Re: Toroid Recommendations?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Tesla729-at-cs-dot-com>

In a message dated 4/11/02 7:29:50 AM Pacific Daylight Time, tesla-at-pupman-dot-com 
writes:

<< Primary
 > 19 turn 20 degree inverse cone
 > 3/8" tubing, 3/8" turn to turn spacing.
 >
 > Seconday
 > 9" diameter 38" winding length 22 AWG single build
 >
 > Tank
 > 15/60 NST, 7 segment RQ/TCBOR fan cooled static gap, 20 nF MMC
 >
 > I was think about using my existing 4" x 15.5" toroid from my previous 
coil,
 > except that ETesla 6 indicates a drop in the free space capacitance from
 > 17.2 pF to 5.2 pF.  I'm now thinking more towards a 4" x 30".
 >
 > What are your recommendations for minor/major diameters and why (i.e.
 > testing, taste, experience)?
 >
 > Thanks in advance,
 >
 > Mark Stolz
 > Houston, TX
 > >>

Hi Mark,

I use a 9" X 30" spun toroid (from the last toroid bulk buy) for
my coil system. However, I'm running at up to 10 kVA since
I'm pole pig powered. This toroid may actually be a little small
for the power that I have available. A 4" X 30" toroid would pro-
bably be good for your coil but I think that you may need to 
consider paralleling a second 12/60 NST(or a third one) to your 
current NST to give the power needed to achieve breakout and to 
properly utilize the other parameters of your coil system. Your 9" X
38", # 22 wired secondary could easily process considerably
more power than 720 VA (12/60 NST) and 30" is a fairly good
sized major toroid diameter that would probably require > 1 kVA
to achieve spontaneous breakout. Of course a small bump 
(like a screw or any kind of conductive protrusion on the toroid 
surface) can encourage breakout at lower power levels and also
"aim" your streamers :-)

Sparking in Memphis,
David Rieben