Preheating the connectors after the connection is made is relatively
easy. UHF and N splices have relatively small mass so preheating the 3
connectors can easily be done. There is a small learning curve, BUT the
connection (in a splice) will be water proof if the glue bonds to the
coax. OTOH, If the connectors are preheated to give a good bond, then
the connectors are chilled prior to the heat shrink removal, the glue
will "usually", break off leaving a relatively clean connector.
"IF" the connectors are preheated too hot, the glue will likely melt
making it difficult to properly position the heat shrink, (it may shrink
too soon), or not enough glue will be left to seal the end(s). For a
splice, preheat the connectors (if desired), quickly slide the tubing
into position and then start the shrinking process FROM THE CENTER and
move out. If the ends are sealed first the center will form an
unsightly bulge. OTOH you can heat the double female connector to
the point of melting glue and thoroughly coat the center first, but LET
THE CONNECTORS COOL enough to allow sliding the tube into place with out
melting the glue lining.
OTOH is it necessary to seal onto the connectors. The water proofing
method with the first layer of 33, or 88 tape wound with the adhesive
side out keeps the metal clean without sealing to it. It depends on the
method used, but connections can be made that do not bond to the metal,
yet remain water proof.
http://www.rogerhalstead.com/ham_files/AV-640/AV640.htm . Check the
left side photo on the bottom row. The next photo to the right is a two
layer EPS 800 over 400 on a TV balun. RG-6 to 300 ohm twinlead.
NOTE: If you want the glue to adhere to a surface, degrease the surface
with a good solvent. Be careful when using solvents.
73
Roger (K8RI)
On 12/21/2015 Monday 6:27 PM, Grant Saviers wrote:
Roger's heat shrink removal explanation shows one peril of adhesive
heat shrink, that is the adhesive is not really adhered to the
connector body. Andrew specifies preheating of Heliax connector
bodies prior to slipping on the adhesive shrink and then shrinking the
tubing. Of course the larger the connector, the more it is a heat
sink that doesn't get hot enough thru the wall of the tubing for the
adhesive to tightly bond to the metal.
IMO, unless the adhesive is adhered to the connector the joint will be
tight, but not totally watertight. However, there still is some
protection and an excellent strain relief. I think the cable jacket
fairly easily gets hot enough to have the adhesive stick to it.
Grant KZ1W
On 12/21/2015 12:08 PM, Roger (K8RI) on TT wrote:
If the connection is cool or cold, this approach works better than
warm or hot.
Room temp works well, but may leave more residue.
There is a bit of a learning curve. Some pick it up right away while
others, not so much.
Using a sharp knife, or box cutter with the blade extended just
enough to cut through the heat shrink.
Make a single cut lengthwise from one end to the other of the heat
shrink. A second cut on the other side works well, but it's another
chance to cut into the coax jacket. The cut does not need to go all
the way through the heat shrink
Using a pair of pliers, channel locks / slip joint pliers grab the
heat shrink at or close to the cut with the other jaw of the pliers
about one third of the way around the coax and pinch the heat
shrink. If you go too far it will pinch the coax. That should pull a
section away from the coax jacket Repeat on each side of the cut
along the length of the seat shrink.
Doing takes less time than explaining.
If the connection is cool, the heat shrink adhesive "usually" breaks
away from the connector, leaving the connector relatively clean.
http://www.rogerhalstead.com/ham_files/connectors.htm The splice
shown in the bottom right side photo shows a N-Type connector splice
after the flooded (adhesive lined) heat shrink has been removed. Some
residual glue is visible on the coax jacket but the connectors are
relatively clean
--
73
Roger (K8RI)
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