Re: [TCML] Primary selfC

[FIFTYGUY@xxxxxxx]

In a message dated 7/24/08 4:19:33 P.M. Eastern Daylight Time,  
list@xxxxxxxxxxxxxxxxxxxxxxxxx writes:

>Does anyone know how to work out , or know of an online calculator  for 

>crunching primary Self Capacitance ?



I would think that for only four turns, you could  do a first-order 
approximation by hand. I'm gonna *guess* that it's close to  the isotropic capacitance 
of a cylinder of the same dimensions.

>I know its not normally needed to know these values, though my  tank cap is 
>3nF in my High Q design, 
 
    Even if you manage an efficiency miracle (and I  hope you do!), "there's 
no substitute for cubic inches". 
 
>and now my primary will be 4 turns of 2" wide strap separated about  1mm 
apart.. 
 
    That sounds like a real pain to tap, so I presume  you're tuning by 
another method?
    4 turns with 1mm spacing between each isn't going  to hold up very well 
past a few kilovolts! 
 
>the dia is about 22" so its a fair length and it could add up to a  few 
hundred pF which is a real >problem.. so I need to know the  values...
 

The proximity of your primary to a ground  plane (or the secondary?) might be 
of equal importance for determining its  self-capacitance.


-Phil LaBudde
Center for the Advanced Study of Ballistic  Improbabilities



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