[CQ-Contest] Help making single stubs
k6ll at juno.com
k6ll at juno.com
Fri Jun 19 13:58:48 EDT 1998
On Fri, 19 Jun 1998 04:59:05 -0700 Sam Ferris <ve5sf at sk.sympatico.ca>
>Need some advice from the contest reflector members who may have
>experience with making stubs
I use a grid dip oscillator, listening on the station
receiver to determine the frequency accurately.
1. Cut the cable slightly longer than the formula indicates.
2. Install a pl-259 on one end.
3. Make a SMALL one-turn hairpin loop, made out of a 2" piece
of hookup wire. Jury rig it onto the pl-259.
4. Bring the gdo near the loop, but keep it as far away as
possible, while still being able to detect the null.
5. Start snipping the far end of the cable, leaving it
unshorted, until it's on frequency. It's not a proper stub
until there are about a dozen little pieces of coax on the
floor, and your hand is all red from using the cutters!
I have tried to use an Autec antenna analyzer in the impedance
mode, but there is a very broad region of zero ohms that covers
the whole band. I have also tried Autec's recommendation of
adding a small resistance in series with the analyzer to
reduce diode "suck-out," which occurs at extremely low
impedances, but that didn't help either. The analyzer read
only the series resistance value across the entire band.
Dave Hachadorian, K6LL
K6LL at juno.com
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