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Strange NST-coil behavior



Original poster: "Andy Cleary" <cleara-at-twcny.rr-dot-com> 

Hello All,

The other evening I was resurrecting one of my larger coils for operation, 
and I figured I would use 3 identical 12/30 NSTs in parallel as the power 
source.  I hooked them together, phased them, and I'm able to pull great 
arcs from both HV terminals to the case and to each other.  I hooked this 
supply up to my TC tank circuit, SRSG in parallel with my NSTs, and then my 
MMC tank capacitor and primary coil in series with the output (the typical 
tank circuit).

Now for the strange thing:  If I use the 2 HV terminals from the NSTs as 
the input to my tank circuit I get no action whatsoever - no sparks in the 
sparkgap, and no charge on the MMCs.  But if I short one HV NST terminal to 
ground, then all of a sudden the coil starts to work (granted, at only 1/2 
the NST voltage).  I tried grounding the NST cases to RF ground and power 
ground, with no change in operation.  If I just don't use one NST HV 
terminal and instead connect the one power input straight to ground, it 
also "works".  The NSTs aren't new, but they seem totally functional!!

Any thoughts?  I'm asking more out of curiosity, as I recently finished a 
6-pack MOT supply that I'll be using instead :)

Thanks,

-Andy C.

Andy Cleary - KC2GVE
Projects Coordinator, RPI Electronics Club
<http://www.ajaxelectronics-dot-com/>www.ajaxelectronics-dot-com
<mailto:cleara-at-rpi.edu>cleara-at-rpi.edu