More NST-sync tests...reso-cap operation nixed

To: tesla-at-pupman-dot-com
Subject: More NST-sync tests...reso-cap operation nixed
From: FutureT-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 24 Jun 1999 16:45:44 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

 Terry, Gary, Malcolm, Richie, all,
 
 I did some more scope observations with near-reso caps with
 NST's and 120 bps sync rotary gaps, and I am liking the combo 
 less and less.  There is a firing position at around 25 degrees
 after the supply peak that gives a large resonant build up, but gives
 poor power factor with firing of the safety gaps, etc.  The voltage
 build ups that can occur in this set up are indeed fearsome, and
 it would seem sensible to avoid the NST-reso sync arrangement.
 I congratulate Terry, Gary, and anyone else who advised avoiding
 the reso or near-reso caps with NST's.  I plan to avoid their use
 from now on.  Despite my good results with them in my 42" spark
 NST TC, I no longer recommend their use.  For anyone who has 
 my plans for the 42" spark NST TC, I now recommend only the 
 LTR option.  I was tending away from the NST's with reso-caps
 anyway, but these scope observations graphicly show *badness*. 
 There are just too many firing postions that produce large 
 resonances, etc.
 
 I tried both a 12kV, 30ma NST with .0077uF near-reso cap, and a
 12kV, 60ma NST with a .0147uF near-reso cap.  Then 
 I tried the 12kV, 30ma NST with the .0147uF LTR cap, and then 
 the 12kV, 60 ma NST with .031uF LTR cap.  The results were 
 similar with the larger and smaller NST's as far as overall behaviour
 and firing times, etc.  Of course the larger system gave longer sparks. 
   
 Cheers,
 John Freau