secondaries

["acmnovak" <acmnovak-at-email.msn-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Howdy,
I have been constructing a small demo coil for my brother's band lately. The
secondary was 1.5" in diameter which puts the small in "small demo coil". The
secondary measured 1.5" x 12"  (4cm x 30cm) with 28 AWG wire before the mod. 
This coil is a beauty, it has nice PVC endcaps, a 1" diameter steel bearing for
a topload, and a deep dark red enamel.  We got it to put out up to six inch
(15cm) arcs, but that took about 500 watts in... and I later found out that the
ground wasn't even making contact! That's *okay* if you're a beginner, but I
know I can do better. So, I set about making some simple modifications to make
it a more conventional, conevtional coil.
First, I removed enough wire and pvc to make it close to a 5:1, h:w ratio.
Next, I potted the secondary's interior with wax, as I intended on getting arcs
as long, if not longer than the coilform. BTW- The topload is connected via a
hole in the top of the seconday. I know it's a no-no, but it looks better. i.e.
"demo coil" Rather than installing a corona ring to stop premature secondary
arcing, I put a nice clear bead or silicone around not only the top but also
the bottom. Upon putting the specs into WinTesla, I got a resonate frequency of
~ 2MHz... Ouch!
That's RF!!! 
I'm planning on a new three layer primary coil made with lexan supports and 10
guage solid copper wire... What do you think of that? Maybe a total of nine or
twelve turns...
 
I like messing with tiny "model" coils, because you can try some really novel
designs without breaking the bank on expensive copper tubing, pvc, epoxy, lexan
etc...
I was thinking of making a conical secondary around 8 or ten inches tall. It
seems easier, but more time consuming, to make smaller coils. Do you honestly
think it would be *easy* to just go out and find a four foot tall conical form
made from a moisture-resistant material for under
$100? 
I'd like to try and use a really big waxed cardboard cup. You know, like a Big
Gulp from 7-11...
A fourty or fifty ounce drink cup would make a great little conical coil. Just
make sure and wind from the narrow end to the wide end... otherwise things
could get a bit frustrating. 
Maybe it wouldn't have the best structure, but you could coat the inside of the
cup with quick set epoxy whil winding, and remove it afterwards... 
 
       
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* Mini-Wardenclyffe *
 
Just one of those thing you think of in the wee hours of the morning...  : O
Safe coilin',
Cheers,
Later,
Regaurds,
Whatever,
 
    -Mike