Jumping in with both feet?

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: Jumping in with both feet?
From: Tesla List <tesla-at-stic-dot-net>
Date: Tue, 27 Jan 1998 23:57:10 -0600
Approved: tesla-at-stic-dot-net

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From:  SBJohnston-at-aol-dot-com [SMTP:SBJohnston-at-aol-dot-com]
Sent:  Tuesday, January 27, 1998 3:48 PM
To:  tesla-at-pupman-dot-com
Subject:  Jumping in with both feet?


Hello, Tesla-listers!

Please allow me to introduce myself:  Steve Johnston, in York, Pennsylvania.
  I'm 34, with 21 years as a ham radio experimenter and 15 years as a
Broadcast Engineer (so I'm not a newbie to high voltage/current RF systems).
 I've had a passing interest in Tesla coils for years, but never took the
time to fully study the details and build a system.  Over the past week,
however, my interest has intensified greatly as I was fortunate enough to
come upon a nicely-crafted TC whose owner had died (hopefully his passing was
not related to TC experiments!).  

This coil stands about 5 feet high not counting a top discharge terminal.
  The primary is made of 11 turns of 3/8" Copper tubing, spread about 12"
high and 26" in diameter.  The tubing is air-wound, held separated by plastic
(nylon?) spacers.  The secondary is wound with about #22 wire around a
cylinder of 1/2" wide varnished wooden strips spaced about 1/2" apart.  It
consists of two sections in series, each 2' long, about 3 inches between the
two sections, for an overall winding length of 4'.  It is 16" in diameter
with about 13 turns per inch.    The secondary sits about 2/3 of the way into
the primary -- perhaps by design to set the coupling between windings?

There is a dome-shaped metal cover about 8 " tall and 6" in diameter that is
probably intended to be a top discharge terminal.   It could connect to the
center contact bolt on the top of the secondary with a short length of solid
wire.

The "exciter" (if that is an appropriate term?) is built into a metal cabinet
and consists of a Variac driving a 15 KV 30 ma neon sign xfmr (half the
winding is used, centertap to one end),  a small series inductor, and four
caps in parallel.  The caps are of unusual physical design (to me) but not
homemade -- the four together measure about 0.02 uF.  The spark gap is also
commercially-made with circular, D-shaped electrodes with cooling fins behind
 -- the gap is easily adjusted.

Any opinions as to the capabilities of this rig?  Would it be meaningful to
temporarily short the spark gap and attempt to grid-dip the primary tank and
see where it resonates?   Does the secondary self-resonate with distributed
capacitance?  To what spacing should I set the gap when I start testing?  
Am I asking too many questions?  I guess I'm way too excited and eager to get
started...

Thanks for any opinions and information!

Steve Johnston

sbjohnston-at-aol-dot-com