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Re: Beehive secondary technique

Original poster: "Eddie Burwell by way of Terry Fritz <twftesla-at-qwest-dot-net>" <eburwell-at-columbus.rr-dot-com>

 I once saw some drainage pipe about 12" I.D. that had ~1.5" x .25" thick
ribs spaced about 1.5" apart. It seemed to be made of a glass filled
material. The problem was it had holes drilled in to the pipe in between the
ribs. I should have looked for the manufacturers name to see if it would be
possible to buy it before the holes were drilled. It was a bright
white-green color and apparently intended for barial in gravel. Perhapse
someone on the list is familiar with this stuff or maybe someone else will
run into it. Without the holes this stuff would make a nice form for a
sector wound coil.

Eddie Burwell

At 08:39 PM 5/3/02 -0600, you wrote:
>Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>"
>The problem of racing sparks running along the secondary is not yet fully
>understood, but the ways to stop it are.  They are:
>1. Reduce the pri-sec coupling.  Trouble is, some efficiency is lost when
>coupling is reduced.
>2. Install several creepage disks along the length of the secondary, to
>make the surface length of the secondary longer.
>Creepage disks have been employed by only a few people, not including
>myself, and good results have been reported, allowing the use of higher
>coupling.  I suspect the reason this is not more commonly used is:
>1. The difficulty of cutting the disks
>2. The difficulty of ensuring an absolutely spark-proof seal where the disk
>meets the secondary
>3. The secondary becomes MUCH larger and more fragile and difficult to
>store when not in use
>I had an idea which does not suffer from these problems.  Rather than
>having just a few creepage disks, the secondary surface is made to be
>corrugated, just like beehive insulators.  What I propose is, after a
>secondary is wound, apply a space-wound layer of nylon rope along the
>length of the secondary.  Then apply the usual several coats of
>polyurethane to the rope and secondary.  It would probably be necessary to
>have a motorized jig turning the works until the polyurethane dries to
>avoid drips and runs.
>I have not tried this and odds are I probably won't, but I thought I'd
>throw out the idea should anyone else be so inclined.
>Gary Lau