[TowerTalk] Mast for a short little stack

[Joe Subich, W4TV]

Given that the A50-3S is spec'd at 1.8 ft^2, the bending force on
a 2" mast is rather small.  Assuming a 6' section of 6061/T6, even
standard 0.058" wall should be more than enough with 0.120" wall
providing plenty of reserve.

I don't know that I would trust 1.5" (1.9" OD x 0.133" wall) aluminum
conduit since it is designed to be bent easily ....

73,

    ... Joe, W4TV


On 2022-08-24 5:42 PM, AB2E Darrell wrote:
> Hi Pete,
> Putting up a 99% identical setup here!
> AB-577
> F12 C3SS
> M2 6M5X (5el 6m yagi).
> 
> An aluminum mast should be fine rather than steel.
> We have a 6ft mast from FD, I thought I would try that, it should probably work fine.
> 6M yagi at the top, C3SS just above the G800DX rotor being added at the top piece
> of the AB-577.
> Do you have a local industrial supply place nearby>?
> I'm fortunate to have one, and they already sold me 12ft double wall T6061 aluminum mast,
> although I bought this to use as a gin pole for a future project.
> 
> As an aside, I plan on replacing the metal cable of the guys with Phillystran of equal size.
> Initially, it looks like 1200lb Phillystran will be a close match to the cable diameter on the AB-577.
> Some have reported interaction with the original guys, and I believe we may have experienced this
> issue as well at FD.
> 
> 73 and best of luck with the project!
> Darrell AB2E
> 
> ________________________________
> From: TowerTalk <towertalk-bounces at contesting.com> on behalf of Pete Smith N4ZR <pete.n4zr at gmail.com>
> Sent: Wednesday, August 24, 2022 5:27 PM
> To: TowerTalk <TowerTalk at contesting.com>
> Subject: [TowerTalk] Mast for a short little stack
> 
> I have a F12 C-3E on an AB-577.  The tribander mounts on a very short
> stub mast out the top of the Yaesu rotator.  There is no thrust bearing
> or other support for the mast.
> 
> I recently bought a Cushcraft 3-element 6-meter beam and want to stack
> it about 5 feet above the tribander.  The antenna weighs about 7 pounds
> and has very low wind loading.  A friend gave me a very heavy 8-foot
> steel mast, which I thought would work, but after handling it for a
> while (it's really heavy), I think it would be overkill, and very
> awkward to install, even with two or three guys on ladders.  Cutting it
> down would help marginally.
> 
> So I'm debating a lighter, thinner-walled steel or high-strength
> aluminum mast instead.  Sitting just above the rotator's top clamp, the
> tribander would impose very little bending load on the mast in the wind,
> and the 6-meter yagi ought to be trivial in that regard too, at only 5-5
> 1/2 feet above the rotator.  I'd appreciate advice - am I better off
> just suffering through the installation of the heavier mast, or if what
> I'm proposing would work, what material do you suggest?
> 
> --
> 73, Pete N4ZR
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