Foundations of Amateur Radio

One of the questions you're faced with when you start your amateur journey is around connectors. You quickly discover that every piece of equipment with an RF socket has a different one fit for purpose for that particular device.

That purpose includes the frequency range of the device, but also things like water ingress, number of mating cycles, power levels, size, cost and more.

As an aside, the number of mating cycles, how often you connect and disconnect something is determined by several factors, including the type of connection, manufacturing precision and the thickness of the plating. That said, even a so-called low cycle count connector, like say an SMA connector lasting 500 cycles will work just fine for the next 40 years if you only connect it once a month.

Back to variety. My PlutoSDR has SMA connectors on it as do my band pass filters, my handheld and one RTL-SDR dongle. The other dongle uses MCX. Both my antenna analyser and UHF antenna have an N-type connector which is the case for my Yaesu radio that also has an extra SO239 which is what my coax switches have. My HF antenna comes into the shack as an F-type and nothing I currently own has BNC, but stuff I've previously played with, does.

When you go out on a field-day, you mix and match your gear with that of your friends, introducing more connectors and combinations.

Invariably you acquire a collection of adaptors. At first this might be only a couple, quickly growing to a handful, but after a while you're likely to have dozens or more. My collection, a decade's worth, which currently includes more than 25 different combinations is over a hundred individual adaptors and growing.

For most of the time these have been tossed into a little tool box with a transparent lid, but more and more as the collection and variety grew I started to realise that I was unable to quickly locate an adaptor that I was sure I had, since it had been used in a different situation previously.

In addition to coming to the realisation that the reason I couldn't find a connector was because it was still in use, I began to notice that I had daisy chains of connectors.

For example, my HF antenna has a PL259 connector that is adapted to an F-type connector with an SO239 barrel, a PL259 to BNC and a BNC to F-type adaptor. At the other end of the RG6 coax that runs from outside into the shack, the reverse happens, F-type to BNC and BNC to PL259. If you're counting along, that's five adaptors to get from PL259 to PL259 via F-type.

At this point you might wonder why I'm using RG6 coax. The short answer is that I have several rolls of it, left over from my days as an installer for broadband satellite internet. RG6 is very low loss, robust and heavily shielded. Although it's 75 Ohm - a whole other discussion - in practice that's not an issue. What is a problem is that the only connectors available for it are F-type compression connectors. To get those to PL259 requires a step sideways via BNC.

My point is that the number of adaptors is increasing by the day.

I should acknowledge the existence of so-called universal connector kits. The idea being that you go from one connector to a universal joiner and from that to another connector. Generally these kits have around 30 connections, giving you plenty of options, but in reality more often than not, you only have half a dozen universal joiners, so your money is effectively buying you half a dozen conversions, great for a field day, not so great for a permanent installation. You could build your own collection and use something like SMA or BNC as your universal joiner, which is something I'm exploring.

To keep track of my collection, recently I started a spreadsheet. It's essentially a list showing the number and types of connections. If you make a pivot table from that you'll end up with a grid showing totals of adaptors you have.

You can use this grid to fill a set of fishing tackle boxes and all of a sudden you've got a system where everything has its own place.

If you start this process you'll quickly notice that the table only needs to be half filled, since a BNC to SMA is the same as an SMA to BNC adaptor. This leaves you space to do some fancy footwork where the bottom right hand of the triangle can fit into the top left of the empty space, but I'll leave you to figure that out.

My table also includes things like TNC and MCX adaptors, but I don't use those very often, so at the moment I'm putting them in their own box together with T-adaptors and other weird and wonderful things like FME and reverse SMA.

For setting the order, I've gone for alphabetic, but if you have a better suggestion, I'm all ears. My email address as always is [email protected].

What ideas have you come up with to organise the chaos that is your sprawling connector library?

I'm Onno VK6FLAB