Hi Scott,
The TH6DXX (plus a 5L 6-meter) is a good amount antenna so I'm not sure
about that, but here's what I did to support some smaller antennas. Perhaps
it will give you an idea.
When I was putting on a new roof (This could be done as a retrofit too...
just a little more work.) about fifteen years ago I got up in the attic and
constructed a saddle over the top of the ceiling joists above a bearing
wall. Then I doubled the rafters above the saddle, added bottom stringers,
extra rafter ties and kickers, and just basically beefed up everything
around and above the saddle. Nothing scientific, I just did what looked
like it would make that part of the roof stronger. I purchased a length of
galvanized steel pipe that when installed in the saddle stuck up about three
feet above the roof. It just sits in the saddle and is U-bolted to the
rafter above it. The guys simply flashed around it when they put on the new
roof. The pipe is offset from the roof ridge by about 2 feet so flashing
was easy. You wouldn't want to come up exactly at the ridge. Most all of
this was done from inside the attic so only the flashing part was made
easier by the fact that a new roof was going on. Flashing a new pipe into
an existing roof can be easy or hard, depending on what kind of roof you
have.
The galvanized pipe is the right diameter (2-1/2" if I remember correctly)
that a 2" mast is a nice slip fit down inside it. What I did was purchase a
50' Rohn pushup mast and discard the two top (smallest) sections so I ended
up with a 30' HD pushup. I installed the antennas (a 7L 2-meter and a
block/pulley to haul up the center point of a 40-meter crossed double
bazooka) onto the top of the pushup mast and dropped it, with antennas
attached, into the pipe. Then I pushed it up and locked the sections in
place, securing the feedlines to the mast as I went. After adjusting the
azimuth I used two HD hose clamps and a flat strap to lock the mast to the
pipe. I subsequently went back and added a small, end mounted 2m/70cm Yagi,
a UHF TV antenna (modified for ATV) and a 4' Andrew solid aluminum dish to
various points on the mast (the dish is near the bottom). I always planned
to go back and add some guy wires (those pushup masts are intended to be
guyed) but I never did. It's been up there for about 15 years and the roof
is still solid. Around eight years ago we had very unusual windstorm. It
blew over the 300 ft. commercial tower our club had its repeaters on, but
all it did to my mast was put a little bend in it about half way up. Didn't
hurt the roof at all.
When I get my new tower up I'm taking down that mast and moving its antennas
to the new tower. When I subsequently take my old MA-550MDP rotating tower
down, I plan to design some sort of tilt mechanism to attach a ten ft.
section of Rohn 25 to that pipe for my AZ/EL rotors and satellite antennas
which are currently on the 550, rotating tower. That hunk of pipe sticking
out of the house has sure been a handy thing to have.
Oh, one more thing, to keep water out of the house be sure you thread at
least the bottom end of the pipe and put a cap on it. I also check the seal
between the pipe and the flashing every fall (before our rainy season
starts). Never had a leak but I did reseal it once.
If you used guy wires at every mast junction as it is intended (they come
with guy rings) as well as at the rotor you just might be able to support a
TH6. It won't tilt over, but it will slide up and down, UNLESS you bend the
mast. Then you'll need a large crew or a small crane to get it down.
You'll also probably need help and a calm day to push it up. I can do mine
by myself but I don't have the weight of a TH6 on top. I've done something
similar to this (the pushup mast routine) with a TH3 and rotor on FD and the
mast strapped to the side of a box van. I can push that up by myself too,
but I usually have help locking the sections as I go.
A few years after I did mine a friend did the same thing for his satellite
antennas only he didn't have a bearing wall anywhere near where he wanted
the pipe to go so he ran it (the pipe) all the way down through (inside) a
wall to the floor.
Just some thoughts.
73 - JC, k0hps@amsat.org
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of D. Scott MacKenzie
Sent: Sunday, July 17, 2005 11:16 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Simple Tower Construction
I live in a residential area, with a limited yard (1/2 acre). Because of
the number of trees and the slope of the yard, the only real location I have
for putting up an antenna is on the top of the second floor. Any
suggestions? I intend on using a TH6DXX, with a 6M5X mounted above it.
Being an old geezer, I would love to have a tilt-over type tower attached to
the second floor so that I could work on the antenna.
Thanks in advance
Scott aka KBØFHP
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
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