Re: Water absorbtion of Gray PVC

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

Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org> 

I must say that I completely agree with Dr. R.  However, I don't think it's 
a necessity for many hobyists, particularly newbies.  I can also say that I 
have wound secondaries on both coated (standard gloss varnish) and uncoated 
PVC forms of different diameters and found that the coated forms were 
easier to find on.  I found that coated forms helped anchor the wire in 
place moreso than uncoated forms.  I have two uncoated PVC secondaries 
started to unwind or have the windings slip if they sat around the shop for 
very long (prior to coating with epoxy/varnish/whatever).  The coated 
secondaries did not have this problem despite a looser wind with thicker wire.

I guess I don't see waht the problem is - it certainly can't HURT the 
performance or lifetime by drying and coating a form.  Small forms are easy 
to dry - use the oven on "warm" for a couple hours, then remove and 
immediately spray/brush with varnish, epoxy, glyptal, or whatever your 
coating of choice is.

IMO, coating the interior of the form is only for sealing purposes and 
really doesn't require sanding.

<offtopic>One of my brother's ex-girlfriends drove a car that had 
experienced a similar treatment to the Mustang - the g/f's father would 
just dump a fresh quart of oil in the engine every 1000 miles and let the 
engine burn off the extra....  My brother, a big car guy, just couldn't 
talk sense into her father - he "knew better."

Cheers

Mark Broker
Chief Engineer, The Geek Group


On Mon, 08 Dec 2003 00:09:49 -0700, Tesla list <tesla-at-pupman-dot-com> wrote:

>Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> All PVC is 
>hygroscopic especially when used at high frequencies.  It's best
>to sand interior and exterior, then paint with 3 separate of Glyptal or
>other HV insulation.  Interior sanding is rapidly accomplished by using a
>sanding "flapper" on a dowel (or other extender) on an electric drill.
>
>Some experimenters would say this is totally not necessary.  I recall a
>friend in high school who put over 90,000 miles on his Mustang without ever
>changing the oil . . . . . . . . . . . . . . . .but, I can't recommend this
>procedure.
>
>Dr. Resonance
>
>
>  >
>  > Dose anyone know how much water Gray electrical PVC absorbs compared to
>  > that of standard White PVC?
>  >
>  > Thanks,
>  >
>  > John