No problem and no hurries.This is about what I was expecting (slightly lower voltage actually). The NST will attempt to put out 240VA. This gets to about a 20" spark length if losses are low enough and the design is decent (maybe a couple inches more on good days). With the NST in mind, here some recommendations:
You want to maximize secondary inductance but you must also be practical. Two means of maximizing inductance withing a given coil length is to increase the diameter and to use more turns within an area. You have already been told that good performing coils are within an average window of 1000 to 1500 turns. I would change that number slightly and say 900 to 1500 for h/d ratios common. There is also the height to diameter ratio (h/d) which should be in the range of 4 to 5.
With this in mind, I would recommend increasing the diameter of the coil to about 4" diameter or near. Then select an h/d (say 4.5). Multiply h/d x diameter to gain the height. In this case 4 x 4.5 = 18" winding length. Within that window select a wire gauge that will put you near 1000 turns. With #26 awg, you'll get about 994 turns.
Build a toroid. Due to the 8kV supply, I would recommend no larger than a 3" minor diameter. For the major diameter 4 x minor diameter.
Determine the cap size to be about 1.4 x the cap size at which the NST inductance would be resonant with. In this case, the NST is resonant with a .01uF cap size, so 1.4 x .01uF = .014uF or near.
Build a flat Archimedes spiral primary using small copper tubing (0.25" diameter) keeping the distance from the primary about 1.25" at the inside start of the primary. Don't use wide turn separation (space the tubing edge to edge distance the same as the tube diameter).
Most of all, run the calculations and decide on a full design before building components.
Crosscheck your design against something like Javatc to be sure there are no gross errors.
http://www.classictesla.com/java/javatc.html Take care, Bart Matthew Stevens wrote:
Sorry I didn't get back to you sooner, but I was out doing field work today. My transformer is a NST, at 8kv, and 30mA. Matthew
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