Assortment of connectors - how do you deal with "standard" connectors? - Page 1
Forum section: electronics / general

author: tkamiya
author_rank: Super Contributor
timestamp: September 15, 2018, 05:35:48 pm
content: I have a problem in my lab concerning huge assortment of RF connectors used in equipment.When I open an equipment to test, or have cables to test, type are not always SMB, BNC, N type. Those are pretty common and I have converters back and forth for them. But I also see, less frequently, SMA, SMC, TNC, an odd Japanese type, subminiature nothing connectors, etc.There are A LOT when I look at what's used on cables.There are even more when I look at module output and input.There are even more when I include what are found on PC boards.To make it worse, some connectors are excellent, some are questionable. I don't want to connect some of my good connector to these. However, cheaper connectors with crappy coax won't allow me to take meaningful measurement.How do you deal with this? How do you have GOOD quality (Instrument grade, not calibration grade) and consumer type for every single cable type? I'm deeply into repairs. Mostly test equipment of various quality but I also deal with consumer stuff. And some are from China and they were cheap. Connectors are really awful.Stuff I deal with are mostly 50 ohms.

author: JS
author_rank: Frequent Contributor
timestamp: September 16, 2018, 04:28:11 am
content: Soldering on to the pcb!A usual probe, dirt cheap and serious high freq in my world (like 1GHz or close, that's dc for others) is a good quality, thin 50Ω wire with the right connector in one end for your test equipment and correctly terminated inside the equipment or with a pass throu load, at the other end, a resistor (1k typ) 1% MF TH type, one lead soldered to the central wire and heatshrink up to half the resistor body. The other lead is your tip, you could cut it shortish but save some length to probe confortably. The shield is the ground connection of course, but you might want to use a lead from a TH to make the connection there to the PCB and add some heatahring to taste. It has a name I cant recall but I think searching for resistive probe will give you the answer.1k makes for a 21X probe, you could use a 950Ω or 450Ω for 20X or 10X probes. Going too much lower or too much higher can bring other problems.With this probe the capacitive loading is really low, the sensitivity for ibductance of the leads is low and the inductance is also low. So, for HF 50Ω lines you can tap without loading too much and have pretty good measurements, and cheap.Expensive active probes provide much higher input impedance, lower attenuation but getting the frequency reaponse of thus is darn expensive. They also come with solderable tips or accesories, as well as other options. Probing with a conector means you can't have the circuit in the working conditions, with it's usual load which could be causing the issue. If you need to test it without the usual load you could add a load or just have a similar wire without the 1k resistor in place, just the wire with the leads.Hope this helps!JS

author: tkamiya
author_rank: Super Contributor
timestamp: September 17, 2018, 07:48:21 pm
content: Thank you for your input! Yes, direct soldering is an option sometimes. It is a must if I am working with inter-stages. But, I often have to measure what's coming out of a port. So I was more interested in having some kind of scheme to accommodate dizzying array of possible connectors.Right now, I'm collecting short piece of harness (with different connectors on both end) and converters. I was wondering what more experienced people do.Anyway, thank you for your reply!

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: September 18, 2018, 07:42:42 pm
content: My answer is just a dizzying array of adapters, all purchased surplus as I'd go broke otherwise. I also make up custom cables if something seems to be needed often. Make a cable a week and in a year you'll have 52!