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Author Topic: PL259 Soldering  (Read 361 times)
VE4HST
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Posts: 88




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« on: May 20, 2002, 05:28:56 PM »

Does anyone have the exact step by step instructions for this?  I have LMR400 Coax and silver coated connectors. I would like to hear from the experts, as to how to do a nice job, what tools to useand so on.  I usually make a mess, every time I do this.
Thanks
VE4HST
Harry  
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WB2WIK
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« Reply #1 on: May 20, 2002, 06:21:03 PM »

Need to have: 120W or greater soldering _iron_ (not pencil, not "gun") with 1/2" wide, or wider tip.

Prepare end of LMR400:

Use single edged razor blade to make a cut through the coax, cutting through all material layers _except_ for the copperclad center conductor, 3/4" in from the end of the cable.  Use the blade to circle the cable all the way around (360 degrees), cutting through all materials except the center conductor (which is very hard, and won't be easy to cut, anyway).

Neatly pull the materials away and discard.  Now, you should have 3/4" of shiny copperclad aluminum sticking out the end of the coax, and nothing else.

Now, go back 1/2" from that point and make a cut through _only_ the outer jacket material (and nothing else), 1/2" in from the last cut.  Use very little pressure for this, you don't want to nick any materials below the outer insulator.  Slice gently all the way around the cable's circumference, 360 degrees, then pull off the jacket you just cut through.

If you nick the braided outer conductor when doing this, just use a large cutter to cut off the end of the cable and start all over again.  It is important to _not_ nick the braid.

Now, you should have 1/2" of shiny tinned braid, and 3/4" of shiny copperclad center conductor exposed.  

Push the outer shell of the PL259 (threads toward the end of the cable!) over the prepared end, and slide it down the cable out of the way.

Use a sharp pair of scissors to snip away any loose hairs of braid material from the end of the cable -- any whiskers that could potentially create a short circuit when you go to install the main connector body should be snipped off clean, right at the end of the cable dielectric, so they cannot possibly create a short.

Insert the PL259 "body," in the obvious manner, by pushing it over the prepared end.  When the body hits the outer conductor of the coax, there will be resistance.  At this point, _screw_ the connector body onto the cable jacket material, in a clockwise screwing motion.  It takes 3-4 complete turns of the connector body to fully screw onto the cable.  Make sure it's fully screwed on, and cannot screw on any farther.

When the connector body is screwed onto the cable properly, the center conductor should be exposed, protruding beyond the end of the center pin, and the tinned copper braid should be exposed in all four soldering holes of the connector.

Use the soldering iron and 60/40 or 63/37 rosin core solder to first solder the braid through the soldering holes in the connector body.  Make sure the connector body is resting on an insulated (not metallic!), non-flammable material.  Place the tip of the iron in the connector body recess near one of the soldering holes, and press it firmly against the connector body.  Wait a few seconds, let solder flow onto the iron's tip, and then rub the solder down to the soldering hole.

"Wipe" the soldering iron tip back and forth, with pressure on the connector body, until the solder freely flows on the connector and starts flowing into the soldering hole.  At this point (which should only take a few seconds from the start), add a bit more solder, applying it directly to the hole, so that it flows through the hole into the coax braid.

Finish soldering that hole with gently wiping motion of the iron's tip against the connector body.  Rotate the connector body (and obviously the cable) 90 degrees, and repeat the process for the next hole.  Do this two more times, and all four holes will be soldered.

With the proper iron and technique, this entire operation takes 20-30 seconds.

Be careful not to flow solder onto the screw threads of the PL259 body, or it may be impossible to actually use the connector.

Let the connector cool thoroughly (about 2 minutes) until you can touch it.

Now, use the iron and solder to carefully solder the center conductor to the center contact pin of the PL259 body.  Flow enough solder into the space at the end of the contact pin so that the pin is "filled up."

Remove heat and allow this to cool.  Use diagonal cutters to cut off the excess center conductor.

Screw the PL259 shell over the connector body.

With the right iron and technique, it cannot take more than 60 seconds to perform this entire operation, other than the "cooling down" time between the body and center pin steps.  That cooling down is not required for some cable types, but is required for LMR400 because that particular cable has a very soft dielectric material that melts at a low temperature and can be damaged from excessive heat.

WB2WIK/6
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K4LIX
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« Reply #2 on: May 20, 2002, 06:33:19 PM »

Don't forget to check your connector with an ohm meter - there shouldn't be any (ohms that is)!

73  de  Jim  K4LIX
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VE4HST
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Posts: 88




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« Reply #3 on: May 20, 2002, 07:30:55 PM »

WB2WLK/6
Thank you so much.  The iron I have is a 80W 1/4 inch tip.  I guess thats to light??  I will have to find a 120 iron.  I do have a 120 gun, but you say its no good? Why.

Thanks for your detailed help.  Much appreciated.

Harry
VE4HST
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AC5E
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« Reply #4 on: May 20, 2002, 09:39:28 PM »

Harry, the #1 problem with soldering PL259's is not enough heat. The small amount of copper in a small iron doesn't hold enough heat to heat the shell hot enough for the solder to wet the surface, much less allow molten solder to run through the holes and wet the shield braid. And the heating element can't replenish the heat fast enough in a small iron.

Personally, I usually use a 175 watt American Beauty "plumbers soldering iron" with a 1/2 inch tip. And I try to have either a vise or an extra pair of hands to turn the coax "between holes" so the hole I'm trying to solder is up. It's a lot easier when gravity is helping you!

I have used 125's with a 3/8ths inch tip - but it was a much slower job.

73  Pete Allen  AC5E
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WB2WIK
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« Reply #5 on: May 21, 2002, 11:08:47 AM »

Indeed, Pete is wise.  Of course, like me, he's probably tried every way to install PL259's and has installed thousands of them.  I have, too.

It's not the "wattage" of the iron that's important, it's the thermal mass of the tip.  Heat transfer from body to body occurs efficiently and rapidly when the source of the heat has much more thermal mass than the body being soldered.  A 1/4" tip doesn't have much thermal mass.  A 1/2" tip has a great deal more.  An even larger tip (3/4") would be even better.

You want to use an "iron" (old fashioned, large, heavy) rather than a pencil or a gun because a real iron, with at least a 1/2" wide tip, will store enough heat to make soldering to a PL259 a very easy job.

The "wattage" rating of the iron only determines how fast it heats up, but nothing else.  A 50W iron with a 1" tip will work great, but might take 30 minutes to heat to soldering temperature.  A 120W+ iron will also work great, and get hot faster.  A 250W "gun" hardly works at all, because despite its ability to heat very quickly, it also cools very quickly -- which is exactly what you DON'T want.  You want a soldering instrument that cools down very slowly, the slower, the better.

WB2WIK/6
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KC7GF
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« Reply #6 on: May 21, 2002, 11:26:35 PM »

The easiest way is to buy the crimp-on connectors from Antenex at about $6 and their crimptool at about $65. (less if dealer cost) I've put on hundreds of N and PL259 connectors on LMR400 using this method and best of all no soldering. Antenex 708-351-9011
Art - KC7GF
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K9KJM
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Posts: 2415




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« Reply #7 on: May 22, 2002, 01:33:43 AM »

As the other posts indicate, it is important to have the correct soldering iron to do the job QUICKLY, so the center foam does not melt. And it is REALLY important to allow it to cool the 2 minutes! I would give it even more time to make sure it is cool. Or you can end up with a mess.......   LMR 400 is about the best choice out there for VHF/UHF operation. Take your time putting on those connectors and you will have a first rate set up!  Good Luck!
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KB0ETC
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Posts: 248




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« Reply #8 on: June 05, 2002, 06:52:40 PM »

Check this out.

http://www.qsl.net/kf4l/coaxez.htm
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