Re: secondary forms

To: tesla-at-grendel.objinc-dot-com
Subject: Re: secondary forms
From: Mattthew <cwolins-at-orion.it.luc.edu>
Date: Thu, 8 Feb 1996 08:04:09 -0600 (CST)
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On Wed, 7 Feb 1996 tesla-at-grendel.objinc-dot-com wrote:

> >From MALCOLM-at-directorate.wnp.ac.nz Wed Feb  7 13:12 MST 1996
> >Received: from rata.vuw.ac.nz (root-at-rata.vuw.ac.nz [130.195.2.11]) by uucp-1.csn-dot-net (8.6.12/8.6.12) with ESMTP id MAA18381 for <tesla-at-grendel.objinc-dot-com>; Wed, 7 Feb 1996 12:52:26 -0700
> From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
> To: tesla-at-grendel.objinc-dot-com
> Date:          Thu, 8 Feb 1996 08:53:34 +1200
> Subject:       Re: secondary forms
> 
> Hi all,
>         Written was...
> 
> >  I see that RF wise PVC is not so good as a secondary coil form (I myself
> > have been using sonotube at first then PVC). Could you use a  long cylinder
> > with a layer of Mylar or Poly on it, then wind the coil over this, coat it
> > with epoxy (Polyureathane), let dry, remove the long cylinder (and possibly
> > the Mylar or Poly), and then coat the inside with more epoxy. Now all that
> > should be left is a coil held togeather with epoxy, no other form, no PVC. If
> > there was enough epoxy it seems like it would hold togeather. Please let me
> > know the + and - of this idea, I am sure someone has thought of this already,
> > but I am curious.
> 
> This is more-or-less exactly what I'm planning to do for my 12" coil.
> I checked the Q of a coil I'd wound on the sonotube (which hadn't been
> all that well prepared) as far too low and dependent on air moisture
> content. I'll be using varnish rather than epoxy and I'm planning on 
> retaining the polyethylene sonotube wrap although my plans are still
> somewhat hazy on this. A free-standing coil is an attractive 
> proposition but raises some interesting problems when it comes to 
> handling strength, mounting terminals etc.
>     BTW, I'm keen to get a large toroid commercially spun to get
> a nice smooth surface and also to go for a large ring cross-section.
> I talked to a couple of aluminium spinners here and it seems that
> the bulk of the cost is in making the wooden formers, so I'm cur-
> rently hunting down a wood turning firm with a large lathe.
>     And in connection with terminals, there's an idea I want to 
> explore that involves mounting two moderate sized toroids, one
> above the other to form a larger "virtual" toroid. I don't know
> what the outcome will be but I intend to try it to compare volt-
> age holdoff with a single large terminal.
>     Any thoughts on these is most welcome.
> 
> Malcolm
> 
> 
> 
**** I have a large wood spinning lathe at my work and would be happy to 
help in any way I can.  I am also looking for commer. spun aluminum 
toroids.  If you could please let me know what dimensions wood forms you 
need I will be more than happy to help if it will fit on the lathe.  What 
company did you call to get this information, and how much will they cut the 
cost if we supply the wood forms for them.

Matthew Klueppel   cwolins-at-orion.it.luc.edu