Re: Racing arc clues...

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Pyrotrons-at-aol-dot-com>

Hi All.

My 2 small copper coins as far as Robin's racing arcs go.

To John Freau:

I respect your knowledge, especially your past (present?) work with coil 
efficiency. Although I agree with most if not all the things you mention, I 
would rule out some of your "tossed around ideas" in your previous post.

The line voltage powering Robin's coil *might* could vary enough to cause 
racing arcs along the secondary, but I doubt it. If it is, then it's possible 
that the voltage is just under the threshold (for racing arcs) when the line 
voltage is on the downside. (Robin, stick a voltmeter in the wall before you 
run and write the voltage down. Also note whether there were racing arcs at 
the time)

I also doubt that humidity or wind is the problem. Aron and I once ran a 12" 
TC system at 10kVA in the *thick* fog and *hard, driving* rain when it was 
*really* windy. (winter storm, of the kind where bad weather lasts for days) 
Water was dripping down the coil like mad, yet the coil performed nearly as 
well as it did on a still Autumn night. There have been times though, on Aron 
and my 6" NST powered system that humidity *completely* killed the output. 
Zip from the topload. Arcs were awesome when it was dry w/ same setup. This 
was done over and over.

We need line voltage measurements, but I suspect one other thing that hasn't 
been mentioned before.

Tank capacitor value has been known to change during coil runs. This changes 
Fr of the tank circuit relative to the secondary circuit, throws things out 
of tune, and in turn causes the racing arcs. Our MMC capacitor for our 4" 
coil used to do that at the end of it's lifetime - the primary would have to 
be tapped a WHOLE TURN IN at the end of a 30 - minute "play" period to get 
much out of the thing.

I theorize that some of the individual Philips cap's were shorting out (it 
had a lot of hard runtime on it at the time), therefore lowering the number 
of cap's per string, raising the capacitance, lowering tank Fr, and requiring 
that inductance be knocked off the primary to stay resonant with the 
secondary circuit. 

I am sorry I missed seeing the cap type before - Robin, what kind of 
capacitor ARE you using? I've seen this effect (to some degree) with other 
capacitor types also. Mail me your cap type off list please.

Take care Robin, John, All.

Justin Hays
KC5PNP
Email: pyrotrons-at-aol-dot-com
Webpage: www.hvguy-dot-com