I have been using teflon dielectric coax cable for my gamma and shunt
capacitors for
years here. I use small variable caps from old A.M. broadcast radios and
low power
(MFJ-259) to get a match initially. This gives me a starting point for the
length of
coax I will need to substitute for each variable capacitor. The coax is
about 30pf per
foot. Of course you need to err on the long side a bit so the coax can be
pruned to the
right length. When a match is achieved, I strip back the outer cover and
braid about
an inch, and insulate the end with electrical tape. There can be high
voltage at the
open far end of the coax, so take precautions. I then coil up the coax and
put it in
a plastic water-proof box used for sprinkler system timers available at
most hardware
stores. Regular RG-8U could be used if you are not going to run QRO.
(((73)))
Phil, K5PC
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