Towertalk
[Top] [All Lists]

[TowerTalk] Lower Mast Question Again

To: <towertalk@contesting.com>
Subject: [TowerTalk] Lower Mast Question Again
From: w9re@worldnet.att.net (Mike Wetzel)
Date: Sat, 21 Apr 2001 13:17:16 -0500
Steve,

You are correct about the elongation of holes in aluminum.  It will take
less time in aluminum than steel but it will still happen in steel with a
large load.  Now if aluminum to aluminum is properly clamped together under
compression, rather than pinning then you generally have no problems.  As
evidence, I have had a 6 element 20  and a 3 element full size 40 on a
2-1/2" aluminum mast for approximately 20 years!

Pinning is not the preferred way to couple joints, (sometimes it is the
easiest and quickest way) but using a machined coupler is one of the best
ways to go.  As evidence in above 20/40 antenna situation, neither antenna
nor mast to rotator is pinned and they have never slipped!

Personally I don't like steel.  I always use aluminum if possible, it's
lighter and doesn't rust albeit it isn't as strong size to size.

I think we've had this discussion before and I still think you are short
changing aluminum masts.

Mike W9RE

> -----Original Message-----
> From: owner-towertalk@contesting.com
> [mailto:owner-towertalk@contesting.com]On Behalf Of K7LXC@aol.com
> Sent: Saturday, April 21, 2001 10:11 AM
> To: steve@oakcom.com; towertalk@contesting.com
> Subject: Re: [TowerTalk] Lower Mast Question Again
>
>
> In a message dated 4/20/01 1:19:24 PM Pacific Daylight Time,
> steve@oakcom.com
> writes:
>
> > Rotational stress will work harden aluminum more than you might
> >  guess.
>
>     You better believe it. Rotational torque will elongate any
> hole with a
> bolt thru it. With an array your size, the aluminum mast will
> have a short
> service life.
>
>     For anyone putting more than one antenna on a mast, one way
> to somewhat
> minimize the total rotation torque is to stagger antennas on both
> sides of
> the mast - i.e.. first antenna boom on the right, second antenna
> boom on the
> left, etc. This will lower the total mast torque and stresses
> everywhere -
> rotator, rotator plate, tower, guys, etc.
>
>     Anyone who doesn't believe this will work hasn't read the articles by
> Dick Weber, K5IU, PE.
>
> Cheers,    Steve    K7LXC
>
> List Sponsor:  ChampionRadio.com - Trylon self-supporting towers,
> safety equipment, rigging gear, LOOS tension guages & more!
> http://www.championradio.com
>
> -----
> FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
> Submissions:              towertalk@contesting.com
> Administrative requests:  towertalk-REQUEST@contesting.com
> Problems:                 owner-towertalk@contesting.com
>


List Sponsor:  ChampionRadio.com - Trylon self-supporting towers,
safety equipment, rigging gear, LOOS tension guages & more!
http://www.championradio.com

-----
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com


<Prev in Thread] Current Thread [Next in Thread>