Folks, my sideline at work is being the only ex RFI/EMC specialist, so I
still do a lot of the work I did full time for Southwest Research
Institute's RFI group many years back.
Whenever we were looking for off cable radiation, we got a handy current
probe for the spectrum in question, and with only a scope, or with one
of our spectrum analyzers if you wanted to quote a level, you could see
if your transmission was coming back on the outside of the shield.
Now, a current probe is just a coil around the cable with the cable
passing thru the middle of the coil. The fancy ones are in two parts of
a coil on a core, that snaps over the cable, but you can use a simple
coil for an experimental probe.
Should be possible to determine if you have any shield current where you
don't want it. The catch is you may have to slide the current probe
along the coax to find a hot spot, but I would expect those to happen
every 11 feet or so, when looking for 15m effects. (a quarter wave at
the band of interest).
If the antenna works as desired, declare victory, and have a cold 807.
Younger hams might not know what that is, but think recreational beverage.
-Stuart
K5KVH
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