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1/4 wave TC (fwd)

---------- Forwarded message ----------
Date: Wed, 25 Jul 2007 12:21:32 -0400
From: Skip Greiner <skipg@xxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: 1/4 wave TC

Hi All
Well after my capacitor literally exploded and destroyed both the 
primary and secondary of the first 1/4 wave TC, a new one has been built 
and is in test. The specs are:
Primary: 7 turns, 1/4" tubing, 19" in diameter
Secondary: 390 turns #22ga, 0.050" overall diameter insulated wire, 14" 
diameter, winding len:19.5", frequency len of wire: 217khz, wire length 
Measured Resonance of secondary is 210 khz. no excitation
With 5 x 20 toroid: 205khz
With two 5 x 20 toroid: 150 khz
Driver: 9kv x 120ma NST
Break: SRSG with 2 poles
Cap: .027

Some of the test results:
Variac set no higher than 40 or about 50 volts input
Spark length:
No toroid: multiple 12" (+) arcs from top turn of sec
One toroid: 20" (+) from breakout point
Two toroid: 27" (+) from breakout point
Operating freq: with toroids: 140khz
Operating freq: without toroids: 190khz

Note that the wire length frequency and the operating frequency with no 
top load under power are pretty close. I am trying to figure out how to 
concentrate the discharges into a single streamer without a top load. I 
seem to be processing a large amount of power and the total amount of 
sparks with or without a top load seems to be similar.

Above the "40" setting of the variac the NST safety gaps really fire 
nearly all of the time and so far I am afraid to open up the gaps which 
are set to about 0.125". Does anyone have a comment as to the maximum 
safety gap opening that I might use on a 9kv NST? It looks like this 
thing will really perform at higher inputs but I do not want to risk the 
NST yet.