Another illustration of this is feedthru capacitors:
Conventional ones are coaxial, the "obvious" way
to make them. However, a much better way to make
them is the so called "discoidal type", which
involves parallel circular plates. Low pass filters
of the TVI preventing type often have homebrew
discoidal capacitors that are large enough, and
exposed, so you can see the construction.
Rick N6RK
> -----Original Message-----
> From: topband-bounces@contesting.com
> [mailto:topband-bounces@contesting.com]On Behalf Of Tom Rauch
> Sent: Wednesday, December 15, 2004 12:34 PM
> To: StephenTetorka@cs.com; topband@contesting.com
> Subject: Re: Topband: HV capacitor
>
>
> > Regarding the need for a HV capacitor...might some copper
> tubing and pvc pipe ala coaxial geometry apply?
> >
> > They're used on small loops where some pretty high
> voltages reside.
>
> Steve,
>
> Two conductor coaxial capacitors always have considerably
> higher ESR than multilayer capacitors. This is because they
> are open long transmission lines instead of compact
> reactances with multiple short current paths connected in
> parallel.
>
> This is why multilayer chip capacitors, good air variables,
> and vacuum caps with multiple concentric plates have Q's
> well up into the thousands. and transmission line type caps
> of lower reactance values can be down well below 100.
>
> 73 Tom
>
>
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