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Re: [TowerTalk] Aluminum mast

To: towertalk@contesting.com, kc8hz@hotmail.com
Subject: Re: [TowerTalk] Aluminum mast
From: K7LXC@aol.com
Date: Sat, 6 Jan 2007 08:00:52 EST
List-post: <mailto:towertalk@contesting.com>
 
In a message dated 1/3/2007 4:20:57 P.M. Pacific Standard Time,  
towertalk-request@contesting.com writes:

>  Back in my early days, we used extruded 6061-T6 in 2 inch  diameter with 
1/4 
inch wall. Many of us sprung for the tubing and put as  much os 20 feet of it 
out the top of the tower. It seemed to hold up and I  don't remember anyone 
having any problem with it.

>  That  being said, I'm planning to put a tower with some HF antennae and I 
found  my old 24 foot 6061 mast in the barn. It's about 30 years old and 
isn't  even corroded.      You know what I'm planning to do, so let me  hear 
why I SHOULDN'T use this.  Especially after all the years of  great track 
record from the locals in southwestern Ohio.
 
    Well, the thing you've got going for you is that  the windspeed ratings 
in Ohio are pretty benign. I think the top windspeed  rating is 75 MPH.
 
    The 6061-T6 has a yield strength of 35,000 psi -  a pretty moderate 
rating. I wouldn't have any problem with VHF/UHF stuff up  there but it 
wouldn't 
handle an HF beam at the top. A typical tribander 10  feet up a mast can exert 
50,000 psi bending moment without too much trouble so  you can see the problem. 
Water pipe is basically the same. 
 
    For more aggressive installations, you'll need  some carbon alloy steel 
tubing - e.g. SAE 1026, A520, etc. Your local  steel supplier can give you the 
specs.
 
Cheers,
Steve      K7LXC 
TOWER TECH 



 
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