Bob-
Hello.
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.
73
Bruce
>From: "Bob Good" <k4bg@planters.net>
>To: "Bruce Ferratt" <uglyatc@msn.com>
>Subject: Re: [TowerTalk] Aluminum mast
>Date: Wed, 15 Mar 2006 14:35:48 -0500
>
>Bruce, I have used 2" and 2 1/4" rigid thick wall aluminum conduit for
>probably 15 or so years. I have had my Mosley PRO-57A on it with about 3
>ft
>above the top of 25g tower for about 8 years. I have encountered wind
>gusts, probably 50 mph and never a problem. It is much easier to work with
>than the heavy steel masts. I would not use anything else. (((73))) Bob
>K4BG
>----- Original Message -----
>From: "Bruce Ferratt" <uglyatc@msn.com>
>To: <towertalk@contesting.com>
>Sent: Tuesday, March 14, 2006 10:56 PM
>Subject: [TowerTalk] Aluminum mast
>
>
> > Hello and thanks for letting me post a question.
> > How strong is a solid aluminum mast compared with a walled/hollow mast?
> > I secured a solid, round 12' aluminum mast 6061-T6511 grade. What is
>the
>likelihood of bending when loaded with a TM-33A and VHF 2m/440 vertical at
>a
>rated 70mph wind load in Northern Virginia? 8ft of mast will be exposed
>above the point of the tower peak (Rohn 25G), with about 4 ft inside the
>tower to rotor plate.
> > Thanks
> > Bruce
> > K4BOF
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
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