RadioBanter - View Single Post

June 15th 06, 04:32 PM posted to rec.radio.amateur.antenna

wrote:
Tom, do you live in the desert?!

You must keep those caps somewhere pretty clean... cool experiment
though... wonder what the record is for capacitor storage over a very
long time.

73,
Dan
N3OX

No; in fact, I live near Seattle! It might actually be worse in a hot
desert, though, because the leakage probably doubles every 10C or so.
Mine are stored with one lead soldered to a PC board, and the outher up
in the air, in a little cardbaord box. Of course, the gates in
isolated-gate PROMS hold their charge a very long time, too. But
modern automated manufacturing in well controlled processes produces
some very consistent materials. I told Bob Pease about my capacitor
'speriment (with two polyester = Mylar caps, and two polypropylene, all
0.1uF, all initially charged to about 12V, the limit of my
high-impedance volt meter) and he told me about being surprised that an
unplugged common printer power supply he had held its charge for many
days. I can tell you that the Mylars have a self discharge time
constant (about 5-10 years) about 1/10 that of the polyprops. The
"supercaps" aren't too bad either--those 1F 5.5V things. Seems to me I
measured a few months for those, though I don't remember for sure right
now.

Way off topic for antennas. Sorry, but some may find it interesting
anyway.

Cheers,
Tom