[TowerTalk] Underground conduit question

[Peter Dougherty]

On 2/7/2011 1:55 PM, Peter Dougherty wrote:
> Hi all,
> Several years ago I had a run of 4" solid white PVC tubing run on a
downward

Very important...How long is this run and how deep.
It's roughly 41 or 42' long, buried about 18" down at the deep end and 12"
on the shallow end. It was installed when an electrician put in a 120 VAC
outlet for our nearby pond. These three pictures can describe it better than
my words can:
http://s291.photobucket.com/albums/ll290/W2IRT/Towers%20and%20Antennas/

Snow won't hurt, it's just a nuisance.

>>IF the conduit maintains a grade all the way it won't fill up with water
>>and freeze. This part I'm afraid to ask. What did you use to block the end
in the
>>yard to prevent "critters" from turning it into a ready made home?

I used 1/2" wire-mesh (hardware cloth) fastened by a hose clamp. The cables
run through the squares.

> After the lines emerge from the conduit they just run over top of the
ground
> to their respective antennae. After a coax failure to my loop, I tried
> pushing a fish-tape through the conduit in hopes of running a new length
of
> cable but it became obvious that the inside of this conduit had gotten ice
> or muck inside, so I need to wait until spring to try and remedy things.

>> If there are more than a few cables in the conduit and/or it's a long
>> run it'll be very difficult to push a fish tape through it once it has
>> cables in place.

If you look at the pictures referenced above, I have a number of cables that
exit the house and then go up to the vertical section just a few feet away
(which now has a 180-degree cap on it) and to an antenna switch box mounted
on the side of the tower. One line (the 160 antenna) comes back down that
riser and along the full length of the conduit. I have 3 or 4 other cables
that run the full length of that conduit (the failed K9AY coax, the control
line and a run of RG-6 for a noise sense antenna, which has just now been
repurposed as the K9AY coax).


> This now leads to a few much broader questions.
> 1) Can I do anything to improve the drainage of the existing 4" conduit
> (remember, it's already on a downward angle)? Digging up the back yard is
> NOT an option.
How deep is it. With cables in the answer is probably not. If the
conduit is "always" on a grade with no low spots it should not need any
more drainage.

I'm *pretty sure* it's on a constant albeit shallow angle down away from the
house.

>> You could build a box for the cables to exit into at the end of the
>> conduit.  Put some plastic mesh in it along with a few mothballs to
>> discourage critters.

I think this is the way I'll go, similar to what our sprinkler-system
installers did for their junction boxes and valves, etc.

> 2) The coax/control-cables lying on the ground will need to be buried.
Do you mean the ones coming out of the current conduit?

Yes, the lines to the K9AY loop specifically, although I'd like to bury the
160 TX antenna feedline as well. It, however, traverses a lot of very
inaccessible terrain (behind rocks, beside an embankment, through a narrow
gap between the garage and a concrete fixture, etc, making that job far more
difficult. That ground rises and falls considerably, too.

>> Have you considered "direct bury" cables?  Or something rugged like
>> Davis BuryFlex(TM) and just leave it on the surface or buried shallow?

I guess this is the way to go for the 160 TX, and maybe for the K9AY. I'm
using direct-bury sprinkler control cable for the K9AY directionality
control and remote power so no worries there. I'm not really a fan of
direct-bury, though, since if there is a failure I'd rather just pull a new
run in minutes rather than either a) dig out the old one or b) dig a new
trench for the new one. I'm definitely interested in a conduit solution.

[pjd] -pjd