[AMPS] isomica

[Ron Hooper]

NE2E wrote:
> 
> Hello All.
> I need to make a plate coupling capacitor for a brew uhf amp, and i need a
> source
> for where i can get isomica at least .005'' or so.
> I tried various electronics catalogs but looks like noboby carries anymore,
> any leads.
> 
> Also some feedthru capacitors.
> 
> Thanks
> 
> Fred Ne2e

HI Fred,
I would use Kapton, polyimide film, its available from Dupont. Try their
office in Wilmington, DE. Ask for the polymer products division and tell
them you want a sample. The sheet they send out is 8.5x11 inches, more
than enough to make several caps. Its the best stuff I have ever used
since it will not absorb moisture. The dielectric strength is 5000 volts
per mil and at 200C. You need to make sure the plates are smooth and
flat, the sample is 3 mils thick. You could probably double the
thickness (6 mils)to obtain the capacitance for the plate diamenters you
have now and have some margin for the irregularities in the plates.

Ron W4WA

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