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Re: [TowerTalk] Biggest rotor that will fit in a Rohn 25G

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Biggest rotor that will fit in a Rohn 25G
From: "Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>
Date: Wed, 20 Jul 2016 16:17:46 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
A heavy duty rotator with a large antenna should be mounted well down into the tower. Mounted at the top, in the tapered section would likely put very high stress at that point.

73

Roger (K8RI)

On 7/20/2016 Wednesday 10:56 AM, Bill Tippett wrote:
What’s the strongest rotor that will fit (or can be made to fit) inside a
25G?

If you can find one, a KLM 1500HD (no longer available) will fit into a
tapered top section of Rohn 25.  I know because I just tried the one I have
in 25G.  You have to mount it in a 25AG series top section at the ~16" open
window without Z-bracing.

Abbreviated specs:

Diameter: 8"
Height with top mast clamp: 16.73"
Weight with top mast clamp: 28 pounds
Rotating Torque: 1,550 inch-pounds
Stall Torque: 1,740 inch-pounds
Brake: 10,500 inch-pounds
360 degree rotation time: approx 60 secs (48V 1A motor)

It's like a small prop pitch (another alternative) with no brake mechanism
other than the motor/gearbox.  The data sheet says it's good for 32.6 sq ft
at 90 MPH when mounted inside the tower.  Mine survived regular 100 MPH
winds and two exceeding 140 MPH in Colorado (but derate by ~15% for wind
pressure at 5000' elevation).  I had a KLM 5L 20 and KLM 3L 40 mounted on
it.

I *might* consider selling it but will not give it away (e.g. I believe
K7NV's prop pitches are ~$3000).  Make me an offer I can't refuse if
interested  :-)  I have the manual and can scan the complete specifications
page if interested.

73,  Bill  W4ZV
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73

Roger (K8RI)


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