[Elecraft] Switching P/S Horror Stories

[Ron D' Eau Claire]

> ...I have one antenna fed with ladder line that interferes with everything
> else in the house...
> Alex N4BYJ

Keep in mind that it is not the ladder line itself that is causing the
interference, but the fact that the currents flowing in the wires are not
balanced. If you have the ladder line balanced, it will not pick up or
radiate r-f.

If you are using some sort of off-center fed antenna, then the ladder line
is  being used as part of the radiator, not as a feed line. Windoms are one
of the common off-center fed doublets. They use the ladder line as a
integral part of the radiator to provide vertical radiation. Those designs
bring the radiating and receiving part of the antenna right down to the ATU.
You should not expect it to be any less sensitive to noise pickup or
radiation than a single-wire feeder.

If you want ladder line to work as a transmission line, like coax, that
minimizes radiation or pickup, you must terminate it in a balanced load at
BOTH ends.

If you have a balanced load at the far end (e.g. center fed doublet) and you
are seeing a lot of radiation or noise pickup, you probably do not have a
balanced feed at the ATU end. IF you are using a balun, that's the first
thing to suspect. Doublets where one end is a lot closer to the ground or
metallic objects than the other can cause an unbalanced termination. Feeder
runs where they run alongside metal, and other effects can also upset the
balance and cause the feeder to both radiate and pick up noise.

Ron AC7AC
K2 # 1289