Is a 20m Antenna also Resonant at 2.4GHz?

In a previous post I wrote that I would be adding SSB and Data capabilities to my recently constructed plastic “ammo case” go-box for operations out in the Big Blue Sky Shack. Those modifications were completed much more quickly than I had anticipated.

I am primarily a CW operator and have no immediate intention to operate phone/SSB mode. I also have no immediate intention to operate data modes. But, it seemed like a good idea to complete my go-box project to provide the ability to use those modes – perhaps for a ham radio demonstration, or a club POTA activation with others who don’t use CW.

DATA Connection

Let’s discuss data modes first. The primary purpose of adding a data connection was to enable me to use SOTAmat for self-spotting on the POTA website. It is unlikely that I would need this connection for any other purpose. That made data connectivity very simple. The data connection comprising a VK3XJM interface circuit, that I purchased many years ago when I was using my Yaesu FT-817 for PSK-31, is a tiny circuit board with a cable terminated in a 6-pin mini-DIN on the radio end and another cable with a 3.5mm TRRS plug for connecting to a phone or tablet on the other end.

The entire device tucks neatly inside the go-box with the radio end plugged into my FT-891’s data port. To use it I simply open the go-box lid, grab the cable, plug it into my phone and send my self-spot over HF using FT8 via SOTAmat. Then re-stow the cable, and close the go-box lid. Job done.

Wired for Sound

If I were to use phone/SSB mode, I would need a jack to plug in a microphone without opening the go-box. So I climbed into my truck and drove off to the hardware store to buy a panel-mount RJ-45 jack. It was a very small investment but it led to a couple of challenges.

First, these jacks are designed to snap into a very precisely cut hole in a domestic outlet face plate. Unfortunately I didn’t have the tools to make the precise cut needed so I ended up using the previously cut hole where the battery cable exited the go-box. With a little bit of fine filing and a small bead of hot-melt glue I secured the jack in place. It isn’t terribly elegant but it’s not too bad, and it works.

The second challenge was that there are two ways to wire these jacks; “wiring scheme A” and “wiring scheme B”. I knew that a standard CAT-5 network cable is all that is needed for a Yaesu MH-31 microphone, but I had no idea whether I needed “wiring scheme A” or “wiring scheme B”. The solution was fairly straightforward. By examining the plug end of my network cable I determined that wiring scheme B would be the correct choice. The short cable was cut from a longer cable that previously had an RJ-45 plug on each end, so the far end was just four twisted pairs of wire. It was a simple job to match the wire colors with the colors printed on the jack. A small plastic punchdown tool was included with the jack so the job was soon completed. I haven’t used it yet, but my jack wiring did pass the smoke test and all functions of the mic work as expected.

I had to relocate the battery cable and came up with an innovative idea. There is a benefit to using a plastic box, combined with the use of a Weller soldering gun with plastic cutting tips. I was able to form a small cavity that neatly and firmly holds a pair of Anderson powerpole connectors in the side of the box. It works well.

First POTA Activation with the Plastic Ammo-Case Go-Box

We had a nice period of mild weather last week so I used the opportunity to zip up the Bruce Peninsula to Black Creek Provincial Park on the shore of Lake Huron. Black Creek is a small, secluded and beautiful park with a great sandy beach. I set up my 17ft whip and go-box radio on a picnic table facing the water. The activation went well – actually better than several other recent activations with one amusing moment to remember.

“Can You Get WiFi on That?”

There were a few other people on the beach and my setup attracted the interest of several of them. One lady who had been watching from a nearby picnic table came over and, looking at my antenna, inquired if I was using it to get WiFi. Interesting thought: is a 17ft whip designed for 20m also resonant at 2.4GHz? She made me smile.

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