Dual radio POTA activation? Sure!

Today I setup both the Ten Tec Argonaut V as well as the sBitx V3. This was because i was not sure if the sBitx V3 would hold up the entire time. You see, it has had an ailing 5 volt regulator for a while and I was planning on replacing it later today, but first… POTA!

So I go to US-2169 and setup in my usual spot and get out both radios so that I can work CW on the Ten Tec if the sBitx flakes out on me. It didn’t, but since I had already gotten it out, I used the Ten Tec Argonaut V anyway and worked what CW I could with it. You see, today was another day that I stayed above 20 meters the entire time. That was the plan from the outset and it was quite successful too. I love using 15 meters in particular since it goes over seas easily for me. I will usually work several DX stations if the band is open and today is no exception. I worked 5 DX stations over an 18 minute span of time, not bad for a 15 watt radio… I worked so much FT8 is short order that I almost didn’t need to setup the CW station at all, but I wanted to work some CW anyway so I just got on the air with it and this is how it went.

The operating position was a little crowded today but not too bad, I used the hard case for the Ten Tec Argonaut V as a table of sorts to sit the radios on so I was able to move them back and out of the way of my writing surface. This left plenty of room for the nanoVNA and my other small items I use when activating a park. I have gotten really comfortable with setting up like this, I can set this up in just minutes and it requires zero use of the park infrastructure (such as trees or picnic tables) over the parking space I would consume either way and some space for my radials.

So in a previous blog post I had mentioned that I was going to use the smith chart on the next outing to show how you get way more information about the antenna under test with it instead of the simple SWR graph and here it is. Contained below is the 15 meter plot from 20.5mhz to 21.5mhz and the marker is resting at the upper limit in the photo. The center line across the chart is purely resistive measurements, anything above this line is inductive and anything below this line is capacitive in nature. As you can see on the display, the line representing the span I am looking at, 20.5 to 21.5mhz, is all above the line showing that my antenna system is inductive in nature so it will have some inductive reactance to the signal. The very center of the chart where the smaller circle intersects the line is 50 ohms - resistive (right below the flag from my measurement). As you can seem the further you move away from this point, the further from 50 ohms you get.if it were to be something like 100 ohms, you would need a 4:1 transformer to correct the impedance mismatch, this is why antennas need transformers. The characteristic impedance of the antenna is not usually 50 ohms which is what the transmitter is designed to see.

In the second photo I have switched the chart over to a simple SWR plot versus frequency and you can see how it is easier to read for the lay-person. It does give you the data you need in the firld really quickly and make it easy to know if your antenna is short or long and if your radials are good to go and such. This is what i use most of the time in the field to just make sure the antenna is presenting a good load to the transmitter.

In the above photo I learned something strange about the sBitx today. The two clocks don’t have to be synchronized to work. FT8 is not time forgiving, your radio time marker has to be fairly accurate (within so many milliseconds or maybe a second or two max) or it wont make connection at all with the other stations. As you can see in the lower photo, FT8 worked perfectly and I made several contacts with this mode so the computer clock must not matter at all… I don’t know what is going on here but it works so I dont question it.

Today saw a bunch of DX early on which always makes my day. But all in all it was a great day for POTA and I was stoked to get 21 calls in the log. Until next time, dust off that key or microphone and see if you can get a park or two into the log.

David

Digital only POTA Activation using FT8 on the sBitx V3

So today was a good day for radio. I had a block of time and wanted to see how hard it would be to get the activation only on FT8. I know it is possible to do this, but I also wanted to do it on 15 meters too and that is where the problems come in. You see the last couple of weeks have been tough for 15 meters operations what with the solar flares and CMEs and all. So to secure the activation on the higher bands will be… interesting…

I get to the park and in the spirit of time savings I chose to go to Sitton’s Gulch which is significantly closer and saved me almost and hour of driving (well, 40 minutes as it is 20 minutes on to the operating position at the top of the mountain and another 20 back to the point at the bottom). I also was happy to see the parking lot was almost empty too. This gave me to opportunity to setup in the corner next to the changing sheds which is a good corner for my antenna radials. This gets them out of the way so that people dont trip over them going to and fro…

I set up in short order for the 15 meter band and get started calling CQ. I call for several minutes and then switch over to answering CQ calls that I see in the waterfall for a few more minutes with zilch to show for it. Literally nothing. I am starting to wonder if there was some sort of flare that I was not aware of or some such as that as I was getting stations into the radio but no one could hear me. I chalked it up to that they must have been running a kilowatt and my paltry little 12 watts into a compromise antenna just wasnt getting it done today.

One of the things that I like most about this radio is the clean layout of the FT8 mode. It is not cluttered with an endless array of different information and on screen settings. The other programs, while very versatile and powerful, are rife with buttons and information that really is not needed for simple QSO contacts. The sBitx could be a little easier though so it is not perfect either. One thing that has come up a couple of times is that it needs the ability to be able to sort the information display to just stations calling CQ so you can pick one easier. I agree with this as it can be tough to grab a calling station in that 2.5 second window of time. So being able to sort by CQ would be a big help there. One other thing that is mildly frustrating is that there is no way to scroll the display so if there is a lot of stations on the band then you will not be able to see them all. It pushes them off the top of the screen and then they are just gone.

Today though, there was plenty of room to see both even and odd stations so it was not a problem. I was glad to see there was a good amount of activity on the 17 meter band.

The truck cab sure it a convenient operation center for POTA!!! I find it almost perfect to be honest. It is so close that I have used it all winter without modifications but at some point I do think I want to modify it. I have been considering the Kenwood TS480 as a permanent installation in the truck just for POTA, but then I would still need either a computer or the sBitx to operate FT8 in thr fireld. This just circles back to using this radio like you see in the photo below till something better comes along.

Here is the antenna setup for today along with the nanoVNA I used to measure it while I “tuned” the system. Tuning literally involves just moving the radials around till the SWR reads as low as possible. Sometimes it involves adding another radial to the system to get the SWR below 2:1 (which is my personal high limit) and I have even done odd things like run one REALLY long radial way out to give the lower bands a chance at working. This has worked really well too when I want to use 40 meters with a hamstick.

To answer some obvious questions that will show up, yes, there are two nanoVNAs in the box…long story but I have two now. Haha. The case came from GigaParts as they had a bunch of them at the Huntsville hamfest one year for super good prices and I got a couple of them. This one houses the nanoVNA and multimeter and the other holds all my POTA radials. You can see it above on the truck bed cover. I plan to get more of these at some point as they are super useful containers for small equipment like you see here. That is why I wrote on the lid of the yellow one, plus it identifies it as mine as that is my handwriting too.

As you can see though, I had a pretty good run on 17 meters FT8, securing the successful activation just in this mode alone. I never like to stop at just ten so once I had worked everyone I could hear I moved down to 20 meters and worked two more there before calling QRT and packing up. 20 meters is the campground of POTA these day and if you want to simply claim a quick activation then go there, it should not take long to get your ten if you are pressed for time. I know some people do activations on their lunch break and 20 meters is great for that. If you want a bigger challenge though, move up to the higher bands. Seems here lately that when 15 meters is open I will work a ton of dx stations and the lower I go in the bands to closer to home the stations. So if you have not ventured higher in the bands, I recommend you give it a shot sometime, you will most likely be pleasantly surprised

WK4DS