Kirk, these towers are now made by Thomas Shelby Co. You can find them
with a Google search.
When you delete the two top sections the tower becomes a model HDBX48 and
the wind loading is 18 sq ft. They always said the maximum boom length
should be limited to 10 ft but most users ignored that directive.
The section #3 top plate is called a BXT3, rotor plate BXR3. The stock top
plate is drilled for a plumbing floor flange. Many users simply screwed a
short water pipe nipple into the flange and used it as a top sleeve for the
mast. If you want an inexpensive bearing, a Yaesu GS065 is only $65 and can
be mounted on the BXT3 plate.
Bolts, most likely the existing bolts are fine but that is your call.
Foundation hole size for an HDBX48 is specified at 5' 9" square, 4ft deep.
It takes 4.9 cu yds. There is a hinged base, BXHC78, with 3/4" anchor rods
and a fixed base, BXB8 made with 4ft stubs available. Some users have made
their own base stubs from galvanized plumbing pipe. A 10ft length of the
1.9" OD size cut into three pieces and drilled for the legs bolts would be a
good choice.
These were great towers for the money back when Rohn was making them. I
have not seen one of the Shelby models and I see the pricing is much higher
now, naturally.
Whatever you do, don't plan on re-galvanizing the sections as the rivets
will melt and you will have a giant erector set on your hands.
Hope you find some use for this info.
73,
Gerald Williamson K5GW
GM Texas Towers
In a message dated 6/14/2016 4:22:27 A.M. Central Daylight Time,
towertalk@contesting.com writes:
Hi, gang,
I will soon be installing a Rohn BX64 in my back yard. To beef up the end
result, I plan to install only 6 of the 8 sections, leaving me with what is
hopefully a much beefier 48-foot tower. According to what I've read, the
full 64-footer is only rated for 6 sq feet of antenna at 70 MPH (with a
10-foot boom). I live in an 80-MPH max zone, and although I've never seen a
Rohn lattice tower fail with only a TV antenna on it in these parts, I'd like
a little more margin and a little more antenna. Minus the two top sections,
the wind load seems to be upwards of 20 square feet (way more than the 8-12
I need), and I'm guessing that a 12-foot boom would also work. The tower
will hold up one leg of a wire horizontal loop and will host a rotator and a
smaller beam (a Tennadyne T-6, a Spiderbeam, a 2-el quad, a hexbeam, a
friend's mothballed Mosley Classic 33, or a multiband rotatable dipole -- only
one at a time!) VHF antennas will be on a different tower.
I have a few questions (naturally :)
1. I will need to purchase or fabricate a top plate and a rotator shelf
for what I think is "section 3" (top two sections of the BX64 are not
installed). I was planning to fabricate a triangular plate with three bent
"mounting tabs" that I can bolt to the three corrugated legs of the now-top
section (two bolt holes exist at the top of each leg). I was planning to use
3/16
steel plate (or something similar), but I'm open to suggestion. I think
Rohn makes such a plate, but I'm not sure what it's called or what it costs
(budget isn't extreme). Suggestions?
2. I'm looking to add some kind of a thrust bearing to this top plate to
save wear and tear on my rotator (a rebuilt Ham xxx, Yaesu 450 / 800, etc).
I'm hoping to use "farm store / farm equipment parts," and don't want to
spend a billion dollars on Rohn's bearing. (Not looking to install massive
antennas...just want a solid, trouble-free installation cuz it's cold in MN
and tower climbing is sometimes impossible.)
3. I'm considering buying new bolts for the tower, and I've read up on the
dangers of using SS hardware, hardware of unknown parentage, etc. I'm okay
using Rohn "shouldered" bolts, but so far the least expensive package I've
found is about $150. It sucks when the bolt kit costs as much as the
entire tower...! Most of the existing bolts are in good shape, but some were
horrendously tight, and when we took the tower down we had to use a huge
breaker bar to remove some of the large-size bolts. I'm not especially keen on
reusing those... Any secret sources for reasonably priced BX bolt kits?
4. I haven't looked at the catalog specs in a long while, but I installed
many BX48s back in the late '70s. I think a lot of installers back then
(perhaps today, too) dug holes that were too small. Still, none I've ever seen
fell over, except when matched against a tornado. I was planning to dig a
4 x 4 hole 5 feet deep, lined with golf-ball size rock for drainage and
probably with a minimal rebar cage and Rohn stubs. My soil type is very sandy,
but well-packed (new to me). I haven't checked with the utility company
yet to see if they have a psi rating for the soil in my part of town. The two
companies that install TV towers in this area don't do anything
differently regardless of soil types (naturally!). And I think their holes are
too
small, anyway... Thoughts?
Thanks, gang, I appreciate your input,
--Kirk, NT0Z My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
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