[TowerTalk] Re: [Antennas] Date: Mon, 19 Jul 1999 13:36:52 -0500

[Jerry Devine]

>>who is "rb" wrote [???]:
>> Question for the reflector group:  is there any commonly available
>>product that can be used for coax connector sealing, and that is easy
to >>save and store for subsequent use?  

>k0hb@arrl.org wrote:
>Visit your local auto glass place which does windshield sealing.  Forget

>what they call that stuff, but it's similar to "coaxseal", $10 buys a
>100-year
>supply, and it stays flexible forever-and-ever-amen.

>Pete N4ZR wrote:
>I thought vapor-wrap was the preferred solution.  I hate
>duct-seal/coax-seal etc -- messy stuff, at best.  Mostly, I just use
Scotch
>33 or 88 tape, wrap it carefully, and leave it at that.  Another
approach
>would be a coat of Liquid Electrical Tape over the Scotch.


The best method I've found has been practiced myself for over ten years.
No water damage ever experienced, No tanished silver,  No varmits prefer
it's taste. Is not temperature effected for most environments which call
for service.  Unlike Coax seal, And the above quoted solutions.  And it 
isn't messy.  I've personally used this method at 0deg F in a stiff wind
and all materials were exposed to these conditions for greater than 2
hours,
including my finger tips, also in the middle of summer here in the north
east U.S. under 99 deg F, humid conditions less than rain...  Electrical
properties are excellent.  Ideal for use on Polyethylene, Crosslinked
Polyethylene,  Butyl Rubber, Oil based rubber,  EPR,  PVC,  And other
common solid dielectrics.  And is flame retardant.  Can handle up to
130 deg C or 266 deg F  and offers at min 35kv insulation. 

My method requires the following materials for use in all weather. They
can be stored at room temperatures and out of direct sunlight for several
years before use as is my experience.  One roll of 3M Scotch 130C
Linerless
rubber splicing tape #00075 (1.5"x30' @ $9.91), One roll of 3M Scotch
Super
88 #10364 or #10307 (1.5-3/4"x 44' @ $3.67-1.94), One roll of 3M Scotch
Super 33+  #10075 (3/4"x44' @ $1.81.  

Instructions:

Warning 130C material is self bonding.

Before application you should make sure your connections are proper.

[Most connectors folks don't need or require 18" pipe wrenches to
 properly torque, in fact usually what your bare hands can manage
 is fine unless the hardware is used and damaged. Follow manufactures
 recommendations for torque requirements to the letter. It's a waste
 to seal something thats going to need servicing soon... If is got a
 wrench slot fine if it's knurled doesn't translate to using vise grips
 nor pipe wrenches.  When it gets cold any fitting torqued wrongly can
 be easily encouraged by mother nature to fall apart. A reminder most
 torque specs are suggested for 70 deg F and must be varied to your
present
 working conditions accordingly.]

Ensure connections are clean and jacket of cable is such for atleast and
a prefered distance of 6 inches either side of area to be protected. A
small
bottle (few ounce dispenser) of 91% isopropyl alcohol and a rag is great
for 
those working at 100+ft. 

Then carefully wrap with 130C tape following the box instructions. Pay
special attention to the user note.  This material is made of Ethylene
Propylene Polymers which do have limits to stretch.  I stretch until it
just begins to get a 50% dull color than right off the roll. This
material
is so much fun to work with and very forgiving.  If it's really cold
outside
I wouldn't stretch it as much though...  You want to wrap about 3 inches
from the connection either side of it to completely cover it with a
single
over lapping layer with not deformities. And this wrap should start from
the
sky end of the cable. 

This tape needs protection. And depending on the temperature I do the 
following.  If it is =< 32 deg F I use Super 88 tape.  Above 32 deg F
I use Super 33+.  Although for those economy minded you can just use 
Super 88 always, It does have advantages being 10mil tape...

Next you want to wrap two 1/2 lapped layers of either 88 or 33+ as above.
For a distance of a few inches from each end of the 130C tape. My first
wrap is from the ground end of the protected area. Followed by the last
wrap from the sky end as before with the 130C tape...  This will provide
the required UV ray protection, abrasion, alkalies, moisture, acids, and
other natural contaminants from destroying the 130C tape properties.


Once sealed in this manner you can be sure that you'll take it off
in ten years and be plesantly surprised that your connector looks 
as new as it did when you installed it on the cable.  Enjoy!

How to remove the seal?  Simply cut a letter I, down to the connector
with a razor blade, then peel back, stretch the 130C alil and cut loose.
Then pull ends toward sky and ground. Sometimes 88 tape has to be severed
slightly depending on age and temperatures involved.  In general it's
very
easy to accomplish.  But don't expect you'll be doing this to repair the
connection but rather to connect something else instead...

I will close with that I fully agree with 3M's Electro-Products
Division's
Important notice to purchasers of thier products.

Normal disclaimers apply, Your mileage may vary.  



73,    Jerry                                     krr2ak@juno.com
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