screw in tungsten-molydenum alloy electrodes for RSGs

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Original poster: "resonance" <resonance@xxxxxxxxxxxx>



We carry threaded 3/8-16 NC copper x 1/2 inch dia tungsten-molydenum 
alloy electrodes in stock for our RSGs.  Contact me off-list if you 
need some. These typically thread directly into 1 1/2 inch long x 1/2 
inch dia brass rod that is pressed axially thru the 1/2 inch dia G-10 plate.

I strongly advise having a machinist do all they work so it is done 
properly and the rotor is at least statically balanced for operation 
at 3450 rpm. Dynamic balancing is even better but not all shops can do it.

3450 offers increased performance over 1725 rpm with most all pole 
xmfr designs as the pole xmfr can provide incredible amounts of rapid 
high current to rapidly recharge the caps enabling high rep rates 
around 575 bks/sec (pps) which "grows" very large and long sparks off 
the sec toroid. After a few years of experimenting we settled into 18 
inch dia, with 17 inch center to center on the electrodes, for most 
of our large pole xmfr powered designs --- using 10 electrodes on the 
wheel for 575 pps.  I made up a jig which enables us to drill all the 
holes using drill bushings for very high accuracy and do it 
rapidly.  We make our oscillator sub-bases with 20 inches of vertical 
height to handle these rather large RSGs.  I also used a 4 gap 
configuration with two gaps on each side of the wheel --- provides 
excellent quenching in the 7-25 kVA range.

with welding rods manganese vapors are strongly suspected for the 
creation of some bad diseases including muscular distrophy  --- there 
are a number of class action lawsuits in progress at this time.  I 
don't know if the thoriated tungsten has an manganese content.  Use caution.

With our jigs and fixtures we also do the RSG rotors for serious 
experimenters but with the individual electrode cost these rotors are 
not cheap.  We also use 1 inch dia stationary electrodes in 2 x 2 x 3 
inch brass fixtures and 4 pcs of these are required at a cost of over 
$100 per electrode.

Large coils are exciting but expensive in RSG and cap costs.

The best route for an experimenter than can live with 7.5 to 8 ft 
long sparks is our dual MOT design.  Matching dual MOTs can be 
obtained direct from AMPI.com for $100 each and the SISG boards are 
inexpensively available from Mark Dunn.  I give away the dual MOT 
plans on off-list request.  It's a great coil, highly portable, easy 
to set up, and most important --- I did the design so it would 
operate from two separate 120 VAC circuits, each circuit driving a 
single MOT at 16-18 Amps.  220 VAC not required for 7.5 to 8 ft long sparks.

We are also making great progress on our "variac eliminator" which we 
will use on this dual MOT design coil.  This VE (Variac Eliminator) 
uses back to back Teccor SCRs vailable from Digi-Key for only $5.60 
each (two required). Our board, which we hope to offer as a kit in 
which you buy the SCRs and heat sinks, should be available by May 
2007.  It will handle MOTs, PTs, and pole xmfrs.  It is 
conservatively rated up to 440 VAC at 91 Amperes Irms so it basically 
will provide the equivalent of 3 stacked 28 Amp variacs and will 
weigh only 2 lbs --- most of this weight is in the aluminum heat 
sinks and SCRs.  It is designed to work with all 120 VAC and 220 VAC 
powered Tesla coils.

Special thanks to the very nice Teccor engineers and professional EE 
Brian Vodvarka who helped advise us as our design and testing is proceeding.

Dr. Resonance