Re: Designing BIG Secondary Coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Dan,

On 5 Sep 2002, at 7:15, Tesla list wrote:

> 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

Personally I'd go for the 12" coilform. Re wire size, I have two 
guidelines:
(1) spacewound coil: the wire should have a minimum diameter of 3 
skin depths (so it could be bigger if you want) at the *lowest* 
frequency of operation (i.e. with the largest terminal you wish to use
(2) closewound coil: the wire should have a minimum diameter of 5 
skin depths (and preferably more) for the same operating conditions. 

Both these guidelines will ensure that the secondary Q is high.

Regards,
Malcolm