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Re: 6" spark



Original poster: "Mr Gregory Peters by way of Terry Fritz <twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>

A small coil running at 9kV and 60mA (500w) should easily produce
1.5' sparks. Two major inefficiencies exist with your coil. Firstly, 
the spark gap is very low Q, but should give bigger sparks than 6" if 
adjusted right. Secondly, the saltwater caps are also low Q. Fix these 
+ the gap, retune, and your coil will scream. Your secondary wire guage 
may be a tiny bit large, but should still perform ok. I got a 4" x 14" 
coil with #24 wire to make 2` sparks easily years ago with similar 
power. The arcing in your caps may be distorted by the glass - are you 
sure the arc isn't going through the bottles? This would also explain 
the poor output. How wide is your gap set? It should probably be around 
1 cm at these voltages. Did you tune carefully? The tuning can come 
down to 1/3 of a turn! The salad bowls aren't the most desirable 
topload, but again, should perform better than this. I would leave 
these for the moment, provided they are over, say, 10" diameter.

Good luck.



Greg Peters
Department of Earth Sciences,
University of Queensland, Australia
Phone: 0402 841 677
http://www.geocities-dot-com/gregjpeters