On Sat, 30 Jan 2016 18:24:02 -0000, wrote:

Sounds like a $200 solution to a $0.75 problem, i.e. an extra foot or
two of coax to allow slack for turning.

Long ago, I had what I thought was a good idea. I was working for a
marine radio manufacturer. Getting decent range with 25 watts into an
omni antenna was problematic in some areas. What worked was a
directional yagi with lots of gain. The problem was how and where to
aim it. Since I was working on an ADF (automatic direction finder) at
the time, that displayed the direction as 0 to 359 degrees, I thought
that coupling the display to a rotator would be a good idea. The
problem was the conventional TV or ham antenna rotator didn't turn
fast enough to switch direction among multiple stations. So, I
installed a rotary joint which allowed swinging the yagi quite
rapidly. The rest was a tangle of junk made from a servo, shaft
encoder, discrete logic, and the usual spaghetti wiring. I switching
to 2 meters for testing.

The results were ummm... interesting. The direction finder output was
not very stable, so the antenna liked to vibrate and jitter over about
a 15 degree swing. If the station it was tracking crossed over 0
degrees, the antenna would swing all the way around to get to the
other side (logic error). A fast back and forth QSO would result in
the antenna doing a "wind vane" simulation. Management was thoroughly
irritated by the noise it made on the roof, which could be heard
everywhere in the building. The consensus among the other engineers
was that this was a truly stupid idea. I wanted to continue, but
testing was terminated when the mast bent at the rotary joint and
someone sabotaged the interface breadboard.

Anyway, an extra long service loop would not have worked for this
project.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558