[TowerTalk] Max antenna weight
Roger (K8RI) on TT
K8RI-on-TowerTalk at tm.net
Tue Nov 10 04:20:05 EST 2015
My experience with the HDR rotators was not good. They depend on limit
switches for rotation stops.
2 HDRs in just a couple of months. One was used, but worked fine. OTOH
Several of us could not remove the mast clamp. I eventually had to cut
it off. As it was heavy cast, that put it beyond a cutting torch. It
was before I had the plasma torch. I gave both away.
Then again, I have little faith in rotators that use wedge brakes and
tiny little motors with a huge gear ratio.
I did not have the big array torque balanced. I released the brake and
the wind took it past the stops before I could stop it with the motor.
It tore up 5 rotator loops. Once the wind was turning the array, I
could not stop it with the motor.
Having said that, I do have a Ham IV for a modest sized C19XR.
I'd not use one except for torque balanced antennas, or relatively small
arrays that are difficult to balance.
Put a wrench on most of these rotators, release the brake and you can
easily turn the rotator. Many can be done with your bare hands sans
wrench. Be careful if you try this. A screw-up can cost you broken
fingers, or worse, particularly if there is a mistake in the wiring, or
the limit switches fail.
Just my opinion based on one set of antennas.
As for units, most of us relate to ft lbs rather than inches, although
for some the metric system is easier.
As Jim pointed out, converting that big number based on inches to ft
lbs, can be rather revealing.
On 11/9/2015 8:47 AM, Jim Thomson wrote:
> Date: Sun, 1 Nov 2015 19:47:00 -0500 (EST)
> From: "jcjacobsen at q.com" <jcjacobsen at q.com>
> To: w8qwdave at casair.net
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] Max antenna weight
> Google and the MFJ/Hy-Gain site are your friends. Hy-Gain recommends the HDR-300, T2X, or the Ham IV for this antenna.
> >From the T2X manual: Max Effective moment is 3400. You get this from the sum of turning radius and weight, so 22' times 88 lbs equals 1936, so that's in limits. Antenna weight is 88 lbs, so that shouldn't be a problem, given the triple bearing race of the T2X. T2X rated at 20 sq ft of area.......
> In closing, I am neither an antenna Guru or an engineer, so you should only consider what is in print, the MANUFACTURES print as in the manuals.............. other wise, YMMV. OR you could spend the bucks and get a REAL engineer to run the numbers.
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