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Newsgroups: rec.radio.cb
Subject: How-to seal coax connectors
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                   Weatherproofing Andrews Connectors
     _________________________________________________________________

   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.
     _________________________________________________________________

   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