Re: PVC vs. sonotube, (was wondering ) (fwd)

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---------- Forwarded message ----------
Date: Sun, 3 Jun 2007 14:08:33 -0500
From: resonance <resonance@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: PVC vs. sonotube, (was wondering ) (fwd)




The problem with sonotubes is the "release agent" coating on the inside of 
the tube.  It is a semi-conductor as the voltage increases beyond 300 kV. 
We often use non-sonotube, non-coated tubes for sec coilforms --- 1/4 inch 
wall cardboard and liberally apply Dolph's AC-43 varnish which soaks up into 
the tube.  We usually heat the tubes first with a few heat lamps to get them 
very hot prior to applying the Dolphs.  We are lucky to have a cardboard 
tube fabricator not far from our shop.  We use fiberglass layup tubes for 
all our commercial coils.

PVC also works very well if thoroughly sanded inside and outside --- again, 
coated with AC-43 in liberal amounts.  You need to get all the "junk" off 
the PVC tube prior to sealing.

Dr. Resonance



>
>> Hi  all,
>>      I know the best material to use as a coil  form would be either HDPE
> or styrene, but if pvc is the best available  choice,  would milling 
> grooves
> lenthwise down the form make it less  lossy?   I'm sure it would be a pain 
> in
> the butt to do, but wonder  if it would be worth the trouble.
>>      Also,  I  cannot seem to find info on whether a sonotube would be a
> better choiice to  reduce losses in the form.
>>    Mike
>
>
>
> Mike,
>
> In reality, PVC is not very lossy for TC use.  You won't see any 
> difference
> in performance using PVC
> vs. styrene in a disruptive TC.  Even for a tube coil, which is more
> sensitive to losses, you
> probably won't see a difference in performance.  The biggest potential
> problem with PVC
> is carbon tracking and burning.  This only occurs if the coil is 
> overcoupled
> or subject to
> flashovers, arcing, etc.