I remember looking into this at one time. I don't recall the source of my
information, but I think my MA-770MDP derates to something like 2 sq ft of
windload at 90 MPH. Again, that 15-20 foot mast changes things dramatically.
> -----Original Message-----
> From: Jon M. Knodel [mailto:jknodel@msn.com]
> Sent: Monday, October 16, 2006 12:59 AM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] Am I asking for trouble? - tower loading
>
> Thank you everyone for the replies. They have been very
> insightful. I was not planning on installing the motor with
> the tower - just the hand crank winch. My original idea was
> to install my 3 element SteppIR along with a 2 element 40m
> beam below it on a tall mast (15 or 20 feet). The tower I
> was thinking about is the UST TX472 which has a wind rating
> of 10.3 at 70 mph. These were my thoughts and the reason I
> raised the question.
>
> I am now thinking, because of everyone's good responses (and
> I really do appreciate the help), that I should not overload
> the tower at the 70 mph as I originally planned. I will
> probably step up to the stronger (and more expensive) HDX
> series and keep my antenna load within the 70 mph rating.
>
> But this raises another question. The city here has adopted
> a sustained wind speed rating of 90 mph and a gust rating of
> 105 mph. I have never seen winds of these speeds and the
> civil PE that I work with thinks that they are definitely
> overly conservative. But we do get some good winds in the
> winter here, being right on the coast - probably around 70
> mph at times. So my question now is this: Since US Towers
> only specs their towers for 70 mph max, is there a way that I
> can calculate a rating at 90 mph, using the same method that
> they used for getting the 70 mph rating? Does anyone know
> the UBC calculations used to achieve the EIA ratings? Do you
> think that US Towers would provide this information if asked for it?
>
> Thanks for all the help.
>
> ...Always wanting to learn more about antennas and towers... Jon, N7XW
>
>
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