Be careful of Steatite ... several kinds will absorb moisture
and cause problems. I had to replace the feedline at a television
station (1600'+ of 3 1/8" rigid line) a few years ago because the
Steatite insulators had absorbed moisture over the years, increasing
the loss and resulting in problems with arcing.
73,
... Joe, W4TV
> -----Original Message-----
> From: amps-bounces@contesting.com
> [mailto:amps-bounces@contesting.com] On Behalf Of Harold Mandel
> Sent: Wednesday, July 12, 2006 5:28 PM
> To: 'Gary Smith'; 'R L Measures'; g3rzp@g3rzp.wanadoo.co.uk
> Cc: 'Amps Amps'
> Subject: Re: [Amps] Mica cap substitute \ alternative
>
>
> Steatite, (porcelain); Corning Glass, PTFE....
>
> -----Original Message-----
> From: amps-bounces@contesting.com
> [mailto:amps-bounces@contesting.com] On
> Behalf Of Gary Smith
> Sent: Wednesday, July 12, 2006 5:18 PM
> To: R L Measures; g3rzp@g3rzp.wanadoo.co.uk
> Cc: Amps Amps
> Subject: Re: [Amps] Mica cap substitute \ alternative
>
> At the risk of straying OT, what is a good insulator at 50 MHz or >?
> 73,
> Gary...wa6fgi
>
>
> ----- Original Message -----
> From: "R L Measures" <r@somis.org>
> To: <g3rzp@g3rzp.wanadoo.co.uk>
> Cc: "Amps Amps" <amps@contesting.com>
> Sent: Wednesday, July 12, 2006 3:46 AM
> Subject: Re: [Amps] Mica cap substitute \ alternative
>
>
> > It's called Dissipation Factor. For example, Nylon, Delrin
> and Vinyl
> > are excellent insulators at 50Hz, but at 50MHz they are not.
> >
> > On Jul 12, 2006, at 2:13 AM, Peter Chadwick wrote:
> >
> >> Rich said:
> >>
> >> >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.<
> >>
> >> Yes, but WHY? What's the mechanism that allows mica to be a
> >> perfectly good insulator in other application, way way up in
> >> frequency?
> >>
> >> 73
> >>
> >> Peter G3RZP
> >>
> >>
> >
> > R L MEASURES, AG6K. 805-386-3734
> > r@somis.org
> >
> >
> >
> > _______________________________________________
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> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
>
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