DRSSTC Additional questions

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Original poster: Skip Greiner <sgreiner@xxxxxxxxx>

Hi all
Ok, the primary feedback using Steve's two coil system works great. 
New questions

1. The tuning of the system is much broader than any TC that I have 
ever built. There is little difference in spark length when adding or 
subtracting two or three turns to the primary. Is this typical of 
DRSSTCs? Per JAVATC the coupling is between .18 and .2. The resonant 
frequency seems to hold pretty steady at 285khz regardless of the 
turns in the primary.

2. Doubling the tank cap size definitely lowers the resonant 
frequency and the input current goes up dramatically but there is 
little effect on the spark length and the primary turns still seem to 
have minor effect on the spark length up to a certain point. Are 
others seeing the very broad tuning that I seem to be getting.

So far I am only inputting 60vac to the full wave dc bridge and spark 
length is approaching 12". The secondary is only 18.5" long. I am 
leery of increasing the input voltage until I understand this 
apparent broad tuning.
Any comments would be appreciated. Thanks Steve and everyone for the 
feedback help.
Skip