Precision RF connectors: Do you measure them? Keep track of cycles? - Page 1
Forum section: electronics / testgear

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: June 11, 2020, 06:12:35 am
content: When it comes to precision RF connectors, such as higher-quality 3.5mm, 2.92mm, 1.85mm, etc, it is well understood that damage can spread as an infection throughout a lab. One damaged/out-of-spec connector when mated to another, undamaged connector can cause this undamaged connector to also become damaged. Now you have two damaged connectors that will risk damaging other connectors, etc.How do you avoid this happening? If you have a large lab where dozens of people might be using these connectors, there might be hundreds of different precision connectors, all of varying age and un-damaged-ness. Even good connectors, treated well, can through simple wear-and-tear become an issue over time. Do you have any way to keep track of this? Do you have frequent 'measure-and-purge' moments where someone responsible for this will just go check every connector in the lab, and remove the ones that are EOL/damaged from the lab environment?

author: 0culus
author_rank: Super Contributor
timestamp: June 11, 2020, 06:25:50 am
content: No specific experience, as 3.5mm is the most precision connector I use semi-regularly in my personal lab (and they are fairly robust as precision connectors go*, especially the ruggedized Maury Microwave ones), but one thing to keep in mind is that precision connectors have a *very* finite lifetime even if never damaged. You'll want to be keeping track of matings especially once you get beyond 3.5mm.If you have gorillas in your lab either (1) train them to do better or (2) keep the good connectors locked in a safe!*This does NOT apply to the female connectors that are found in HP cal kits!! These have tiny fingers inside that are incredibly easy to destroy in one moment of stupidity. These should 110%absolutely never everbe mated with an SMA male.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: June 12, 2020, 06:18:51 am
content: I'm aware of the finite lifetime, but how do you keep track of it? Any tips?In a setup with 10 different adapters, it is very easy to get them all mixed up.

author: coppercone2
author_rank: Super Contributor
timestamp: June 12, 2020, 06:24:46 am
content: increase your budget, playing chess with the equipment is ridiculous in addition to the design challenges (main focus)

author: 0culus
author_rank: Super Contributor
timestamp: June 12, 2020, 06:25:34 am
content: Simplest method would be a spreadsheet I would imagine. If you're handy with VBA you could probably automate it. If you really have alotto keep track of, I recommend an actual database instead. I believe the recommendation found in the manuals for HP VNA cal kits is to clean (high purity IPA + some kind of lint free method of wiping), visually examine (stereo microscope), and gauge precision connectors before every use. It's probably easier in the long run to just make that a habit...if you find a connector that is damaged or out of tolerance in your examination, you Widlarize it and replace it.

author: coppercone2
author_rank: Super Contributor
timestamp: June 12, 2020, 06:26:12 am
content: Quote from: 0culus on June 12, 2020, 06:25:34 amthis is just too much for a home lab, that is something you falsify at work

author: 0culus
author_rank: Super Contributor
timestamp: June 12, 2020, 06:29:24 am
content: Quote from: coppercone2 on June 12, 2020, 06:26:12 amLOL. Probably true. But the OP wanted suggestions...

author: coppercone2
author_rank: Super Contributor
timestamp: June 12, 2020, 06:35:11 am
content: dude this makes me think of battle star galactica, when the president writes on the white boards how many people are left alive in the beginning of the episodethis is seriously post apocalyptic unless you are doing it to test a new connectoreven dave bowman said fuck it and found the monolith instead of rationing some half alive starvation diet

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: June 12, 2020, 06:37:09 am
content: Quote from: coppercone2 on June 12, 2020, 06:24:46 amQuote from: coppercone2 on June 12, 2020, 06:26:12 amCoppercone, I have no idea what you are trying to achieve here. You have no clue as to the budget of my place of work, and if anything, budget really doesn't matter. It's the simple fact that when you have a setup with 10 1.85 to 2.92 adapters that all look alike, it can be hard to keep track of which ones are which, and how often they are used. We have tried using a numbering and color coding system, but in both cases, the ink wears off pretty quickly (and yes, we have tried a large number of markers, none really seem to work).I'm gonna think of how we might practically be able to keep connectors appart and track mating cycles. My main worry with something that requires the human to keep track is that when you are hooking connectors up and disconnecting them from the scope to check where your signal is failing, you will just loose count of disconnects. Same with cables.

author: DaJMasta
author_rank: Super Contributor
timestamp: June 12, 2020, 06:59:40 am
content: I don't do this because in my home lab I buy used equipment with unknown histories, so there's already a built in unknown and uncertainty that wouldn't stack up to metrology grade measurements.That said, I believe the standard way is, rather than keep track of cycles, you just regularly gauge the wear on your equipment. You of course buy good equipment and only new/verified in specification, but then you get the appropriate calibrated pin gauges and just make sure you measure them on a regular schedule.There can be conditions where you just get rid of it because of improper use (not using a torque wrench, not holding the other connector to prevent rotation when connector mating, kinking or pinching, etc.), but I think the real measure of whether it's alright to use is just the current dimensions and surface condition of the mating contacts, rather than just the number of cycles. This also means you have a way to measure the connector without connecting it to a VNA or something and risk damaging those connectors with it.