[TowerTalk] Cable Feed Thru for Removable Cables

[Gary "Joe" Mayfield]

Barry,

   We have weather here in South Dakota too.  Your local hardware store
sells a "closed cell" pipe insulation that has a slot down one side to slip
it over a pipe.  It comes in various diameters.  Start with a small diameter
that barely accommodates your cable bundle.  Then continue to add layers
until you can barely slip it through your pipe.  It will be wind and rain
tight, yet easy to remove.  If your cable bundle gets bigger simply remove
the inner most layer of insulation.

73,
Joe kk0sd

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Barry Merrill
Sent: Monday, November 19, 2007 3:03 AM
To: 'towertalk reflector'
Subject: [TowerTalk] Cable Feed Thru for Removable Cables

 

Work is close to completion on the ham shack at EI/W5GN, and I need
suggestions on how to create a feed thru for the RF and Control Cables for
the antennas and (eventually) tiltover tower.  They will be pulled thru only
when we are here and will be removed and the feed-thru sealed when we're not
here.

The concrete wall is 14 inches thick, and my contractor says he can easily
drill a 3 inch hole thru that wall, about
12 inches above the ground level.
 
I need about 3 inch diameter so the DB25 for the BigIR controller can be
pulled thru, but the actual cable cluser will probably be only about an inch
in diameter, as I'm strictly low power from here.

So my concerns are:

 a. How do I "seal" with something that is removable
    when the cables are in place to prevent wind-driven-rain
    and the wind noise (we are on a bluff on the Atlantic).
    I thought (briefly) about using expandable foam, but
    past experience suggests it would NOT be easily removed.
    Rags seems to be the current thought.

 b. How do I seal the "hole" when we're not here.
    I've though about using a threaded pipe with caps
    both inside and outside, but don't know how
    reusable the threading will be, especially exposed
    to the salt water environment. 

 c. Assuming a metal pipe is use, is it important to
    bend the outer end downwards, or will horizontal
    work?  I don't think PVC pipe can be threaded and
    be reused?  

73

Barry, EI/W5GN


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