[TowerTalk] Am I asking for trouble? - tower loading

[Richard M. Gillingham]

I gotta tell you, I really regret not getting the MDP 750 with my MA-550 
tower from UST.  It's a significant bit of work to crank the thing up and 
down on a daily basis.  I'm seriously considering taking it down and 
trailering it to Lincoln KS and having the motor drive retrofitted.

Something to ponder.
Betst luck,
Gil, W1RG
----- Original Message ----- 
From: "Jon M. Knodel" <jknodel at msn.com>
To: <towertalk at contesting.com>
Sent: Monday, October 16, 2006 12:59 AM
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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