I removed 3 LDF5's from 3" conduit that was still well lubricated but
with a capstan winch. We would pull 3', reset the sling noose and
repeat to remove 110' of cable. You don't need steel wire rope and 210'
is more than most winches will hold. Use a low stretch dacron,
dacron/polyester double braid or 8 plait, not a 3 strand line. A 1/2"
diameter is strong enough and much easier on the hands. Use plenty of
cable pulling lube. Plan on at least 4 persons, two managing the pull
side, one feeder + lubricator and at least one unspooling. Pull all at
once, and pull extra coax, control lines, CAT5, RG6, etc.
You have a significant challenge re the bend radius at both ends being
tighter than the larger hardline should endure under a pulling load.
Adding large radius (> 36") 90 degree sweeps to your cable duct at both
ends may be a solution, or extending the access pit so a pull will be
more horizontal. The PVC duct edge can be very abrasive so care is
needed to not damage the coax.
A rentable tripod used as a hoist point over a manhole, sometimes used
as a man-safety recovery device, plus a small chain hoist would work
instead of a capstan winch for a vertical pull. Check out the knot
books for how to tie a resettable grab knot on the pull line or use a
technical climbing ascender.
http://www.rei.com/search.html?ir=q%3Aascenders&pagesize=90&page=1&q=ascenders
Grant KZ1W
On 4/15/2015 6:50 AM, Alan Ibbetson wrote:
I have a 210ft run of 4 in smooth bore plastic cable duct going in a
straight line 3ft underground from outside my shack to a small shed at
the base of my tower. There is a brick-built man hole (aka inspection
chamber?) 3ft x 2ft 6in at each end.
Presently I have LDF2-50A in the duct but it's a tad lossy and I have
the option of some LDF4-50A or LDF5-50A coax.
I have a draw rope running through the duct and a pulley set into the
floor of the man hole each end just outside the duct opening but I am
wondering how easy it is doing to be to pull either of these thicker
and heavier cables into the duct?
How do you guys at big stations do it? Will 3/8" polypropylene draw
rope and a strong young man (ie not me!) be able to do the job, or are
we looking at steel wire rope and a power winch?
Thanks,
Alan G3XAQ
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