Designing BIG Secondary Coil

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Original poster: "Mccauley, Daniel H by way of Terry Fritz <twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>



I'm planning on building a relatively large secondary coil and primary
set-up which will be the basis for my future (high power 3kVA + ) coils.  

What should be my primary concerns for a large secondary when i do my
design.
Right now I have an enormous spool of 20AWG wire and I was planning on using
an 8" or 12" sonoform as my coilform.

What should be my primary concerns for designing something this size.  I
guess i want to shoot for a frequency around 100kHz?  (with a proper toroid
of course)  Aspect ratio of around 4.5 or 5???  Anything else????

Thanks
Dan