[TowerTalk] Mast Material

[jimlux]

On 3/15/16 3:27 PM, john at kk9a.com wrote:
> Your 10-15' of mast sticking out of the tower plus the rotator being near
> the ground requirement makes all of the inexpensive suggestions unsuitable.
> If you decided to not substitute mast for tower and either add a tower
> section or mount the antenna 31' high with the rotator 5' inside the tower
> you probably could use fence post, water pipe and even aluminum which is
> easy to obtain in most cities. I would rethink your requirements.
>

using cheap pipe/tube as a torque member from ground to mast is probably 
an ok way to go. This assumes you've got two bearings at the top of the 
tower to support the (presumably more rigid and strong) mast.  The 
bending loads on the torque tube are small.

The only dicey part would be the springy-ness, and whether you could get 
into some sort of wind driven oscillation.

I'd just build it and see how it works. If you twist and ruin 30 feet of 
EMT or it works horribly, you're not out a lot of cash, and there's no 
safety aspect to the failure of the EMT.