Hi Alex,John Freau sells toroids which he himself manufacturers from time to time. You'll have to check with him on what he has available. Toroids of this nature are expensive. Every now and then the TCML people get together and go in on a bulk buy of toroids. Dr. Resonance is also another source you should check with. But even Al duct toroids work well. I used those before and after I bought a 9" x 30" spun Al toroid. My last toroid for my 4.5" coil I simply used Al duct and maneuvered it into the 6" x 21" size I was looking for (used a single Al tape to connect the ends). I then used a mixture of Plaster of Paris and another similar compound and coated the whole thing. Basically, I sanded smooth and Al taped over it. It came out very nice.
Your streamers are 2"? Is that a typo? 2" is not good. Your gap is probably the biggest area needing improvement. I would go after that before messing with the top terminal. I have had good luck with multi-segment gaps. Not the kind laid out flat, but mounted in a pipe for air control. Lot's of air is important. I personally like large tubes and not the small 1/2" type. I really hate static gaps using tubes that are laid out flat on a slab. I've never had good performance with those.
Here's a pic of the gap I use on my 4.5" coil (ignore the brass electrodes in front, they sucked!).
http://www.classictesla.com/photos/ba45/s2752.jpg And the coil. http://www.classictesla.com/photos/ba45/ba45.html Here's a schematic of the coil. http://www.classictesla.com/photos/ba45/sch45.pdfBTW, the schematic states 7 electrodes (should be 6). Everything else is as shown.
Take care, Bart b alex pettit jr wrote:
Hi Bart,Can you recommend a source for 18"-20" toroids ?Places I found for 18" sizes price them at $250..This seems a bit costly...The multi-tube spark gap IS an issue. I plan to taper the tubes to force the breakdowns to be centered rather than adjacent to the teflon or fiberglass end spacers. After a few seconds, the arcing carbonizes the insulation material and functioning terminates.I have been able to use the coil with a makeshift dual gap tungsten spark-gap and am up to perhaps 2" air streamers, but I feel it is not optimally tuned....Best, Alex P*******************************************************Hi Alex,<snip>Your coil should do well. One thing I personally would like to see at some point is to increase your toroid size. I use a 6.25" x 21" toroid and breakout is no problem (and it's a very smooth toroid). Your 3" x 12" is a little small. It will work fine, but I think you would have improvement with a toroid nearer to the 6" x 20" range. Not only does this allow more energy to be stored in the top load at breakout, but also lowers the frequency to about 225 kHz, so say about 8 turns on the primary. Heck, if you had my toroid, we would have nearly identical coils! Cool! If gap is worthy (and only time will tell) the coil is good for 40.5" spark lengths on average at 120V and say 45" at 140V.<snip>Take care, Bart _______________________________________________Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla