If you have been an electronic engineer for a while you know that you cannot escape the nightmares of too many types of cables and connectors. There are millions of each and if you are like me you never seem to have one that you need. There are power cables and connectors, RF coax cables and connectors, TV and video cables and connectors, audio, microphone, and speaker cables, and a whole slew of test instrument cables and probes. Oh yes, fiber optic cables and connectors. How about AC power cables too including 3-phase? What did I leave out?
A typical situation for me is setting up to test a design or some piece of equipment. It needs to be “hooked up”. You may need a power cable first or maybe that is just an AC cord. Great, now just be sure you have a power strip with an empty slot to plug it in. Then there are input and output cables. These are often coax. How many different kinds of coax are there? And, of course, the dozens of different kinds of coax connectors. I never seem to have just the right type of cable or connector. Or as it often turns out, not having a long enough cable. I regularly keep several types of coax connector adapters to change BNC to UHF or UHF to N-type and so on. Very useful.
One thing I have stopped doing is making my own cables, unless they are extremely simple, like a speaker cable or some hook up wire. Trying to attach a coax connector to a cable is a tedious process and fraught with potential shorts and opens. And you typically need a special crimping tool that costs more than the cable and connectors you are trying to assemble. Did you ever try to put an RJ-45 Ethernet connector on a CAT5 cable? Fun, fun, fun. Anyway, I now buy preassembled cables with connectors. They cost more but it saves time and massive aggravation.
Someone once told me that I shouldn’t be fooling around with cables and connectors, that’s what technicians were for. There is some truth in that as early in my career I worked as a tech and spent an inordinate amount of time screwing around with cables and connectors. But where have all the techs gone today?
Then there are the special cables that go with test instruments. Scope and analyzer cables are special cases. They need to match the instrument. Furthermore, at very high frequencies and data rates, special probes are needed to get accurate measurements. And these cables and probes are really expensive. I had to replace the probes on my old Tektronix scope not too long ago and they cost more than what the scope is probably worth today.
It was all so easy in the olden days. Hook up wire, banana jacks and plugs, alligator clips and fahnestock clips. (Whatever happened to fahnestock clips anyway?) No more. We still do have screw terminals, F-connectors, RCA “phono” connectors, punch-down blocks and DB9/DB25 connectors. Those Centronics parallel printer cables did go away.
When you are designing new equipment how do you select a connector? Thankfully most use standard types like USB, HDMI, or some coax type. But what about PCB connectors, power connectors, or inter-PCB connectors on wiring harnesses? Lots to choose from. One more thing they don’t teach you in school. There needs to be course or webinar on cables and connectors. Catalogs are helpful but they don’t tell you which one to choose.
I guess we all experience cable and connector hell at one time or another. It is just one of the many not-so-much-fun aspects of design and test. And by the way, what connector does one use for a JTAG port?
