Digital Station

This is my portable digital radio station, as it is as of Sunday morning. I have Winlink Express, WSJTX, and JS8Call all running the KX3. Image captured with iPhone 13 Pro Max.

A week or so ago, I was motivated to get some of the digital modes operational on my portable station. I did not bring the Digirig Mobile that I specifically purchased for the Elecraft KX2/KX3 radios with me this trip. It was one of several things left behind because I simply did not have enough time to prepare for the trip. So, I did what I always do… I bought another module.

It is not actually a waste because I will put one in each of the KX3 and KX2 go-kits. Then there will not be a (significant) risk of leaving the module behind (again).

The WSJTX software gives access to the FT8 and FT4 modes, which are useful for quick exchanges such as those for a POTA or SOTA activation, or for a contest1. I have yet to use these modes for any of those things. But I do use them when home (in the radio noise) so I can play a little radio. I have yet to use FT8 for a park activation, although that is a thing.

JS8Call is a digital mode based on the FT8 engine, but permits more text than the quick exchange of the latter mode. That is, a full conversation contact is possible along with a lot more capability. This is a potential mode for emergency communications when voice operations are not possible or not advisable. I do use this mode to make contacts when at home and the noise is too much for me to hear other stations.

Both FT8 and JS8 are called weak signal modes because the computational engines are capable of extracting usable signals at the noise floor or below. This is amazing!

I spent a good part of Saturday getting everything running and testing the results. The main issue I encountered was a change in Windows 11 that treated the soundcard (the Digirig) as a DVD device with a data rate of 48KHz. I think the software was expecting a datarate of 44.1KHz (the CD rate).

Once I sorted this problem out, all three programs worked fine. I was able to send and receive email (Winlink) via HF radio. I was able to make contacts using both WSJTX and JS8Call modes. And these tasks were accomplished with the KX3 at five watts output into the Elecraft AX1/AXE antenna. The antenna is a tiny thing that I use when there is no room to deploy something larger. It is truly a compromise antenna. Yet I was able to accomplish my goals in a noisy environment using a compromise antenna and five watts.

The next step is to get the FLDIGI suite working on my Surface Go 2 and with the KX2/KX3 radios. This is another digital software package that has a lot of capability for many modes. It will be useful in an emergency setting when other means of communication (Internet, phones) are unavailable. But, for now, I want to spend time working with JS8 so I can learn its capabilities. I also need practice with Winlink so I can get around in it efficiently.

  • Setup of WSJTX and JS8Call are closely related (use the same engine). Once one of them is working, the odds are that the other will work with only some small adjustments.
  • Use the USB mode and not the DATA mode on the KX2/KX3 radios. That is what works best, at least for me.
  • The bitrate of the soundcard is a big deal. It took some hunting to find it and I did not see it documented anywhere else. The search engines failed me in that regard.
  • Getting VARA HF to work with the soundcard can also be a bit fiddly. The sure to pay attention to the ALC function of the radio (set the audio output of the soundcard or audio input the radio carefully). Any audio compression should be turned off. I suspect the same will be true of other modems (ARDOP, Packet, etc), although I have not tried them (yet).
  • If you find you do not have enough headroom with the audio input or the audio output, an adjustment to the soundcard levels is appropriate through the Windows Sound setup page. (Which one will depend on what version of Windows you are running.)
  • I am generally good at remembering how to do these configurations once I sort the approach out. However, it is probably a good idea to get the setup procedure recorded in one’s radio notes in case adjustments need to be made under the pressure of required operations.

That is my report for this little exercise. In total, I probably spent five or six hours fiddling with the equipment and software and another few hours playing with the radio. It was an intellectually challenging exercise because there are so many moving parts. But, it was still a good day.

I also had the chance to visit with my buddy in Montana, who decided to work on some of this as well.

Maybe some of these notes will help someone else over the hump. I know there was a lot of research to solve simple (ha) problems.

Life is good.

1Yes, some contests permit use of the FT8/FT4 digital modes.

AAR Parks on the Air — K-10387 Joe Crighton SRA

This was my KX2 station setup at K-10387, Joe Crighton State Recreation Area. Shot with iPhone 13 Pro Max.

I was up early Wednesday morning to see Older Son off to work. He leaves the house about 0630h and I like to get up and spend an hour or so with him as he readies himself for the day. I have a cup of coffee and chat with him and DiL. She also gets up to spend time with him before he heads off and her day starts.

DiL runs the Springfield Barnes & Noble, so her hours are variable. She sometimes leaves just after Older Son. And sometimes she leaves much later. That is the nature of retail work. But she always gets up with him and I respect that.

After he leaves I sometimes return to nap for a few more minutes. It all depends on how well I slept the night before. As I age, I find that sometimes I do not sleep as well. I am sure my experience is not unusual.

Fortunately, my work permits me a lot of flexibility. I like that and take advantage of it.

But, Wednesday morning I warmed my cup of coffee and sat at the desk. A hydraulic model I am working on completed late last night and I wanted to review the work and decide what to do next. In reviewing the results, I had good ideas for what needed to be done. So, I got started on it. I worked until my brain rebelled, so I decided it was time to take a break.

DiL had returned to bed, so I got a shower and dressed for my day. That brought Sera out to see what I was doing. I decided I needed a waffle in my face and Sera could tell I was moving with purpose.

So, she went with me. We drove up to the Waffle House and I had sausage and eggs and a pecan waffle. I saved some of my sausage and my hash browns for Sera. She was very excited when I returned to the rig with a treat. 🙂

We drove home and I returned to my hydraulic model. I finished the amendments about noon and started a run. Once the preprocessor finished developing the solution grid and the computational engine started, I knew it would be a few hours before I had any results.

That meant — I had a few hours to play. The weather was gorgeous so I decided to get out and activate a new park. Sera and I headed out, I bought a sandwich and a bottle of water, and we arrived at the park in a few minutes. I got lunch and Sera out and we shared my sandwich and chips. She sniffed around while I deployed an antenna.

It took four or five tries to get a line over a branch. This is a new skill for me and I can tell I need practice judging where to aim to get the line over the branch I want. But the equipment I have is just about right for the light wires that I typically use.

I setup the little Elecraft KX2 with the Tufteln end-fed random wire antenna, connected directly to the radio. I brought a small Bioenno LFP battery, which I connected. I also brought a N3ZN key along as well. It took longer to get the antenna setup than any of the other equipment.

I had a cellular signal, so I was able to spot myself on the POTA website with my iPhone. I also used my iPhone to log contacts with the HAMRS app. I find it easy to log on the iPhone, although I am sometimes a bit fumbly and fat-finger the text.

I have a CQ message stored in the radio, so I set it off to call while I finished getting ready to take calls. And take calls I did. Even running just five watts of power, I worked a pile-up on the 20m band for nearly 45 minutes. When the hole was fished out, I changed to the 17m band, found an open frequency, and started calling. The Reverse Beacon Network picked me up and the POTA scraper respotted my activation at the new frequency.

I worked another pile-up for another half hour or so.

One thing I noticed was that my passband was a little too narrow. I had it set that way during my last activation, probably trying to improve the signal-to-noise ratio or because another operator work working on a nearby frequency. Nonetheless, I could hear a couple of station outside the passband, so I opened it up a bit so I could copy the signals and worked those callers too.

After a couple of hours, I had 32 or 33 contacts in my log, plenty for the activation. The sun was starting to get low in the sky and I still wanted a walk before the day ended. I also needed to attend to the model run and see what needed to be done, if anything.

It did not take long to recover the station and we were off towards home.

When Older Son arrived, we got The Girl out for a good walk. We got home just after the Sun fell below the horizon.

As usual, I learned a few more things.

  • Using an arborist throw kit is a learned skill. I need more practice to get the weight and line over my target branch. It is just practice.
  • I really like the lighter throw weight and the 1.7mm or 1.8mm line that I got on my second buy. The first kit is too heavy for what I do. The lighter kit will be perfect for the light wires I use and is a lot less weight and bulk to carry, should I decide to pack the kit in.
  • I need to work with the Tufteln EFRW antenna more. I could not get a good match on the 30m band (10MHz) with the KX2 and the EFRW antenna connected directly to the radio. This should work. I have an adjustment to make, I think.
  • The little KX2 is a fine radio for this kind of application. It is not as good as the larger KX3, but it is a lot smaller rig.
  • I should have used headphones for the activation. There was enough traffic noise to be distracting and interfere with my ability to copy the calling stations. I do not like to be isolated from the surroundings, however. So I have to get my powered headphones setup to wear while running the radio. They are also active ear protection, so they have microphones to provide situational awareness with control over the balance between communications and environmental sound levels.

All in all, it was a good day. I am grateful. Life is good!