[TowerTalk] Pulling cables through conduit -- results

Dave Sublette k4to.dave at gmail.com
Wed May 2 17:33:09 EDT 2018

Good afternoon,

A few weeks ago I posted a request for advice and information on pulling
cables through underground pipe.  A lively, detailed and educational
discussion ensued.  Yesterday, I put all of that to work and pulled a run
of half inch hardline (not Superflex) and an eight wire rotor control cable
through 200 feet of inch and a half, schedule 40 PVC buried pipe.

The result was 100% successful.  It took less than 30 minutes to do the
pull after I had everything in place. We had two places where the riding
mower was stopped because there was a hangup.  Both times the hangup was
cleared by slacking off and pulling back on the smaller diameter rotor
cable.  The fellow helping me was a retired engineer from the power company
who had pulled miles of cables over the span of his career.  He told me
that when two cables of different diameters are pulled at the same time,
the smaller cable wraps itself around the larger and causes them both to
bind. Pulling backward often clears the problem.  Fortunately it did both
times.  The other thing that helped was the old cables pulled by hand with
about 25 pounds of tension.  By using the riding lawn mower, I avoided
breaking or jamming because that sorry mower can hardly pull itself!  I
figured the wheels would slip before the cable broke.  Sure enough, that's
what happened.

The other item we discussed in detail was what type and how much lubricant
was necessary.  I ended up buying four quarts of clear cable lubricant and
a paint mitt at Lowe's.  That was enough.  In fact we only used half of one
quart and I am taking three quarts back (at $8.50/qt).  I suspect we needed
a smaller quantity that expected because the PVC pipe was already slimy
with water, mud, and who knows what sort of organisms that had collected
during the 28 years since I put the pipe in the ground.

Now the really amazing thing is the coax I used 28 years ago is
International Cable Type 9086.  As I recall, it was cheap.  But I now know
it was a risky and somewhat foolish choice because the construction was of
the type that used a coil of poly whatever for insulation.  We all know
that that type of construction is subject to ingress of water.  I am amazed
that the thing worked as well as it did for 28 years.  The reason was
probably that it was only used at 1.8 and 3.5 MHz. It was showing a loss of
3 dB over the 200 foot run at 1.8 Mhz at the end.  This is the reason I
changed it out.

All things considered, I feel that my situation was about the best case
that could have been.  The run was straight, the pull was low tension and
it all went very quickly and easily.

Part of the reason I had such an easy time was the excellent advice I
received from this group.  I think that's what we are supposed to be
doing!  Thanks.


Dave, K4TO

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