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Re: [TCML] Coil forms, any good?

Hi Gary, just to confirm what I hear you saying...thick walled PVC secondary form doesn't have any downside with respect to its electrical properties - it's just a matter of adding unwanted weight to the system...Is that correct?? 

Reason I'm asking, I've got some 6" heavy-walled PVC I can use.? But if it hurts performance, I'll have to track down some thin-walled pipe.

Thx, Dennis Hopkinton MA

-----Original Message-----
From: Lau, Gary <Gary.Lau@xxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tue, 15 Jan 2008 2:46 pm
Subject: RE: [TCML] Coil forms, any good?

The only credible reported difference in secondary form materials so far as 
losses are concerned have been in the paper-based "Sonotube" concrete forms.  It 
wasn't the paper, it was the unknown binder that was believed to be responsible 
for the losses, and even then, the losses were theoretical based on (I think) 
ringdown measurements.  It was felt that such losses might only be an issue on 
CW or solid state coils.  The many, many pig-powered Sonotube coils that work 
just fine are evidence that it's not a deal breaker.

There was also a report that PVC pipe often contains random debris that in at 
least one instance, proved to be conductive, causing a secondary short.  PVC 
itself is just fine though.

I think there would be no measurable performance difference between the 
materials you mentioned.  I would base the choice on material strength, 
machinability, color (aesthetics), will glue and polyurethane stick to it, and 
weight.  I would choose the thinnest wall that's structurally adequate, but only 
to minimize weight.

Regards, Gary Lau

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Tesla
> Sent: Tuesday, January 15, 2008 1:59 PM
> To: tesla@xxxxxxxxxx
> Subject: [TCML] Coil forms, any good?
> Hi all.
> I have just struck a little bit of gold, I now have more or less
> unlimited supply of
> coil forms in glass fabric, cotton fabric and paper. The resin in
> these forms are some of the
> following: Phenolic, Epoxy, Melamine, Silicone and Polyester.
> Are they all good for winding coils on or are there some that i should avoid?
> Also if they're good, does the thickness of the wall(RF losses)
> affect the coil performance
> with these materials?
> Of course i have seen several on the web using fiberglass so i guess
> that should be ok
> but what about the other materials?
> Any input appreciated as i can get any diameter in any length for
> free. Lucky me....=)
> Thanks!
> /Matt
> www.tesla.nu (in Swedish)

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