[TowerTalk] Tower specs, putting a package together
kinzli at kinzlicoils.com
Wed Feb 21 15:20:09 EST 2007
I'm working on getting some aluminum up here. The antennas I plan to
use are a 4L Steppir and a 3L M2 40 (40M3L). One requirement is that
this stack goes on a crank up, as I'd like it cranked down most of the
time (weather, neighbors, etc.). I'm also not one for climbing, so I'd
like to do any maintenance at the cranked-down level (or tilted).
70-75 or so feet is really my goal tower height, and I'm in a 70MPH
wind rated area. I'd plan to have the tower nested or at 50' or so
unless the winds are calm or 0mph.
So, from what I can tell, there's really only two choices - US Tower
HDX-472, and Tashjian LM470 or DX70. There doesn't seem to be any
beefier crank ups on the market that I can see.
I want positive pulldown, and I like the fact that US Tower has a
levelable base, it doesn't appear that Tash has that. There also seems
to be a lot more HDX's in the field. So I'm leaning towards the HDX.
I'd like to do a 3" OD mast (stacking the 40 around 10 or so feet
above the Steppir), but this represents a concern about rotational
torques on both the tower and mast. Then again, the Steppir and 40 are
pretty close to each other in weight and wind load, but the 40
obviously has longer elements, which I would think would contribute to
those rotational torques. I'd like to get the 40 as high as possible,
hence I'd like it at the top of the mast (and why I'd like to use a 3"
I also noticed that it seems that Tash has a 2" max mast size. I'm not
sure if the top mast hole is "borable", to make it 3" and fit a 3"
thrust bearing there. I don't see any specs on the HDX for maximum
I'm wondering if anyone has a similar set up, and/or has
recommendations. This would be my 3rd tower but the first crank up so
I'm a little green there. I'm also thinking I could use a suggestion
on a rotor, the M2 rotor seems like the one.
For the final work, I have an architect and engineer involved to do
the final calculations, get the permit, etc. but I'd like to at least
have a place for them to start with reasonable guesses about what will
work, what won't, etc. and what I want to achieve with their help.
Thanks for any ideas,
Jeff N6GQ (ex KA6LAF)
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