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Re: [TowerTalk] TowerTalk Digest, Vol 39, Issue 40

To: "Bruce Ferratt" <>
Subject: Re: [TowerTalk] TowerTalk Digest, Vol 39, Issue 40
From: Robin Midgett <>
Date: Mon, 20 Mar 2006 17:29:49 -0600
List-post: <>
Hi Bruce, et al,
I suggest a two piece shaft collar be placed on the mast so as to 
transfer the weight of the mast and antennas to the TB-3. The shaft 
collar is designed for such, it will not mar the mast, and is 
available in stainless steel from industrial supply and/or bearing 
houses. This is the method I use and it has worked very well for several years.
Look up or and search for "shaft 
collar", then narrow the search by inside diameter and desired material.

At 03:01 PM 3/15/2006, you wrote:
>Message: 7
>Date: Wed, 15 Mar 2006 15:47:09 -0500
>From: "Bruce Ferratt" <>
>Subject: Re: [TowerTalk] Aluminum mast
>Message-ID: <BAY101-F105BD7A97332E512A33A09B4E60@phx.gbl>
>Content-Type: text/plain; format=flowed
>My mast is 1 1/4" OD.   It is solid, round.  It states on the side 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!
>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.

Robin Midgett K4IDC
615-322-5836 office - rolls to pager
615-835-7699 pager
615-301-1642 home 


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