Te> From STEVE.GREENFIELD-at-rook.wa-dot-com Tue Dec 20 14:14 MST 1994

 SG> Correct me if I am wrong, (someone will) but if you don't 
 SG> ground the bottom, doesn't that act like a 1/4 wave trans-
 SG> mission line that is -not- shorted at one end, therefore a 
 SG> high impedance and voltage does -not- appear at the top? 

Not always, not necessarily.

 SG> Or since it is only locally grounded, with weak capacitive 
 SG> coupling to global ground, you have a 'weak' ground and there-
 SG> fore not as high an impedance or voltage as with a good
 SG> ground. 

What do you mean by "locally grounded". Do you mean "pumping 
out lots of RF current that is conducting away from the system"?
(Across floors, down drains etc.) ?

 SG> Could you get around this grounding requirement by using a 1/2
 SG> wave coil, ie, both ends are high impedance and voltage, with the
 SG> center either grounded or not grounded? Didn't Tesla do just this
 SG> with some of his coils? steve.greenfield-at-rook.wa-dot-com

I think you are confused, and that must be what is confusing me.
Ungrounded coils can shift nodal points. The 1/2 wave coil is a coil 
that has a nodal point (nul voltage) located in the center of the 
winding. The two 1/4 wave peaks work off of the nul voltage node, 
no external ground is required, but providing an external ground 
connection to the center of the coil stabilizes the position of the 

Tesla worked with a lot of 1/2 wave systems in his RF lighting 
systems. He also worked with every other possible resonate coil 
combination that I can think of. When he intended to load a 1/2
wave coil, he always used a ground on the secondary system, and 
generally used two seperate windings coupled to the same primary.

Richard Quick

... If all else fails... Throw another megavolt across it!

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