static gap.
I put a clamp-on AC ammeter on the AC input. Rotating the motor housing,
the highest current corresponds to the best discharge, brightest RSG
arcing, as well as minimum safety gap arcing. The optimum angle was
surprisingly non-critical, it seems I heard others mention that it is.
What really surprises and disturbs me is how hot my choke series resistors
now run. With my static-only gaps, I was using a pair of 750 Ohm/50W
units. These used to run somewhat hot, but smoked in a very short time
with my sync RSG. I've gone to 500 Ohm/75W units, but even these begin
to smell like they're burning after about 15 seconds. Assuming they're
dissipating 100W each, that means they're passing 447 mA??!!
Observing the RSG, the gap arcs appear to be about .5" long, does that
sound right? (This is the length of the arc before it breaks, not the
RSG gap spacing, which is about .03")
Gary Lau
Waltham, MA USA