[TowerTalk] Rotator Choice for Larger Yagi

[Patrick Greenlee]

Oh, by the way... There is a Green Heron controller especially for the 
K7NV prop Pitch conversions.


On 5/3/2016 3:47 PM, john at kk9a.com wrote:
> I am not even sure that torque means much. All of the rotator issues that
> I have had (broken gears, worn keyways, failed potentiometers, etc)
> occured while the station was QRT.
>
> I currently use a small and a medium prop pitch.  The small has a 9576:1
> gear ratio and the medium has a 7063:1 ratio.  It is possible that the
> small one has the same or more torque than the medium.  Which one is less
> likely to break, I would guess the medium.  I think you would be happy
> switching to prop pitch rotator and Green Heron controller.
>
> John KK9A
>
>
>
>
> To:	towertalk at contesting.com
> Subject:	Re: [TowerTalk] Rotator Choice for Larger Yagi
> From:	David Gilbert <xdavid at cis-broadband.com>
> Date:	Tue, 3 May 2016 11:14:23 -0700
>
>
> In my opinion, and in general, turning/braking torque as a spec makes more
> sense than surface area. In theory, with normal winds, surface area of a
> perfectly balanced antenna would have little to do with with how strong a
> rotator would be required to turn it. Mass and length would be far more
> relevant.
>
> However, in my somewhat unique case, balance and mass of the antenna isn't
> all that relevant ... but rated torque of the rotator still is. I live on
> a hillside that blocks the normal flow of wind, and I get these monster
> swirlers that roar down the hillside as the wind is forced to come around
> the ridge line. I've measured them at over 100 mph on a clear day and I
> watched one literally lift my 16 year old son about two feet off the
> ground. When one of those hits my tower straight on the forces on the boom
> ADD UP and put incredible torque on the rotator. I have a PST-61D with
> stripped gears to prove it, and the total surface area of my antennas
> (OB16-3 and OB2-40) is less than 20 sq ft. The gears were stripped while
> in a resting state.
>
> I was going to upgrade to a PST-71D or even PST-110D, but WA7NB's litany
> of woe with two different PST-110D's (Hall effect pulse detector issues, I
> think) has me leaning more toward a prop pitch. The gears on the Smart GE
> 2500 NS Rotator by Giovannini look totally awesome but it appears to use
> an AC motor, and that would involve a permit process I'm not anxious to
> pursue.
>
> At the moment I'm still considering what I'm going to do.
>
> 73,
> Dave   AB7E
>
>
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