On Jul 11, 2006, at 12:39 AM, Peter Chadwick wrote:
> Rich said:
>
> >Indeed, and frequency counts too since mica dielectric needs to be
> derated above 5MHz.<
>
> What goes wrong with mica above 5MHz?
Unlike barium-titanate dielectric (ceramic) doorknob capacitors,
whose current carrying ability increases from 5MHz to 30MHz, mica
dielectric caps' current carrying ability decreases above 5MHz.
> it got used a lot in receiving and transmitting tubes, and as
> insulation in cavities at VHF and up where quite large RF currents
> were flowing. And as windows in tubes feeding wavguide, carrying
> appreciable power (like MW pulses). Is it just the wya mica
> capacitors are made?
>
> 73
>
> Peter G3RZP
R L MEASURES, AG6K. 805-386-3734
r@somis.org
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