Re: Secondary coil forms

• To: tesla-at-pupman-dot-com
• Subject: Re: Secondary coil forms
• From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
• Date: Tue, 17 Nov 1998 16:12:53 -0700
• Approved: terryf-at-verinet-dot-com

Hi Bill,

> Original Poster: Bill Fuller <wfuller-at-home-dot-com> 
> 
> It seems like the most common coil form is PVC pipe. I have seen post's
> that discuss coating the pipe with a low loss insulator since PVC is
> apparently lossy. 
> 
> Does it make sense to place plastic spacers equally around the coil form
> to lift the wire off the PVC to reduce the losses? This would seem to
> have the added benefit of reducing the parasitic capacitance caused by
> the PVC dielectric and adjacent coil wires. I would think that a "pure"
> inductor (the secondary) and a "pure" capacitor (the top load cap) would
> give better performance than having some of the capacitance down in the
> coil.  
> 
> Bill

I don't think distributed capacitance is an issue as the elctric 
field inside the pipe is equalized and wouldn't bother with lifting 
the wire off the former either. Coils with excellent Qs can be wound 
on shoddy old thickwall drainpipe.

Malcolm

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