I installed my new 3 el SteppIR antenna a couple of weeks ago. Some pattern
distortion was noted on the bottom of 20 meters. No F/B. The antenna works
great, except for the bottom of 20M.
I built a small shielded loop on the end of 3' of PVC last night. Hooked it
to a relative signal strength meter. Set the rig to 100W and went sniffing.
It was like a mine sweeper. Get within a couple of feet of a radiating
object and the meter would jump. It turns out that it's the 160M drop wire.
I shorted it out with an aligator clip and the problem with 20M F/B goes
away. Very repeatable.
It's a Rohn 25G tower, guyed with Philly, beam at 45', 40M dipole at 43',
90' of wire runs north to act as the inverted L on the tower. The shunt
taps at about 42' level. It extends out about a foot or so.
Now what? How am I going to get this to load on 160M without ruining the
pattern on 20M? Shortening the shunt will result in an even lower R value
making it real tough to load.
I'm all ears...
Ford-N0FP
ford@cmgate.com
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