Ideal coil forms (was: Re: Sonotube's high RF loss!...yes or no?)

["Alex Crow" <user-at-xxxxxxxxxxxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Hi Mark, All,

I wrapped a skin of 1mm polystyrene sheet (the stuff modellers use, we call it
"Plasticard" in the UK) around a wooden skeleton form, glued it at the seam,
sanded the seam flat, removed the skeleton and plugged the ends. This was
solely because I had great difficulty finding any amount of 6" PVC. However, I
recently saw it mentioned (was it here?) that this is an excellent material in
terms of RF losses and dielectric strength. I believe others have used it with
good results. However, it is easy to split it at the ends if your plugs are a
little too large - easily cured with a good slop of epoxy/PU.

Alex Crow


Tesla list wrote:

>  Since we're (still) on the subject of other materials for TC forms,
> what "exotic" materials have been used and rejected i.e. various
> plastics, glasses, and so on? From first principles, I'd have said glass
> was the ideal material, but nobody seems to recommend it. There needs to
> be a TC-specific FAQ on this somewhere IMHO. Looking up RF absorption
> curves for various materials can be a pain because researchers will look
> for losses in their area of interest (what they're funded to do) which
> sometimes leaves us out in the cold. The Devil's in the details.
>
>   Mark L. Fergerson
>