Re: capacitors

["Tesla list" <tesla-at-pupman-dot-com>]

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

When I started coiling, I didn't know a thing about rf loss factors. I 
made my caps from mylar because it had the highest dielectric strength. 
I could package amazing capacity into very small volumes. The caps were 
well made, they had very high current bus connections and short, thick 
plates. However, the sparks resulting from these were thin and purple. 
They also got hot and died fairly regularly. A switch to an LDPE rolled 
cap of exactly the same capacitance, same tuning, same gap resulted in 
longer, hotter white/blue sparks. I still use this cap, 6 years later. 
However, I am sure commercial polypropylene caps are fairly low loss 
too, as polypropylene has fairly good loss properties. I just thought 
that using so many small caps would be inefficient. It's a relief to 
see that it works well, because I've had it with heavy, oil filled 
units. Thanks for the site, most useful! 

P.S. I think homemade mylar caps would work well in rf protection. 

Cheers,

Greg Peters
Department of Earth Sciences,
University of Queensland

Phone: 0402 841 677