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Re: Pole Xfrmer, what is the best voltage choice???.....



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

I would suggest using the highest voltage you can possibly handle ( 
things start getting difficult over 30kV). I would aim for a 22kV pig 
if I could get one. By the time you ballast it and so on, the voltage 
will be more like 20kV. The advantage of using a higher voltage is 
twofold. Firstly, less current in the primary circuit. This means that 
your spark gap electrodes will last longer. It also means easier 
quenching of the spark, creating a more efficient coil and bigger 
sparks. To get the same energy into the primary with a 7500v pig would 
require alot more current and shorter gap. This is VERY difficult to 
quench. Secondly, although the cap voltage must be higher, the capacity 
can be much smaller to provide the same energy. This is advantageous 
because a smaller cap can discharge quicker (especially if we are 
talking rolled poly caps). Your primary may arc between turns if the 
voltage is too high - build a new primary or shield the turns with 
LDPE. Using a higher voltage also means that smaller conductors can be 
used for tank circuit wiring. Richard Quick used to run a 10kVA 22kV 
pig and a 25kVA 11kV pig. He pretty much dropped the 11kV unit because 
his vacuum and rotary gaps (which I may add, were very efficient) could 
not quench the arcs. Go with the higher voltage.

Cheers,

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