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Registered Member #62104
Joined: Thu Jan 25 2018, 06:52PM
Location:
Posts: 2
Hello all, I am gathering parts for my next build. It will be a spark gap 10KVA pole pig running a magnifier setup. The third coil will be 12.5" x 30" (1,000 turns of 22 awg). What size toroid should I aim for? At this point I think I am ready to fork over the cash for a commercial spun toroid (yes I know it will be expensive). Due to the cost I want to get it sized right the first time. So does anyone have experience with this power level and sized coil? What do you suggest? Thanks!
Registered Member #62119
Joined: Sun Feb 04 2018, 04:59AM
Location: Cedar Rapids, Iowa
Posts: 136
My 8.6" x 38" RSG coil draws 6.5 KVA and works well with my 30" x 9" spun aluminum toroid. A little bigger might be better but keep in mind the weight. Mine weighs about 20 pounds and I frequently have to lift it from the top of my 6' tall coil. I wouldn't want anything any heavier. The weight of a toroid is proportional to the major diameter but rises with R**2 on the minor diameter. Admittedly a spun aluminum toroid looks fantastic but if I needed anything bigger I would consider making one with ribs and covered in fine mesh screen wire just to keep the weight manageable.
I would suggest trying different toroid sizes with JAVATC to see what effect it might have on the streamer length. Or go ahead and build your coil and make several "expendable" toroids from screen wire. After you find the best size then you can think about having a spun aluminum toroid made to match those dimensions.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
From various observations and a little experience; . I have never heard of a coiler wishing for a smaller topload than originally planned for . larger = shorter (lower voltage) fatter sparks'n'arcs, smaller = longer and thinner . better performing sgtc appear to have toploads of similar minor diameter to coil diameter, and major diameter between (coil height)/3 and (coil height)
Simulating your coil beforestarting construction is wise, I agree with the idea of prototyping with a cheaper topload before commiting to a final desgn - rigid expandable aluminium ducting is good enough.
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Topload Suggestions for a 10KVA coil?
