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[TowerTalk] Crimping PL-259s, Installing PL-259 Connectors

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Subject: [TowerTalk] Crimping PL-259s, Installing PL-259 Connectors
From: (Steve Fraasch)
Date: Fri, 19 Nov 1999 08:22:06 -0600

I would recommend against using a crimp connector on VHF/UHF lines. 
Compressing the dielectric and shield to something other than nominal
will force a discontinuity or reflection on the line.  Solder-type
connectors are designed to maintain the coaxial line's characteristic
impedance as best as possible.

Mech crimp connectors are notorious for failing early.

I would recommending trimming and cleaning the coax per install
instructions, and finishing with proper solder and weather proofing of
the line.  After sustaining failures on all my improperly installed
connectors, I now take the time to do it right.

I use the following procedure which is pretty quick:

1.)  Slip the threaded piece on the coax.

2.)  Cut the outer sheath per manufacturer's spec.

3.)  Wrap black tape around the shield to keep.  Align the tape such
that the top is aligned with the braid cut point.  The black tape acts
as a cutting guide.

4.)  Use a utility knife with a fresh blade, and cut the braid right
above the tape. Remove the cut braid.

5.)  Take the utility blade and cut the inside dielectric length-wise in
2 or 3 spots.  I recommend AGAINST trying to remove the inside
dielectric with a circular cut.  You can easily nick or cut-off a center
conductor strand of RG-8 or RG-213 with a circular cut.  Cutting
lengthwise, and removing strips is much easier and reduces the chance of
nicking or cutting the center conductor(s).

6.)  Cut the inside dielectric pieces at the top of the tape.

7.)  Take care to not nick the center conductor or the braid.

8.)  Remove the tape by pulling it off from the center conductor.  The
braid should be evenly trimmed, and lie flat when you're done.

9.)  Clean the braid, center and solder with isopropyl alcohol.  Using
cleaned solder seems to help solder flow and wet more easily.

10.)  Slip the connector over the braid.  If you followed the previous
steps, you'll have no problem keeping the braid against the dielectric. 
The braid will not bunch up and push down the inner dielectric.

11.)  Solder the center conductor.  Solder the braid.  I use a 50 watt
pencil iron.  I believe that guns and torches apply way too much heat; a
25 watt pencil won't do it.  Make sure that solder fills the braid holes
completely and wets and flows to the braid.

12.)  Pull the threaded shell over the connector.

13.)  Wrap black electrical tape behind the connector and continue to
wrap until the tape is flush with the connector body.  Now, you can wrap
the tape over the back side of the connector to keep out water.

14.)  To keep water out, and to keep the threads from galling, I apply a
small amount of silicone grease or motor oil to the mating SO-239
threads.  Keep it off the center conductor.

15.)  I then thoroughly tape the entire PL-259 and SO-239 connection
with tape.  I think you can use coax seal if you can still find it.  If
you need to get something apart, tape is easier.  To get coax seal
apart, I would recommend freezing it, rather than applying heat.  You
can then use a knife to get the coax seal apart.  If you use heat,
you'll just have a mess.

The black tape shield cutting guide works well on N connectors, since
the dimensions are more critical.


Steve Fraasch, K0SF

Bob Jaeger wrote:
>    I was looking for crimp style pl-259 . Is there anything of this type
> that are durable
> and will work at vhf frequencies . Thanks
>                                  BOBJ
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