[TowerTalk] Putting together a tower package...
viking at world-net.net
Sat Feb 24 22:33:26 EST 2007
My tower is a US Tower HDX772 MDPL custom specification 70sq ft, 700 lbs, at
70mph. Mast is 4130 CM 2 7/8" x 20' with two US Tower TB-3 special 2 15/16"
thrust bearings. I have a SteppIR MonstIR antenna in boxes in my garage
waiting to be assembled. I'm still considering other antennas to be mounted
above: 2nd SteppIR, Sigma-280 (or -180 Ultra), Sigma-160 Ultra, 2-Meter
EF-902, 2-band vertical Ruby-270S. The HDX772 is the HDX5106 minus the top
two sections. I had UST ship 20', 2-7/8" 4130 CM mast with tower. I also had
UST custom build a motorized TRX-1000HD Raising Fixture for me rather than
the standard crank operation. Buying a MRF Mast Raising Fixture is also
For my rotator I bought an incredibly rebuilt "new" small prop pitch rotator
from Kurt Andress, K7NV, http://www.k7nv.com/proppitch/id35.htm and bought
his Green Huron Engineering modified controller
Available from Array Solutions is a new PE Certified Mast coupler that
allows extending Masts up to 42 feet.
http://www.arraysolutions.com/Products/masts.htm Installs a 2" mast inside
the 2-7/8" mast for additional length (e.g., 22' 2" CM inside 20' 2-7/8" CM
providing 40' CM mast).
This info should start to get you excited regarding your expensive options.
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"mast).
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 mast
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)
More information about the TowerTalk