The Art of Soldering (PL259 to RG8/U)

The other day I finally installed the 2 meter J-Pole I’d bought late last year.  I made use of a run of coax that had been used for a dipole antenna, and I had cut the run shorter to use the minimum amount of cable between the shack and the antenna.  So, I had to solder a new connector to the feedline in the shack.

Technically, it’s not RG8/u, but rather RG/213U, which is the modern part number.  Still, old time hams have been calling the cable RG/8U for decades, and as both part numbers look the same from a few feet away,  a rose by any other name ….. to quote the Bard.

Attaching the common PL259 UHF connector to this 1/2″ cable looks simple, until you actually try to do it.  The cable is thick, and not very flexible, and difficult to handle.  The operation of striping the insulation and tinning the copper braid is a messy operation with the thick cable fighting you all the way.  Over the years, I’ve figured out a method of taming the beast, and produce a good strong and perfect electrical and mechanical connection between the ancient connector and the coax.

I really don’t know why new amateur (and CB) gear continue to use this relic from WWII, but the PL259 (and it SO-239 mate) just refuse to die.  You’d think that the superior N type connector would have supplanted it by now, but alas no.  Not that the N connector is any easier to attach to coax, but it is simpler to solder to, and has a lower SWR bump, especially above 30 Mhz.

Anyway, the first thing I do is to strip about 1.5″ of the outer insulation off of the cable to expose the copper braid.  Normally, you’d then cut the braid back to size (about 1/2″) and the tin it, however that will leave rough loose ends of braid about, ready to end up inside of the completed assembly to short it out.

So what  do is to tin about an inch of the braid from the outer insulation towards the end of the cable.  First smear a good amount of rosin flux on the braid and then melt a thin layer of solder on it.  Use a Weller soldering gun, NOT a wimpy pencil or iron.  A 140 watt or higher gun is ideal, though I have been able to get good results with my old 100 watt Weller Junior gun.

After tinning the braid, I file off the excess solder to leave a smooth evenly tinned braid with no solder lumps.  Now we will cut the braid back to 1/2″ in length.  The ideal tool to use here would be a tubing cutter.  I’ve used  a pipe cutter for this with good results, but you have to be careful to only cut through the braid, and not all the way though the insulation to the center conductor.  I’ve also got good results with a hack saw, or a jewelers saw.

Next peel away the rest of the braid to leave the center insulation and conductor.  About 1/16″ from the end of the tinned braid cut away the center insulator to expose the inner conductor.  Twist this some and then tin the end and cut it just long enough to stick out of the connector.  Use the connector as a size guide.  Now slip the connector clamping ring over the cable (with the open end towards the end of the cable!), and screw the connector on to the cable.  You should see the tinned braid through the four holes though which you will solder, and the center conductor should be sticking out the front by at least 1/8″.

File or sandpaper the connector where you will be adding solder to remove any corrosion that would result in a bad solder joint, and then wipe on some rosin paste flux.  Use a small vise to hold the cable while you solder the connector to the cable at the four body holes, and the center connector.  Trim the excess center connector off, and touch up the soldering here.  Now screw on the clamping ring (You DID remember to slip it on on the cable the right way didn’t you?), and the job is done.  A thing of beauty forever.

 

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