Re: Sonotube HV properties (fwd)
---------- Forwarded message ----------
Date: Sun, 02 Mar 1997 13:17:16 -0800
From: Skip Greiner <sgreiner-at-wwnet-dot-com>
To: Tesla List <mod1-at-pupman-dot-com>
Subject: Re: Sonotube HV properties (fwd)
Tesla List wrote:
> ---------- Forwarded message ----------
> Date: Sat, 01 Mar 1997 11:27:46 -0800
> From: Greg Leyh <lod-at-pacbell-dot-net>
> To: Tesla List <mod1-at-poodle.pupman-dot-com>
> Subject: Re: Sonotube HV properties (fwd)
> Ken Smith wrote:
> > My thought was to use 1 inch poly tube as verticals spaced say around a 3
> > foot circle with a suitable number of formers up the height of same and at
> > the top for rigidity. Although this would only be an approximation of a
> > circle (depending upon the number of pipes) - is seems to me that this
> > wouldn't matter. How you would rig this on a jig for winding is another
> > matter - but in principle would it work ?
> That was my thought as well, when I wound my coil. Due to financial constraints
> I ended up using 2x4's (wood!) as the verticals, 12 verticals total between two
> circular sheets of plywood. The secondary therefore has 12 facets and 12 edges,
> far from being a smooth right circular cylinder.
> But apparently 12 facets is a close enough approximation, as there is no visible
> corona from the edges, and the popular equations and nomographs for predicting
> standard coil parameters work on this coilform as well, with good accuracy.
> In fact, the secondary coilform is one of the few components on my coil that I
> haven't had to replace, modify or upgrade in over 6 years of operation.
I build all of my coils using skeleton frames of acrylic plastic. I use
0.5" rod for the verticals and 0.125" sheet material for the interior
stiffeners. I find that a 12" spacing between stiffeners is more than
adequate. I generally use two 0.125" sheets glued together for the top
and bottom plates. I have fabricated 6", 12", 14", and am presently
building a 17.5" diameter secondary. I use 2.5" to 3" spacing between
the verticals. Winding the thing is simple. I put a 0.5" hole thru each
end plate. I mount 0.5" wooden dowels in two 2 x 4 s which I mount
vertically on my bench about 0.5 " farther apart than the height of the
secondary. The sec coil form rotates on the two horizontally mounted
dowels. If you have a source of scrap acrylic, you can build very high Q
coils quite inexpensively. Hope this is understandable.
By the way I have had no problem applying the standard design formulae
to the slightly out of round coils and they perform extremely well.