Larry,
I used to have a Hy-Gain HG-70HD, which had a manual winch. I don't have
the specs, but I don't think that's what you have. That tower does not have
positive pull-down, so the winch and cable just hold the sections up, and
gravity brings it down.
The older style US Towers, including mine, had Z bracing; the current style
uses W bracing. I don't know which is stronger. The motorized US Towers
have positive pull-down, and the cabling is different than a "gravity
pull-down" tower.
It sounds like it might be a US Tower TX-472MDP. The TX series are lighter
duty than the HDX series. They were advertised at the time to be rated at
18 square feet in a 50 mph winds; the HDX series was rated at 30 square
feet. The TX-472MDP has a weight of 1210#, and the HDX-572MDPL (five
sections) weighs 1600#. I'm looking at a US Tower catalog from 1986.
There's no HDX-472 in the catalog, as the 72' HDX towers have five sections,
based on the catalog I have.
US Tower should be able to supply the information on the base requirements,
which have changed, at least since I bought mine in 1994. In each of the
three times I've installed my tower, I've had to get a structural PE's
review/calcs/stamp in order to get a building permit. Each of the PEs used
the factory info as well as the previous PE's/PEs' work to review and
incorporate.
The rotor should be able to be unbolted and lifted out through the side of
the top section when the tower is extended. I've never had mine extended
when the tower is horizontal.
US Tower will probably tell you it needs new cables and pulleys. Most
comments on the reflectors say to replace them only if the cables appear
frayed, worn, or rusty. I wouldn't do that work myself, though some owners
have. Some commercial riggers do it, and US Tower can quote you a price to
travel to your QTH and do the work, but the cost is very high, in my
opinion. Mine still has the original cables and pulleys, though most of its
life was in AZ or NM (I'm in IL now).
Jim N7US
-----Original Message-----
I picked up a used crankup tower several years ago and had it hauled to my
home. The non-ham seller had promoted it as a US Towers HDX-472, but after
getting it home, I found out it wasn't that tower at all.
This is a 4-section telescoping tower, with a motorized raising system (no
hand winch), and looks like it would be around 70 feet when fully extended.
I think it's a lighter-duty tower than a HDX-472 since this one has a
distance of just 20" between the bottom legs.
The construction of the tower is each section having three legs with solid
rod bracing in an "N" pattern (when the tower is horizontal) or a "Z"
pattern if the tower was standing up vertical. It came with a "T" shaped
steel base, but no "Raising fixture" that would allow it to tilt over for
service and raising/lowering.
I've done a lot of searching on the internet and looked at lots of pictures
of ham towers. It doesn't appear to be like any of the Tri-Ex, Tristao,
Hy-Gain or US Towers that I've found so far. I did find one picture of a
Tristao tower that was somewhat similar, but the Tristao appeared to use
some much heftier metal bar material instead of rod material for the
horizontal bracing in each section.
If anyone has an idea of what I have, I'd sure appreciate an email. I'd like
to find the info for getting the necessary specs and paperwork for getting a
building permit, digging the hole for the base and rebar cage construction,
ordering some appropriate J bolts, etc. I don't have a web site, and the
list doesn't accept attachments, but I can send anyone who'd like to see
them a few .jpg pictures of the tower and the motor drive assembly.
The tower came with a HAM-M or similar sized rotor mounted in the top
section, I don't see how it gets removed, which I will need to do since I do
have some brand-new HAM-IV and T2X rotors that could take the place of the
one in the tower that's been out in the weather for some years and probably
needs some major service.
Thanks in advance for any suggestions. Hopefully, this year will see a tower
planted in the yard, and I won't have to keep complaining about having just
a little roof-mounted multiband vertical as my main HF/6M antenna. I'd like
to use this tower to support a 3 or 5-band quad.
Larry
direct email: larryj@teleport.com
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