Barry,
A professional, albeit, more expensive way to do it very nicely is to
get a wall tube entry kit made by Valmont (Microflect Division).
The B101 goes through 12" (Tessco 51447 while the B241 (Tessco 89840)
is rated to 18". It is 4" OD, threaded PVC with screw on ring nuts to
lock it in place. It may also come with a face plate to sandwich on the
outside. Mine (installed many years ago at a commercial site) had a large
washer for the outside face. Use appropriate sealant behind the faceplate
and perhaps around the tube at the wall (Do you need to use better
expanding foam or some other cold weather stuff?).
They sell plastic covers (sealing caps), that actually come with their
multi-port plate products, until the ports are use whereupon heavy rubber
cap-boots (waveguide boots) are used instead with a selected doughnut /
cushion to make the feed-through grommet face match various numbers and
sizes of various hardline and RG-8 that will be run through the port.
You'll have to seal up the small RG-8 hole with duct-seal (p/n B202;
Tessco 69729) or something assuming you have a separate hole for the
smaller SteppIR control cable.
Look through the various combination choices of "cushions" they sell.
Just make sure it is for the 4 inch not 5 inch product line. They also sell
rubber plugs to fill the pre-cut holes for standard communication cables
if you want to use the heavy rubber boot all the time even without cables.
You can purchase the plastic cover (p/n B267; Tessco 36984) - you may want
to get one for inside and perhaps a spare. They are cheap. Get a couple
of good stainless steel hose clamps that fit 4+ inch and hold the covers
in place. If you put a cover inside and clamp it at least you are backing
up the outside protection while unattended.
Then you just remove the cover(s) while you are there and either buy a
suitable rubber waveguide boot and doughnut assembly or fill the gap
with a rag and tape a plastic bag around the cable entry. I understand
you are only there for summers or short trips?
This solution may run you as high as $100 or $150 or so but it will
do it nicely.
Go look on Tessco's website and look up the stuff. They also sell a
Competing line from Wireless Solutions. I don't know if their parts are
interchangeable. Or use any number of other cheaper ways. This is one
of the more elegant, professional looking methods.
Other regional communications suppliers may also handle this stuff.
Good luck.
Kimo Chun, KH7U
Delta Communications, Inc.
Honolulu, HI
-----Original Message----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@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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