The Entire Universe, Divided Into Two Parts
As we search for absolutes amidst the variables and vagaries of life, we find that there are few real truisms. Here’s one in our field:
|Click on the Image to Enlarge
A graphic from InterPower Source magazine, which has been running an interesting series on plug standards.
The entire universe is divided into two and only two parts: connectors and adapters.
I was reminded of this by a headline in a newsletter from Interpower, a firm that specializes in power cables for supplies and general power interconnect. It read:
“21 Plug Standards and Counting”
And these folks were talking only about international power connection plugs for small loads!
Seemingly forever, Arrow Hart graciously has provided us practitioners in the power industry a nice desk protector that annotates, visually and numerically, the spectrum of single- and multi-phase power connectors through 60 amps. One side has straight plugs, like the typical wall outlet, and “lockable” (which we should make to read as “twist lock”), while the opposite side has ring lock type. Some 60 connector types are listed — and we’re just talking about power.
If we stray into data and telco, we can add another plethora of options. Audio, video, standardized (and I use that term loosely) control system connectors … and we’re picking up speed to pass hundreds more devices that wind up on cable ends.
In these realms we have connectors for all seasons and reasons.
And then there’s RF.
Oy vey, carumba, holy frijoles, ahhhhh ja … In RF, the connectors are a’plenty and the adapter permutations are endless.
Let’s start a separate list of the most common.
Ham and CB use made the lowly UHF/PL series recognizable even to the least technically oriented appliance operator.
People got tired of all that screwing on PLs; and the BNC (B for bayonet) — with its half twist and compact connection — gained traction.
Cable TV and the ubiquitous VHS or CD unit made the “F” connector as familiar to Americans as hamburgers.
Early “bag” and handheld cell phones introduced the specialized “SMA” connector to first adopters.
As spectrum use crept to SHF, the “N” connector surged into use until design competition and cost pressures brought the DIN series of RF connectors from Europe and Asia to the U.S.
DIN! DIN has doubled the RF connector count and quadrupled (as a minimum) the collection of adapters you need for flexible connection of test gear, antennas, devices, etc.
My introduction to adapters was in Father Kelly’s physics class, when I was president of my preparatory high school’s radio club. He let me borrow a nice but unbelievably heavy World War II-surplus Army Signal Corps RF signal generator to align some receivers. In it were about four adapters to go between the two sexes of UHF and BNC.
I well remember Fr. Kelly’s admonition to me not to lose any of those adapters; they were hard to find, and their loss would limit the use and flexibility of the generator.
Wow, have things changed.
Before I came to my senses and got out of the field service business, my Subaru wagon was a rolling toolbox of tools and test gear. One box that traveled with me (and is now in the shop) is a medium-size chest containing a Bird Wattmeter, a counter and about a hundred (I’m not kidding) adapters. Though many are duplicates, we’re talking about a massive number of necessary adapters — some of which are really expensive.
Just to mention a few that are used most often: N male to BNC female, DIN medium male to BNC female, SMA male to N female, BNC male to BNC male … and then the special cables to go cross-series, such as to get baseband digital signals into your low end spectrum analyzer …
If you’re new to this, you’re beginning to get the picture. If all this is familiar to you, you know I’m emphatically with you.
Yet even with years of gathering all those adapters, all those permutations of sex and type, all those odd and strange jumpers … up on those high mountaintops after miles of travel, at challenging broadcast sites, in the wee hours of the night … it always seemed that one never has the right adapter.
Life is cruel.
Charles S. Fitch, P.E., W2IPI, is a registered professional consultant engineer, broadcast consultant, licensed master electrical contractor, former radio station owner and former radio/TV director of engineering. He writes the columns Certification Corner in Radio World Engineering Extra and Milestones in Radio World.