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[TowerTalk] Installing Coax Connectors - Summary

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Subject: [TowerTalk] Installing Coax Connectors - Summary
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Date: Fri, 28 Mar 1997 07:06:53 -0500 (EST)
It looks like this thread is gradually thinning out----thanks for some very
interesting comments from a multitude of folks.  We've covered the Bill Orr
procedure, the use of butane torches, "Old Yeller" the beloved ancient
Weller, professional crimping tools, the alternative of feeding your antennas
with twinlead, and spawned a whole new series of corny limericks containing
the word "eutectic".  This productivity truly boggles the mind.  And I think
it was KE3Q who suggested a videotape of W0UN installing a PL259 for
presentation at the Dayton antenna forum....actually, one could have a
contest of all these respondants in action, using their favorite
methods....oops, Contesting is another reflector.

Here are a few additional responses to the query that were sent to me
directly that I wanted to pass on to the reflector:

---From K6NA:

The method mentioned to you by N4SI is pretty close, but I don't much like
the torch unless you are on a 100-ft tower and there is no other way.

The key is proper pre-tinning of the undisturbed braid.  Let it cool, and
then make the cut with a miniature tubing cutter. Buy one, they are not

Another key is use only teflon connectors if you don't have perfect
technique.  That way you do not melt the connector dielectric if you are a
bit slow.

Another hint:  The common generic "USA made" teflon PL-259's available
everywhere these days (i.e. non-Amphenol) have a design flaw which if not
addressed will lead to problems every time.  These have a body which has too
large an interior diameter in the area where the tinned braid is to be
inserted.  If the braid is smoothly pretinned, and then the connector is
screwed on over the outer jacket as it should be, you can look closely at
the holes and see that THERE IS A GAP ALL AROUND, between the tinned braid
and the body!  I really think the designer thought he was doing us a favor,
thinking that we needed "help" stuffing all that braid in there.  (Some
people actually fan the braid back on itself and jam it all in there, and
never solder it... maybe the designer was one of these guys.)

Anyway, the gap is a killer.  As we all learned on page one of our Heathkit
CONTACT.  So after I insert the plug body onto the tinned braid, I lay the
connector on a piece of soft wood (this keeps the exposed male thread from
being damaged), and with a hammer and dull punch I make four indentations,
between the four holes, in the body so that the body touches the braid in at
least four places.  Now you have excellent conductivity and heat transfer to
both surfaces, and a finished connector which is also much stronger and
won't pull apart with a load on it.

Believe me, I have seen or heard of many PL-259 failures using these generic
teflon connectors and I will bet that most are due to this design flaw and a
failure to correct for it.  Since I developed my hammer-and-punch method
years ago, I have never seen a failure.  I use the method on Amphenol, too,
even though the gap is smaller (I have not measured it).

Last tip:  Use a minimum 140-watt gun for soldering the body.  Bigger is
even better (which means faster heat transfer).

---From KL7HF:

The secret is in proper tinning of the shield and center conductor after
cutting the insulation to the proper dimensions.
The connector should screw on tightly. (If you don't have to use pliers,
then it isn't correct!) And then, a good solder job on the shield without
melting the insulation. It is tough, but can be done. Don't use a torch.
I take the tip off the soldering gun and use the connector as the tip.

Also - a lot of coax is not designed to have PL-259 connectors.
RG-213 is an example. It is a tad smaller OD than the connector requires.
It can be done, but is not recommended. RG-213 is supposed to use Type
'N' connectors. To use PL-259s, you have to increase the diameter of the
shield in some fashion. (Real thick solder will do it, but again, you're
on your own that way. Not a good process.

---From W7NI:

There are couple of things I find are very helpful:

1.  Use the best quality connector you can find.  I use Amphenol, silver
plated, teflon insulation.  They cost a couple of bucks each but they are
worth it (and they will take the power of two 4-1000As!)

2.  Make sure the coax braid is bright and shiny copper.  If it is oxidized
or black, it won't take solder very well.  Try stripping a foot or so
further back to see if the braid looks better there.  If not, toss the coax
and get new stuff.

3.  Use a big enough iron.  I use about a 200 watter.  This may be overkill,
but it heats the shell of the connector up real fast and you are done with
the job before you can melt the dielectric of the coax.

4.  Use a little soldering paste where the shield is visible through the
holes in the connector.

Thanks again for the interesting and helpful responses.  73 - Phil, N6ZZ

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