Tube coil, level shifter madness

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

Hello coilers,

There's been a test I've been wanting to try for a long time.  I figured
I wouldn't let the year slip away without doing this.  I finally tried
the level shifter circuit on my small original staccato (pulsed) tube
coil (16" sparks).

The power xfrmer has two secondaries; 2kV, and 3.6kV.  I normally
use the 3.6kV secondary, but since the lever shifter doubles the
voltage, I figured I'd switch to the 2kV winding for this test.  This
gave me 4kV.  I'm afraid that 3.6kV x 2 or 7.2kV would be way
too much for the 4-250A tube.

Anyhow, I expected that the output would be a little better due to
the little higher voltage, and due to the way that the level shifter better 
utilizes the xfrmer's capabilities.  Well, the results were disappointing;
the sparks were no longer, and the sword-like spark was ruined in
the staccato mode.  Rather the sparks became forked and branched.
I did not try re-tuning, or anything like that.  Also, the 72LS123 based
TTL pulse timer circuit is not too happy with the level shifter.  It seems
to misfire at times due to RF interference.  I saw the same thing with
the larger staccato coil in the past, and I had to use the 555 timer 
based pulse circuit at that time.

Well this goes to show the criticalness of these tube based systems.
Everything has to be just right.  Very touchy indeed.  There hasn't 
been much talk of tube coils on the list lately.  They lack the
frantic raw power of a good spark gap system.  I will say though,
that the 38" tube coil sparks were a sight to behold.  I do want to
build a new high-powered tube coil at some point.  I also plan to
build a mostly new spark gap TC to replace my old research coil,
which was the precursor to the TT-42 project.

Onward to the new TC Millennium......   !!
John Freau