We Need a Better UHF Connector

The venerable UHF connector was developed in the 1930’s.  It has withstood the test of time and for the most part is a good connector for HF and VHF applications in amateur radio.  It’s fairly inexpensive, has somewhat intuitive assembly, and is mechanically robust.  From an RF perspective it’s not bad at HF and VHF, but despite the UHF name it exhibits an impedance bump at UHF frequencies and is usually avoided for UHF applications.

The UHF connector suffers from two problems, in my opinion.  One is that it’s not weatherproof.  You absolutely, positively should not have a UHF connector outdoors without weatherproofing.  If you do not weatherproof it, you will have water intrusion into the connector and probably into the braid of the coaxial cable.  Weather. Proof. It.  Connectors like the N connector  (a very common connector in commercial RF applications) which sports rubber gaskets on the mating surface and within the body of the connector are weatherproof, although it’s still advisable to use weatherproofing with the N connector.

The second issue is the difficulty in soldering the braid.  The holes in the body of the UHF connector expose the ground braid and you’re supposed to solder through these holes to make a positive connection between the braid and the connector body, and provide mechanical strength and stability.  Some folks pre-tin the ground braid before inserting it into the body, others do not.  You need a high wattage iron to do this properly and the heat required can melt the dielectric in the process.  I think many people don’t solder this well and some avoid doing it at all.

K3LR demonstrated an alternative method of soldering the braid to the PL-259 in this video:

I’ve tried this technique and for the most part it works.  (I prefer to use heat-shrink tubing around the exposed soldered braid.)  However, as you can see from the video it’s not pretty as it requires increasing the diameter of the dielectric with electrical tape, and there is not a snug fit between the connector body and the soldered braid and the coax jacket.  This technique in my opinion does provide a better braid electrical connection than most mere mortals can accomplish using the proper solder hole method, as the connector is intended to be used.

I think a PL-259 connector needs to be designed for this technique.  The body of the connector should have a smaller inner diameter in order to fit the diameter of the RG-213 dielectric.  The outer part of the connector body where the braid is soldered to it could be of a smaller diameter as well and perhaps have a gnarled surface in order to promote better adhesion of the solder.  I would like to see some sort of rubber gasket employed with the threaded sleeve for some weatherproofing, however I can’t think of a good way to implement this without affecting the electrical connectivity to the body.

Unfortunately I’m more a software guy and not very good at fabricating metal parts.  Someone with manufacturing experience could probably design this connector and perhaps make a small fortune.  It’s problem waiting to be solved.

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8 responses to “We Need a Better UHF Connector

  1. Yes, I agree with you that it is time to get a replacement for the PL-259. Many manufactures probably will not change from a SO-239 .
    I have solved the problem of soldering the shield of a standard PL-259 connector. I manufacture a crimp tool that crimps the shield on all !/2″ cables and the smaller cables with the proper adapter/reducer.
    You can check it out my web site. http://www.k4avu.webs.com. 73, Paul K4AVU

  2. Hi Paul. That crimper is a good idea. Do you recommend tinning the braid prior to inserting the cable into the connector and crimping?

  3. When I was in the Navy and maintained aircraft we still had some birds that the Avionics was old enough that the PL259 and RG8 was still used. The problem with water (salt) was big. We used a compression type PL259 that was like the type N connector and it was water tight. I looked and found this site that sell them for LMR400 Rg213 and RG8 as RG8 has the same dimensions as the LMR400 take a look: http://www.aliexpress.com/item/5xUHF-male-solder-connector-for-LMR400-RG213-PL-259-Clamp-type-wholesale/902101332.html

    Timothy R, Peck

    CPO, USN, DAV ret.

    Date: Fri, 18 Sep 2015 22:51:52 +0000 To: wa0psq@arrl.net

  4. IMHO, The biggest problem with the UHF connector is the problem that unless the collar is screwed down tight the connectors are intermittent! As far as soldering the braid goes, I have seen the light, and I only crimp PL-259s now. It is true that the crimp tools and strippers are expensive, but what’s your time worth?

    Crimp N connectors might be better, except they don’t fit in my radios.

  5. Hi Anthony, there are compression versions of the UHF / PL259 connector ie same as the N types you described. I have used these and they and they work well. Also there are crimp versions of the UHF / PL259 connectors. By the way I really enjoy reading your articles. Thank you. 73 Clive GW0PPO

  6. I wholeheartedly agree, it IS time to replace the PL259/SO239 combo.
    The four major difficulties with them are described above, uncertainty with the locking ring; No waterproofing; flat response to ca. 200MHz; and those awful holes to get solder through.

    Ok. the newer types with compression sleeve or gasket help a little but I much prefer the N types, TNC and BNC I use professionally. Either crimped or compression sleeve techniques. But can one re-use a crimped connector??

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