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PRACTICAL TUNING QUESTION

 > From: EDHARRIS-at-MPS.OHIO-STATE.EDU
 > Subject: Practical Tuning Question

 EH> OK all, 

 EH> I'd like to pick your brains about optimal tuning for coils.

 EH> When does one find that the optimal secondary sparks occur? 
 EH> (A) When the system is  tuned at low power (no secondary 
 EH> discharge)? 

No.

 EH> (B) The system is only  optimally tuned when the coil is run at 
 EH> a given power level (tuning is a  function of power level)? 

No.

 EH> (C) none of the above. 

Yes

 EH> I can't exactly say what I  mean by "optimal" sparks because I'm 
 EH> not sure if one gets fatter or longer or  brighter discharges when 
 EH> the tuning is optimized. 

You get all three.
 
 EH> The point behind all of this is that I've been wondering how
 EH> much the discharge's capacitance changes the tuning of the coil.

This depends on the size of the discharger. If you have small toriod
that breaks out all over the place (three or more streamers at once)
then things like conductive ion clouds (descernable with time photo-
graphy) affect the discharger capacity, and that affects the system 
tune. This ion cloud, and therefore the tune, will vary with power
levels. 

On the other hand if you have a very large toriod, and only one
streamer issues out most of the time, the discharger capacity remains
much more constant. A consistant tune can be maintained through
a variety of power levels.

 EH> This probably  isn't a very simple problem from a theoretical 
 EH> point of view since the  capacitance chages in time as the 
 EH> discharge progresses outward. But, I would just like to have 
 EH> people's observations of their own coil(s). 

Well tuned with a very large discharger; the spark adds a neglible 
amount of additional capacitance to the system. 

Richard Quick
... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12