[TowerTalk] FW: electrically operated vertical antenna raiser

[Van K7VS]

Seems to me that building a small mount and attaching a cheap $50.00 radio 
shack tv rotator would be the simplest way to do it and a heck of a lot 
cheaper than buying one of those tarheel devices.  You could also add a 
couple of limit switches to prevent it from coming down further or exceeding 
vertical position very easily.  (should I patent this idea??) Van, K7VS
----- Original Message ----- 
From: "Julio Peralta" <jperalta at tampabay.rr.com>
To: <TOWERTALK at contesting.com>
Sent: Sunday, January 07, 2007 11:57 AM
Subject: [TowerTalk] FW: electrically operated vertical antenna raiser


>
>
> -----Original Message-----
> From: Julio Peralta [mailto:jperalta at 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 at contesting.com
> [mailto:towertalk-bounces at 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.
>
>
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