[TowerTalk] [Bulk] Re: 2" OD Long Masts

[Grant Saviers]

Much cheaper than 4130 is the "1026" alloy A513  72,000psi yield.  I see 
onlinemetals.com has some 0.120" wall x 2.25" od which would make a 
great sleeve for 2" masts.  They will get full lengths if you ask as 
they are owned by Thyssen-Krupp or go direct to a service center.

Grant KZ1W


On 8/26/2014 7:48 AM, john at kk9a.com wrote:
> I would run the mast calculator first. Not every mast needs to be 4130 and
> most likely 1026 DOM is more than adequate for VHF/UHF yagis.
>
> John KK9A
>
>
> To:	"'Byron Tatum'" <bjtatum1 at att.net>,	<towertalk at contesting.com>
> Subject:	Re: [TowerTalk] 2" OD Long Masts
> From:	"Marsh Stewart" <marsh at ka5m.net>
> Date:	Tue, 26 Aug 2014 08:41:55 -0500
>
> I'd recommend considering chrome molly steel, 1/4" wall, galvanized and
> rated at least 100,000 psi mast yield strength. A 22-foot mast like that
> weighs about 125 pounds. Then run the calculations for the antennas you want
> to stack using their wind load areas, heights above the top of the tower,
> and your wind speed.
>
> AntennaMast.xls available on the web for download is easy to use.
>
> Marsh, KA5M
>
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Byron
> Tatum
> Sent: Tuesday, August 26, 2014 8:23 AM
> To: TowerTalk at contesting.com
> Subject: [TowerTalk] 2" OD Long Masts
>
> Hello-
>    For years I have used the 2" OD, 6061-T6, 1/4" wall x 24' long aluminum
> masts to stack VHF and UHF antennas. I have seen these take a bend a time or
> two over the decades.
>    I wanted to ask:
>      1. If I was to switch to 2" OD steel, as a mast to extend about 15'-18'
> out the tower top for stacking VHF/UHF long boom yagis, what would be a
> suitable grade of steel, the finish and wall thickness?
>      2. I have heard of inserting a smaller aluminum tube inside the 2"
> aluminum mast, in the area where the mast exits the tower top and on above a
> bit. I wanted to ask if someone here has experience with inserting an
> aluminum tube inside the 2" OD mast? I would assume it would be 1-1/2" OD,
> of similar material and length and what wall thickness?
>    I guess reasons I have stayed with the aluminum masts is that they are
> lightweight and easy to handle, plus no rusting down in this Gulf Coast
> area.
>       Thanks, Byron WA5THJ
>
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