Re: OLTC maggy

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

Original poster: "Stephen Conner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

At 13:07 07/04/03 -0600, you wrote:
>Original poster: "boris petkovic by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <petkovic7-at-yahoo-dot-com>
>
>How to realise 120+pf capacity in small machine with
>800 W max power?Toroid?Even in (1,2,3) mode 60 pf
>toroid will look stupidly big on your OLTC.
>However here are consideration how these and bigger
>capacities can be realised:

I wouldn't worry about it. By the time I've enclosed the secondary coil in 
thick plastic insulation of some sort (dielectric constant about 5 to 8) 
and then wrapped a wide copper foil primary (effectively grounded because 
OLTC primary voltage is so low) round about half of its height (required to 
get k=0.5) there will be no shortage of capacitance to ground. In fact 
there may well be too much. My calculations for (2,3,4) say 52pF is needed. 
For (1,2,3) it was only 24pF.


>b)Another constructing possibility is putting grounded
>cylindrical screen inside driver coil cavity.The
>continuity of the cylinder to be broken from top to
>bottom in few places (ie.vertical cut) in order to
>prevent shorted turn effects due to intensive magnetic
>field presence in driver.

That's what I'm talking about: except the primary will be on the outside. A 
screen could be added inside too of course.


>c)If someone finds these constructing efforts pain in
>a#% there is,as always, straight forward solution
>(money is price) :
>Getting/purchasing 200KV+ rated high pressure gas cap
>in 100 pf range (or something similar,with vary cap
>options the best).As of dimensions,200pf-at-200 KV   high
>presure cap I saw in local lab was 50-60 cm high.

No way, this is getting done on a strictly limited budget (unless I get a 
high-powered job soon) and besides I like building stuff...

Steve C.