Re: drying coil forms

• To: tesla-at-pupman-dot-com
• Subject: Re: drying coil forms
• From: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Wed, 05 Jan 2000 18:34:41 -0700
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi Rob, all,

> Original Poster: "ROBERT CRESSLER" <59CREROB-at-MENASHA-dot-com>
> acrylics (cast,extruded) are indeed hygroscopic , for comparison
> rigid PVC has a water absorption of .04-.4%  and  acrylics with
>.2-.3%  (wt. gain after 24hours per ASTM D570). This has come up
>before and I am still unclear as what dictates (or why)  a superior
>coil form.To really confuse   me the dissipation factor at 1Khz
> for acrylics is .02-.03 and PVC is.009-.017 !!??

Well consider the length of the E-Field lines in your secondary.
I think some 500mm is an okay average. Now consider your
PVC pipe wall thickness. Some 5mm maybe. So you are
loosing AT MOST 1% in your coil former. Nothing to really
worry about, I would say. Your gap is -by far- much lossier.

Personally I donīt think the material is THAT important. There
are a few that I would stay away from (such as cardboard),
because of its (non) resistance to flashovers. In contrary to
some on this list, I think preparation of the former and really
embeeding the wire in epoxy and / or PU varnish is MUCH
more important if your coilīs former is too survive a flashover.

My primary tilted away once during a run and I got massive
flashover between primary and secondary. I switched off
immediately, and found......... nothing, not a single mark. Iīm
pretty sure my magnet wire would not have survived this, if
I hadnīt coated it 5x (3x epoxy and 2x PU varnish, including
sanding in between). Plus the glass hard surface looks just
great.


Coiler greets from Germany,
Reinhard

(Gee, Iīm really flooding the List today, ainīt I ;o))

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