Marlon K. Schafer wrote:
> Most pipe is quite strong. I've used quite a few things over the years.
>
> The worst I've seen are the masts that you get at Radio Shack or similar
> products. The Tubing is far too small, thin and light weight to be useful
> for anything more than a UHF TV antenna.
>
> Muffler pipe works well and is cheap. But it does rust quickly and will
> leave stains on a building. But if you're in the middle of no where it's
> quick and easy and effective.
>
> Water pipe is heavy but comes in 21' sticks. And it can be screwed together
> if need be.
When using water pipe, I make a collar out of the next size larger and
pin it. It has a habit of coming unscrewed if you have much wind area
up there. It's also too soft for much of a reach
However my choice is either schedule 40 structural steel tubing, or
Drawn over Mandrel (DOM) which is seamless and very strong. Yes, either
is heavy and the DOM is about 3 X the price of the structural steel tube
but worth it. I'd think most towns of 75,000 or more would have a steel
supplier. They can get either and most likely have 1.5 and 2" in stock.
http://www.rogerhalstead.com/ham_files/Tower29.htm shows 40' of tubing
from the rotator (PST-61) about 20' down in the tower (don't remember
the exact distance) with thrust bearings at the top and half way
between. I would not suggest putting this much *stuff* above the top of
the tower. Those 2 11L yagis on 440 and 2 12 L on 144 look like they
are on a Bluegill fly rod that just tied into a Bass when the winds get
really strong. I'm amazed they haven't been shedding parts. The 144
and 440 stacked pairs on a cross boom at the top are coming down so
there will just be the HF antenna at the top of the tower and the
6-meter 7 C3i about 12 to 15 feet above that. OTOH the tribander is
likely to come down and end up on top of 50 or 60' of 25G. leaving only
the VHF/UHF antennas on top of the 45G. I'll know for sure when I
actually make the change.
I need to update the tower project page as a lot of it has been changed.
73
Roger (K8RI)
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