Jim Thomson wrote:
> Date: Sat, 27 Feb 2010 06:36:49 -0500
> From: Pete Smith <firstname.lastname@example.org>
> Subject: [TowerTalk] Rotator loops
> I notice that typical ham rotator loops involve an unsupported loop that
> is perpendicular to the mast, and attached at top and bottom. It seems
> to me that this means a lot of flexing through 360 degrees, and in the
> wind. I have also noticed that TV station remote trucks seem to use
> another solution for their rotating dishes - they wrap a few turns of
> coax loosely around the mast, so that a one-turn rotation only slightly
> loosens or tightens the wrap. Seems like this would be a better, more
> durable practice for ham installations too.
My standard practice has been to use a three turn coil around the base
of the mast at the top of the tower. If you have a tower with a flat top
plate (I do) the coil can be neatly laid on that. The ROHN 25 and 45
have ears on each corner that are bent down. A bolt can be tightened
into each of these to serve as retainers to prevent the coax loop from
sliding too far, or even off the edge.
I'd not coil the heavy coax around the tower as there are just too many
things for it to catch on such as bolts and side mounted antennas.
> 73, Pete N4ZR
> ## It does work.. and very well too. The usual procedure is to mount the
> lowest yagi a little higher up the mast though. IE: 2-3' instead of the
> ## using that method you can actually use coax that is very rigid, like
> LMR-600. I have see cases where LMR-1200 was used in
> the same fashion.... 3 x wraps around the mast, 3' in diam.
> They both rotated just fine.
> later.... Jim VE7RF
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