[TowerTalk] Joining sections of aluminum mast

[Dave KØEKL]

Thanks for your replies. 

To answer some of your questions, the tower is 56 feet of Rohn BX. The rotator is a Ham-4, but there would be room for a larger rotator at the tower base. The antenna is a 3 element SteppIR 6 thru 20m.

I live on the top of a hill which slopes away in all directions. To the northwest 1/4 mile away is a 300 acre lake, the water level is about 200 feet below the level of the SteppIR. The prevailing winds, especially in the winter, are from the NW and with nothing to act as a wind block up here on the hill it's not unusual to experience gusts to 40+ MPH for hours or days at a time. This tends to chew up the brake slots in a Ham-X rotator pretty easily. 

Another option would be to install a beefier rotator but I am getting older every day and having one less reason to climb the tower is appealing. BX-style towers are no fun to climb or stand on.
There is a Rohn thrust bearing at the top of the tower,  a rotor shelf 3' below the top of the tower which holds a sheet of Delrin through which the 2" mast passes, and a the Ham-4 is on a rotor plate 8 feet below in the second section from the top. 

As intermediate mast supports I'm thinking of triangle-shaped sheets of Delrin with a slightly larger than 2" hole to check any horizontal movement of the mast. 

-----Original Message-----
From: TowerTalk <towertalk-bounces at contesting.com> On Behalf Of Dave KØEKL
Sent: Saturday, August 20, 2022 6:09 PM
To: TowerTalk at contesting.com
Subject: [TowerTalk] Joining sections of aluminum mast

To ease maintenance I want to relocate my rotator to the bottom of my tower.

The existing mast is 2" diameter ¼" wall 6061-T6 aluminum tubing. The rotor is 8 feet below the top of the tower / thrust bearing.

What is the best way to join additional lengths of tubing together to reach the bottom? I'm thing about buying tubing that is 2" ID, cutting it into 18" or 24" sections, slitting it and slipping it over the 2" OD sections to be joined and clamping with SS U-bolt clamps like those sold by DX engineering. Will this provide enough coupling friction between sections to prevent slippage?

Also, can I get away with using 1/8" in wall 2" OD tubing from the existing mast to the base of the tower or should I use ¼" wall all the way to the bottom.

Thanks.

-Dave K0EKL
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