Hi Craig,
> W8JI had a 4 element array that was quite a bit from his shack (was it
> almost a mile Tom?) I think I remember Tom telling me he used hard-line.
Near Cleveland OH, my receiving antennas were about a mile away. I had a
mixture of RG-6 and hardline (using regular CATV fittings). The only
problem was I went under a road through a culvert, and vermin would eat
through the cable occasionally. I just kept replacing that section when it
would go bad.
The system ran audio tones through the single RF cable, superimposed on 48
volts AC for power, to switch antennas and preamps. Sixty four remote
functions were available.
The system used enough pre-amp gain at the remote box to overcome
feedline loss and put a fairly "stout" signal in the cable. I also put
"tilt" in the pre-amp so gain and attenuation were
equal over the entire spectrum from VLF up. The amps all used high power
high voltage CATV transistors.
My present system is similar, with RG-11 running for 1000 feet to one
antenna array, and .750 inch 1400 feet to another. Once again push-pull
CATV transistors are used for line drivers at the far end, and equalizing
networks for gain.
A word of caution!!! Use good fittings designed for CATV systems. They are
cheap, reliable, and prevent problems with lightning and RF ingress through
poor shield connections.
There are no tricks, I periodically ground the cable, and decouple the
cable with high mu (ui>10,000) beads to reduce common mode excitation by
"forcing" the cable back in current balance, that also reduces chances of
lightning-induced problems. At the control/switching box, everything is
well grounded and decoupled by beads that look almost purely resistive
placed over the cables. Of course the Beverage transformers all use
isolated windings in the 73 mix core transformers to prevent common mode
coupling, with each Beverage having it's own ground. The individual
Beverage feed cables are all grounded about 10-50 feet from each antenna to
independent ground rods.
This system is so effective that even when I totally lost a shield
connection on one control box (from a cow chewing on a cable) the signal
directivity barely changed except for about ten dB of additional loss.
In either case, the system went totally dead when a empty port (terminated
or unterminated) was picked. My present system has survived lightning hits
on my tall tower 500 feet from one control box, even though the feed and
control lines run under the radials on that tower. Properly installed, I
doubt you would have any problems for years (except for rodents chewing on
flexible cables).
73 Tom
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