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@contesting.com> on behalf of Pete Smith N4ZR
<pete.n4zr@gmail.com>
Sent: Wednesday, August 24, 2022 5:27 PM
To: TowerTalk <TowerTalk@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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