Hi Dirk, Thanks for the specs.Tuning looks good. Your about 4% high on inductance which is where I like to be. Coupling was slightly low at k = 0.11. You could probably do some coupling adjustments if you can raise the primary or lower the secondary. A k of 0.13 is when the primary is about 1" above the secondary. The coil probably won't like going beyond that.
The coil could probably do about 30" to 35" spark length. But power is low with the 30mA supply. A 60mA or 90mA supply would certainly help on this coil.
These coils can handle rather high power with no problems as long as you keep racing sparks away. About 5% more primary inductance above the resonant tune point is good to help with this especially when power is increased. The other item is to keep coupling high but not so high that racing sparks occur. Also, if high powers are used (say greater than 100mA transformer), you have to keep an eye on the lower secondary windings as they can begin to burn. I run a very similar coil but I had to lower coupling due to the bottom sec turn burning (no racing sparks, just burning). The transformer is a 12/60 NST with 1/2 the shunts removed. Since I fixed that I've done some rather long continuous runs on the coil (20 to 30 minute runs which is extreme for a coil, but it just keeps on going).
Here's some photo's of that coil for reference. http://www.classictesla.com/photos/ba45/ba45.html Take care, Bart Dirk Stubbs wrote:
Sorry I should have included some details. Power: Neon Transformer 15KV @ 30mA Capacitor: 14 doorknob capacitors 30KV @ 590pF = 8.2nF Secondary: 4" PVC with 22" total winding of 24-28 gauge(Don't remember the exact gauge but do recall it was about 1000 turns) Primary: 1/4" copper tubing, 13 turns, 22" overall diameter, approximately 3/8" spacing(5/8" center to center), currently tapped at 11 Toroid: 2 - 8 pie pans with 4" flexible duct. When I originally built my coil, I used TeslaMap to determine what I needed.
_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla