Please excuse the misspelling in the last post. I got distracted and
didn't run it through spell check.
Julio, W4HY
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Julio Peralta
Sent: Sunday, January 07, 2007 2:57 PM
To: TOWERTALK@contesting.com
Subject: [TowerTalk] FW: electrically operated vertical antenna raiser
-----Original Message-----
From: Julio Peralta [mailto:jperalta@tampabay.rr.com]
Sent: Sunday, January 07, 2007 2:57 PM
To: 'Jim Lux'
Subject: RE: [TowerTalk] electrically operated vertical antenna raiser
Check the Tar Heel antennas site they have just what your looking for.
http://tarheelantennas.com/mounts
Also the acuator mechisum from a old satalite dish could work whik is
what the Tar Heel thins is made from.
Julio, W4HY
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Jim Lux
Sent: Sunday, January 07, 2007 2:39 PM
To: Towertalk
Subject: [TowerTalk] electrically operated vertical antenna raiser
I've been looking at ideas for electrically raising and lowering a
vertical antenna (like a 6BTV or R7000 style... basically 20-30 ft of
aluminum tubing). One idea is to use a garage door opener (or a
similar chain/track or leadscrew arrangement from some other source,
but a garage door opener is probably the cheapest way to get a 8 foot
long linear drive, 1/2 HP motor, etc.).
The other way would be to find some inexpensive gear box that runs
at, say, 1 RPM (it would take 15 seconds to go 90 degrees) and has
the torque capability to handle the wind load on a 30 ft mast. Any
ideas on consumer products with this sort of capability (I don't
think electric window drives are quite in the ballpark, but maybe?)
The moment load is about 700 ft lb for a 30 foot, 2" diameter mast in
a 60 mi/hr wind. I suspect you could get away with a lot less as the
drive, accepting the fact that the drive might slip if you try and
actuate during a windstorm. You could have mechanical stops to take
the load once all the way up. Of course, some drives (worm gear
window motors come to mind) can't backdrive, and will break if
overloaded on the output shaft.
700 ft lb @ 1 RPM is a pretty small mechanical load (550 ft lb/sec is
1 HP, so we're down in the 1/5th of HP or smaller... a pretty small
motor, with suitable gearing.. on 12V, something like 10-15 Amps.. a
couple amps for a 110V motor). probably a bit much for an
inexpensive TV antenna rotator..
The overall idea is to hide a vertical antenna on a rooftop by laying
it down when not in use.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|