AW: [sdiy] precision/matched capacitors??

[pfperry at melbpc.org.au]

Czech Martin <Martin.Czech at Micronas.com> wrote:
> If you need a very precise cap, use a air gap package rotary capacitor.
> Or build your own air gap sandwhich.

I don't think air gap caps have REALLY good stability. I saw one used once
as a humidity indicator! (running a FM transmitter). It was made of invar (a 
metal that does not change dimension with temperature).
I think those little ceramic NPO caps are pretty stable, temp wise.
Often ham radio people rely on the opposite tempco of some ceramics to cancel the opposite tempco of the inducance coil. If you think diy-synth people are 
fussy & obsessive, you havn't met the homebrew hams ;D

-paul perry Melbourne Australia
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