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Re: polyester resin
> Date: Wed, 5 Feb 1997 22:41:41 -0700
> From: Tesla List <tesla-at-poodle.pupman-dot-com>
> To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject: Re: polyester resin
> Reply-to: tesla-at-pupman-dot-com
> Subscriber: sgd1-at-acpub.duke.edu Wed Feb 5 22:30:31 1997
> Date: Wed, 05 Feb 1997 01:35:38 -0500
> From: Stan <sgd1-at-acpub.duke.edu>
> To: tesla-at-pupman-dot-com
> Subject: Re: polyester resin
>
> Tesla List wrote:
> > Mike,
> >
> > I used two coats of polyester resin to overcoat the #12 AWG THHN wire
> > employed on the secondary of my large system, dubbed LTC. It is
> brittle
> > and cracks easily, and did not *stick* to the clear plastic sheath
> > overcoating this type of wire (is this nylon?), but it sure adheres
> > well to the eight equally spaced 1.5 inch ABS pipes I used to make the
> open
> > form. This coil performed very well in the only test yet conducted
> about two
> > years ago yielding an 18 foot strike on 10-11 kVa input. It appears
> that
> > the use of this resin probably isn't hurting the performance. I am
> > eager to try some Behr Super Build 50 on a coil sometime, but I think
> > it would also be brittle. A two part coating that is more flexible
> > would be nice to find to coat and hold together large open frame
> > secondaries. Anyone out there have any suggestions?
> >
> > rwstephens
>
> RW,
> Would you mind sharing the rest of your large coil's specs? ie.
> secondary and primary width, primary spacing, etc.?
>
> [Part 2, Text/HTML 32 lines]
> [Unable to print this part]
Stan,
No problem. I don't have my specs handy but the coil is here and I
can give you at least accurate physical dimentions, plus that
available from memory. The secondary is wound on an octagonal open form
employing eight 1.5 inch ABS black plastic pipes equally
spaced around four 30 inch diameter plywood disks. Brass woodscrews are
employed to hold the pipes to the edge of the plywood. Plywood is
well sealed with the usual varathane treatment. The disks are
pressed onto a central column made of 1/8 th inch wall, 5 inch PVC
drain pipe for rigidity. Wound length is 67.5
close wound inches of #12 stranded copper THHN wire. The wire is
coated with two coats of polyester resin. Toroid is a 33 foot
continuous length of 15.5 inch O.D. aluminum flex duct which is
vacuum compressed to a length of around 12 feet. This pulls the
corrugations together improving the sidewall strength. I had this
piece of duct custom made at the factory, they normally saw this up
into 10 foot lengths before the distributors get it. The resultant
toroid is 15.5 " X 67". I estimate it around 84 pF. I also have a
smooth walled commercial toroid about 2 inch diameter spaced one inch
above the secondary end and 6 inches below the main toroid. It
is just slightly larger than the secondary diameter and represents a
shorted turn. It protects the top winding from corona damage. The toploaded
secondary swings at 54 kHz. Primary is a flat spiral made of 3/4
inch O.D. bared aluminum CATV distribution coax, 12 turns on 1.25
inch centers. The spiral starts about 2 inches outside of the
primary diameter. The inside of the primary and the bottom of the
secondary were both tied to RF ground. I used a pair of Plastic Caps Inc, 0.025
uF -at- 60 kVDC hi-rep rated pulse caps (polypropelene and sillicon oil)
to resonate the system. Tune was achieved around 8
turns. The rest is your standard rotary with air blast and a 10 kVa,
16000 volt pole pig. You may see a picture of this coil as setup for
its one and only run on the funet archives in the rws pictures files.
I believe the photo is called LTC01RWS.jpg. The primary was
supported closely above a large cable reel end which is full of steel
nails. The wooden platform itself was just a couple of inches above
the frozen gravel driveway. Magnetic shunting of generated RF would
have been a significant factor in this test. Nevertheless, it did
good for a first test!
Build one yourself and have fun!
rwstephens