Weatherproofing Andrews Connectors
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Sat, 16 Mar 1996

Hello OMs!

Does an Andrews Female N-connector that has been PROPERLY installed on
Andrews LDF5-50 7/8 inch Hardline need to be sealed against moisture
entry?

Here is my situation. I have a run of Andrews LDf5-50 terminating at
the top of my tower. It has a CORRECTLY installed Female N type
connector with the connector pointing straight up. Mted to the female
connector is an Andrews manufactured jumper with a Male N-Type
connector on LDF4-50 1/2 inch hardline. The coonector on the jumper
points straight down into the female connector. The jumper has, what
appears to be a plastic collar down about 3 inches of the half inch.
When I installed this stuff last September I did not wrap it with tape
or coax seal. At the time it appeared that both ends would be
waterproof due to the design of each connector,etc.

Well, yesterday a new sustained winds record was broken here in the
Greenville, SC area. The winds were clocked at 87 miles per hour,
shattering the old record of 72 MPH. I spent 15 minutes indoors
looking up at my towers and watching my antennas being tossed about
like rag dolls. Fortunately there doesn't appear to be any damage and
fortunately the winds all came from the same direction and my antennas
were pointing in to them. What worries me is the possibility of rain
water being forced by the winds around the Hardline connector seals.
Having been in a Typhoon on Guam and seeing water pouring out of the
electrical outlets after being forced into the A/C entry conduit by
high winds, I wonder if the same will happen to a PROPERLY installed
connector. Are the Andrews connectors designed with such calamities in
mind? Would sealing the whole splice keep any trapped moisture from
exiting? Or should I just leave it the way it is? Any thoughts? Thanks
in advance.

73 Ken


Sat, 16 Mar 1996

... as you know, the Andrew connectors are designed to be pretty
weatherproof by using tight tolerances and O-ring gaskets in a couple
of places. It is ALWAYS a good idea to weatherproof any connector
joint; in fact, it is done practically 100% of the time by
professional installers.

The Andrew recommended method is:

1) Apply two wraps of electrical tape over the joint (I recommend
Scotch 33 or 88 myself).

2) Apply a layer of butyl rubber vapor wrap over the joint making sure
that there are no air cavities or openings in the wrap. BTW, this is
BETTER than CoaxSeal.

3) Apply 2 wraps of electrical tape over the joint with the final wrap
going UP to minimize water migration.

4) Somewhat optional -- coat joint with Scotch-Kote sealer. I've seen
some guys use spray urethane over the joint. It's another layer of
protection whichever you use.

This technique should be used with ANY outdoor coax joint. It'll last
for years and when you take your razor knife and open the joint up,
it'll be just like new inside.

73 and good luck, Steve K7LXC


Sat, 16 Mar 1996

Hi, Steve. I've been doing the tape-ScotchKote-tape thing, but not
the vapor wrap. What is this stuff and where should I look for it?


Hiya, Steve --

Good question, actually. I didn't mean to be so hard on CoaxSeal
(personally I don't care for it) but it will work in this kind of
scenario. The problem is most guys apply it DIRECTLY to the connector
which makes the connector unusable again. YUCK! Install the CoaxSeal
OVER the first layer of tape and it will work.

As far as the butyl rubber vapor wrap, try the yellow pages for a
local Andrew, DB Products or Antennas Specialists dealer; they should
have it. The manufacturers always pack some in with some of there
products but you may be able to get small quantities. Otherwise, check
back with me a a few weeks --I may have some for you.

73 and good luck, Steve K7LXC



Sat, 16 Mar 1996

What is this stuff, where is available and does it have a Scoth part
#?

There are 2 tapes - Super 33+ and Super 88; 88 is about 20% thicker
but they have the same properties. Any electrical supply store or
electronic distributer that handles Scotch products will probably have
them. They're $3-4 per roll but worth it. Do yourself a favor and
don't use the "10 rolls for $1.99" hardware store specials.

I know Scotch makes a "self-annealing" tape but I can't seem to find
it anywhere in Northern new Jersey. Does anyone know the Scotch part #
for this tape, too?

3M has a number of products in this line and I don't have the catalog.
The phone number I have is an old one so I'll try to get you a number
you can call to get additional product info.

Let's see if I have this right: You apply a total of 5 layers of tape
over the joint?

Well, four is usually sufficient but I was giving the Andrew spec.
This is an bomb-proof, highly reliable industrial-standard
weatherproofing technique. That's what you want in your tower and
antenna system, don't you?
Sat, 16 Mar 1996

I have already researched this thread with 3M back in December. The
product that you guys are looking for is Scotch 130C, Linerless Rubber
Splicing Tape. It is a self sealing tape used in high voltage
applications. Several of the PVRCers use this tape in lieu of Coax
Seal.

3M will fax/send you the Product data sheet upon request:
1-800-364-3577 or 1-800-245-3573.

The Data sheet on the 130C shows that it is HV, moisture sealing, UV
resistant, WX extremes functional, etc...

73! Bill, N3RR


Sat, 16 Mar 1996

Walt,K2WK asks:

I know Scotch makes a "self-annealing" tape but I can't seem to find
it anywhere in Northern new Jersey. Does anyone know the Scotch part
# for this tape, too?

I use either Scotch #23 Rubber Splicing tape (it is described on the
package as High-voltage, Self-fusing, Insulating Tape based on
Ethylene Propylene Polmers), or Scotch 130C Linerless Rubber Splicing
Tape (again described as based on Ethylene Propylene Polymers). I'm
told both of these don't stand up well to UV so they should be covered
with two layers of Scotch #88. I normally don't cover the Scotch #88
with anything and I have had no problems. But I have also used Plasti
Dip Spray-On over the #88 for connections that will be on or under the
ground.

73's Pete-N8ATR


Sat, 16 Mar 1996

I have always been able to find the Scotch 130C and super 88, and bulk
UV okay wire ties at Grainger. They have locations all over the place.
If you work for someone that has an account with them, then you
probably can buy at the wholesale price (I do).

73 de N1PBT...ron (rro Sat, 16 Mar 1996

3M has a home page that can help you identify and locate their
products. Have a look at http://www.mmm.com if you have a graphical
web browser. I tried to look up Scotch-Kote, but my text based browser
doesn't work with 3M's search page. I can look it up from work on
Monday if noone beats me to it.

73,

Greg AA0XZ

Disclaimer: I work for 3M but don't have anything to do with tape.


Sat, 16 Mar 1996

Just a couple of additional thoughts on Steve's comments about sealing
connectors.

1) Apply two wraps of electrical tape over the joint (I recommend
Scotch 33 or 88 myself).

Scotch 88 is really the all weather tape to use. Scotch 33 tends to
get brittle in cold weather and has more of a tendency to lose its
grip with time, weather, and just a little stretching. 88 is a little
more expensive but I would never use anyhting else outdoors.

2) Apply a layer of butyl rubber vapor wrap over the joint making
sure that there are no air cavities or openings in the wrap. BTW, this
is BETTER than CoaxSeal.

Butyl rubber tape is available from most good electrical supply
houses.

4) Somewhat optional -- coat joint with Scotch-Kote sealer. I've seen
some guys use spray urethane over the joint. It's another layer of
protection whichever you use.

I think Scotch-Kote is a waste of time if the connection is exposed to
the sunlight. Within a year it has degraded from the ultra-violet and
has pretty much flaked off (at least in Colorado). It is fine for
direct burial, for which it is intended. I actually like Plasti-Dip,
which is available from most hardware stores and is used to dip tool
handles for insulating them. Use the black color for better UV
resistence. It can be painted on (pretty thick goop) or there is a
spray version as well.

For things like splitting out the pigtail lead of coax to hook to a
sloper or a dipole (after the balun) I do a couple of layers of Scotch
88 with alternating layers of the Plasti-Dip by just dunking the end
into a gallon can of the stuff. Put some masking tape over the
terminal lugs to eliminate having to clean them off.
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Another technique I use for weather proofing the pigtail ends of coax
is to put some heat shrink over the entire length of exposed
dielectric up to the point where the braid splits off. Then, taking a
length of larger diameter heat shrink, I cut a little slot in the
middle and place that over the jacket and heat-shrink-covered
dielectric in such a way that the braid sticks out the little slot. I
dip this whole thing into a thinned down version of Plasti-Dip (you
don't need their thinner--it is just expensive paint thinner/mineral
spirits). This thinned down material soaks into the braid--filling up
the gaps to reduce the possibility of wicking moisture into the region
between the braid and center conductor.

Yep, I know it is a lot of work, but how many times do you want to
replace your coax because it got water inside and the losses
sky-rocketed.

73 John W0UN


Sat, 16 Mar 1996

Thanks for all the responses guys! The answer is Yes. Extra
waterproofing is needed for an absolute watertight seal. Every splice
at my QTH is triple sealed with layers of electrical tape and Rubber
sealing tape.(coax seal). This is the way I have always done it. This
combo has always worked well for me. The N, PL-259, whatever, type
connectors remain shiny and uncorroded when they are taken apart when
sealed in this manner, even after years of use. There was a reason I
chose to leave this particular joint unsealed except for the Andrew
connector seals.

I don't remember why though. HI!

I climbed the tower earlier today and took the connector apart from
the 7/8 and am happy to say that it was bone dry with no corrosion
internally as far as I could inspect. I reassembled and sealed it
using the proper techniques. I can say though that properly installed,
genuine Andrew connectors do a good job of keeping the moisture out. I
was certain that water would have made its way inside after those 87
MPH winds with rain that we had yesterday. Extra preventive measures
never hurt. Thanks to all who responded with their personal
experiences.

73 Ken KP4XS/W4