Topband: 1000 feet 5/8" hardline or 600ohm True Ladder line.
Richard (Rick) Karlquist
richard at karlquist.com
Sat Apr 26 12:10:33 EDT 2014
I used to have a 1000 foot long open wire line using
4AWG stranded insulated aluminum wire with an impedance of
450 ohms. At the time, the wire cost $0.15 per foot.
I think 4AWG was the smallest size available in aluminum.
It is much easier to build a transformer
for 450 ohms than 600 ohms, because 450/50 = 9 is
a perfect square. The spacing is something like 12.5
cm. It is supported every 15 meters with a support that
spaces the wires apart by 12.5 cm. There are no intermediate
spreaders. Originally, I had some intermediate spreaders but
found them to be unnecessary. At each end there is a 50 ohm unbalanced
to 50 ohm balanced transformer in cascade with a 50 ohm
balanced to 450 ohm balanced transformer. The supports
are PVC pipe slipped over "T-posts" (used for fences).
I see that the web site you mentioned shows this same
technique. Maybe they copied me, hi.
It is easily deployed/redeployed. The end to end loss
including the transformers is a few tenths of a dB on
I moved the shack closer to the antenna and shortened the
line to 600 feet. The line has served me well for over
10 years now. There are some photos of the line on my
web site www.n6rk.com.
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