[TowerTalk] Rotor Loop - How to ??
K8RI-on-TowerTalk at tm.net
Fri Sep 26 14:02:05 EDT 2008
> I am in the final planning stages prior to the installation of a 4el SteppIR onto a 70' Trylon self-supporting tower.
> The antenna will be positioned about 3' above the top of the tower.
First: How many degrees rotation from your rotator?
My preference (there are a number of ways to do this) I like to put a
minimum of 2 and preferably 3 turns around the tower with the rotator
loop. If the tower doesn't have a flat top plate (like the 445G) I'd
put supports on each leg at the top. I'd lay those three turns loosely
on the top plate or supports. The coil needs to be able to expand and
> How do I prepare the coax and control cables for the transition from the rotating antenna to the fixed tower?
> Do I fabricate lengths of replaceable cable just for the transition (rotor loop)?How do I route the cables? Multiple turns loosely around the mast like a spring? Just a single drooping loop?
> How long should they be?
I use 3 turns of about 18" in diameter. Remember this must be able to
move freely. It only has to hang up once to ruin the installation and
that stuff is strong.
> Any special coax? The antenna coax fitting is not accessible. Will Bury-Flex provide adequate service?
BuryFlex should be more than adequate.
As you can not access the antenna coax fitting and if you are running
BuryFlex all the way I'd not bother with an extra fitting although I use
them on my installation and I can not *easily* access any of the
antennas. OTOH it might be kind of handy if you do have to take the
antenna down. Also if the coax fails the rotator loop is the most
likely spot as it's moving against the tower.
I'm sure others have different ways of doing it but this has worked for
me over the years.
73 and good luck,
> Dave - N7DRK
> Rice, WA
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