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Re: Medium coil considerations



Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Mike,

You won't see a difference in the 5.3:1 or 5:1 ratios. Because they are so close, you would be hardpressed to find a difference. Most people take Dr. R's recommendation of building an h/d somewhere in the vicinity of 4:1 to 5:1. 5.3:1 is fine if that's what you choose.

John had a good idea of putting a smaller second toroid below the half toroid, but for a more permanent solution, I think you have the right idea of welding (and of course smoothing out the weld) a flat disc to close up the open side. A flat disc will work perfectly well. Many toroids are built this way.

Take care,
Bart

Tesla list wrote:

Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>

Hi all! First let me say, thanks to everyone on the list. I've been
monitoring this sight for over 10 months, gathering information, and learning
as much as possible while lerking in the shadows. I found about it from Dr.
R back in late october when I bought a pig, 18" fiberglass coil form, and a
34 X 8.5 inch toroid. I am working on a big coil. I succesfully built a 4"
coil that gives me about 40" sparks with a 15/60 NST.
I sent this same intro a while back in the middle of another thread. My name is Mike
and as can probably be seen I live in Wisconsin. For that matter I would like to
meet/ corespond with other Wi coilers. Maybe at the comming Cheeshead Teslathon,
if not before.
I think before i fully dive into the giant coil, I should build a medium coil and start
playing with 3 - 5 KW. I plan on winding 20 awg wire for 30 to 32 inches on an exact
6 inch o.d acrylic form.
First question; Am I better of winding for 32 inches with a H:W ratio of 5.3:1 and
957 turns -or-
for 30 inches with a H:D of 5:1 , and 897 turns.
Here I figure the greater the distance from toroid to primary the better, but is keeping
under 5 preferable?
Second question; I bought the 'half toroid' from Norman F. Stanley. see
'half toroid for sale' in july archives for pics. Anyway it is a 24' spun toroid. It is not a
conventional toroid, that is O-----O as a cross section, but rather (_____)
with an 18 inch hole in the top. I was wondering if simply tig welding an 18"
plate in the hole (properly smoothed etc.) would be adaquet for controling the field,
and preventing breakout of my top turns. Or should I try to find a concave aluminum
dish to weld in the hole, so the toroid fits down, and 'hugs' the top of the secondary.
Again much thanks to a fantastic group of folks!