Wednesday, March 30, 2022

Interactions: Degrees of Degradation

Everything interacts with everything. When you swing a hammer the moon jumps. The laws of physics tell us so. It's a matter of by how much: some interactions are stronger than others!

The same applies to antennas. Antennas interact with everything, including that hammer. The critical metrics for the interacting object include:

  • Distance
  • Resonance
  • Material characteristics

It is not true that non-resonant conductors and insulators don't interact with an antenna. For example, a long plastic tube 10 meters from a 20 meter dipole has negligible interaction. But wrap that tube around the dipole and its effect is very apparent. A dielectric in the near field of a radiator reduces the VF (velocity factor) and a fraction of the energy, depending on the material's dielectric properties, will be dissipated as heat. We need to take care when selecting insulated wire for our antennas.

The Earth itself interacts with our antennas. Ground proximity and quality similarly affects verticals, their radials and really any antenna. Its proximity, dielectric properties and conductance can have a profound impact on loss and resonance, often far more than interactions with other antennas.

The same is true of non-resonant conductors. A short conductor near the tip of a 20 meter yagi element will alter the resonance of the element and thereby impact performance of the yagi. It is never invisible. But move it a few meters and, again, the interaction is negligible. The conductor can be a 2 meter dipole, a segment of a broken up steel guy, a power line or a metal clothesline. 

Interaction is not a binary phenomenon: it's a matter of degree. It varies in accord with the previously listed metrics. Some interactions are easy to mitigate by, say, moving an antenna or interacting object a short distance. In other cases the impact of the interaction may not be concerning and therefore not worth the trouble of taking corrective action. Only you can decide. There is no one right answer.

Analysis and mitigation of interactions has been a recurring topic for this blog. Type interaction into the search box and you'll see. Examples include this, this, this, this and this, and there are many more to be found here and elsewhere in the ham literature. No matter how small or large your station it is worthwhile to give interactions some thought. I did it when my station was small and I do it now that my station is large. The only difference is that my objectives have changed.

In this article I will focus on two type of interaction, using a reference 3-element 20 meter yagi:

  • Parallel 20 meter dipole in front of the yagi
  • Parallel 40 meter dipole in front of and above the yagi

These will highlight "worst case" resonant interaction and non-resonant interaction, respectively. The characteristics of these simple interactions are both interesting and illuminating. Mitigation will be touched upon but not discussed in depth.

Parallel antennas resonant at the same frequency is a worst case scenario. Interaction is guaranteed. It is so severe that its effects are clearly discernible in the model with the dipole up to 20λ (400 meters) ahead of the yagi, rippling the azimuth and elevation patterns. The yagi azimuth pattern at right is for a separation of 10λ (200 meters). Resonant interactions have a long range! On the left the separation is reduced to 1λ (20 meters) to show the induced current when the coupling is extreme.

The antennas are placed 15 meters above real ground (EZNEC medium ground). This is more realistic than in free space since the ground reflections that are responsible for the elevation pattern (lobes and nulls) distort the pattern in a particular fashion. Height and antenna separation are important factors, however this aspect will not be isolated and studied in this article. But please keep it in mind when you plan your antenna farm, be it large or a small one.

The elevation plot shows the degree of pattern distortion due to interactions, with the dipole placed 200, 100 and 40 meters directly ahead of the yagi's centre. At 200 meters (10λ) separation there is a just a slight wiggle to the yagi's pattern. At 100 meters (4λ) the wiggles get larger and the increase of side lobe magnitude (more is visible in the azimuth plot, which isn't shown) steals 1 db of forward gain. At 40 meters (2λ) the wiggles are gone but the pattern distortion is severe and gain is sharply reduced.

Conservation of energy applies. Energy that balloons those side and rear lobes and fills in the nulls is not available for the main forward lobe. Interactions degrade both the pattern and the gain.

Of further interest is the effect on the yagi's impedance. The separation is 40 meters for the SWR plot above. At the design centre of 14.125 MHz the resistance drops from 37 Ω to 30 Ω while X barely changes -- for simplicity, the model uses a transformer to take 37 Ω to 50 Ω. Another important change is the antenna's Q, which has noticably risen. The higher Q reduces the SWR bandwidth. 

By modifying the transformer, the SWR can be brought back down to 1 at 14.125 MHz. However, the SWR at 14.0 MHz still increases from 1.2 to 1.4, and from 1.6 to 2.0 at 14.350 MHz. With the seemingly large 2λ separation there is enough coupling to significantly alter the yagi's impedance and Q. The situation rapidly deteriorates at closer separations.

There is a lesson here with regard to resonant interactions. As the interaction increases (separation decreased in this example), we see the measured deterioration occur in the following order:

  1. Side lobes and nulls (or RDF if you prefer)
  2. Forward gain
  3. Impedance

Which is to say, trying to detect interaction by measuring the impedance or SWR is ineffective except in the very worst cases. Antenna performance can degrade quite a lot without any change in SWR. In this example, the SWR barely changes at separations of 60 meters (3λ) and greater. I had to reduce the separation to 40 meters to see a significant change in the SWR.

The metrics for non-resonant interactions are different. Let's briefly explore that interaction by replacing the 20 meter dipole with one for 40 meters. Although 14 MHz is the second harmonic of 7 MHz, you have to go to the odd harmonics, starting with the third at 21 MHz, to have a resonant interaction.

As expected, the interaction with a non-resonant antenna is weaker. It is so weak that we have to bring the 40 meter dipole closer than 1λ from the 20 meter yagi's centre to see appreciable pattern degradation.

The yagi's impedance is similarly less affected by close separation. The SWR plot is for a separation of only 10 meters (½λ) from the yagi's centre. Unlike the case with a resonant interaction the effects on pattern, gain and SWR for a non-resonant interaction like this one tend to occur together while varying the separation. When stacking the dipoles on the same mast or tower (above rather than in front) the interaction is lower for both cases since the yagi has a weaker field in that direction. That's been discussed in previous articles on interactions so I won't say more about it in this article.

If the interaction is concerning and the antennas must remain in their position there are methods for reducing the interaction to an acceptable level. The obvious one is to make a resonant interaction non-resonant by loading the antenna elements for the lower band to shift the harmonic resonance out of band. This is what I did to my 3-element 40 meter yagi to remove its affect on the 15 meter stack. 

If the non-resonant interaction is with a guy wire segment or other part of the near environment you may have fewer options to reduce the interaction. You may have to live with it since those "fixtures" can't be moved. But do measure the impedance and build models if possible to remove the uncertainty. The degradation may not be as bad as you fear.

Let's consider another alternative that some hams have chosen. I will make a simple change to both the 20 and 40 meter dipoles at their closest separations of 40 meters and 10 meters, respectively. The interaction with the modified 40 meter dipole is on the left and on the right is with the modified 20 meter dipole.

The change to both is that the dipole has been cut open at the centre. This is done with a high resistance load in the EZNEC model. That's signified by the open box at the dipole centres in the antenna plots above. For those runs the resistance was 0 Ω, which leaves the dipole unaltered. Notice that the 40 meter dipole interaction worsened and the 20 meter dipole interaction has almost vanished. The SWR curves are not shown but show a similar response: better for the modified 20 meter dipole and worse for the modified 40 meter dipole.

In the case of the 20 meter dipole, opening the centre has converted the dipole into a 2 element collinear 10 meter array. When the same is done with the 40 meter dipole it becomes a 20 meter collinear array. At lower resistance values, including 50 Ω, the interaction is intermediate between these patterns and SWRs and the worst case scenarios described earlier. 

I am not including those additional plots in the article since they add little to the discussion. Modellers can easily explore those and more complex scenarios, including transmission lines and complex loads.

There has been some misunderstanding about whether interaction due to an antenna not currently is use can be mitigated by shorting or opening the transmission line or the antenna feed point. Opening the element is best but this is rarely done since it is difficult except, perhaps, for verticals by opening the connection to its radials with a relay. 

Doing it at the end of a transmission line -- most commonly at the antenna switch -- is not usually effective since the electrical length of the transmission must be considered, and it is rarely a multiple of ½λ. At other lengths, a short, open or resistor termination appears as a complex load at the antenna feed point. In any case, as stated above, any load on the unused antenna may only modestly reduce the interaction, and can make it worse. This includes a 50 Ω resistor, which some favour. This is easy to test by inserting various loads in the model.

A further difficulty is that this mitigation technique must be done for every element of an interacting yagi. Insertion of a load at the driven element or on the transmission line that would be effective for a single element antenna will be ineffective because the other yagi elements will still interact. You have to do all of them. For severe cases it is better to do what I did for my 40 meter yagi or, if you can, position your towers so that antennas that can interact are not pointing at each other most of the time.

Deal with interactions directly rather than by implementing token measures such as switchable loads in your antenna switch. Use those switches to ground unused antennas for lightning protection instead. We go to a lot of time and expense to design, build and raise high performance antennas so it makes good sense to effectively deal with interactions that degrade the performance. Anything else is wishful thinking.

Wednesday, March 16, 2022

South! 6 Meters Opens

It takes a lot of EUV to light up the ionosphere's F-layer bring 50 MHz signals down to Earth at my geomagnetic latitude. That happened this week for, as far as I know, the first time in solar cycle 25. Despite lasting only 3 minutes it made an impression on me. Here is what I found on my screen late afternoon of March 14 while I was busy elsewhere.

LU, CE and CX. It is the north-south path that is the first to open at this latitude as the MUF rises. Of course I cannot be certain that this is truly an F-layer phenomenon. There is TEP and southern hemisphere sporadic E that may be in play for part of the path. I can discount sporadic E at this end of the path since these openings have correlated well with the recent rise of the solar flux, and persistent for several days at a time of year when sporadic E is historically rare. Unfortunately for us the propagation only reached as far as the southern and central US.

It was no accident that I was monitoring the southern path. There have been ample reports of contacts between southern Europe and southern Africa, Japan and Australia and South America to the southern US. The propagation was there, tracking the solar flux and slowing creeping northward. Digital modes make it convenient to monitor the band to discover elusive openings while I go about my day. 

A friend has been using DXmaps (see screen capture at right) to plot the openings. He found them there as well. There are many tools available to help discover openings.

We are on the cusp of F-layer global communication on 6 meters. It will occur even if this solar cycle is no better than the historically weak previous cycle. What we probably won't get is extensive east-west propagation or on northerly paths from this part of the world. Time will tell.

The openings this week are most likely due to what I call the holy trinity of north-south propagation:

  1. Moderately high solar flux, in the vicinity of 115 to 120
  2. Equinox
  3. Aftermath of a geomagnetic disturbance.

The planetary K-index was at 5 to 6 for 15 hours the previous day. During each equinox period there can be extended north-south propagation after sunrise and before sunset, assisted by gray line propagation along a great circle that intersects both geographic poles. I was not surprised to hear and work stations from southeast Asia (YB, E2) on 15 and 17 meters early to mid-morning.

On its own a solar flux of 120 is usually inadequate to raise the MUF above 50 MHz this far north. The other two factors were likely needed to open the band. A flux of 140 would significantly raise the probability of an opening without other factors coming into play. That has only occurred once this. The other two factors were in play and 6 meters didn't open here. Over the two days following the March 14 opening, as we moved past the disturbance, there was nothing heard here despite the stable solar flux.

As the solar flux rises further we'll see propagation extend to the southeast and southwest. That includes southern Africa, Central America, W6 and New Zealand. As the flux rises towards 200 we should get openings to northern Africa, most of Oceania, southern Europe and, eventually, all of Europe. 

F-layer openings to Asia are unlikely if the solar cycle continues on its current track. Of course the propagation will be better further south. At the exceptional peak of cycle 22 in 1989/1990 there were only a few days when I heard Japan, and worked none of them. In contrast, I have around 100 sporadic E contacts with Japan, via FT8. Sporadic E will remain an important propagation mode even during the cycle's peak years.

My station is ready to go so I am eager for F-layer propagation to arrive. I need it to extend my DXCC count on the magic band since sporadic E is inadequate to reach most of the world. But I am eagerly anticipating its return in May. Sporadic E will remain the dominant DX propagation mode in 2022.

Tuesday, March 15, 2022

Amateur Radio in a Time of War

Before I begin, this is not a article about politics or political opinions. It's about amateur radio. I am taking care to keep it on topic. Hopefully this will be of interest regardless of your stance on the current war in eastern Europe. It was easy to write, though the decision to publish it was less easy.

I was licensed at the tender age of 15 in the early 1970s. Although it was a time of great change and conflict, like most adolescents knowing nothing but life in a stable democracy my understanding and interest in world events was limited. That is curious since my parents were immigrants from a country (YO) that neighbours the current conflict, and they lived through WW II and its aftermath.

Many of my friends had connections to Ukraine since western Canada, where I was born and raised, is home to the world's largest diaspora from that country. That included fellow teen hams. Indeed, there was a large population of second and third generation youth from families that hailed from eastern Europe. Ukrainian and other east European languages were often spoken at home by their parents and grandparents. Connections to the "old country" were strong 50 years ago. That has faded as the decades rolled by and the first generations passed on.

In the mid-70s I was really just a child. The world seemed far away when news was rarely live. It was long before the public internet and the microelectronics revolution was only beginning. Amateur radio brought the world closer, and that was one of its draws for me and my friends. Speaking to people far away was an incredible experience. It was also fascinating to my non-ham family, neighbours and teachers. I was encouraged in my pursuit, despite occasionally interrupting Hockey Night in Canada with TVI during contest weekends!

There was the appearance of a lull of conflicts in the mid-70s. We were past several serious wars and high tension among world powers, and it was before the next round of major conflicts. China was a closed society that was barely known or cared about in this part of the world, and there was detente with the USSR. There were no hams in China but there were an awful lot in the USSR and eastern Europe. Talking to hams in that part of the world was a little surreal to me and those watching me do it.

Conversations never went deep: name, QTH, power, antenna and tube count. The last was interesting to me once I came to understood that most hams in that part of the world made their own equipment. It encouraged me to try my own hand at building despite my lack of ability. I had success with small projects but not with receivers and transmitters. I soon decided to stick with commercial gear and focus my home brewing on antennas. 

The more adventurous hams over there might mention the weather or that they were operating from a club station (very common) at a university or other institution. To my surprise there a handful of more garrulous hams who said a lot more. These were rumoured to be powerful "party" members who were unafraid to speak more freely. However, even they didn't stray beyond the invisible boundaries.

I clearly remember a visitor from those years. A passerby saw my small tower and TA-33jr and knocked on the door. This trim gentleman of middle years was ushered downstairs to my shack by one of my parents. He told me, with a light central European accent, that he had been a ham years before (OK). Curiosity drove him to inquire. 

It was early enough in the day that 20 meters was open to Europe. I spun the VFO, letting him listen to CW and SSB stations from Europe. When I came across a strong Russian station on SSB I asked if he'd like to make a QSO. If you know anything of that time you might cringe at my naivete. He graciously declined with a smile, saying that he was happy just to listen. It was only after he'd gone that I realized the indelicacy of my suggestion. He was one of many from that country that found their way out after the failed revolution of 1968.

Jumping ahead many years, after the Berlin wall came down, it seemed for a time that free communications between the citizens of formerly antagonistic countries would be the new normal. That didn't last. New conflicts began as others faded into history. I clearly remember when over 30 years ago one of our networks interviewed me in the aftermath of the invasion of 9K. Wide use of the internet was a few years in the future and amateur radio remained a viable communications link that media and others leaned on when necessary. The interview was interesting enough that it was aired.

Not long after that I made my first visit to that part of the world. I remember the curious sight of BMWs and Trabants sharing the roads of east and west Berlin. A friend visited Russia around the same time and had a wonderful trip meeting hams in Moscow and St. Petersburg, including quite a few from the central Asian former SSRs and from JT. We were both looking through his pictures of that trip just a few days ago. He had a fine time and was treated as a minor celebrity since visitors from western countries very still rare.

But the world is ever changing. Although we are now more connected than ever, we remain far apart culturally, economically and politically. The canvas changes but human nature and ancient grievances stubbornly persist. Amateur radio no longer provides a critical link between far flung individuals now that the internet and commercial communications systems are globally pervasive. 

A few countries still ban amateur radio (P5, EZ), and more control cross-border communication of all types. Now we add UR to the list, though for long is anybody's guess. That said, there are a few UR stations on the air. This may seem surprising until you do a little digging. Plug those call signs into a search engine or at and the answer will be found.

During the present conflict hams have opinions like all people do. The difference is that we have the ability and desire to reach across borders to speak to strangers. At least for those who share our hobby and passion. There are many hams that are at present uncomfortable talking to Russian hams even though they are not personally at fault. That is a difference from the 70s when reaching out across those political barriers rarely merited a debate. Online discussions of the present dilemma that I've run across show a diversity of opinions and, I am happy to relate, remain polite. People (and hams) can agree to disagree.

In my case, I work them. That means little since my operating is almost all contests and in-and-out DX QSOs. I had no caller from those countries the one time in the past few weeks when I sat on an SSB frequency with a kilowatt and stacked yagis and worked a long list of European stations. Those are the rare times I am willing have an actual conversation.

If I do get a call from there during one of these outings, what will I do? Truthfully, I know I'll talk to them. What I wonder is how deep I'll get into a conversation. I suspect neither side of the QSO will want to take chances with too much easy talk. I'll wait to see how it goes when it happens.

On a pragmatic note, there is no possibility to purchase Russian vacuum tubes for amplifiers and other products. That segment of the global supply chain may not recover for a long time, if at all. Think carefully when shopping for an amplifier. There are very fine amplifier tubes from China, like the one in my Acom 1500, that continue to be available. I suspect that the war will accelerate the migration to solid state amplifiers. 

Amateur radio can continue to bridge the divisions caused by war. It isn't easy, nor should it be. We exist in the world and each of us must find our way on and off the air. Unfortunately this is not the only war going on at present, and it is not the one with the highest number of casualties. But we tend to focus on those where our cultural and radio linkages are strong. Give the others a thought as well.

Wednesday, March 9, 2022

Failure and Re-invention: Antenna Selector

I hate to admit it, but I have had a spectacular failure. Longtime readers may remember the prototype work I presented last year for all-inclusive antenna selector. This winter I made a concerted effort to progress and hopefully complete the project. I give up. A different approach is needed.

Let's recap what this device is intended to accomplish:

  • One button press to select direction (or disconnection) of the Beverage receive system
  • One button press to select the 80 meter yagi direction one CW, omni-directional on the CW or SSB segment, or the 160 mode
  • One button press to select high or low antennas (physical height or elevation angle), for bands from 80 to 10 meters, both antennas for bands with stacks (20, 15, 10 meters), or the tri-bander(s) for the high bands
  • Automatic antenna selection using band data from two radios (SO2R or multi-op), and prevent or delay switching when the rig is transmitting
  • Electronic switching of all the remote relays

If you click the above link you'll see that the construction is as designed. The article includes details of the mechanical, electrical and software design that I won't repeat here. You can at least get an idea of how it is used from the above photo of its current state of construction. 

LEDs indicate the selections, and for the top row the colour is green for low (ground) and blue for high (sky) antennas. When you press a button on the top row it advances through the available options (e.g. high, low, both for the stacks) and, for the high bands, the TH6 tri-bander. Tri-bander selection is blocked if it is in use by the other radio; I have no triplexer

For the 80 meter yagi the mode button cycles through CW, SSB and 160 meter options. A long hold of a direction button selects omni-directional, and all direction LEDs turn off. Buttons are easy to manipulate during a contest when your attention is elsewhere and the LED colours are highly visible and intuitive. The 80 meter selector is on the left and the Beverage selector is on the right.

There's a lot inside the enclosure: software, controls, switching, communications and power management. Although conceptually simple the execution is more difficult than I anticipated. I'll briefly list the challenges I ran into:

  • Too many LEDs (25) and buttons (18) resulted in a rat's nest of wires and wiring harnesses. Soldering, routing, and connections were dreadful. Then there were the resistors for the LEDs and the voltage divider network that needed their own boards and connectors. The initial version requires 21 relays and buffer stages, and at least 20 more are needed for antenna switching.
  • Arduino GPIO pins are sufficiently current limited that many of the LEDs, due to size and colour, were weakly lit. The correction requires a buffer transistor stage (NPN + resistor) to access the power supply directly. Hence more connections and devices.
  • Momentary push buttons do not close cleanly. Software correction and de-bouncing is possible, however the simple algorithm I developed for the prototype is inadequate. A better algorithm requires more work and experimentation, and the reliability is yet to be determined. 
  • Labelling of the controls and external connections is fairly easy with water slide decal paper. The labels are ready but I have run into problems. For example, both white and clear backings are needed for different graphics, which I only discovered after trying to apply them.
  • Coming up with sensible behaviour and access to all switching features with the simplest tactile devices has been difficult. The current version uses momentary push buttons throughout, some with integrated LED illumination. The hardware and software is more work than I planned for.
  • There is a lack of flexibility. No matter how well I plan the controls and layout there will be misjudgments and mistakes. Once you punch a hole in the enclosure there's no turning back. For a flexible user interface (UI), software has the upper hand. All amateur radio equipment is headed in that direction for good reason.
  • GPIO pins are a scarce resource. I selected the Arduino Mega2560 for its large number of GPIO pins, and even that is not enough. A second Mega is required for interpretting band data and controlling the 2 × 8 antenna switch and second level switches for bands with more than one antenna or antenna stack. Communication between the Arduino processors is required.

You will get an idea of the mess of wiring from the above view taken from the open side panel. The Arduino is on the right, the 5 volt supplies bottom centre, direction buttons overhead, band selector LEDs and buttons at upper right and studs for the boards that will house the relays and transistor switches are at the front. Not everything is visible at this awkward camera angle, and the relay boards and their wiring harnesses to the Arduino and panel jacks are missing. The mess can be reduced with custom circuit boards and Arduino shields, but that has its own complications that I won't get into.

My patience is not what it once was. My aging eyes make it difficult to work in small and tight spaces. Soldering and wiring errors are inevitable, little things break, the small enclosure is a difficult space to arrange components and work on them. Microelectronics demand careful handling to prevent static discharges, shorts and excess heating. Errors can be expensive: mostly of my time and peace of mind since the components are not expensive.

The challenges can be overcome, but I no longer want to, at least for now. I am therefore skipping over the first generation of physical controls to pursue a software UI. The hardware switches and LEDs will be disconnected. I'll keep the enclosure since has been prepared, and I might resume wiring of the buttons and LEDs in future. There is also the benefit of freeing up desk space since it can be placed anywhere.

For the software UI, physical buttons are replaced by mouse clickable buttons, and eventually touch screen buttons. LEDs are replaced by button colours and other indicators. The Arduino GPIO pins will be solely used for antenna switch control lines, which greatly reduces the wiring challenge. Once band data for the radios is included it will still fit on one Arduino Mega. Eliminating much of the soldering and wiring is a great relief.

In my initial prototyping of the software I have established communication between the Windows PC and the Arduino, come up with a simple protocol with human readable data (for ease of debugging) and created a development environment on the PC. The first priority is to get it working. The appearance can be improved later.

My preference is to use a dedicated computer or monitor for the UI. But for now the UI will share the PC and display alongside other station software, including the multitude of windows I have open during contests. The mouse will eventually be replaced by a touch screen. In a multi-op conteset, each operator can reach over to use the common screen. Later, I may have a screen at each operating position. For SO2R just the one will suffice. 

I am using multi-platform software so that the UI can be easily ported from a Windows PC to a Raspberry Pi or other computer. There are alternatives available. For example, I know many hams who use Node Red. For my needs I prefer an architecture that allows complex customization and algorithms.

Details of the software UI will be the subject of a future article, once I have it working. The project is not too daunting since I was a software professional and I am using tools I was once familiar with. However, I have to refresh my stale knowledge and much has changed over the intervening years. The screen shot provides a hint about how I am proceeding.

I am relieved to put down the magnifying glasses and soldering iron for a few days while I get the basics of the software system designed and implemented. Some of the questions I am pondering at this early stage include:

  • Where to place the antenna selection logic: in the PC or the Arduino or both.
  • The UI must be easy to use and the indicators clear so that the operator can make selections easily and without ambiguity, and protect against untimely or poor choices.
  • Abstract the communications protocol so that it can expand as features are added and be compatible with a serial (USB) or IP (wireless) link.
  • Hard coded switching algorithms and system configuration versus programmable via the UI. The latter entails enough additional complexity that I may never bother.
  • Dual UI coexistence -- software and physical -- should I later finish restart work on the hardware controls.
  • Last summer's lightning strike on the Beverage did damage in the shack. That experience compelled me to reconsider solid state (Darlington transistor) switches. I will use relays.
  • Computer dependency is increasing in my station. A PC or software bug can lose a contest. I have ideas for risk mitigation which require investigation.

This turnabout is quite a change from the original design. It is nice that my frustration level has declined now that progress has accelerated. Perhaps I should have taken this route from the start. I have always been impressed at some of the beautiful antenna switching systems others have built. Those were a strong influence when I started this project. I love those large maps and lamps that indicate antenna selection and direction. 

What a physical box does not allow is easy experimentation with alternative UIs. It is easier in software to move buttons around, change colours, change buttons to switches, etc. I'm looking forward to the flexibility.

The lesson I will leave you with is that you should never be afraid to discard or replace a project if it doesn't work out. It may be an antenna, electronics or other device for the shack. Stubbornly standing by a mistake is itself a mistake. To adopt the common cliche from the technology industry: celebrate your failures. The experience and knowledge gained leads to future success.

The weather is warming up and tower work is on the horizon. I'd like to get this project in a sufficiently usable state by April so that I am free to dive into my long list of tasks to meet my goals for 2022.

Thursday, March 3, 2022

The Amusing Side of FT8 Slowness

Recently I wrote about my perspective versus others on the slowness of FT8. I would rather use the faster FT4 but since few bother I am stuck with the slower digital mode. A recent experience demonstrates a peculiar advantage of its slow speed. I relate the story so that you can laugh along with me. (I know that I need a distraction, if only briefly, from world events.)

I was monitoring FT8 activity on 160 meters (1.840 MHz) one evening while I was busy with other tasks in the shack. My interest was to monitor the activity for interesting DX. I would occasionally glance at the monitor to see what was coming through. Perhaps something rare would pop up to incite me to transmit.

Nothing terribly exciting was heard other than some countries to the south. One of these had a compound call sign of the form XX/YYYYY. I could see about 6 or 7 stations vying for his attention. On a whim I called and he came back to me.

We exchanged reports and he sent RRR. Before my 73 message could be sent, WSJT-X crashed.

The error message meant nothing to me so I closed the Windows info boxes that popped up and tried to restart WSJT-X. Nothing happened. I opened the Windows Task Manager and paged through the active processes and found an orphaned process belonging to the app. I clicked the process, pressed End Task and exited the Task Manager. WSJT-X started successfully this time.

I expected to find that the other station had abandoned our QSO and gone on to work one of the other callers. But when the decoded messages scrolled past there he was still sending me RRR. Surely at least 2 minutes had passed! I'm surprised that he stuck with me through at least 4 transmit periods.

Since WSJT-X lost its state data in the crash I had to jump into the QSO manually. I clicked on the RRR message, selected a clear frequency to transmit and clicked Enable Tx to send 73. I don't know how fast I did all this since it worked and the QSO was completed. My reflexes are fast since I am a contester. Luckily I remembered the sent and received signal reports so that could I manually entered them in the log window.

As soon as I did that and breathed a sigh of relief WSJT-X crashed again.

I went back into the Task Manager and killed the orphan process. Then I checked the log to confirm that the QSO was saved. Before restarting the app I went to the WSJT-X web site to see if this was a known bug. It was and it was fixed in the latest release (2.5.4), which I had not yet installed. The text of the bug fix was perfectly descriptive of what had occurred:

WSJTX: - Repair a defect that caused occasional crashes when in QSO with stations using nonstandard callsigns.

I have a habit of delaying installation of software updates since they can introduce new bugs, I may not use the features that have been fixed, and I am in no rush to explore new features. This is a case where I should have updated sooner.

Completing a CW or SSB QSO with such a long period of silence would never have happened. The slowness of FT8 came to my rescue. Sometimes slow can be good.