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Re: drying coil forms
Hi Rob, all,
> Original Poster: "ROBERT CRESSLER" <59CREROB@MENASHA.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 don�t 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 coil�s 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. I�m
pretty sure my magnet wire would not have survived this, if
I hadn�t 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, I�m really flooding the List today, ain�t I ;o))