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Re: flat coil ?

Original poster: "Paul Nicholson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>

[coffee table flat coil]

Chris Swinson wrote:

> Are you saying wind the coil around the outside of the flat coil or
> under it ? 

Under it, because you don't have the space otherwise.

> I never thought about if it would be possible to wind the
> primary under the actually coil and not around the outside of it.

You've got to avoid the hot center, and in view of the voltage 
profile, for center read the area within a 50% radius of the center.

The primary I suggested is a cylinder winding down inside the
'table' legs, as wide as possible to both maximise inductance and
to keep away from the center.

> If it was that simple then I could use my 2 foot dia primary and
> not bother to build a 4foot dia primary.

Well your 2' diameter primary would just line up nicely with the
hot 50% center of the secondary. I suppose that's about as bad as
you can get.  To get a usable coupling coefficient the primary would
have to be around 10-12" below the secondary.  You'd need some 20 or
more turns on a 2' flat spiral to tune 12nF to the Fres.
Paul Nicholson