Double Cone Coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>

Last year I had the good fortune of purchasing a double cone coil on eBay.
I bid on a hunch, just from the apparent age of the coil.  The copper tube
primary was very old and heavy patina.  The secondary looked great.  I put a
very large bid on it just to ensure I won it.  I was not disappointed.
After winning the bid the other person who was bidding informed me that he
owned the form for making this coil.  It was given to him by his father who
received it directly from Nikola Tesla.  The copper tubing looked like
1920 - 1930 patina, and the cotton covered copper wire on the secondary was
a material used by Tesla, so I feel very confident it's the genuine article.
I am also aware of Tesla's many references to conical coils.  Although I
haven't seen a good picture of a conical coil by Tesla I assume it was one
of his trade secrets.  The fellow who owns the form also mentioned this coil
has antigravity properties.  I don't know about that as I haven't fired it
off yet.

Doing a rough measurement I calculated 127ft of wire on each 6" x 6" cone.
The measured inductance is 2.36mH from end to end.  It would appear the
quarterwave frequency for the secondary is 968.75kHz.  I'm going to build
both a double aluminum air gap plate capacitor and a variable high voltage
Plexiglas plate capacitor with a range of 10 to 18pF.  I'm shooting for the
resonant frequency of 968.75kHz.

I have rewound the primary with new copper tubing.  It has a measured
inductance of 10.6uH end to end.  I will build a high voltage variable
capacitor out of Plexiglas for the primary.

I have transformers of various sizes from 7500V 30mA NIST up to 15KV 60mA
NIST.  I also have a couple 240V input 19KV transformers I haven't learned
to use yet.

Pictures of the double coned coil are at my web site
www.tesla-coil-builder-dot-com.  I'm looking for some input regarding the
parameters and any feedback from people with experience with these types of
coils.

Thanks,

Dave