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Re: [TowerTalk] electrically operated vertical antenna raiser

Subject: Re: [TowerTalk] electrically operated vertical antenna raiser
From: Richard Thorne <rmthorne@cox.net>
Date: Sun, 07 Jan 2007 13:42:33 -0600
List-post: <mailto:towertalk@contesting.com>
Jim:

I had the same question some time back.  The best suggestion I received 
was using an elevation rotor.  I never installed the vertical but if I 
did I liked this idea.  I probably would have used some sort of counter 
weight so the system was balanced.

The other way is to use a satellite dish actuator.  While on a smaller 
scale Tarheel mobile antennas uses this idea.

Rich - N5ZC


Jim Lux wrote:
> 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.
>
>
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