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

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Yes, JAVATC uses the center line for topload heights. When I use the program defining topload heights, I use the cells math function (each cell can be used as a calculator). For example, if the top sec winding height is 40" and the toroid is 4" x 12", I would insert into the cell 40+2+3 where 40 is the sec top height, 2 is one-half of the cord, and 3 is the height from the top of the secondary to the bottom of the toroid. As soon as I click out of the cell, the cell automatically calcs to 45 and will graphically display the correct height ratio for the coil. You can model up to 10 toroids (although that is slightly ridiculous).
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For the center disc of a toroid, use the disc topload input. The disc for the above 4x12 toroid would be (od/(2xid), so the disc size would be 12/8=4. I do all the math in the cells, as a matter of fact, I'm too lazy to do even that example in my head, so I enter 12/(2*4) and let the cell do the calcs. The center height would be 45 (the same as the toroid) in most cases. If you have a toroid with a disc on each end, just enter both discs dimensions and heights. If you ever want to know what math commands can be used in a cell, just enter a . into any cell and the commands will popup.
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The disc input can also be used for strike ring analysis on the system. The id would be the diameter of the inner edge of the ring, the od would be the outer edge, and of course the center height would be the height of the ring from the ground. But also, be sure to click the "grounded" checkbox (because the ring is at RF ground). See, there is a reason for that checkbox <grin>.
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Take care,
Bart

Tesla list wrote:

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```Original poster: "resonance" <resonance@xxxxxxxxxxxx>

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The base would be the lowest part of the toroid. The center is referred to in Bart's JAVATC program as the "centerline" of the torus.
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Dr. Resonance
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