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My 17 meter band pass filter and POTA…
Today I met up with some other hams that routinely go out together and activate POTA parks and was able to fellowship with them for a while before and after I made some contacts. There was (Jonathan Frye AA6H, Allen Padgett KN4FKS and Danny Wooten AG4DW) and they were running what appeared to be FT8 and SSB stations today. Allen and Jonathan were operating SSB the whole time and made quite a few contacts themselves. It was kind of neat to plug in the nanoVNA and see one of the other stations transmitting and messing with my antenna reading and when they stopped I could see the graph again! HAHA!
I built this band pass filter after having a couple of activations with my friend in Florida, Chas (NA2B). We were is such close proximity that if I didn’t have a bandpass filter for the band I was working, I simply couldn’t hear. The sBitx is notorious for front end overload and when the antennas are just a few yards apart, you are going to get front end overload! Well, on the bands that I had bandpass filters for, I had no issues, it was only the bands I lacked filters that I had a problem. It is pretty easy to find bandpass filters for the non-WARC bands, but WARC bandpass filters are kinda rare.
Well, I never let that stop me before…haha. A while back I went down the rabbit hole of wanting to make my own bandpass filters and I figured I would start with the 17 meter band since it is harder to find. I now own a spectrum analyzer with a tracking generator so I can sweep the filter in real time to see what tuning does to the filter shape. That is kinda awesome in its own right, but you could easily do the same thing with a nanoVNA too.
So here is the current iteration of the 17m bandpass module I built. IT sure looks like I home-brewed it, doesn’t it? HAHA! That big inductor It is a classic Pi design with an inductor and capacitor in parallel to ground at the front and back and a series inductor and capacitor in the middle. The input capacitor is underneath that massive 5.31uH inductor in the middle.. I taped it to keep the coils from moving around while I tuned it and then put the ziptie on it to hold the coils in place once I got it like I wanted it. I pulled the values for this filter from the internet off of one of the many website calculators that are out there…I don’t remember which one though… It has been a minute…haha.
Adding this filter literally stopped all the 20 and 40 meter signals that I had from my neighbors today. It isn’t even all that great of a filter, it does have decent rolloff, but it isnt some knife edge vertical skirt filter. I grabbed a quick photo of the plot on my nanoVNA with the marker on the 20 meter band. I have a little more insertion loss (mine is 1.3dB as compared to a commercial unit at about .65dB), but it works almost as good as one that would cost 200$ and I have about 10$ in it. The filter was even better on the passband before I put it in the chassis. Since I used open air coils, they are interacting capacitivly with the aluminium body to ground. This added capacitance increased the passband insertion loss about .6dB, but it is so clean, I chose to just leave it as is and use it for now. The 20 meter band being over 40dB down compared to the 17 meter band, I was able to setup right next to Danny, who was on 20 meters at the time, without him coming into my radio at all from what I could tell. All the lower bands past 20 meters are lower than that too, so all of them are pushed out of the way so to speak. The higher bands are interesting to me. Before I mounted the unit in the aluminium chassis, it fell off on the high end too. Once mounted it looks like it is about 35dB on 10 meters and about 20dB on 15 meters, which is still good. Another problem that I encountered wtih the added capacitance is that it moved the passband up some. I had it to where the high side of the passband was right at the end of the 17m band before I mounted it. This gave me more attenuation on 15 meters, by probably 6dB or so, but you use what you have and move on with life… This would have also raised the 20 meter rejection some as well, by probably about 6dB or so.
This band pass filter project looks really simple.. The aluminum box, the two BNC connectors, some 16ga magnet wire, three capacitors and a piece of pc board material for a build plane and I am good to go. I lost the lid to the aluminum box hence no cover, but it appears to work just fine like this so I used it. It turns out that if you use toroid inductor cores, that this is a lot easeier to build as the toroids are LESS affected by the chassis ground plane. Notice I said less… they will still change values, just not as much as air wound inductors like I used here. I deliberately chose air wound inductors due to their high Q, which is what gives me the sharpness to the skirts you see in the plot below. I have it marked with “IN” and “OUT” but I honestly think it doesn’t matter which way it is inserted into the feedline as long as it is there. Another benefit of adding a passband filter is that is works both ways, it keeps out stray signals from strong nearby sources and it also only lets the part of your signal LEAVE that will fit through the passband. This makes a huge difference in your signal purity as you are adding a filter to the output of your radio.
Today I met up with some other hams that routinely go out together and activate POTA parks and was able to fellowship with them for a while before and after I made some contacts. There was (Jonathan Frye AA6H, Allen Padgett KN4FKS and Danny Wooten AG4DW) and they were running what appeared to be FT8 and SSB stations today. Allen and Jonathan were operating SSB the whole time and made quite a few contacts themselves. It was kind of neat to plug in the nanoVNA and see one of the other stations transmitting and messing with my antenna reading and when they stopped I could see the graph again! HAHA!
You can see the antenna right behind Danny’s (AG4DW) truck looking out the windshield of my truck today and I moved as far away from the other people as I could muster without driving in the yard… This area is really small to be fair. It just doesnt have a lot of room to setup too many stations. In reality I was probaby the last one that could fit without too much trouble being caused by other radios. Now that doesnt mean this park is overloaded with three stations. Not at all! There are 5 other locations to set up radios that I can think of right off hand with out even trying hard so we could setup several sites at this park very easily. Now, that turns it into something else thoguh, that might be enough activity to trigger the need for a permitted activity, but I dont know. I normally just hand out wtih these guys or go by myself for the most part so it is pretty low key like that.
Those band modules in the above photo are a precursor to what I did today. I opted to stay on the higher bands no matter what. I knew I could land the activation with FT8 and CW, but I had no idea just how hard it would be…haha. This poses a good challenge though as I know I can easily land the minimum ten QSOs to get the activation if I just start on 20 meters but lately the bands have been up and down and have been real inconsistent on the higher bands so to get my ten would take a bit more work on my part. Challenge accepted!
So, natuarally I started on 17 meters…haha. I actually planned to work my way up to ten meters, hence all those band modules you saw earlier. I found W1AW operating CW on 17 meters and busted his pileup to get in their log! That was my first QSO of the day too, I knew right then that it was going to be a good day. As you can see in the photo above, the station was setup in the truck cab to keep me out of the sun as much as possible. I also was using the Begali Traveler key and the HamGadgets Pico keyer as well. Also if you will notice, I dont have the common mode choke installed today. I was testing to see if getting the SWR below 2:1 made using it irrelevant or not. I had really good SWR all day at the radio so I dont think I need this thing adding losses to the system when I was having a good showing on the radio. (It is the thing laying next to the radio in the background.) Do you use one every time you go out or is it something you dont worry too much about? I ran this one through the nanoVNA and it said it had from -.06dB to -.19dB of loss just inserting it in the line. Look at the chart below to see what it looked like across the HF bands for this common mode choke on the nanoVNA.
160m: -.06dB
80m: -.09dB
60m: -.10dB
40m: -.12dB
30m: -.13dB
20m: -.15dB
17m: -.16dB
15m: -.16dB
12m: -.17dB
10m: -.19dB
While this might not sound like much loss (all of them being less than 2/10ths of a single dB), if the bands are in bad shape and you are trying to hear stations near the noise floor, this can make a difference. I routinely listen along the noise floor with headphones for stations that are really weak. Today was one of those days. The bands were really bad for the most part. CW was not being used much because of this. I did get a good run on FT8 on 17 and then 15 meters, but the CW portions were all in the tank.
I started on 17 meters as mentioned earlier, I started by hunting a little and found W1AW was making contacts so I worked them first thing. It only took me three or four trys to get them in the log so I was pretty stoked about the day at that. But then it took me 50 minutes to land the 5th QSO in the log! That is super slow for my normal operations. So I opted to switch to FT8 so I could get the activation locked in before I went off on the higher bands playing…
I worked five FT8 contacts in a little under 20 minutes just using hunt and pounce. This had my ten in the log so now the rest are “gravy” at this point. Next thing I did was re-tune the antenna to 15 meters and since the sBitx was already running, I hunted on FT8 there for a while. I netted 6 QSOs in something like 14 minutes. This is actually a pretty good rate for me on this radio so I was happy with that. After landing those in the log, I set the Scout 555 back up and called CQ on 15m CW for a while… I had zero replies… It was like the CW portion was simply turned off. Seriously, where did all the CW ops go? FT8 was booming! I saw a ton of DX on FT8, even though I couldn’t work them, but they were there. Anyway, after calling CQ for like 15 minutes with no replies I figured I would hop on 10 meters and listen for my beacon and then see if I could get at least one QSO there before calling it quits for the day.
It took me about 50 minutes of calling CQ into the void to finally land a contact between 15 and 10 meters. The last FT8 QSO in the log and the one on 10 meters CW are literally 50 minutes apart! That is a lot of calling CQ with no responses. I actually was listening to the radio while talking to Jonathan and just letting the keyer do its thing. When suddenly there was a reply out of the ether! KE2FUA up in New York heard my pitiful pleas for a call and felt sorry for me. Giving me the QSO on 10 meters I desperately wanted. With that in the log, I called QRT and broke down the station. Afterwards I was able to spend some time with the other operators on site and chat with them a little. This is the main reason I love activating with these guys, the camaraderie is incredible.
This view shows the tight conditions pretty good. The pavilion in the back has the SSB setup and the white truck had the other station with me kinda in the middle. As long as we used band pass filters or there was enough band space between us, I didnt have a problem. While I was on 10 meters I didn’t have a filter for that band, so I was open to interference and didn’t hear anything from the other stations. I know that at this time, one was on 17 meters and the other was on 20 meters. Band pass filters are a life saver as well as a little coordination between stations. When I arrived, the others were already setup and operating so I went over to each one and gathered some intel about how it was going for them and their current band so I could pick one that they were not currently on. They were both running band pass filters so I was able to start literally anywhere I wanted except 20 and 40 meters. I love the higher bands so that was when I cooked up the idea to do just the higher bands to see what I could net with that sort of restriction. It also allowed me to use my newly minted 17m band pass filter too…
I cant say enough good things about this little keyer. The stark contrast between the cost of each item is not lost on me… I like things the work well and serve me without too much fuss. Both of these tools have done that well. I have finally used the keyer long enough to need to replace the battery in it. Which is a simple task, but does require a screw driver… I thought I would hate having a battery powered keyer, but to be honest, it is kinda nice being able to put it literally anywhere and it just works. I printed the operation manual and keep it in the case with the Scout 555 so if I need to do something in the menu that I dont remember how to do, I can just look it up right quick.
At the end of the activation, I had to break down early and go run some errands and I did itjust in time too as this was what greeted me when I pulled out of the parking lot onto the main road. Sometimes you just get the right amount of things to happen in the right order I guess…
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73
WK4DS - David
60m Band Module Part 5: SSB Operation
Getting SSB to work on a converted band module for 60 meters is tougher than I thought. It takes mods in the radio too…or it is not possible at all. One or the other is the fate of this TenTec Scout 555 HF radio and the 60 meter band module project.
If this is your first time seeing this project, please go back and take a look at the full series so you will be up to speed on this project.
- Part 1: Initial Conversion and Filter Design
- Part 2: Crystal Selection and Mixer Circuits
- Part 3: Field Testing and Troubleshooting
The Single Side Band Problem
Today, we are taking a look at the TenTec Scout 555 60m band module that we built and figure out how to make it work on single side band properly. This band module was created by using a donor 80 m band module and from there things were changed and re-tuned to make it work on the 60 m amateur radio band.
One thing that has turned up though is that the 80 m band module operates on lower side band. To get the side band correctly oriented for the 60 m band I need it to transmit on the upper side band. This is not the normal convention for amateur radio operation though. The normal convention is as follows; bands 30 meters and lower, such as 40, 80, 160 and so on, will use lower side band. All bands 20 meters and above use upper side band instead. Someone a long time ago decided this was how we will do things going forward and here we are. Well for some reason, the 60 meter band is not like the other lower bands. It is using upper side band so I have to figure this out. The next step I have to do is figure out how the radio determines what band module is installed, and which side band it chooses. The radio automatically chooses either upper or lower side band, depending on the band module in use. So something is either telling the radio to monitor the actual frequency or it is looking at the band modules themselves and it is determining it that way somehow. All we have to do is figure out how it’s determining it and tell it to choose something different. Simple enough.
40 meter band module showing the soldered in ground jumper installed on pin 6.
Finding what triggers the shift from upper to lower side band
Everything we need to figure this out is in the TenTec Scout 555 owners manual. The manual has an complete set of schematic diagrams on the radio inside. I first start by looking at the band module schematic itself and found that there is a pin marked “band” with a jumper shown on it. This is a very suspicious connection and has me very interested in this particular pin. So this is where I’m going to start my journey since this sounds like it is what tells the radio which band the it is operating on. The next thing I had to do was figure out where it went in the radio, so I dig out the prints and found what follows…
The first image is an exert from the schematic of the band module itself showing pin 6 “band” being grounded with an optional jumper.
Band Module Edge Connector Pinout showing Pin 6 as the “Band” pin.
The next stop for this circuit is the Low Level driver board and it lands on a pin on connector 48.
Section of the Low Level Driver Board Schematic showing the path from the “band” pin on the module edge connector up to a pin on cable 48.
It then travels along cable 48 over to the Low Level Driver board.
Low Level Driver board wiring showing connector 48 and 49 for the “band” selector.
The next place it went was from connector 48 to connector 49 on the low level driver board where it exited the low level driver board. I am going to be honest here, this wiring makes no sense other than to add two points of corrosion with bayonet connectors that are not needed. There was no reason to goto the LLD board just to exit the board without doing any work with this signal from the band module. Yet, so is life…
It leaves connector 49 on the low-level driver board and goes to the Logic board. Once on the logic board, it goes to pin 10 on the PIC16C57 controller Chip. This chip is probably being used to control all sorts of stuff, but this pin is being pulled low when the band module is grounded and it is being pulled high through R14 (4.7K ohm) resistor when the band module is not jumped to ground.
After tracking it down to the PIC controller, I have come to the conclusion that if you pull this line low (tied to ground), it determines one side band mode and if it is left ungrounded, it is pulled high by a pull up resistor to set another side band mode. So I went and retrieved my multi-meter and checked a full set of band modules to see and this is what I found:
10m - open
12m - open
15m - open
20m - open
30m - shorted
40m - shorted
80m - shorted
160m - shorted
60m Single Side Band on a TenTec Scout 555 is hard!
Once I saw this pattern I knew that this was how it knew what each mode needed to be. It had no way of knowing which band, but it knew which side band mode…or so I thought… As fate would have it, I learned something else today. I took my 60m band module to the workbench and de-soldered this ground contact so it would transmit on upper side band. Knowing that I didn’t touch any of the other stuff in the module I merrily trotted back to the shack to test it out.
Turns out more happens with the radio than just choosing the side band… Turns out there is a second thing that happens when you cut this trace. You see when you look at the chart of the frequency path on the NA5M website, you see that 30 meters and below, the 6.142mhz IF is subtracted from the Local Oscillator sum and 20 meters and above it is added. So when I cut the trace, the radio now transmitted on 17.616mhz and not 5.332mhz! Yeah, sure, now I had upper side band but now I was on the other end of the world from where I needed to be… Little good having upper side band does me if I am off frequency by over 10mhz!!!
I figured out the following:
The band module has a pin on the edge connector that when grounded, makes the radio operate on lower side band and it subtracts the 6.142mhz IF from the signal. When it is open, the exact opposite happens. So what I need is for the radio to be like a “low band” module for the mixer, but use upper side band for the voice and some of the data modes. This is the problem I need to solve and the answer was on YouTube. After looking at the problem for a while and understanding how the two sidebands are literal mirror images of each other spaced out from the center frequency. I finally found a fellow ham from Australia that had the answer. Simply flip the audio frequencies only and adjust the radio as if it were lower side band. This sounds silly till you see his video. I currently have center tapped audio transformers on the way so I can build a circuit that mixes a 2500hz tone with the audio stream as the audio passes through a diode ring mixer. This will invert the frequencies when it does this. If his video is not fake, I will have solved the SSB problem on the Scout 60 module. Sure it will take an homebrew external converter module, but at least it will work! I have to invert the audio on both transmit and receive so I have to control the microphone input as well as the speaker output. The speaker is easy as I can simple grab the headphone jack audio and process it to a set of headphones or external speaker, but I will have to put microphone connectors on the unit as well so I can intercept the audio from the microphone as well as have it trip a relay when you press the “push to talk” button. All of this should be pretty easy to accomplish so I am confident this will work.
So here is the plan, I want to use that pin right beside the “band” pin on the module edge connector to ground it. Then I can route that to a new plug on the back of the radio to allow me to control a relay with it. This will “enable” the reversing circuit to get the audio corrected for use with this module. Since all the other band modules don’t use this pin, it will only work with the 60 meter module. This is if I have to build the circuit outside of the radio too. If I can get it to fit inside the radio, then I can make the whole thing look original and not need a small adapter to correct the sound and microphone audio. Other wise, I will be piping it through a converter box with the ring mixer in it and a relay to switch the path from transmit to receiver.
The TenTec Scout 555 owners manual has a lot of the information that I need to make this happen, but it doesn’t tell you everything. It mostly describes circuits so you understand what your adjusting it, to trim it back in and get it running right.This means you have to figure out what is going on with the circuits so you can understand how to modify them. This is the hard part for me. For now, at least, the SSB problem remains. I hope to be able to solve it, but right now it looks a little unlikely…unless you know something that I dont and see it in the photo of the schematic above.. haha. If you see a possible solve, please email me or leave a comment and lets talk about it, I am really enjoying this project and would love to get that one last mode to work right.
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WK4DS - David
Activating with the TenTec Scout 555 after a 2 month hiatus!
When you love CW, you tend to migrate to certain kinds of radios. I migrated to TenTec and Elecraft rigs mostly, with a few smaller radios thrown in for good measure. I love TenTec radios for CW operation as they seem to have been tailor made for the mode. They work well as SSB machines too, but they REALLY shine on CW. Since we all know this about me, it is a given that if I want to activate with a simple radio that isn’t a lot of fuss, that I will choose the Scout 555 or mt Argonaut 5 over about anything else in the shack.
When you love CW, you tend to migrate to certain kinds of radios. I migrated to TenTec and Elecraft rigs mostly, with a few smaller radios thrown in for good measure. I love TenTec radios for CW operation as they seem to have been tailor made for the mode. They work well as SSB machines too, but they REALLY shine on CW. Since we all know this about me, it is a given that if I want to activate with a simple radio that isn’t a lot of fuss, that I will choose the Scout 555 or mt Argonaut 5 over about anything else in the shack.
TenTec Scout 555 ham radio running cw on 20 meters
Setting up a POTA station at a local state park
When people start out activating a park in POTA, they tend to want to go to a local park first to get the bugs out of their kit. I am no different here. The only real exception is that I love going back to this park over and over. Back to the subject at hand though, I normally setup in a similar manner every time I go to a park. It usually goes something like this.
Find a spot that I can back into the parking space since my antenna mount is built for my receiver hitch on my truck and I prefer to lay ground radials so I don’t want people running over them when they drive by.
Once backed into the space, I will deploy the antenna first. I do this for a couple of reasons. First is that I want to get it up as fast as possible to avoid rain if it is imminent. Second I will spend some time tinkering with the antenna system to see what it does on the nanoVNA and this is kind of fun to me by itself. Antenna theory is fascinating and I love looking at how these devices work. Once I have the vertical up, radials deployed and the coax ran to the truck cab, I move on to the next step.
Tune the antenna to the band I am going to use. This seems obvious, but I have forgotten to do it in the past and it doesn’t work well unless I do it… I use the nanoVNA and I will usually tune the vertical first by collapsing it till I am close to the desired frequency, then I will move the radials around till I have the best SWR possible with the system I have deployed. Usually this lands me between 1.1 and 1.5:1 SWR at the base of the antenna.
Get out the radio and deploy it in the front passenger seat of the truck like you see in the photo above. I use the storage case for the radio as a table to sit it on. This works really well. I keep the keyer and cables for everything in the case with the radio. This even includes the earbuds I use with it. The only thing not in the case with the radio is the Begali Traveler key as it lives in a case of its own.
Setup the computer to log with (if I brought it) or get out the pens and notebook. Go ahead and write all the pertinent data in the log or computer before I start calling CQ.
Spot my activation on the POTA website before calling CQ as well. This has turned into a mess for me in the past to be honest so I do this step before calling QRL too. I want the whole system to be primed prior to starting the activation proper.
Call QRL and find a clear frequency before launching into calling CQ. This is a big deal to me and a step I make a deliberate effort to do so I don’t walk on someones QSO that I cant hear immediately.
Once all of this is done, which takes only a few minutes in reality, I start calling CQ and get going. Now I also understand that my spot and my actual operating frequency might differ due to people being on a frequency that I chose to start with, but this isnt too big of a problem as the RBN will usually update it pretty quickly once I start calling CQ.
Tuning the antenna for use on a band.
As you can see in the above photo, I have already tuned the antenna for use on the 17 meter band. It is centered on the CW portion of the band and I have also tuned the radials to get the lowest SWR possible with the setup like it is. With it like this, I think I am going to use this plot to figure the inductance and capacitance on the Smith chart to see what it would take to get it to 50 ohms resistive or as close as possible to that. This is why I use the nanoVNA too. You can see the plot of SWR versus time here on a portion of the radio spectrum of my choosing. This time I chose 17mHz to 19mHz and the marker is set to 18.080mHz for my point of reference. With it set like it is, I can also see it is at 48.05 ohms of impedance and it is capacitive 440pF as well. I can take this data directly into the Smith chart and calculate the needed components easily.
This is the setup I use currently. I find it easier to use this small jumper than trying to read the nanoVNA directly connected to the base of the antenna. The sun makes it very hard to read this device and adding the short jumper allows me to put it in the shade. Also, just look at how small this instrument is compared to regular antenna analyzers… That one thing in itself makes it a winner in my book.
The procedure for tuning goes a little like this. I will first get the antenna put together. This whip is long enough that it will tune to about 12 mHz if fully extended. This is good as it will allow me to shorten it to 20 meters by simply collapsing a few sections. Then when it gets close, I will pull down the bottom section a little at a time till the curve looks like what you see above on t he nanoVNA. I try to get my rough tune by shortening the top first as those sections are smaller in diameter and doing this will allow for the passband to be the widest possible. I can usually get the whole CW portion of the band this way on everything except 80 meters which has a huge area for CW… also this vertical is woefully short for that band anyway…but that is a different conversation.
The operating position for POTA
The truck will usually look like this when it is up and operational. I really like operating out of my truck, it is so simple for me now that I have the system dialed in. POTA can look like a lot of things and I find it interesting how each one of us comes up with a unique setup for our uses. I prefer to setup in my truck for a couple of reasons. The main one is that in the summer, I can run the AC and keep cool! The second one is that I can access my truck power as I have a diesel and that means I have two batteries in the truck. I dont run over about 40 watts with any of my POTA rigs so this never depletes the batteries even when I setup for several hours. Plus I can simply crank the truck to recharge the batteries too… win win.
This is the operating position for this day. It looks like this on most days as it is the fastest way for me to get on the air with my POTA rigs. You have the Dell Inspiron computer running Linux Open Mandriva, a Hamgadgets Keyer, the Begali Traveler CW paddle, and the TenTec Scout 555 portable HF radio. This is a solid rig for someone who wants to run SSB or CW and maybe could get this to work with an external sound card for some of the digital modes too. My friend, Roger KG4WHI, has gotten a Scout to do FT8 so i know it is possible.
This was the last band I operated on today. I started on 20 meters, made a dozen or so contacts then moved to 17 meters where I made probably 16 more and then I finally finished with me making 2 on 15 meters if memory serves me right. It wasn’t many, but I was able to get a couple in the log on 15 meters as well. Shoot I was even able to get a Spaniard in the log today. They were weak but I was able to get decent copy on them. It is always a good day when you can add DX to the log on a POTA activation in the USA. You can also see something else in this photo. This is how low I hold the volume when I operate a radio on CW. You want the volume just above the noise floor. This allows you to hear stations that would normally be impossible if the volume was turned up just a little more than this. It is a phenomenon that I learned a long time ago and it is real. It works on any radio too.but you have to wear good headphones for it to work.
All in all it was a great day with 30 contacts in the log from all over the country and one from the EU. I decided to break the system down as a storm front started to roll in so I would not have to do it in the rain… haha. This turned out to be accurate as it started raining cats and dogs right after I left the park too. That was a close one…
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Till next time, I hope you have favorable conditions and the DX is calling! POTA on and 73!
David
WK4DS
Back on the Air for a POTA Activation
Today saw me back at US-2169 for the first time in a while…
Today saw me take the old Dodge over to my local park (US-2169) for a short activation. I have been busy in the machineshop these last few weeks so there has not been much time for POTA. I have actually not been to a park in several weeks and was starting to miss it.
Update on the park visitor center upgrade in progress. The grade work is done and they are framing the new building at this point. It is coming along nicely too.
Setup of my POTA rig for HF operation
I went up to the frisbee golf course again as this is a great place to setup for POTA. A lot of people will use the nearby pavilion when they setup, but my antenna mount, being attached to the truck, makes it alot easier to operate from the truck. This is an amazon 18’4” whip that I bought, you can get one too at this link: Link to 18’4” whip on amazon Now, to just let you know, this is an affiliate link, but it doesn’t change the price from what I can tell… At the time of this writing, they were on sale for 27$, which is incredible!
Today I used the 18’ 4” foot vertical telescoping antenna and two radials attached to the base. Then ran a coax into the cab of the truck to the front seat where I normally set up the radio in the front passenger seat. Something I noticed today was that no matter what band I was on, the SWR plot would never get better than 1.5:1 (which is perfectly fine BTW) but I can normally get way better matches with different radials, which tells me that the radial length is more important that people let on…
Next, I chose the TenTec Scout 555 as it is a wonderful CW machine. It does have a little bit of drift in the VFO, while it warms up, but it is not enough for me to worry about. I started on 20 m in the CW portion of the band and hunted stations to start with. I worked another POTA site for a park to park contact before finding my own space and setting up there. I made 19 CW contacts on 20 m before I decided to move to 15 m to see what I could find there next.
Pay attention to bad antenna connectors…
When connecting the antenna today, I had trouble getting the BNC to attach, upon closer inspection I had found that it was crushed from impacting something in the truck… Probably when it was in the red Chevy as there is less protection in the back of that truck as compared to how I store it in the Dodge. Oh, and yes, my heat shrink tubing on the coax has slipped back for some reason. I noticed it when I was breaking down and simply slid it back into place…haha. I did not notice this until I attempted to use it today to operate this activation.
I attempted to straighten the damaged BNC connector with my Leatherman as best as I could, but it didn’t work really all that well so I got in my adapters for my nano VNA and robbed the one that was in that pack and used it instead.
This is a great example of why you always carry spare parts for all of your connections so that you don’t get shut down because of something getting broken unintentionally that you are not aware of.
The HF Signals sBitx V3 and native internal FT8
Once I finished working CW on the Scout 555, I decided to get the sBitx out for a while to work some FT8. I really love using this radio for FT8 and CW in parks, it works so well and with the version 5.3 software, it has a metric ton of great features. The waterfall works well and the automatic modes in FT8 are really handy too. This radio is 25 watts on the lower bands and trails off to about 12 watts on 10 meters. This is plenty for me as I work a lot of QRP anyway so little to no power output is fine for the most part. Would it be nice to work with more, yes, but I can manage without it just fine.
Today I only used it for FT8, but I also will use it for CW from time to time. It is a little temperamental in CW since it is a Raspberry Pi 4 running in the background, but once you learn the keying, it works fine up to about 23WPM for me without too much issue. Using something like the Begali Traveler CW Key in the photo below also makes it more fun too. A really nice key is always a good thing to have with you.
Once I worked a few FT8 contacts on 15 meters, I dropped down to 17 meters and worked a few more there before shutting down for the day and heading home.
I noticed when I was getting ready to leave that the truck motor was “squeaking” when it was idling and when I investigated further, I found that it was a pulley on my fan belt had a bad bearing in it. So I went to the auto-part store and got a new one to replace it with. Once home I was able to replace it in short order so that I would be ready for the next POTA outing that I wanted to go on. Sometimes things just come up and you have to take action…haha.
Thank you for following along and I look forward to sharing something with you again soon, till then 73!
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Chito Branch Reserve: First FT4 Contacts, Meeting a Fellow Park Hunter, and the Quest for 1000
Doug's been activating Chito Branch quite a bit lately, and if I'm being honest, we seem to be in a friendly race to see who hits 1000 contacts from this park first. Spoiler alert: he's winning. But it was great to finally shake hands with someone who understands the appeal of spending beautiful Florida mornings in a park with Spanish moss hanging from the trees, headphones on, working the world.
February 10, 2026 • US-5524
Sometimes the best part of a POTA activation isn't the DX you work or the pile-ups you run! it's meeting another operator face-to-face who's been chasing the same goals you have. Today at Chito Branch Reserve, I finally got to meet Doug, KQ4SXW, in person.
I finally got to meet Doug, KQ4SXW
Doug's been activating Chito Branch quite a bit lately, and if I'm being honest, we seem to be in a friendly race to see who hits 1000 contacts from this park first (well, between us at least). Spoiler alert: he's winning. But it was great to finally shake hands with someone who understands the appeal of spending beautiful Florida mornings in a park with Spanish moss hanging from the trees, headphones on, working the world.
The Setup
I rolled into Chito Branch mid-morning with my usual portable arsenal. The park is close to where I'm staying in Tampa, which makes it an easy choice for activations, and I've been systematically building toward that 1000-contact milestone. As of today, I'm sitting at 769 QSOs logged from US-5524, so I'm getting close.
For antennas, I ran my 1/4-wave vertical with two counterpoise wires, tuned for each band. Simple, effective, and quick to deploy. I use the nanoVNA to utne the antenna with. As you can see in the plot above, I get it to something less than 1.5:1 SWR and call it good, I have found that if I get it to that level that I dont have any trouble making contacts at all. I have done OK with the SWR higher in the past…much higher actually, but it is a lot tougher to make contacts like that.
The main rig was the sBitx V3 from HF Signals for digital modes, and I brought along the Ten-Tec Scout 555 for some 15-meter CW work since the bands were looking promising.
Speaking of which… let me tell you about my grid square insurance policy.
A Sticky-Note Solution to a Real Problem
If you operate FT8 or FT4, you know that your grid square locator needs to be correct. It matters for awards, for logging accuracy, and frankly, for not looking like you don't know what you're doing. Recently, I completed an entire activation with the wrong grid square set in the software.
Not ideal.
Sometimes the best solutions require the simplest answers…
So I came up with a foolproof solution: I now keep a note in my radio case that says "FIX GRID BEFORE USING FT8." It sits right on top of the sBitx when I open the case, impossible to miss. I also store the Bluetooth keyboard in the case with the radio so I can easily update the grid square in the field without fumbling around with the tiny on-screen controls.
Is it a high-tech solution? No. Does it work? Absolutely. Sometimes the best fixes are the simplest ones.
Starting with FT8 on 20 Meters
After getting the sBitx fired up…with the correct grid square, thank you very much… I started the activation with FT8 on 20 meters. I spotted myself on POTA and the responses started rolling in. There's something satisfying about watching those waterfalls fill up with decodes and seeing callsigns appear in the queue.
My very 1st FT4 QSO with the sBitx!
I worked through a solid session and logged about 18 contacts on 20-meter FT8. The band was cooperative, signals were good, and the activation was off to a strong start. Something to note about my sBitx V3 is that it has developed a sort of internal noise on 20 meters that lingers in the CW portion of the band. It goes down in frequency as the radio warms up so I have to figure out what is causing this problem when I get home the next time. I have it on the list right next to fixing my microphone pre-amp circuit for proper operation as well.
First FT4 Contacts at a POTA Park
After the FT8 run, I decided to try something new: FT4. I've run plenty of FT8 from parks, but FT4 was uncharted territory for me in the field.
FT4 is faster than FT8, cycling every 7.5 seconds instead of 15, which makes it great for contesting or when you just want to move quickly through a pile-up. I updated my spot on POTA again and started calling CQ. To be honest, I had used it a little in the shack before with no luck so I didn’t hold my breath today, To me utter surprise, I saw a QSO forming in the call feed on the left! Then it finished and logged it! I hurriedly got out my phone and snapped a quick photo to share with you guys…
First contact: AA5WH on 20 meters. Clean decode, solid signal, contact in the log. Then I switched to 15 meters and worked N1KLF. Two FT4 contacts, my first ever from a park, and honestly? I was pretty stoked. There's something satisfying about trying a new mode and having it just work.
15 Meters CW Was Alive
The TenTec Scout 55 is pictured with the HF Signals sBitx V3 where I was changing over to CW after working 2 digital modes today.
After the FT4 session, I switched gears completely. I packed up the sBitx and pulled out the Ten-Tec Scout 555 for some CW on 15 meters. The band was in great shape, though there was a bit of QSB rolling through. I got the radio all connected up to the keyer and then plugged in the Travler. My Begali Traveler key has become one of my favorites—smooth action, compact enough for portable ops, and it just feels good. It is sensitive, but that is how I use my keys, I prefer a light action myself and that is why I made my own paddles back in the day. N3ZN (Tony) and I2RTF(Pietro) make some of the nicest keys around at the moment and I am glad I have one from each.
DX Contacts That Made It Worthwhile
Right out of the gate, I snagged some DX that made the whole activation worthwhile:
EA4MZ in Spain
DD1LD in Germany
YV1GIY in Venezuela
PY5XT in Brazil
Four different countries, all on 15-meter CW with 40 watts and a telescoping 1/4 wave vertical, what more can you ask for? Days like this remind me why I love this hobby. Some of them were a little on the weak side but the Jones filter in the Scout actually helps if you open it up instead of closing it down. This seems counter intuitive, but opening the filter up just ever so slightly will let a lot more of the other operators signal though and just a little of the background noise, it is almost like having them turn their power up 50% or something, if you have not tried it with your Scout 555, I suggest you find a signal you can barely hear and give it a shot.
43 QSOs and Counting
By the time I packed up, I had 44 contacts in the log, though one turned out to be a duplicate, so 43 that counted. Not a huge number, but solid for a few hours of casual operating across three modes (FT8, FT4, and CW) and two bands.
Meeting Doug in person was the cherry on top. It's always good to connect with like-minded people in the hobby, especially when you're both chasing the same quirky goals. A thousand contacts from one park? Yeah, it's a bit obsessive. But things like that are what makes it fun.
SIDE QUEST TIME:
I ran into a unique problem today that is worth mentioning here. I was charging my computer with an inverter that I have wired into the cab of my truck. I was also running the truck so I could power the inverter and charge the computer as well as the sBitx V3 at the time. Well it turn out that I have some issues with this inverter that need resolving. The next few photos show the RF hash that this inverter is producing when under load! It is unreal how bad it was, I couldn’t believe all I had to do was simply shut off the engine and unplug the power cord from the logging computer and it went completely away…
The above photo shows the hash of running both devices on the inverter with the engine running on the truck.
The next photo shows what happened when I shut off the truck and unplugged the computer.
The last photo shows what the band looked like once I went around to the other side of the truck and powered off the inverter completely. This goes to show that you need to check these things if you plan to use RF devices like radios in the presence of RF trash generating devices like this inverter… Better inverter coming up!
END SIDE QUEST
Hit me up!
231 contacts to go until I hit the big 1000 from Chito Branch. At this rate, it'll take a few more activations, but I'm not in a hurry. Well, maybe a little… Doug's still ahead of me.
If you're in the Tampa area and see someone set up at Chito Branch Reserve with a vertical antenna and a tablet running digital modes, stop by and say hello. Chances are it's either me or Doug, and either way, you'll be in good company.
**Gear Used This Activation:**
- **Radios:** HF Signals sBitx V3, Ten-Tec Scout 555
- **Antenna:** 1/4-wave vertical with dual counterpoise wires
- **Key:** Begali Traveler
- **Digital Mode Software:** JJ and the sBitx 64 bit Development team version 5.301 (FT8/FT4)
- **Computer:** Dell Inspiron with Linux and HAMRS
- **Accessories:** NanoVNA for antenna tuning
Have you tried FT4 for POTA activations? What's your go-to mode for portable operations? Drop a comment below or find me on Facebook or shoot me an email on here.
What is FT4 and how is it different from FT8? FT4 is a digital mode similar to FT8 but with a faster cycle time (7.5 seconds vs 15 seconds), making it better suited for contests and quick pile-ups.
What equipment do I need for POTA FT4 activations? You need an HF transceiver capable of digital modes, a computer or tablet running WSJT-X software, an interface between your radio and computer, and a suitable antenna for your chosen bands.
Where is Chito Branch Reserve located? Chito Branch Reserve (US-5524) is located in the Tampa Bay area of Florida and is part of the Southwest Florida Water Management District.
How many contacts do you need for a valid POTA activation? You need a minimum of 10 QSOs to qualify for a valid POTA activation.
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73,
David WK4DS