Topband: top loading

[Ford Peterson]

I have had some success with top loading my tower on 160 with the 80 meter
dipole.  As it turns out, I mounted a remote switch at the top of my tower
to switch between 4 HF antennas.  The antennas are all fed with coax.  The
shield is tied to the switch, the switch to the tower.

The plan works well on 160 when 1/2 of the 80 and 40 dipoles are the "L" at
the top, 80, 20-15-10, and 6 meters (the other antennas on the switch) work
well.  The 40 meter dipole is all screwed up though.  It turns out that the
switch is at 68 feet.  The ground mounted vertical tower just happens to be
very close to 1/2 wavelength on 40 meters.  Poor performance on 40.  The
tower is actually a transmission line tied to a very efficient ground (at
the base) through a 1/2 wavelength line (the tower).  Needless to say, it
stinks on 40.

Just an FYI

Ford-N0OQW




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