Dave Kaiser said,
"....First, and most important, the 2-inch pvc is NOT
large enough in diameter to accomodate my coax,
rotor cables, etc. If I had it to do over, I
would go with at least 4-inch and perhaps two
4-inch to/from EACH tower."
and
"...Another thing to make sure of is that you have
A/C outlets at the base of the tower, they come
in very handy for soldering or using a drill."
**************
Let me second his statements and add some personal notes. I installed two 4"
diameter runs of PVC drainage pipe and a separate 1 " pvc conduit for 117
vac and have found that to be barely enough to comfortably pull two 3/4"
hardlines, three 1/2" hardlines, one RG-213 coax line, two 8-wire rotator
control cables and two 12-conductor lines for relay control and position
sensing. The AC line is #12 three wire and goes to the base of each tower
ending in an above ground, weatherproofed box with Ground Fault protection
outlets. At approximately every 50-75 feet or so I placed a 'junction box'
made of a Rubbermaid 5 gallon or 10 gallon snap top lid box. (About $5 at
Albertson's grocery). holes were cut in the sides of the box to allow the
three conduits to enter and exit. The entry and exit points were sealed with
bathtub caulk to minimize the entry of ground water and a couple of hole
punched in the bottom of each box to allow water that does enter to drain
out. (In locations with a really high water table I would expect this might
not work). The junctions are located at points where one or more of the
hardlines exit or where the run is over 75 feet or where the run needs to
turn slightly in direction.
Inside the tubes I have run a black covered Dacron rope available via ham
ads. Each section has one loop; that is a single rope goes through one
section and then threads back via the second tube to the starting point. The
ends of the rope are tied together so that an endless loop goes through the
section. This rope is used to pull another rope through the conduit when I
want to pull a feedline or control cable. I do NOT use the loop for pulling
anything except the special line that will be used to pull the feedline. I
found that when pulling 3/4" hardline and similar feedlines it was much
easier to pull a single feedline through a 50-75 foot run than to try and
pull 100-300 feet of feedline through a single conduit run. My boxes are
located so the tops are below the surface of the ground by an amount
sufficient to allow each of them to be covered by a sizeable flagstone which
is buried in the grass at ground level. This allows me to easily locate a
junction box when necessary and does not cause me to dig up substantial
parts of the yard to find the box or to work with the lines moving through
it. The flagstone is XYL acceptable. At each junction point I built a 2" x
4" frame that is larger than the Rubbermaid box. The frame is covered by
several 1x4 boards and the flagstone goes on top of the boards. (Use redwood
or cedar or treated wood). By taking the time to built the frame this way I
found that when I wanted to open the box and pull a new feedline or control
line I was able to easily remove and replace the flagstone in its original
location. The frame also kept dirt away from the top of the box which was
located inside the frame about 2 inches below the cover boards.
The extra diameter for the PVC runs for coax and control made it
dramatically easier to install lines than when I did a more modest
installation in Minnesota using two 2" PVC conduits. The 117 VAC at the base
of the tower eliminates the long extension cord assemblies previously used.
I believe that one should view this as 'underground infrastructure' that is
worth investing in with an eye to the future. The fact is, that most of us
are never satisfied with whatever antennas we have --- we always want to try
something a little different to see if it will work better for us. Having
flexibility makes such changes much less challenging. Having all of the
feedlines and control cable underground and out of sight seems to make my
XYL less concerned about the fact that I have an elaborate antenna
installation that works fine, but that I seem to want to change all the
time.
Tod, KOTO
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 100 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|