[TowerTalk] Cable Feed Thru for Removable Cables

[Kimo Chun]

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 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