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Re: [TowerTalk] Aluminum mast

Subject: Re: [TowerTalk] Aluminum mast
From: "Bruce Ferratt" <>
Date: Wed, 15 Mar 2006 15:49:13 -0500
List-post: <>
My mast is 1 1/4" OD.   It is solid, round.  It states on the side of the 
mast ASTM 6061-T6511.  It is 12ft long and will be mounted 4-5ft inside my 
Rohn 25g tower to the rotor plate with a thrust bearing at the top open 
section (Thrust bearing is the TB3).  I am looking to mount a Mosely TM-33A 
Tribander and stack a Diamond 2m/440 vertical. The aluminum mast weighs less 
than the old 6' steel mast that came with the tower and I paid $66.
I purchased this mast because there is a bushing inside the top of the 25g 
top section that limits me to 1 1/4" OD.  I welded a sleeve on the bottom of 
the mast so that my HD-73 rotor will clamp down on the mast.  Alliance 
HD-73's will tighten only down to 1 3/8" OD so the mast was too small.  I 
like the bushing in the top section to stay there as it will keep everything 
nice and snug but will be free enough to rotate the beam with some grease 
applied to it.  I think the bushing is plastic but there was some rust 
around the old 6 ft steel pipe/mast that I am replacing.  I can't believe 
that Rohn designed this tower to have a rotor mounted just below the top 
section!  It makes multiple accessory shelves worthless unless you don't use 
a thrust bearing!
Thanks for your email.

>From: doc <>
>To: Jim Lux <>
>CC: Bruce Ferratt <>,
>Subject: Re: [TowerTalk] Aluminum mast
>Date: Wed, 15 Mar 2006 11:21:14 -0600
>>So, to answer, for the same weight of tubing (which is how you buy it, by 
>>the pound), the tube is stronger than the rod.
>Unless or until the tube takes a blow which
>compromises its relatively thin (compared to
>the rod) thickness -- it is less likely to
>resist the impact thus denting and becoming
>more prone to collapse (depending on the side
>and depth of the impact area).
>Is that correct?
>Thanks! & 73, doc kd4e
>            |_|___|_|
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>============\ #
>      KD4E     =====================================
>West Central Florida


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