A possible approach for control lines is using 4/20m current loop
modules that are cheap and readily available on Amazon. They are low
impedance and relatively insensitive to most noise pickup. They can be
made insensitive to RF by using shielded twisted pair with a few ferrite
chokes. They are based upon the principle that current is identical
throughout a loop no matter how long it is, as opposed to voltage having
a drop depending upon the resistance of the wire.
Just search for "4/20ma converter". They come in both
voltage-to-current and current-to-voltage versions. Here are some
possible examples, and although I haven't tried either of them current
loops are long time standard in the control industry and long distances
are common.
https://tinyurl.com/ytdhyxvu
https://tinyurl.com/5xf953xe
Just a thought.
73,
Dave AB7E
On 2/17/2026 1:05 PM, George Collins wrote:
Hello,
Have put up a second tower that will be used just for HF antennas. It's in
a nice location except for one problem: it's 500 feet away from my shack.
I'm looking for suggestions on how to deal with a very long rotator cable
run. There is a barn with electricity a 100 feet from the tower where a
controller could be located. I'm thinking that I could run light-gauge
control wires from the shack to a controller in the barn, thus avoiding the
large IR drop in the motor wires. The difficulty I see with this
approach is the long run for the position indicator wires. I think they
will likely pick up RF or other electrical noise. Perhaps some type of
buffer or line driver could be used.
I would also consider just running heavy-conductor cable directly from the
shack to the tower, if affordable cable was available. I think I would
still have to deal with long position-indicator lines.
Perhaps a wireless solution may be the best method, but I would probably
need to copy someone else's design. I am familiar with various
microcontrollers and SBCs, but I haven't done anything programming of WiFi
networks, etc. I would like to use the typical Hy-Gain/CDR type controller
and I will probably use a HAM-IV rotator, although a Yaesu rotator is a
possibibly. Making electrical modifications to the rotator or controller
is not a problem.
Any suggestions (other than moving the shack to the barn hi hi) will be
very much appreciated.
73,
George, KC1V
FN31
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