I guess that not so many guys have used monofilament to trim as several have
asked for clarification. What I do is cut maybe 16"-18" of line and with
the coax secured in a wooden block I've set up, I clamp it in a vise. I then
use the fishing line to saw into the outer insulation moving around the
radius until the cut is cleanly through to the braid. I've also used it on
the inner insulation but it is easier on some types of foam than others. The
advantage is of course that you don't knick the conductors. On LMR-xxx it
doesn't work quite so well so a tubing cutter or a very carefully used razor
knife gets most of the cut made which can be finished with the monofilament
I share your concern with the foil Ken and I have either picked it down a
bit with an O ring pick or finger nail and pull it out slightly so it can be
snipped with a small precision scissors. A really sharp razor knife will
trim it...I go through a lot of blades when building cables.
Date: Sat, 22 Jan 2011 08:58:29 -0600
From: "Kenneth Goodwin" <firstname.lastname@example.org>
Subject: Re: [TowerTalk] Crimp Connectors
Content-Type: text/plain; charset="us-ascii"
Having converted myself to crimped connectors but still a neophyte with the
method, I have come to almost the same set of conclusions that you put
forward. However, I don't understand what you are saying " I now have gone
back to stripping with 40lb monofilament fishing line" I am using a tube
cutter to prepare the center conductor and an DX Engineering coax tool for
just the outer covering. Using the (modified for LMR-400) tool for the
center conductor was just not to my standards for coax with a foam center
insulation like LMR-400.
I, like you, believe that trimming excess braid after crimping is a key
factor to having a good crimp. Plus it is much neater, doesn't require
precise measurement and better insures a uniform distribution of braid for
the outer crimp.
What I really want to ask is, do you do anything to foil shield prior to the
crimping operation? My only concern with coax like LMR-400, is the
proximity of the foil to the center conductor. Even the tube cutter
compresses the foam inner insulation which brings the remaining foil closer
to the center conductor. The best I can seem to do is just peck at the foil
with my fingernails until I am satisfied that the foil has not shorted over
to the center conductor. The only way I've been able to provide some
separation distance between the foil and the center conductor is to use a
grinder on the foil which wasn't a good plan in my estimation (just too
destructive even being very careful). I can see no way to remove the foil
without doing damage to the inner insulation.
On the center conductor, I wonder if a solid center conductor like LMR-400
as compared to a stranded center conductor like RG-213U doesn't also force
the issue of soldering the center conductor. I was considering going to a
fully crimped connector but if I need electricity at the connector for the
heat shrink tubing then using a soldering iron is no more of an impact.
Soldering the outer braid has always kept me up at night wondering about the
condition of the inner insulation even when using all of the good
suggestions others have mentioned (tinning the outer braid, liberal use of
flux, cooling the connector ASAP after soldering, etc.) Soldering the
center conductor leaves me with warm fuzzes.
73 Ken K5RG
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