[TowerTalk] Rohn 25G Wind Load Capability

[K7LXC@aol.com]

In a message dated 97-08-30 17:13:06 EDT, jmohler@bga.com writes:

> I have 50 feet of un-guyed Rohn 25G with a house bracket at 20 feet from
>  ground. Can anyone please tell me what the Rohn specificatons call out for
>  maximum wind loading under those conditions. Thanks.

       Rohn bracketed specs call for a typical distance of 14 feet from the
upper bracket (they specify two housebrackets) to the top of the tower; you
have 30 feet of distance which is out of their spec which means you probably
only have a couple of sq.ft. wind load capacity. We're talking a VHF vertical
or so.

      I've installed your configuration myself and have not been happy with
the results. My solution was to take the top 10 feet of and have a 40 foot
tower. A 40 foot housebracketed tower @ 70 MPH has 15.3 sq.ft of antenna
capacity; @ 80 MPH it's 11.3 sq.ft. and @ 90 MPH is 7.7 sq.ft.

    BTW, Travis County is a 70 MPH wind speed zone.

73,  Steve  K7LXC

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