PL259 plug assembly

[murphyv310]

Hi
Hopefully in the correct section. The veritable PL259 has been around for a long time and is still the mainstay of amateur radio equipment.
The thing is are we fitting them properly and are we damaging the coax?
Way back in the 90s I remember the odd time I was talking to an engineer who worked with Sony Broadcast in the same facility as our workshop he was saying that to solder the braid of the coax to the plug properly a very high wattage soldering iron was required or one that was had a large thermal Hysteresis so the bolt would retain the heat while soldering. The joint would need to be completed within a couple of seconds tops or damage would occur to the coax.
Sony took this seriously and would use solderless wherever possible, not only PL259 but BNC and other varieties. As amateurs we often don't have suitable soldering equipment to carry out this in a couple of seconds. The issue with too long application of heat is it damages the cable and foam dielectric properties chance this can be clearly seen on a cable analyser and adds to the losses especially at VHF & UHF. Personally I use Ultraflex 7 and the specified PL259 plug. Patch leads can be made with good quality screw on plugs so long as they are for semi permanent use.
I do occasionally solder plugs but I have a very old Henley Solon chassis bolt and leave it for at least 10 minutes to heat up, make sure that all is to hand and ready then solder any longer than a few seconds I give up,retrim the coax and start again. One reason I prefer other plugs.

[Cruisin Marine]

They are awful plugs, the compression type by Greenpar though were excellent. But they were only designed for RG58 smaller coax?

[Radio Wrangler]

To add to the fun, most far-eastern-sourced PL259 plugs are nickel plated for shiny goodness which makes them even harder to solder, so people have to get them much hotter to try to get the flux to do something.

For even more fun some of said cheapo PL259 have slightly the wrong thread. This works in two ways, the thread jams up before the ring has clamped the bodies together and you're left with some slop where the zig-zays engage. THEN you find that due to the plating, the threads have galled and you can't get the damned thing off!

On top of this, the so-called 'UHF' connector isn't even constant impedance through it.

If you don't want to change the connectors on gear, fit an N-plug on the cable, and use an adaptor. This way you aren't at risk of wearing out your special vocabulary.

David

[G6Tanuki]

There are plenty of PL259 plugs available which use the compression-gland approach (as usually found on N and BNC plugs) rather than the horrible type that need soldering through the hole.

Unlike the twistne grease before assembly and they'll stand 3 or 4 years outdoors without water ingress).

Why struggle with the nasty twist-and-solder types when there are better solutions available at a sensible price?

Greenpar are now part of "TE Connectivity" Their version for RG141,RG58 is part no. 1-1337473-0

Other brands do versions for fatter cables; I have sone here for RG213 and the solid-aluminium-jacket 75-Ohm 'cable-TV' coax used in the US>

[murphyv310]

Certainly agree re the nickel plated plugs. It's difficult to access quality when buying online so it's turns out a gamble. The companies I still have accounts with after closing my business do good quality ones but they are not far off the excellent Messi and Paoloni plugs and cable for prices

[G6Tanuki]

Originally Posted by Radio Wrangler

If you don't want to change the connectors on gear, fit an N-plug on the cable, and use an adaptor. This way you aren't at risk of wearing out your special vocabulary.

David

This is my approach too; I use loads of PL259-to-BNC adaptors. BNC/TNC can handle a couple of Amps of RF on the inner conductor so is a no-brainer for anything plug-and-play under 100Watts.

For my juicier stuff if I were The Shamen and this were the best of all possible worlds I would _like_ to use N connectors, but is it really needed? I've regularly shoved 200W PEP of SSB through a BNC/TNC and it's not unsoldered itself or welded the plug into the socket.

[Radio Wrangler]

The SO239/PL259 interface itself is not sealed against moisture ingress.

The gland type may seal reasonably well onto the cable, but you can get trouble with H20 outdoors. They fix the connection issue but the N-type with its integrated gasket sealing the mating of the outers has advantages for outdoor use. Even if you mummify the whole thing in self-amalgamating tape, an extra layer of barrier still makes you feel better.

David

[murphyv310]

I agree that no PL259/SO239 is immune to moisture ingress, the Messi & Paoloni plugs are excellent but I always wrap with Denso tape. Lanolin grease on the inner of the plug too.
Self agalmagating tape is one I don't use as bird's peck at it.

[beamcurrent]

The PL259 connector was the connector of choice for video in the 1946-1963 period. they were made well in those times and the broadcast world had a solution to terminating the screen.

See picture, the connector had a tapered tube at the back and the screen slid up it and was crimped with an o-ring. There was also an adaptor to convert a standard plug. The "O" ring was a standard hydrolic crimp part still widely available .

The BBC & ITV used these by the millions. We have used a lot on MCR21 (to be historically correct) and with a bit of practice quick to fit.

[murphyv310]

Hi Brian
Now that brings back memories. British Relay used these in the Equipment Room for relay TV and yes I remember fitting them in the very early 70s. We used O clips with each side they had a tang you compressed. Cracking plugs and extremely well made...... I'd completely forgotten about them.

[dglcomp]

Also used a lot for VHF wireless systems

[G6ONEDave]

These connectors were also used on the early Beta and VHS video recorders for composite video signals. Toshiba had them on their equipment for one.

Dave