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Author Topic: Rohn 25 base  (Read 371 times)
K8DIL
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Posts: 12




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« on: August 21, 2008, 06:45:25 AM »

I recently acquired four new sections of Rohn 25; three standard sections and a tapered top section.  I also got a used HyGain TH-3JRS beam.

I've read several threads here about placing a section about 3' or 4' deep into concrete, then bracketing the tower.  Does it really add anything to have a section buried in concrete as opposed to sitting on a pad if the tower is guyed or bracketed?  I'm no structural engineer, but as long as the tower is guyed or bracketed, I don't see any advantage to burying the section.

My plan is to pour a very small concrete pad, and buy a Rohn base that sits on the pad with a small "pin" to keep the base from moving laterally.  Then, bracket the tower at about 17' to the side of my house.  The antenna is about 3.4 sq. ft. wind load, and a rotor adds about 1 sq. ft.  Any comments?

73,
John K8DIL
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WA5UHK
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Posts: 131




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« Reply #1 on: August 21, 2008, 06:46:53 AM »

Buy the base.  If you ever move the tower you'll be glad you did.
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KB9CRY
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Posts: 4284


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« Reply #2 on: August 21, 2008, 09:30:52 AM »

My plan is to pour a very small concrete pad, and buy a Rohn base that sits on the pad with a small "pin" to keep the base from moving laterally. Then, bracket the tower at about 17' to the side of my house. The antenna is about 3.4 sq. ft. wind load, and a rotor adds about 1 sq. ft. Any comments?



What you're describing is the Pier Pin flat base.  Use of that base assumes you're using guys.  A single house bracket may not be acceptable.

Also Rohn specifies exactly what size that base must be for the tower height.  Go to the Rohn on-line catalog and always follow the manufacturer's recommendations exactly.

Do a Google search on Rohn Radian and find the online catalog.
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K8DIL
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Posts: 12




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« Reply #3 on: August 21, 2008, 12:14:18 PM »

Thanks for the replys.

I've looked at the Rohn catalog, and the trouble is, they have a page for self supporting tower antenna area, with the disclaimer that the towers must use fixed bases; this makes sense to me.

The have a page on "Bracket Elevation", but it also says all towers must use fixed base.  The wind load areas are greater than what I need.

They sell the pinned pier base plate, and I think the Guy Details pages may apply.  However, there isn't anything that covers a case close to mine of about 4.5 sq.ft. total wind load.

73,
John K8DIL
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