Re: Primary/NST case coupling effects

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

Original poster: Esondrmn-at-aol-dot-com 

In a message dated 11/20/03 6:49:55 AM Pacific Standard Time, 
tesla-at-pupman-dot-com writes:


>Does situating the earthed metallic case of a large NST below the primary of
>a TC have much of an effect on:
>
>1) Changing the resonant frequency of the primary
>
>2) Changing the coupling
>
>3) Inducing eddy currents into the NST case
>
>4) Inducing RF into the NST windings?
>
>Just wondering.
>
>Tom L.


Tom,

I haven't noticed any problems locating a normal metal cased nst, with case 
grounded, below the primary when the spacing is about 12" or greater.  I 
haven't tried it closer but we know any large metal objects will load the 
primary and rob power from the system if located within the field produced 
by the primary.  I would expect it to lower the self resonant frequency of 
the primary as you reduce the distance between the primary inductor and the 
transformer case.  It should induce RF currents into the case, which is 
grounded.  I doubt it would couple through the case and into the 
windings.  I don't think it reduces coupling since that is determined by 
the physical relationship between the primary and secondary.  Since it robs 
power from the primary system, you could probably then increase the primary 
/ secondary coupling without causing racing sparks because the amount of 
power being coupled to the secondary is less.

Just my thoughts, Ed Sonderman