[TowerTalk] Need Help For Cable Runs To Tower

[Tod Olson]

Like you I dug the trenches and placed the runs prior to getting the tower.

I have a separate EMC conduit for the 117 VAC/230 VAC

I have one 4 inch Diameter conduit through which I ran 3 CATV 3/4" diameter
hard lines and one CATV 1/2 in diameter hard line
I have 1 3 inch Diameter conduit through which I ran control cables
including the rotor control cable. I also used this conduit for high quality
coax that feeds 80 meter dipoles, etc.

The conduit I used was white PVC with no drain holes. I arranged for the
trench to dip in the middle and then arranged drainage into the ground
there. [in Idaho on the Snake River Plain the water table is 220 feet
down,]. At each end I placed angled PVC with a final 45 degree section which
keeps out rain. Condensate drains to the middle and disappears.

I have access boxes at regular distances so that I can pull additional lines
if needed. I have Dacron covered polyester line that goes from one access
box to the next in  a round-and-round configuration. The polyester line goes
though the 4 inch section in one direction and back the other direction
through the 3 inch section. I use this round-and-round line to pull through
the actual pulling line when I have added a cable.

Take time to think through exactly how you might install the initial cables
‹ best to install them when the trench is open and the PVC sections can be
moved. Think of how you might do maintenance if one of the feed lines needs
to be replaced. Planning for such small disasters will make it a lot less
stressful if one actually takes place.

I have brought all of my control and feed lines up out of the ground and
into a wooden box at the base of the tower I constructed out of plywood. You
do not need to shield these lines. In the box I have installed RF Common
Mode Chokes [I have them at the antenna feed points too]. The coax lines go
through high quality barrel connectors to the actual feed lines going up the
tower. I expect the tower feed lines will need replacing before the
underground ones and having the barrel connectors In a protected environment
will help when that time comes. Others have given pointers for how to handle
the lines when they enter your station/house.

I have a junction connector for the rotator in the box. I have 117 VAC in
the box. If desired I can bring the rotator controller out to the base of
the tower and easily run the rotator from the bottom of the tower.

I have used an AIM 4170 to characterize the several feed lines going to the
10-15-20 and 40 m beams. This allows me to test at the base of the tower and
check to see if something has changed significantly with any antenna.

Again, think about how you will use things, plan that maintenance will be
required and figure out how to organize things so they will be as easy as
possible for you to do.

Good Luck,

It takes a long time to get a good installation, but once it is in place you
will considerably lower stress.

Tod, K0TO 



On 5/25/13 10:36 AM, "Wayne Willenberg" <wewill747 at gmail.com> wrote:

> While I am waiting for my 89¹ crank-up tower to be built and delivered, I
> thought I would get busy running the various control lines for the rotator,
> the AC power for the motor that lifts the tower and, of course, the RF
> cable for my antenna that will be on top of the tower.
> 
> I would like to place these lines underground from the panel entrance to my
> shack to the base of the tower.  (That total distance is about 175 feet)
> My first thought was to run the cables through PVC pipe, and to use Andrew
> LDF5-50A Heliax (7/8²) for the RF cable.  Of course, I will have to use a
> flexible coax from the base of the tower to the top of the tower.
> 
> I would really appreciate some advice before I start trenching.  For
> example,
> 
> 1)  It would seem logical not to put the RF cable in the same PVC pipe as
> the 220 VAC wire for the motor and the power and control lines for the
> rotator.  If it is better to separate the RF cable from the other lines,
> how far apart should the 2 PVC pipes be?
> 
> 2)  Should I drill holes in the bottom of the PVC to allow any water that
> gets into it to drain away?
> 
> Thanks as always for your help with my first tower.
> 
> Wayne, KK6BT
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