cap firing voltage scope measurements question


 I'm seeing some strange results in my TC:
 Here are some cap voltage measurements under different conditions:
 I set my input variac at 60, and the scope indicated the output voltage
 of xfrmer was 15.2kVpeak, without the TC connected.
 At the same variac setting, but with TC connected, but with the 
 spark gap removed, the cap voltage reads 22.3kVpeak.  I suppose
 I'm getting some resonant charging here with this particular ballast
 At the same variac and ballast setting, but with the gap firing 
 (120bps), and the TC producing sparks, the cap voltage reads
 30.4kV.  This means I'm obtaining a 2X voltage increase during 
 ~1/2 cycle, I thought this degree of resonant build up was possible
 only when using DC charging?
 Does this seem normal?  I would have expected the voltage to be
 lower with the gap firing since there's less time for resonant voltage
 build-up.  In there a gap in my understanding?  Or is my scope
 reading wrong?  The 30.4kV makes sense from a Joule perspective,
 since it comes out to 840 cap watts or so, and the meter reads 1000
 watts, which seems about right. 

 Mystery, or insanity?
 John Freau >>