I've successfully moved my top-loaded vertical from Chicago to
Santa Cruz.
http://audiosystemsgroup.com/K9YC/k9yc160TopLoad.htm
The vertical is really an 80/40 dipole with loading coils to make
it resonate on 80, and fed with old 72 ohm KW twinlead and no
balun at the top. On 40, the loading coils self resonate and act
as traps. When I load it as a dipole, I use a balun at the antenna
tuner. When I load it as a vertical, I tie both sides of the
feedline together and load it against radials.
Here in Santa Cruz, the feedline is almost straight up and the
dipole section is in the clear. That makes it a lot closer to
ideal, so it loads like a quarter wave on 160. So far I have 13
1/8 wavelength radials under it, and bought the wire yesterday to
do another 12 or so in the next few days. Z at the feedpoint is
about 32 + j5 at 1790 kHz. It also seems to talk pretty well based
on only one evening of operating.
Another nice thing is that it is loads and talks well for DX on
40. With the loading coils it's acting like a 3/4 wave vertical on
40.
My question is with respect to loading it on 80. In Chicago, it
was far enough from an ideal full wave that my tuner handled it
just fine, but here in Santa Cruz where it's almost a perfect half
wave (with the loading coils), the Z is far too high. What's the
best way to load it on 80? It's only about 25 ft from the shack,
so a ladder line stub as a transformer is not very practical.
73,
Jim K9YC
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