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Re: [TowerTalk] Coax Connectors

To: <>, <>,"'Roger Kissel'" <>, <>
Subject: Re: [TowerTalk] Coax Connectors
From: "Gary Schafer" <>
Date: Thu, 4 Jan 2007 16:14:38 -0500
List-post: <>
The way Dick describes installing connectors is the correct way to do it.
Very nice Dick!

I might add that with some of those not so well plated connectors you might
try some liquid or paste flux applied inside the connector with a small
brush before putting the cable in. Go lightly as you want the flux only
where you want the solder to go to.

Tinning the braid first as Dick describes ensures that solder is distributed
clear around the shell and not just in the holes area of the connector.

As pointed out it is also important for the jacket to be well inside of the
connector for stress relief. Bending a soldered braid repetitively as with
soldering the braid to the outside of the shell is a recipe for failure. 

Gary  K4FMX

> -----Original Message-----
> From: [mailto:towertalk-
>] On Behalf Of Dick Green WC1M
> Sent: Thursday, January 04, 2007 1:02 PM
> To:; 'Roger Kissel';
> Subject: Re: [TowerTalk] Coax Connectors
> To solder PL-259 connectors, I use a Weller temperature-controlled
> soldering
> iron with a large flat blade tip. I've used a couple of different models,
> but the one I have now has adjustable temperature control. Fixed or
> adjustable, the important thing is that these irons maintain the tip at a
> constant temperature. They have large power supplies that quickly pour a
> lot
> of juice into the tip to raise the temperature very quickly, but don't
> overheat the tip. I've also used a Solder-It butane soldering iron for
> installing connectors outdoors. It works almost as well.
> I use the following procedure. It's not original with me. I think you can
> find pictures of the process somewhere on the web if you're good with
> Google.
> 1. I use Amphenol silver-plated PL-259 connectors. Regardless of the
> method
> used, silver-plated connectors make the job much easier. The regular
> plated
> connectors just don't take solder very well. You have to heat them to the
> point where the dielectric melts. Import silver-plated models are OK, but
> I
> use Amphenol because the quality is first rate. I figure if a connector is
> going to be in the air for many years, it's worth a few extra pennies to
> get
> the best.
> 2. Always put the connector cover (the part with the threads) on the coax
> first, facing the correct direction. This is so you don't accidentally
> forget to do this. Nothing worse than soldering the second connector on,
> only to realize that you forgot to slide the cover on first. If necessary,
> tape the cover to the coax to keep it from sliding around. I use Cushcraft
> coax booties (available from Texas Towers) for outdoor connections (I use
> tape and vapor wrap over them, too.) If you use them, they have to go on
> before the cover.
> 3. Using a very sharp utility knife, strip the coax jacket to about 1 1/8"
> from the end. You can hold the connector body next to the coax, using it
> to
> measure where to strip the jacket. Strip the jacket from a little beyond
> the
> connector tip to the threads. Be careful not to nick the first 1/2" of
> braid
> from the jacket.
> 4. Starting at the end of the jacket, quickly and *lightly* tin at least
> 1/2" of shield. Don't let the iron linger or you'll melt the dielectric
> and/or jacket. If the dielectic melts, the connection will be no good. If
> the jacket melts, you won't be able to screw the connector on. Also, don't
> let the solder blob on the shield. The idea is to create a light, thin,
> uniform coat.
> 5. Use a small tubing cutter (the kind plumbers use) to score the tinned
> braid 3/8" from the jacket. I use a tiny one-handed cutter designed for
> small pipe. Very gently tighten the cutter screw until the shield is just
> barely cut through. Don't tighten it too much or you'll start cutting the
> dielectric, which you don't want to do. I twirl the cutter around a couple
> of times, then grab and wiggle the end of the coax to see if I'm through
> yet. If not, I tighten the cutter a little more and go around again. When
> it's ready, the tinned shield breaks at the cut when I wiggle it.
> 6. Using a pair of "nippy cutters", cut the braid from the circular cut to
> the end of the coax and remove it. Starting from the jacket, this leaves
> you
> with 3/8" of tinned braid, followed by about 3/4" of dielectric-enclosed
> center conductor.
> 7. Using wire strippers, remove the dielectric from the center conductor
> from about 1/16" beyond the braid. The little ridge of dielectric keeps
> the
> braid from coming into contact with the connector body below the center
> pin.
> On coax with a double shield (such as Bury-Flex), the little ridge will
> have
> foil on it. Use a sharp utility knife to scrap it off.
> 8. Lightly tin the center conductor. Again, don't let the iron linger or
> you'll melt the dielectric. With a stranded center conductor, the solder
> should sink into the wire. Don't let solder blob on the center conductor
> or
> it won't fit though the center pin.
> 9. The problem with PL-259 connectors is that the solder holes are not
> large
> enough for the size soldering tip you need to quickly heat the connector
> body. The solution is to slightly enlarge the holes. Using a reamer,
> enlarge
> the solder holes in the connector body just enough for the tip of the iron
> to fit in. You don't want to enlarge the holes too much or you'll weaken
> the
> connector body. In fact, I enlarge the holes a little less than the size
> of
> the tip, but enough of it fits through the hole to transfer heat to the
> braid.
> 10. Slide the connector body over the center conductor, past the braid,
> and
> screw it onto the jacket. Make sure it screws all the way down over the
> jacket. There should not be any space between the connector and the
> jacket.
> I usually have to use a rag to hold the connector and protect my hand.
> You'll feel the connector bottom out when it's screwed all the way on, and
> a
> small amount of center conductor will stick out the center pin.
> 11. Put the tip of the soldering iron in the first hole and heat the
> connector body. Most of the tip should be contacting the connector body,
> not
> the braid. You want to avoid heating the braid at this point because if it
> gets too hot the dielectric will melt. It takes about 20 seconds to heat
> the
> connector with my Weller iron. Be sure the tip of the iron is well-tinned.
> If the tip isn't tinned, you won't get efficient heat transfer. When the
> connector body is hot, rotate the tip of the iron so it also contacts the
> braid, wait a second or two, and start feeding solder into the hole. If
> the
> connector and braid are hot enough, the solder will sink into the hole
> (i.e., you won't get a raised blob of solder.) Quickly move to the next
> hole. This time, you don't need to heat the connector body -- it's already
> hot enough. Just touch the tinned iron to the edge of the hole and braid,
> then feed solder into the hole. You know the joint is hot enough when the
> solder flows in, coating the braid and clearly connecting it to the edges
> of
> the hole. When it's right, the solder is concave and you can see the
> threads
> of the braid through the solder. Repeat with the last two holes.
> 12. Let the connector cool a bit. Then solder the center conductor to the
> center pin. This will take much less heat and time than the holes. First
> make sure the tip of the iron is well-tinned. All you need to do is touch
> the iron to the center conductor just above the pin, let it heat for a
> second or two, touch the iron to the center pin (the thin silver heats
> fast), and feed solder into the point where the center conductor emerges
> from the top of the center pin. Hold the connector slightly above
> horizontal
> so that the solder flows down into the center pin. Don't use too much
> solder
> or it may flow all the way down the pin, shorting it to the connector
> shell
> or braid. Use just enough to ensure that the upper 1/8" or so of the
> center
> conductor is well-soldered to the center pin.
> 13. Let the connector cool completely. This takes longer than you think,
> and
> you'll burn yourself badly if you touch it too soon.
> 14. Using cable cutters, snip off any excess center conductor sticking out
> of the pin. Test whether the center pin will fit into an SO-239 connector.
> If there's excess solder on the outside of the pin, it won't fit. If this
> is
> the case, you can gently scrape or file the solder off the pin.
> 15. Check the connector with an ohmmeter. Make sure you have zero ohms
> from
> the center pin to the center conductor and zero ohms from the braid to the
> connector body. Then make sure you have infinite resistance between the
> two.
> 16. When both connectors are on, connect a small dummy load to one end and
> use your transmitter or an SWR analyzer to make sure the SWR is flat
> across
> the entire spectrum for which the coax will be used. An ounce of
> prevention...
> Yes, it's elaborate, but it really works.
> 73, Dick WC1M


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