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Re: [TowerTalk] Weight of mast material

Subject: Re: [TowerTalk] Weight of mast material
From: Mahlon Haunschild <>
Date: Tue, 20 Jan 2004 21:41:08 -0600
List-post: <>
I don't know about the mast per se, but your overall plan concerns me.

Assuming that the 40m antenna you are talking about is the Cushcraft XM240, a little math shows:

           Weight      Wind area (sq ft)
mast         90                2 (est.)
C31XR        82               10.7
XM240        55                5.5

totals 227 18.2

Rohn 25G is only rated for 8 sq ft at 70 ft. & 110 mph per their drawings (you are in 105 mph land, per EIA/TIA 222, so you need to design for that). Also, 227 lbs rotating weight is a LOT for the 25G structure to withstand. How will you control the torque caused by the antenna stopping & windmilling?

If you're married to the idea of a 70 ft 25G tower, one thing you should do is get an aluminum alloy mast. Cuts down the weight dramatically. Another thing to do would be to not use a 40m beam.


Mahlon - K4OQ

Julio Peralta wrote:

Thanks to all who replied RE: the weight of Chromolly. I think it would be safe to figure it a about 90#.

Our radio club here in Tampa is considering using this mast to support a Force 12 C-31XR and a shorty 40, maybe the Cushcraft, on a Rohn 25 tower.

Does anyone see a problem with the weight of the mast material in this application?

The tower is planed for 70' and guyed at 3 points.

Julio, W4HY


See: for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.

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