[Amps] Mica cap substitute \ alternative

[R L Measures]

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 at somis.org