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.

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.

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 QRZ.com 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.

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.

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.

ARRL DX CW Contest (2022)

I occasionally recap my contest experience to relate events and to discuss topics that may interest others and not just me. The 2022 running of the ARRL DX CW contest is one of those. I'll try to keep it concise to avoid boring readers who have not been bitten by the contest bug.

Choosing a category

It has to be said up front: I have no illusions about winning. These days I am up against the big guns, often with even bigger stations, better propagation and better operating skill. When I choose a category I try to balance testing the station, testing myself and having fun.

Due to technical problems I was at first reluctant to operate in an all bands category. One temptation was 40 meters single band, assisted, to put the new antenna to the test. I could also rest during the day and avoid the drag of a 48 hour marathon. This worked well for in CQ WW SSB last fall when I entered the 15 meter assisted category.

With conditions good and a positive attitude I decided to see what I could do with an all band effort. I demurred going assisted to focus on improving my running skills and test the potential of the new 40 meter yagi. I believe I made a good choice, although it's likely I'd have been happy regardless of my choice.

Run versus hunting multipliers

I have a tendency to linger too long when attempting to work multipliers since I'm a passionate DX'er. This is where the logging software helps to give you perspective. I use N1MM+. On the score summary window there is a statistic at the bottom that tells you the incremental value of a multiplier. For example, it might say "1 Mult = 5.5 Q's". That is, the score will increase the same amount by working one new multiplier or 5.5 QSO's (of average point value).

If you are a big gun it can pay to keep running and not hunt multipliers. It takes time and effort, even if you are assisted. The potential value of hunting multipliers is reduced by the fact that a big signal attracts many callers, including new multipliers. When the running is good it is often best to keep at it.

Big guns benefit from hunting, and the experienced operators know it. When there is a brief opening to a difficult area of the world to work -- for us, that is always true of southeast Asia -- taking time to sweep for those multipliers or to call CQ while pointed in that direction pays dividends. When the bands are closed to Europe -- for us, that is mid-afternoon at this point of the solar cycle -- the runs slow considerably and the time may be better spent multiplier hunting.

For whose doing SO2R, it is possible to hunt while running. Indeed, that may be preferable early in the contest when running on two bands (2BSIQ) can be difficult because of the size of the pile ups.

For those with low power or small antennas the choice more often favours multiplier hunting. Every situation is different and you have to continually assess whether to stop and run rather than keep hunting. When I had a small station I would try to run at intervals and stick with it if the rate was acceptably high. Otherwise I'd return to spinning the VFO. Now I am far more likely to keep running when conditions are favourable.

2BSIQ

Running concurrently on two bands is a difficult skill to learn. Most SO2R operators run on one band and S & P on another. However when it's done well and you get into the "flow" it can be tremendous fun and your score will grow at an impressive rate. I have had SO2R success in contests like NAQP but not the major international contests. The reason is interesting.

In NAQP a large majority of stations run 100 watts. That narrows the range of signal strengths of callers, and signals are usually not exceptionally weak. When I run a kilowatt on a band with QRN and QRM there are many weak callers. The "rhythm" of 2BSIQ is lost and bedlam ensues. 

For example, the late night opening on 40 and 80 meters (after their sunrise) only lasts 1 or 2 hours, so it is very productive for 2BSIQ. Unfortunately, the many callers and their low SNR requires concentration to separate one signal from among many and to copy them well. I ultimately failed at the attempt. It would go well for a while and then I'd get a large burst of callers on one or both bands and I'd lose control of the timing and end up with pile ups raging in both ears. Half the time I'd abandon one of the run frequencies to regain control of the situation.

Saturday on the high bands the rate of European callers is high. My full attention is required to run on one frequency. Running on two bands is beyond my ability, so the second radio is only used for S & P if at all. On Sunday when the rate is lower it is a little easier to do 2BSIQ on 15 and 20 meters. But for me it is remains difficult. All I can do is keep practicing.

Automation and equipment woes

The bigger the station the greater the number of things that can go wrong. There is always something that needs repair or maintenance, or there are projects still incomplete. My rush to get the 3-element 40 meter yagi finished before severe winter weather arrived put many other jobs on hold.

Here is a selection of the equipment challenges I faced during the contest:

• The prop pitch motor turning the upper 20 and 15 meter yagis does not work well or at all in cold weather. By that I mean below 0° C. In our climate that's a huge issue. Since the weather during the contest was typical for February I parked the yagis to 330°, at east Asia, and used the lower yagis to work Europe. The stacks were never in play during the contest.
• The rotator for the side-mounted TH6 was stuck. I had parked it at its west stop to protect it from wind storms and it appears that the Ham-M brake wedge would not retract. On Saturday it freed itself, much to my relief. Due to the prop pitch problem, the TH6 was the only antenna for 15 and 20 that I could turn to the west and south. 
• Lack of automation causes a "fear and loathing" of  band changes. Each band change requires switching antennas, switching the BPF, switching the amp and tuning the amp. There are no rapid band changes to sweep for multipliers or to check propagation. For quick band changes I left the amp offline and operated without the amps.
  
• Lack of good visual indicators such as LEDs caused antenna selection errors. For example, I inadvertently used the low XM240 rather than the 3-element yagi on 40 meters to run Europe Saturday evening. I was struggling but didn't discover my mistake for 2 hours.
  
• Despite the BPF, the FT950 receiver cannot deal with a few band and antenna combinations. There is enough RF from the other radio and amp to cause excess noise and make SO2R difficult. Turning off the pre-amp helped but on the high bands that affected copy of weak stations.
• A series of unexpected strong wind gusts on Sunday turned the 3-element 40 meter yagi by 10° on the mast. I believe this was caused by an unfortunate mistake during installation. It is easy to repair. The storm also damaged one element, and that repair will be more difficult. However the antenna continues to work very well so it's more of an inconvenience for now.
  

Once the warm weather arrives I have a long list of maintenance tasks to deal with. I no longer have the excuse of major antenna projects to distract me so I'll just have to get down to work. The same goes for progress on station automation. I expect to be in far better shape for the next contest season.

40 meters

The new 3-element yagi worked well. One glitch was due to my poor switching system, whereby I was on the low XM240 for a couple of hours by mistake. I wondered why my rate wasn't what it ought to be during the European opening!

Over the pole it brought in welcome multipliers from Asia. I even managed a brief JA run after our sunrise. This experience bodes well for the future. One dark spot is that the antenna suffered minor mechanical damage during house-shacking wind bursts Sunday afternoon.

Remedial work will be done when the weather warms up. For now the antenna continues to work well despite the problems. Details will be left for a future article.

QRL?

In the heat of competition many contesters searching for a run frequency on a crowded band fail to first ask "QRL?" or even to listen for a few seconds. Only a few of these are deliberately attempting to steal the frequency. It is too easy to be trigger happy in a fast paced contest: you listen for a second or two and start up the CQ machine. Others see a hole on the SDR spectrum display, click and punch the CQ button. 

Almost all will QSY when I announce my presence. The reason for the silence that entices them is usually that I'm listening to a weak or slow station, probably one within their skip zone that they cannot hear. This is mostly a high bands problem since the crowding is less and the skip zones smaller or non-existent on 80 and 160 meters.

A related problem is for stations within my skip zone. That includes a populous region of the United States. Unless we hear each others' callers it is easy to believe the frequency is open.  We can't hear each other so we don't copy the "QRL?" We may not realize what happened until we hear the confusion of callers. The frequency isn't big enough for the two of us so one of us must go.

Propagation

Experienced contesters check propagation paths a day or two before a major event. Admittedly I don't often do it but this time I did. It helped me to plan and to ultimately select my category. 

RBN (reverse beacon network) is a valuable tool since listening for stations and calling CQ are not enough. Outside of contests few hams appear for these brief and unusual openings. I call CQ hoping for a reply, but I will settle for data from the RBN. Unfortunately there are few nodes in Asia, Africa and Oceania, and those are critical to propagation research. Despite that lack the exercise is valuable.

One example is the path to northeast Asia during our early evening and their post-sunrise morning on 15 and 20 meters. The prospects for good openings were promising and indeed there were productive JA runs during the contest at the predicted hours which had been rare during the solar minimum.

Another propagation path that is particularly valuable in the ARRL DX contests is Europe on 80 and 40 meters after their sunrise. When the geomagnetic field is quiet the opening can extend 2 hours or more  after sunrise on 80 meters. Hundreds of contacts were logged during those openings. The path is less valuable in contests like CQ WW since Europeans are more inclined to move to the high bands in the morning since they are not only looking to North America for contacts.

With the high solar flux and still good low band conditions, quite a few station were worked on 6 bands. This was rare during the solar minimum other than the occasional Caribbean station.

W/VE callers

Many casual operators participate in major contests. Sometimes their willingness to hand out points isn't helpful. For W/VE stations in the ARRL DX contests, contacts with W/VE stations are worth zero points. Yet they keep calling. W call W, W call VE and VE call VE. No one wants to be rude but it becomes annoying when I have multiple DX callers that are covered up by one or two strong zero-pointers.

Sometimes I politely tell them "sri dx dx only pse". Half the time they keep calling regardless. Other times I work them to clear the frequency but don't log them. I know that other contesters do the same, while some are more rude and others shrug while working and logging them.

Many casual operators don't read the rules, know the exchange and have little understanding of each contest's unique rules and procedures. I am happy they are always there when I need them, so I keep it polite. It is more difficult to explain the situation on CW than on SSB.

Live and let live

Do you believe that everything goes in a contest? I don't but many do. When I operate in contests I avoid narrow channels of activity devoted to non-contest operating. Examples include FT8, beacons and a few SSB frequencies used to monitor for emergencies. I avoid running or calling stations on those frequencies. A few times I've violated the rule to work a juicy multiplier so I am not blameless.

Too many jump on those frequencies and run and ignore requests (or demands) to QSY. Those with a big enough signal may get away with the transgression. Their reputations is another matter.

Future

I have never been enthusiastic about operating a weekend-long contest by myself. It was true when I was a teenager in the 1970s and it's true now. I need to get my station into a state where I can invite others to join in a multi-op team now that the pandemic is abating.

My objective is to have fun and share in the energy that a team operation generates. It is an experience I have only rarely enjoyed since returning to the hobby and contests not many years ago. At first it was nice to do what I wanted when I wanted, which is sensible with a small station and QRP. But with a bigger station the demands of a contest weekend are far greater.

There is much work yet to be done, work that I've deferred during the pandemic. Major tasks include the shack desk, equipment and automation. Getting the antennas and rotators in good shape is important but is of lesser priority. This is the year to get it done.

Final note

It feels surreal to be discussing a topic as mundane as a radio contest in light of current world events. Had the contest taken place a few days later everything would have been different. In a way it both surprises and doesn't surprise me that few hams talk about the war on the air or in personal conversations. Life goes on. My family has history in that part of the world and I know many hams with close ties to the region. Conversations on bulletin boards are lagging and so are the page views on my blog while all of us are preoccupied by world events. 

73 to all.

Farmers and Hunter-Gatherers

Let's roll the calendar back several thousand years, before humans developed civilizations and cities. The major preoccupation was survival. That required growing or finding food. Tribes that learned how to farm continued to hunt game and gather plants and fruits necessary for a healthy diet. Whether a child grew to become a farmer, hunter or gatherer was determined by ability, family and culture.

Mechanized farming in our highly developed civilization is done by a small fraction of the population. Today's farmers produce what our ancient ancestors farmed, hunted and gathered, and do it so well that the rest of us can barely comprehend how our ancient forebears lived. A better understanding can help increase our contest scores -- really! So let's push the analogy.

If you know anything of contests you will have made the connection by now. Farmers run and hunter-gatherers S & P (search and pounce). Little pistols can only do well as primarily hunter-gatherers, and will farm (run) when they can. Big guns are farmers, but will occasionally forage (or concurrently using SO2R) for multipliers. Those with stations between the extremes, or in assisted classes (including multi-ops), more equally balance their tactics.

Farming, hunting and gathering are hard work, just as they were in the distant past. A farmer is forever worrying about the weather (propagation), terrain (geography) and predators (frequency "theft"). Seed must be kept, stored and planted, the fields irrigated, weeds picked, predators dissuaded and the crop efficiently planted, harvested and processed. 

Runners must find and protect their frequency on prime spectrum (fertile land), have a signal and tactics that withstand or overcome external forces, attract hunter-gatherers, and periodically abandon the farm to hunt and gather multipliers. Since game will cross the farm from time to time or be attracted to the crop there is opportunistic hunting as recompense for staying put.

Hunter-gatherers are always on the move. You must move or you die since food sources are scattered, those with legs move around, and once you deplete an area you must find another. The old and infirm who cannot follow the tribe fare poorly. So, too, the S & P operator must keep moving. You may not die when you stop moving but your score will plateau. A seer among the tribe (DX cluster or skimmer) may tell you what and where but you must go forth to seek and take what you need.

Early farming societies were often prone to poor nutrition due to the reduced food variety. Early civilizations dependent on agriculture were vulnerable to more mobile invaders because they had to defend their land and crops. For example, the Mongols needed to keep moving as their herds (temporarily) exhausted what the fields could provide. No matter the strategy, survival was difficult and risky.

Contest operators who exclusively run or S & P will plateau and fail to achieve the top of the contest rankings. I know contest enthusiasts who are uncomfortable running because it is difficult for them to deal with multiple callers or their signals are too small to hold a run frequency for long. Others love to sit on a frequency all weekend and let the hordes, including multipliers, come to them. They enjoy being sought and the attention a big signal attracts and may dislike the work of spinning the dial and hunting.

Runners (farmers) rarely work other runners since neither moves around much. The S & P operator (hunter-gatherer) will never work other S & P operators since they can only call runners. Specialization reduces score potential. Expanding skills and pushing ourselves out of our comfort zone requires effort and, at least at first, may not be enjoyable. Many mistakes will be made before significant improvement is achieved. SO2R multiplies the discomfort and effort.

An alternative is to join a multi-op team. Those who prefer running get to run and those who prefer S & P get to hunt and gather QSOs and multipliers. Both are needed. Early in my contesting career I preferred S & P. Operating from VE3PCA in the early 1980s I liked to man the station overnight when the pickings were slim and scouring the bands to eke out whatever I could -- we were approaching the solar minimum and spotting nets didn't exist. When the high bands opened at sunrise, I ceded the station to the runners and get a few hours of sleep. Our small group included both farmers and hunter-gatherers.

I expect that most readers have by now decided that I've pushed the analogy too far! I'll switch gears and close the article with a related topic that is too small for an article of its own.

Chasing DX and hunting multipliers in a contest require similar tactics. It is a challenge to be heard in the pile ups so that you can quickly log the entity or multiplier and move on to the next. Consider the following quote from the 3830 comment by V47UM in this weekend's ARRL DX CW contest:

"successful callers were mostly about 50-100Hz up or down"

CW signals that are near zero beat with each other are difficult to distinguish. Although calling high or low can be an effective tactic, it can backfire. When too many call high or low they will zero beat each other and the tactic can fail. The reason is that you can't offset too much or you'll be outside the other station's receive filter. However, keep in mind that what you really want is to call where others are not. When the majority call high or low, calling on frequency makes you distinctive. Listen to what others are doing, find the hole, wherever it is, and call there.

Since my transition from QRP with small antennas to my present big signal, tactical calling has less value. I usually do better by zero beating or calling on the frequency of the last successful caller. Big guns have the advantage of brute force. 

In the coming days I will describe my experience in the ARRL DX CW contest. There were high and low moments, and there were lessons learned. A few are worth sharing.

Hy-Gain Rotator Mast Slippage

As the temperature crept above freezing this week I made my first tower climb of 2022. It was to re-align the antennas (yagis for 6 and 40 meters) on the 21 meter high Trylon. The rotator is a Hy-Gain T2X (Tailtwister). This is periodic maintenance that is needed due to mast slippage in the rotator mast clamp. It happens approximately once per year. It has already happened once on the TH6 side mount and Ham-M rotator with the nearly identical mast clamp.

My story is familiar to owners of Hy-Gain rotators turning medium and large antenna arrays. The mast clamp has never been improved over the decades of production by Hy-Gain (now MFJ). After all, why would they incur the cost of risk of a major product change when there is no impact on their business? Hams keep buying them despite the flaws.

The number of rotators on the market is small and at least Hy-Gain is a known quantity despite the products' flaws. There are few cost-effective alternatives. I use them but I never buy them new. They are only worth the far lower price they command on the used market.

Here's a question about these rotators that is worth pondering: When the mast slips in the clamp, is it a sign that the clamp is deficient, improperly adjusted or that the the load exceeds the capacity of the rotator?

If you have a quick answer to the question, I suggest that you think again. Let's consider the capacity specification for the T2X for the common case where the rotator is largely isolated from bending stress by one or two thrust bearings. From the Hy-Gain documentation, as extracted above:

• Braking strength: 750 ft-lb (9000 in-lb)
  
• Antenna wind area: 20 ft²
  
• Maximum effective moment: 3400 ft-lb
  

It is interesting that the several manuals of Hy-Gain rotators I perused for this article do not mention braking strength or vertical dead load. It is shown on the MFJ product page. The vertical load capacity is sometimes quoted as ~700 lb, but I can't confirm that value.

The precise values are somewhat tangential to the main thrust of this article. However, note that the braking strength is less than 25% of the MEM. Is the brake deficient or are the specs less than enlightening? It's the latter, and I have more to say about it further below.

Many hams worry more about the dead load weight than the braking torque limit. So much so that, in my experience, they insist that the thrust bearing take the weight of the mast and antennas to protect the rotator beneath! This is despite the facts that the rotator is designed to support the vertical load and the widely used thrust bearings are incapable of supporting any vertical load. The most common explanation I've heard is that the rotator is expensive and must be "protected". It is a peculiar belief with no basis in fact.

This may seem to be an irrelevant observation in the context of the present article. It is relevant since most hams are not as mechanically adept as they believe and the same lack of understanding appears in discussions about mast slippage.

For example, assuming the 9000 in-lb braking strength is valid, it can be reached by applying 75 lb of force to a 10' long lever attached to the mast, such as the antenna boom of a yagi. Failure would be catastrophic should the bell housing fracture. In practice it is more common for the ridges in the lower bell housing to wear or for the solenoid to bend or break, both of which will allow the mast to spin freely. The reduction gear train of a Hy-Gain rotator has little braking resistance on its own.

For the sake of discussion, let's assume that we install an absurdly large antenna on the mast. One so large that we are certain the braking strength will be exceeded in a moderate wind. If the mast clamp is perfect (no slippage possible) the brake or bell housing will fail. That would be an expensive failure. There is the immediate risk to the tower, antenna and property below, and the cost of a new rotator. You never want this to occur.

When the mast clamp is imperfect the mast will slip and the rotator will not suffer a catastrophic failure. The torque at which slippage occurs is far too difficult and imprecise to calculate. We can only hope that slippage occurs well below the threshold for catastrophic failure. Absent clamp or bell housing failure it is also important that the mast slip before there is sufficient force to damage the bell housing "teeth" and brake solenoid. Under the stress of continuous assaults of a too large antenna array the brake will eventually fail.

What I've described is a mechanical fuse. The slippage, although annoying, reduces the risk of catastrophic failure. Unfortunately that slippage often occurs with torque that is well below the braking strength of the rotator. Hy-Gain recommends pinning the mast to the rotator clamp (part 136, above). They helpfully mark a blank for the hole on the bell housing and provide a hole on the clamp plate. Following that advice can be a costly mistake.

With a pin through the mast and clamp there is no give. When a sufficiently large force occurs, and it will occur, something will break. In a typical installation the weakest link in the chain is the bell housing. The mast, pin, u-bolts and the exterior mast clamp plate are stronger. You can choose a bolt grade of lower tensile strength for the pin, however there is no good way to calibrate it to break at just the right amount of mast torque to protect the rotator. It will almost certainly break at too low a torque or not break when it should. A weak bolt will fatigue and fracture over time and it will then break at a low torque.

There is also a maintenance issue with pins. To insert or remove the pin the holes in the mast and clamp halves must be perfectly aligned. That can prove very difficult unless the holes for the pin are punched with the mast fully seated in the rotator clamp and when the wind is calm. Otherwise the weight of the mast and antennas must be precisely manipulated to align the holes to remove or insert the pin. One instance of removing and re-installing the rotator can make you regret using a pin.

There are less extreme methods to increase resistance to slippage. A few common ones are:

• Increase contact area between the clamp and the mast
• Teeth or grit to penetrate the surfaces of the mast and clamp
  
• Set screw

Like many universal clamping systems the surfaces have a V shape. A range of mast diameters can be accommodated at the price of a low contact surface area. The ridges on the bell housing side of the clamp reduce the contact area and provide no sharp striations to penetrate the mast. The other surface is smooth. Even that might be enough if the clamping material was steel. Unfortunately, the clamp plate relaxes over time no matter how much the nuts are tightened, and aluminum striations will not penetrate a steel mast.

Last year I inserted a thin galvanized mesh to see if it would be gritty enough to bite the aluminum and reduce slippage. It made no noticable improvement.

The clamp hole for the pin can be threaded for a large set screw to penetrate the mast at one point. I doubt that would work because the flex in the clamp would relax the hold of the set screw as it already does for the u-bolts. I've seen it done but I have never bothered.

One thing you should not do is over-tighten the nuts on the u-bolts. The clamp will relax regardless and you risk breaking or galling the stainless bolts or, worse, cracking the bell housing.

It is possible to machine a one or two piece mast shim with an inner surface that conforms to the mast and an outer surface that conforms to the V shaped clamp surfaces. The increased surface area will increase the mast torque required for the mast to slip. I've never seen one but I have heard of it being done. I doubt that it worth the effort.

I earlier put aside the "maximum antenna size" specs and it's time to delve deeper. How did Hy-Gain arrive at the maximum square footage and MEM limit and what do they mean? This is less than obvious. For example, 20 ft² of antenna surface area tells us little without a great deal of context. Let's provide some.

For the 135 kph (85 mph) wind zone which is most common, at that wind velocity the lateral force on a cylindrical 1 ft² of projected area the static load is 20 lb. For the listed 20 ft² the lateral force is 400 lb. That's a lot, however none of it is seen by the rotator when the mast, tower and thrust bearing(s) are doing their job. The rotator will only be sensitive to torque. 

Torque is roughly in linear proportion to both antenna surface area and MEM. That tells us little since yagis are balanced by weight (CoG is at the boom-to-mast clamp), and by the cross-wind principle the torque should be zero. It isn't zero because the boom and elements are not in a laminar wind stream. At high wind velocities the air flow and mechanical oscillations are non-linear, 3-dimensional and can create brief periods of high torque. The 6° of motion the T2X brake allows adds to the peak strength of oscillations and mast torque. It is the peak torque that the rotator and mast clamp need to resist.

The MEM spec is no more than an heuristic tool to guess at what the rotator can deal with. As mentioned earlier, that the MEM is so much greater than the T2X braking strength makes it clear that the weight of the antenna is never applied to a lever equal to the length of the turning radius. The spec is little more than a rough guide, and that guide is of little value without more precise conditions where it applies. The lack of those conditions in the specs is telling: don't trust MEM!

There is no simple or straight-forward calculation, and two balanced yagis with the same surface area and turning radius will give different answers. Tube diameters, alloy and wall thickness, along with taper schedule, truss and element placement are all factors that make for the difference. So how do we interpret and what are we to do with Hy-Gain's specs?

MEM is defined by Hy-Gain as the product of antenna weight (lb) and turning radius (ft). This is a rough analogue for the expected torque under undocumented conditions. For example, a Hy-Gain TH7 has a cylindrical surface area (elements broadside) of 12 ft², weight of 75 lb and a 19' to 20' turning radius. 

MEM of the TH7 is 75 × 20 = 1500 ft-lb. This is less than half of the specified braking strength of the T2X rotator. Is this reliable? Can the T2X handle an antenna of the same size but twice the surface area (40 ft²)?

Certainly my recently installed 3-element 40 meter yagi is too much for a T2X with its MEM of ~8000 ft-lb. The wind load is 27 ft² but the weight is 4× that of the TH7. Doubling antenna size typically requires 2² the weight to be structurally sound.

My T2X survived moderately high winds with a TH7 and 6 meter yagi on the mast (total MEM of 1700 lb-ft), but that is hardly definitive. It's like proclaiming that I plan to live forever -- so far, so good! Tomorrow the T2X could shatter in a wind storm. There will always be a storm that will destroy any installation. It's a matter of probability: is that storm likely to occur once a year or once a century? We can only estimate, build and hope that century storm doesn't happen during the life of the installation. Building for a century storm may be unjustifiably costly for the ham budget.

With this in mind, is pinning the mast all that bad? We eliminate slippage and assuming our antennas are within the rotator's specs the rotator will survive. There is also the matter of the tower. Even if the rotator can survive the torque with a pinned mast the tower must also survive the torque. I have personally witnessed a tower twist and break in a strong wind, and the Ham II rotator survived. In that case both the tower and rotator were overloaded, and the mast was not pinned.

If we don't pin the mast, the rotator and tower can survive many severe wind storms. But we must climb the tower after those storms to realign the antennas. It would be nice to avoid this maintenance chore since I have so many others with my large antenna farm. I have already been up once to realign the side mounted TH6 after a wind storm. That is likely to be a regular chore since the antenna is not centred on the mast.

In the face of the several uncertainties I choose not to pin the mast. I prefer the maintenance over the relatively low risk of rotator or tower failure. I'll continue to grumble about mast slippage despite my choice. For those who must hire a tower rigger to do the job the balance may shift in the other direction. 

Alternatively, buy a rotator that is less prone to slippage and that has no brake mechanism. For example, one with a worm gear drive and a better mast clamp (e.g. AlfaSpid). Of course there are the matters of cost and the trading of one set of issues for another since every product has shortcomings.

There is no universal answer. But that is no reason to shrug and be complacent. Make a sensible choice based on calculations and facts. If you live in a hurricane zone or you have doubts about your tower, your choice should take that those facts into account. Rotator and tower failures are costly, and there is the risk of high liability for those living in a densely populated urban or suburban area.

Life in the Slow Lane: FT8

[Note: I've been busy so I have no well-developed technical articles in the pipeline. Instead I am going to start February slow. Real slow.]

Slowness is a notable characteristic of FT8 communications. That is an objective fact, no matter your opinion of digital modes and your operating habits -- casual, technical or competitive. The fastest QSO takes 1 minute and 2 minutes or more is not uncommon with QRM and QSB in the mix. That a long time to exchange call signs and signal reports! Although FT4 is twice as fast it is used far less. The few decibels of relative merit doesn't appear to be the reason.

I may be an outlier of my generation since I still like to drive fast, send and copy CW fast, eat fast, maximize my QSO rate during contests and not dwell too long on any one thing. I don't like speed because I'm a contester but it may be that I remain a contester because it's fast and exciting. Slow contests often bore me. Watching FT8 activity during a digital or VHF contest is as exciting to me as watching paint dry.

Occasionally I ask my non-contesting friends if they find FT8 too slow. From their surprised reactions the question appears to be unexpected. It's as if they're thinking: faster than what? Or: what's the rush? Those underlying questions seem to be ever present even as their answers touch on other issues, including the small stations that make digital modes so attractive to them.

I should not have been surprised. I am in the minority in my age group with my "need for speed". People my age tend to drive within the speed limit and prefer to savour their QSOs. Speed is more alluring to the young.

Most hams are growing old and are inclined to slow down the pace of their lives. They aren't contesters and they are not interested in rate. FT8's 15 second regimented periods are no impediment for the casual operator. It is not too slow to irritate and not so fast that it requires rapid reactions. The "Call 1st" feature provides additional relaxation by eliminating the need to make a decision about which caller to answer. Digital modes welcome and may encourage passive behaviour.

I use FT8. It is my go-to mode for DXing on 6 meters. I like what it can accomplish and so I tolerate its slowness. Attempting to spur activity on 50.318 MHz FT4 by calling lots of CQs has been unproductive. Few are listening.

I also use FT8 on 160 meters when the DX is lacking on CW, which is almost always true outside of contest weekends and the rare DXpedition. Mostly I just monitor to see what DX paths are open. I do not use FT8 on HF because there is plenty of DX on SSB and CW. At least, so far.

Digital is not my preference even though I love the technology for its ability to scrape a QSO from the merest wisp of a signal. FT8 is a mode you like or don't like, use or don't us. It's a personal choice. An increasing number of hams choose it and accept its fixed and pondering pace. That is not a problem for them. I am happy to use it to monitor 6 meters for transitory openings that are so difficult to exploit with the traditional modes.

My preference for CW and SSB is typical for hams of my generation. Younger hams feel differently. Many have never learned CW and have no intention of doing so. For many of them, their entry into ham radio was technology. For me and my peers it was communications. In the 1970s, ham radio was just about the only way for an ordinary person to reach out and talk to someone across the globe. Modern communication services have made our passion for HF and DXing look quaint to most people. 

Why does the speed of the mode matter? I'm a contester, but that's not why it matters to me. Indeed, when QRP was all I had I was not frustrated by the slowness of getting through to another station. I used it as an opportunity to hone my operating skills. I know many hams who use amplifiers so that they can rapidly log the QSO and move on. QRP is an undesirable handicap in their pursuit of speed.

Enticing more hams into contesting or FT4 is a losing cause. They like their slow CW and casual phone QSOs, and they're perfectly fine with the speed of FT8. It makes perfect sense to me when seen from their perspective.

Tedium of Single Band Contests

As I write this, the 2022 CQ WW 160 Meter contest is not over. But it's over for me, and has been since Saturday evening. The endless tedium wore me down. Better DX conditions would have helped, since without that the prospect for contacts is severely limited.

Some people like that and will work with whatever the propagation gods (or devils) provide. I can live with that in most contests. You make do since you know that everyone else is in the same situation. Skill and technology are what make winners.

In a single band contest the application of skill is narrower. When the DX isn't there on top band you have two things you can do: call CQ endlessly and trawl the bands (and cluster/skimmer spots) for fresh meat. I can maintain my enthusiasm for a while. Eventually the tedium gets me down. I have regularly bailed early from contests such as these. This isn't a new problem for me, since it was the same when I first got into contesting as a teenager in the 1970s.

My strategies for countering the tedium have been to operate with a handicap like QRP or as a member of a multi-op team. With an inferior signal every QSO is an accomplishment. There are always more stations to work and challenges to overcome. With a kilowatt and a full size vertical on top band the QSOs are not so difficult. After the first 600 to 700 QSOs you have milked at least 80% of the available stations and the rate falls off a cliff.

I had over 700 QSOs in the log when I shut down in the wee hours of the first night of the contest. I worked every available state/province multiplier and over 50 countries, despite the mediocre conditions. Many other countries were heard but they did not hear as well as the hordes calling them. Productivity suffered and the long tedium had begun.

When I resumed Saturday evening the rate improved as many stations made their first foray into the contest. Very soon that pool dried up and the tedium resumed, worse than before. Many contesters love the challenge of scrapping for every contact. The best operators scan the bands or jump on spots with one receiver while listening to answers to their CQ machines on another receiver. A few have sophisticated equipment to allow them to do both concurrently. The rest of us can only listen on the second receiver when the CQ machine isn't transmitting.

I am not happy with that style of operating. DX conditions were worse the second night and that accentuated the tedium. So I quit the contest. I never had the inclination of winning in any category and, frankly, my station, good as it is, is inferior to many others. There is added frustration from the Beverages which allow me to copy too many stations that cannot hear me. Oftentimes a kilowatt is no more productive than QRP. At least the amp keeps the shack warm during winter weekends.

I can sustain my enthusiasm in a multi-op because off times break the tedium. Every time I sit down to do a shift I am refreshed and able to dig in and get the job done. As a single op the tedium is unremitting and it wears me down. I admire the operators who deal with it better than I can.

This problem is common to most single band contests. It also occurs in contests with limited participation. I place ARRL Sweepstakes in a similar category since you can only work stations once regardless of band. The outcome is much the same, but with more spectrum to cover.

For the contests I most enjoy you respond to conditions and ever-changing activity levels by band and mode changes, alternating CQ and S & P, SO2R, watching signal strengths and spectrum scopes, among other strategies. Building and operating a multi-faceted station that permits these tactics sustains my interest and enthusiasm before, during and after the contest. In many respects I enjoy that more than operating in contests.

Single band contests rarely suit my desires. There are exceptions. Examples in 2021 include my 15 meter single band assisted entry in the CQ WW SSB contest and my (unofficial) 20 meter assisted entry in the ARRL DX SSB contest. I had fun putting to the test the recently completed stacks for 15 and 20 meters. I may do the same on 40 meters in one of the upcoming ARRL DX contest weekends to see what I can do with the recently completed 3-element yagi.

I will continue to operate the ARRL and CQ 160 contests but probably never with the objective of winning. To become competitively oriented I would need to make it a multi-op operation. As a single op, it's mostly an opportunity to work DX that is otherwise sparse on top band and to compare my antenna and station capabilities to those of others. The latter spurs my technical side to improve my station. 

Outside of contests, there is now far more top band DX to be worked on FT8, and I do make regular appearances. That's a story I'll defer to a future article.