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We Need a Better UHF Connector
18 September 2015 | by 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.
8 Responses to “We Need a Better UHF Connector”
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Good post on PL259. I may try this method.
Anthony, thanks for sharing this method of attaching uhf 259’s.
I will try it.
73
Neil, Vancouver Washington
I do the pre tinning of the braid & soldering through the hole method with a high power soldering gun, but I found the trick is to clamp the connector between 2 pieces of wood with a small drill press vise. Then there’s no heat sinking action drawing all the heat from the connector. That way the heat from the gun stays concentrated at he hole your trying to solder. Plus I cut a very small piece of solder & coil it up & place it inside the hole. So when I apply the soldering gun I’ll initially have some solder melting into the braid & then I just add more solder as needed. But I agree it would be great if someone could come up with a better improved PL-259 UHF connector with weatherproofing & easier shield soldering.
There is a replacement for the UHF connector. It is called an N connector.
Crimp connectors!
In commercial and aircraft use it is very unusual to find soldered connectors.
Crimp connectors are faster, more repeatable, and less likely to damage the coax.
The only negative I can think of is that you have to have the correct crimping tool.
I have some rubber boots that slide on the coax over the connector. They do a reasonable job of keeping the connectors out of the elements. I also use self amalgamating rubber tape over the finished product.
Make sure you have the right connector for the coax, and the right crimper.
If you are concerned about the poor RF qualities of a UHF connector, just use N connectors.
I agree on the comments regarding the N connector. I’d replace every darn UHF connector in my shack with N, if amateur radio manufacturers would do it.
Joe, good ideas on technique.
Rob, the old school RF guy in me (I’m 46 hihi) doesn’t like crimp connectors, but I agree that they’re definitely more repeatable. We found this at work. Solder connectors in theory should be more reliable, but a lot (most?) people can’t solder correctly. It’s a lot easier to get 50 field guys to crimp a connector correctly than solder one. Have you had good results with the rubber tape? I picked up two rolls in Dayton this year and almost did a blog post on it. However, I got moisture under the tape on one of my mid-span coax splices. I’m thinking now of using electrical tape as a first layer and the rubber second for extra protection. I’m concerned the rubber tape alone isn’t sufficient.
On my blog K4AVU commented that he makes and sells this neat little product that crimps the solder hole area to the braid, using a standard connector:
http://k4avu.webs.com/apps/webstore/products/show/1298625
It looks interesting. (I have no financial interest in this.)
You have a choice of N and BNCs, depending on application. They are far superior in performance. I suspect the PL259 etc are used by manufacturers because of cheapness. Why they use them on UHF equipment I do not know!!!!! Crimping is often superior to soldering in high vibration environments where the solder “wicking” makes a very rigid connection in the connector and subject to vibration fracture.