Re: Primary Materials (fwd)

---------- Forwarded message ----------
Date: Mon, 20 Jul 1998 06:52:12 -0500
From: Bert Hickman <bert.hickman-at-aquila-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Primary Materials (fwd)

Tesla List wrote:
> ---------- Forwarded message ----------
> Date: Sun, 19 Jul 1998 00:42:11 -0500
> From: Adam Parker <park_e_r-at-hiwaay-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Primary Materials
> Once again a fledgling coiler has yet another question. Yesterday I made my
> flat pancake coil form out of four pieces of 1/2 inch PVC mounted radially
> on some painted plywood. After making my coilform, I tried winding the
> thing with thin-wall 1/4 copper tubing. I had trouble. The tubing kept
> kinking and never formed a good circle. After struggling with about 6 turns
> I called it quits and removed the tubing. Yesterday's fiasco has swayed me
> to winding the primary with coax. Now, will using coax reduce coil
> performance? I thought maybe eventually I could try tubing again and
> replace it if it does. Do you use both coax conducters or just the outer
> sheilding? One the coil masters out there should write an article on
> primary winding (RQ seems pretty with that type of thing) Well, anyway, my
> next post will either be me asking for help with trouble shooting my
> completed coil or a link to some great operating pictures. I'm hoping for
> the later. Thanks Again,
> Adam


You might want to use four more PVC radials so that you have a total of
eight to provide the copper tubing with a bit more "guidance". Also, by
spacing each radial slightly more outward as you go around, you can get
the nice spiral pattern you need. By carefully bending the tubing in or
outwards from the coiled supply, and then securing it as you go. BTW how
are you "holding" it in place onto your radials? Winding the primary
make take an extra pair of hands, one to hold the winding in place while
the other secures it to the PVC radials. It doesn't have to be
perfect... it just needs to have adequate clearance between turns so
that you don't get any turn-turn arcs.  

Unless you use something like "hardline", most coax uses braid as the
shield. Braid has been found to be extremely lossy when used to conduct
the high RF currents seen in a Tesla Coil primary circuit - and will
introduce an unnecessarily high amount of loss in your system. Even 4 or
6 guage THHN copper wire from your local hardware store will work much
better (and will be less expensive) than coax... 

Good luck!

-- Bert --