Stray Capacitance in Interaction Models

Measuring stray reactance -- L and C -- can be difficult because the values are typically quite small. Yet that is a requirement I've dealt with when modelling antenna interactions. Test fixtures can only be built with some difficulty and then measured with suitable instruments, and I've never done that before. The literature addresses some of the cases I run into but not all. Then there's the matter of whether the quoted figures are reliable since the measurements methodology may not be described.

There are two cases in particular that I want to discuss since they are prevalent in my station and I've harboured doubts about my methods and calculations:

• Coupling of guy cable segments at insulators. There is coupling due to field interactions (naturally dealt with in NEC engines) and the series capacitance of the overlapping guy grips.
• Coax common mode leakage across transformers with galvanically isolated windings. I use lots of these in my Beverage systems, and I use more in long runs of RG6 lying on the ground that may be parallel to Beverage antennas for some distance. 

When I first developed interaction models in EZNEC for my guyed towers I modelled a wire for each non-resonant guy segment and overlapped by a length and separation approximately that of what was built. That was cumbersome and not really very accurate, but probably good enough. For the small Beverage transformers I represented the coax with connected wires and placed series capacitive loads on the wire to model the series capacitance between the transformer windings. I used values gleaned from ON4UN's Low-Band DXing and other sources.

The latter method of modelling stray capacitance is easier than the former, so I've been using it almost exclusively for the past several years. However, I don't know how accurate either method is or can be.

It struck me as an ideal small project to tackle during the extraordinary and persistently bad weather we're going through this April: rain, snow, wind, cold. There are always jobs to do in the shack and the workshop when tower work is too uncomfortable. I set out to measure the series capacitance in the cases listed above with the hope of designing better interaction models in the future.

I have a 1:1 Beverage transformer on a BN73-202 binocular ferrite core with 3 turns of insulated #26 wire for both windings. It was left over from a project and is identical to what I use for isolating coax segments in my long RG6 runs to the Beverage antennas. For the other case, I quickly constructed a "dummy" guy segment termination from a 504 insulator and two 5/16" guy grips. This is what I use on my big towers supporting stacked yagis and large 40 meter antennas.

There are 3 instruments that I have available for the measurements:

• RigExpert AA54 antenna impedance analyzer (single port)
• VNWA3 2-port VNA
• 35 year old LCR meter (made in Taiwan, and the brand is defunct)

I first did the measurements with the AA54. The results, at first, seemed sensible, but did not pass scrutiny. This shouldn't have been a surprise since these analyzers, even one of this quality, have increasingly poor accuracy as you move farther from its 50 Ω reference point. A pure capacitance in series with an infinite resistance (open circuit) has a very high SWR indeed. It is a poor LCR meter in these circumstances.

You may have to click on the image to improve the resolution. On the right are two measurements of the transformer, one open and one with the transformer in circuit. The ends of each winding are joined for the measurement of inter-winding capacitance. I compared the two calculated capacitance values with the expectation that their difference would be close to the actual value. In this instance, the difference fell between 2 and 3 pf: measurement precision is no better than 1 pf.

Notice that the R value is 0 Ω for all of the measurements. That casts suspicion on the results. The open circuit is so out of bounds from what this single port device can accurately measure that some deviation was to be expected. The measurement of the guy cable series capacitance is about the same, further casting doubt on the suitability of the instrument for this application.

I tried the measurement from 1 to 50 MHz in the hope that there would be an island of stability, if not accuracy, at least at low frequencies. At low frequencies the calculated capacitance was far too high, only stabilizing above about 5 MHz. So I chose 50 MHz and got the same result at a few other randomly selected frequencies. The poor accuracy really isn't the fault of the antenna analyzer. I asked it to do a job it was not designed for. 

I moved on to my old and trusty LCR meter. Like most of these instruments it does its measurements at a low frequency, although that is not documented. But I have had a lot of success with it over the many years I've owned it, measuring fixed and variable capacitors from a few pf up to a large fraction of a μF. A major downside of the meter is that it eats through 9 volt batteries very quickly.

The LCR measurements were quickly done with the aid of the short alligator clip leads. The stray capacitance of the instrument plus leads is slightly below 6 pf, so we subtract that from the measurements.

The results are far more in line with my expectations: 5.6 pf for the transformer and 11.3 pf for the guy termination. The Xc at low HF frequencies is close to what others have measured for a transformer of this design. That gives me confidence that these values improve my interaction models. Greater measurement accuracy may be desirable for capacitors used in antennas and matching networks.

I did not do measurements with the VNWA 3 at this time. With the many recent PC upgrades I made this winter it would take some time to set up the software to use it. The single port (S11) measurement would likely be better than with the AA54 but probably not by a lot. More accuracy requires a 2-port (S21) measurement of the series reactance, using a fixture that includes the outer coax conductor. Maybe when I have nothing better to do at a future date I'll make the measurements if only to satisfy my curiosity.

In practice there are many parameters that determine guy wire interactions, with the series capacitance just one of them. As you go higher in frequency the Xc falls enough that there is significant conductance through those guy terminations. For example, Xc of an 11 pf capacitor 30 MHz is just 480 Ω. It's 10 higher on 80 meters. Those non-resonant guy sections are not as isolated as they appear! Don't be surprised if they model differently than you expect when you include the stray capacitance between supposedly non-resonant guy segment.

There are also induced currents from the antenna itself and among the guy segments despite each segment being non-resonant in isolation. Perfection isn't possible: we can only do the best we can. I intend to use the LCR meter measurements in my EZNEC interaction models until I have better.

Is it worth the effort? I believe so. I've put enough years and sweat into my "big gun" station that it is only sensible to get the most from it. That doesn't mean I'll make major changes when an interaction is worse than I'd like, but I'll know what to expect. That's valuable information even if it isn't good news.

Ignorance is not bliss. 

Did FT8 Save Amateur Radio?

It was with some surprise that an article I wrote a few months ago went "viral". Well, viral as far as it can be within a limited population of hams. It has been the most popularly viewed article in the recent history of this blog. 

Digital modes court a range of emotional responses from hams that have been licensed for a long time. Newer hams just shrug and carry on. Digital is undeniably popular. Many of the public comments and private feedback to my article seem to have missed the point. I was drawing attention to the way the world is, not the way any of us might wish it to be. So, yes, digital has won. You don't have to like it.

At the risk of being seen as taking advantage of the controversy I will revisit it for a particular reason. It isn't for the financial reward since I get none from the blog. That reason comes from a throwaway comment made by a friend when we spoke recently. That's the source for the title of this article. We laughed it off, but I kept coming back to the question over the following days. 

It's worthwhile to flesh out the arguments pro and con. I might as well since I am unable to get any tower work done due to weeks of poor weather. The above photo was taken this morning. I envy those of you that don't experience spring snowstorms. Warm weather is on the way so technical articles will follow as I start into my long list of tower and antenna projects.

First, what if there were no FT8? What would have been the implications on licensee numbers and on-air activity? There is no way to know for certain. Instead we have to look at the evidence that exists, circumstantial though it may be.

Let's review a few facts, not all of which have hard data attached. I am not willing to invest the time to do extensive research for a brief article like this. Hopefully there are no significant errors:

• There are more hams in the world than ever before. It is certainly higher in Canada, the US and many Asian countries other than Japan, growing at rates faster than the total population. It may also be true in Europe, though not so much elsewhere.
• Towers for effective HF communication are being eschewed by new and young hams in developed countries for a variety of personal and societal reasons. That was not true decades ago. They prefer simple antennas, portable operation (e.g. POTA) or may avoid HF entirely.
• Few new licensees know CW and only a fraction of them learn or are planning learn. Yet phone and conversational digital modes can be difficult for those with small stations. Like long time hams, there is more interest in making contacts, DX or otherwise, than having conversations. Conversations take place off-air, even among hams.
• VHF/UHF FM is the gateway for many new hams, for local communication, public service and emergency preparedness. Many of them let their licenses lapse. A few of those that stay migrate to HF. 

It is a commonly held belief by many older hams that if there were no digital modes that new hams would be active on (what they like to call) "human modes." That is, where a computer is not an active component of the QSO. This mainly is meant to mean CW and SSB, although some will include RTTY and other computer encoded/decoded modes that permit conversations or data communication.

Is that true? We can only speculate since there is no way to do an experiment. Take a look at the waterfall spectrograms shown in that earlier article that caused such a fuss. Do you believe all those FT8 signals would transfer to CW and SSB if we auto-magically and retrospectively eliminate digital? In my frank opinion, no, that would not have happened.

There are few conversations taking place on HF. Most are "599" DX QSOs or POTA activations. Those that are actual conversations are between hams of long acquaintance who have a regular schedule or participate in so-called nets. If we restrict our focus to CW there are even fewer conversations, and those are typically not between or with new and young hams.

CW won't die but it will become a niche mode. SSB will continue since it is easy. Few new hams that are solely on FM will stick around, or will find their niche there and stay there.

Digital modes, FT8 in particular, are undeniably popular. New hams with small stations can work a lot of DX on HF, and they do! They really enjoy it and have been bitten hard by the DXing bug despite the naysayers. It doesn't interest me as a contesting mode though some promote it as such.

That said, is there an attraction for a digital-exclusive HF operator to spend more time on SSB and to learn CW? The answer is yes. Many are learning CW to improve their POTA results, mix it up in the pile ups and to become more versatile contesters. It has been said (and I agree) that CW is an ideal contesting mode.

Of course, many of those using digital on HF are unlikely to ever learn CW and they are discouraged by attempts to DX with SSB from their small stations. We are well below replacement numbers on CW, so its use will decline as elderly hams depart. It has had a wonderful 100 year run but now its time has passed. SSB will continue as a DX and contest mode and for some conversation. FT8 will likely be a mainstay for general operating and DXing on HF for many years to come. However, we can't reliably predict far into the future. Time will tell.

I've droned on for longer than I intended. But it's relevant to the original question: did FT8 save amateur radio?

If we restrict ourselves to HF, I am leaning towards yes. I'm not convinced but I am persuaded. Had there been no FT8 (by far the most popular digital mode on HF and VHF) those hams currently active on FT8 would not be on CW or SSB. The spectrogram of a CW band segment like that in the earlier article would likely look very similar.

That's not the end of the story since FT8 does more than just increase activity at 7074, 14074 and the other FT8 watering holes. Once these hams get hooked on HF, DX or POTA, their ambitions grow. Many hams new to CW and SSB have migrated after being almost exclusively on FT8. SSB first, of course, yet many are learning CW. Why? What incentive do they see?

The answers are various, with no one overriding reason. The following are ones I've personally heard from newer no-code hams. Keep in mind that these observations do not comprise a statistically valid sample:

• The challenge of learning and becoming proficient at the code
• Improve results in radiosport activities: POTA, SOTA, DXCC and contests
• The high rate potential in competitive contesting
• Relatively simple home brew CW equipment for the technically oriented

Communication isn't in the list since that isn't the attraction in 2026. It seems to only attract a minority of new hams. Again, it isn't about what ought to happen (however you may feel about it) but what is happening.

There is a story in the current (April-May 2026) issue of the National Contest Journal about one relatively young ham, WM6Y, who took the CW challenge after spending time on FT8. You have to be an ARRL member to read the article so I will quote a few sentences:

"Do not dismiss digital modes. They can be a gateway, not a replacement. Sometimes the path to CW does not start with a key. Sometimes it starts with a computer screen — it did for me. FT8 brought me back to amateur radio. It motivated me to upgrade my license. It led me to portable operations and ultimately to CW. Without FT8, I might never have returned to the hobby at all."

In his case the activities were POTA and contesting. That agrees with my experience talking to newer hams, as I mentioned above.

Digital isn't so bad, so cheer up. These modes can contribute a great deal to the future health of the hobby, whether or not hams decide to later migrate to CW and SSB. I regularly use FT8 on 6 meters and a few other cases, despite initial reticence. I guess you could say I took the opposite migration path: from CW to digital. 

The future is potentially bright for our beloved hobby, and digital may be an important reason why.

CQ WPX SSB 2026

I did not operate the WPX SSB contest. I don't particularly like it and I said why in an article many years ago. There is no reason to repeat any of that here, so read that article if you want to know why. Indeed, I've provided other reasons in articles before and since. Search the blog if you are interested. This is not to say it's a bad or problematic contest! This is about my personal preferences; many of my acquaintances feel the same.

I was therefore happy to make my station available for another contester to operate the WPX SSB contest this weekend. Shel VA3AA took up the challenge. He's operated here a couple of times before, most recently in ARRL DX SSB. This was a learning opportunity for him, to put in a lengthy 36 hour effort and make tactical decisions as a single op rather than as part of a multi-op team.

Conditions were reasonably good. His raw score was a very respectable 7.5M, including more than 2400 contacts and just shy of 1000 prefixes. There were times he was frustrated and times when things went wrong. Yet in the end he left Sunday evening with a big grin on his face. He is certain to do better in future contests. Contesting is a skill that can take years to perfect.

I made myself available for the entire weekend to resolve station problems and to help him make the best use of the station. Having many antenna choices is both a blessing and a curse: there is a lot to deal with. From time to time we discussed operating tactics and techniques. Those of us who have been in the game for a long time often don't realize how much there is to learn before we become proficient contesters.

Big stations run a lot in this contest, especially in the early hours. The reason is that there is little need to chase multipliers when almost everyone is a multiplier. But if everyone runs there is no one to work. It can be a good strategy to hunt stations at first rather than run since the rate can be better. Soon, though, you have to run if you're to do well. Happily that is effective with a big station like mine. Stations running low power or QRP have a more difficult time in WPX than in many other major contests.

Despite its importance, getting too comfortable with running can work against you. It is vital to frequently switch between running and hunting to maximize rate and multipliers. When the run rate isn't what it should be, switch bands or make use of the second radio to hunt stations. With SO2R capability it is generally advisable to always run on one radio and hunt on the other. For the proficient, there is 2BSIQ. In WPX, hunting on the second radio is usually the better strategy for most competitors.

SSB SO2R is more challenging than for CW or RTTY. Call signs at the very least must be voiced. For a variable exchange (serial numbers in WPX) the challenge is greater. At the very least it is important to use voice messages (CQ, Thanks, call sign, repeat please, alternative call sign phonetics, etc.) to save the voice, avoid unnecessary improvisation and leave your voice free to speak on the second radio. 

TTS (text to speech) and related voicing technologies are increasingly being used to make SO2R and 2BSIQ almost as easy as on CW or RTTY. It is in its early phases and implementation is not yet easy. It is already available as a feature in N1MM Logger+. Not everyone approves of the new technologies, but don't let that dissuade you. It will become routine and universal before long.

I have never seriously operated SO2R in phone contests. I have the basic capability but it was mostly untested. It took some effort to configure the station to switch message playback and microphone to the appropriate radio. Foot switches for each radio are useful, or VOX can be used, however these only work if the software switches transmit focus accordingly. Operator action is required to ensure the routing of the mic is correct. 

I am mostly familiar with N1MM, and it does phone SO2R pretty well once you climb the learning curve. It's a skill that competitive contesters need to learn. I did the setup but Shel had to practice doing it effectively. Now that it's working I'll probably use it more myself.

Agility is critical in any contest operation, and can be especially important in WPX. You have to run but when it doesn't deliver results you have change something. The station must enable agility so that the operator is not inhibited. For example, having to tune amplifiers on band changes, large frequency excursions (e.g. clicking on a spot) and changing antennas, discourages the operator from adjusting tactics on the fly. Although it may not take long it is a burden when every second counts. 

I am planning to acquire a second solid state broadband amp this year and to increase the availability of antennas with low SWR across the bands of interest. This will be a busy year if I'm to be ready by the fall contest season. There is also the rewrite of my antenna selection software (user interface only) to improve the visibility of available antennas, their selection and direction control for rotatable yagis and steerable fixed arrays. That project is ongoing but unlikely to be completed for several months.

There were technical issues, as is typical for a large station with so many potential points of failure:

• We courted disaster a couple of times because my home brew prop pitch motor controller doesn't check for over-rotation. I put off development of that feature until a future version, which may have been a mistake. Operators (including myself) are almost certain to forget whether, when pointed south, it got there in the clockwise or counter-clockwise direction.
• The Icom 7600 is known to have a power spike when the transmission begins. It doesn't happen often and it is notoriously difficult to measure. The Acom 1200S protection tripped numerous times during the contest. The only solution is to replace the transceiver. I may do so this year for this and other reasons.
• The TH6 is tuned for CW and therefore has a moderately high SWR at the upper ends of 20, 15 and 10 meters. That made the antenna almost unusable. Plans to replace the antenna (which is fixed south) are proceeding.
• The 40 meter reversible Moxon does not function in the reverse (south) direction. That made it difficult to work as many US stations as are necessary in this contest. Wintery weather has made repair impossible. I hope to get it done in April. Nevertheless, Shel found that it worked quite well since the F/B is fairly poor above 7200 kHz.
• SO2R Mini switching of the mic input occasionally misfired. It could be fixed with a software reset but that cost time. It's time to upgrade the firmware and hope that solves the problem. Having not done mic switching before I was unaware of these issues before Shel encountered them.

Back to the contest, Shel found that it was difficult to choose off times and focus geographies based on activity levels. Single ops only get to operate 36 out of the 48 hours, making the choice of off times very important. The same is true when operating in the Classic overlay category (24 out of 48 hours). Make the wrong choices and your score will suffer -- don't prioritize personal comfort over operating schedule if your objective is a high score.

Conditions were pretty good for the contest duration, or at least consistent and predictable. We are late enough in the season that 10 meters was poor on the important NA to Europe path, and 15 was poor the second day. The noise level on 80 meters was higher now that spring weather has arrived. 40 meters was, as usual, a zoo on the SSB segment. Running meant staying below 7125 kHz for DX and above 7200 for the US to avoid the din between 7125 and 7200 kHz. Of course many Americans called when Shel was outside the US phone band and Europeans called when he operated above 7200 kHz. Too many operators do not pay attention when chasing spots.

When DX conditions are poor we have the large population of the US nearby. That is not as useful as in years past since contest activity in North America has declined. The decline, while not large on phone, has a noticable impact on scores. There are records established years ago that may never be beat. Setting those as an objective can lead to disappointment. Whether propagation or activity, a contester must adjust his or her tactics to deal with what we have to work with.

After so much negativity I should admit that I'm tempted to enter WPX CW in late May. If nothing else it will be an opportunity to practice my SO2R skills. I typically don't care for contests in the warmer weather so this exception might not happen if the weather is particularly fine that weekend. 

Wall Decorations

Over the decades my shack walls have always been bare. The one exception was when I was a new ham (1970s!). At that time I pinned a few treasured QSL cards on a corkboard in the basement shack of my parents' house. None of my many shacks since have had any such adornment. 

I never framed my license, contest achievement awards or anything else. QSLs lie forgotten in boxes, certificates discarded or filed away and plaques stacked on bookshelves. I have never applied for DXCC or any other operating awards so I don't have those either. About a decade after graduating from university I finally framed my science degrees yet never hung them up. Plaques, paper certificates and educational accomplishments never leave their storage boxes. The same was true of family pictures until recently. 

I am not one for public displays, particularly those regarding personal accomplishments. It looks too much like bragging, a behaviour I hate to see in anyone. Plaques on walls don't have to be about bragging but may be. Everyone has their reasons.

In my dotage I have relented to a degree. Family portraits and even an original painting now adorn the walls of my house. There is some comfort in that since I've lost so many family members. Yet until recently the shack walls continued to be bare. That changed earlier this month.

It isn't an impressive array of contest plaques compared to some others. It is just what I have, or at least all that I've found. There may be plaques from contests much early in my contesting career but I honestly can't remember. If they exist they are buried deep. I feel no great urge to dig through dozens of boxes that I haven't opened for many long years.

Since I've never done this before and it isn't intended to be a brag wall, there has to be another reason. It's a simple one really. When I organize multi-op contest efforts and invite younger contesters to participate the plaques might provide inspiration. For seasoned and new contesters alike it is a reminder of why we're here: to do our best and hope to win.

If you were able to see detail in the photo you might have a chuckle. Most of the plaques are for QRP. That isn't the category most contesters care for. Indeed, some have told me outright that they don't consider QRP a sensible cateogory to enter. Obviously I disagree. There are plaques on the wall for two overall wins in CQ WW SSB and another two in ARRL Sweepstakes. 

I've been #2 or #3 several times in past contests but there are no plaques given for that. There can only be one winner. However I do have what could only be called "consolation" awards, such as those for winning Canada in a major contest. Since our contesting community is relatively small that isn't a great achievement. Nevertheless those plaques are now on the wall with all the rest.

That isn't so terrible here in the Great White North since, for example, in CQ WW we are in a poor position to win plaques for the major categories. Propagation isn't favourable, scoring for US and Canada is asymmetric (thus the separate range of US plaques for which we don't qualify) and we lose in competition with the Caribbean for North American plaques. We take what we can get! 

I know many contesters who strive to win plaques. When an overall win isn't possible due to geography, station, competition or other reasons they choose a category they can win. Otherwise unpopular categories may seem enticing. These may be for lower power levels (LP or QRP), single band, assisted vs non-assisted, etc. There's nothing wrong with that if that's what you desire. 

I am more interested in having fun and achieving a personal goal. I don't even care if my choice of category isn't officially recognized. Plaques are never on my radar. When one shows up in (or more likely on) my mailbox it is almost always a surprise.

There are also no plaques on my wall for DXCC or other non-contest operating awards. As I've mentioned more than just once on this blog that I don't need formal recognition to celebrate my achievements. I have 315 countries confirmed on LOTW, and over 100 similarly confirmed on all bands from 160 to 6 meters. My DXCC Challenge count has almost reached 2300 despite the award not being an objective. I know what I've done and that's good enough for me.

It was interesting when a friend (Dave VE3KG) recently sent me the adjacent photo. Doug VE3KKB was digging through his boxes and found this plaque from a contest we did together, along with Brian VE3CRG, well over 40 years ago. That was in the time of paper logs, hybrid tube/transistor radios and no spotting networks. His call and mine have since changed yet here we are in 2026 still enthusiastic about the hobby and still contesting.

I vaguely recall that we entered M/M since M/S, which we usually entered, didn't allow a group of keen operators as much time in the chair as we'd like. How we won I'll never know. 

Look at that score. Can you imagine winning WPX in 2026 with a score that low? Single ops nowadays score far higher than we did M/M. Of course we now have assistance, SO2R, more agile technology and, specific to WPX, far more prefix multipliers on offer. 

The special prefix helped. Those were less common back then.

Although times are ever changing it is fun to reminisce a little about how it used to be. We had a lot of fun contesting then and we still do today. I am expecting to have a guest op for WPX SSB later this month. WPX is no longer one of my favourite contests so I'm happy to clear the way my calendar for someone else to aim for a contest plaque. I hope that he achieves his goal.

Puzzling Digital DXing Tactics

DXpeditions to rare entities can bring out the worst in people. The pile ups are unruly, DQRM is rampant and every complaint imaginable is seen on social media and spotting networks. I expected to see all of it during the 3Y0K Bouvet Island operation and I have, regrettably, not been disappointed. A few well known DXers and contesters are among the worst offenders.

After so long in the hobby none of it surprises me. Technology has changed the ways in which the nonsense is performed, but human behaviour remains the same. I simply work around it and marvel at the human comedy of my fellow DXers. If working rare DX or winning a contest were easy we wouldn't value it as much. Nobody is entitled to a QSO.

I thought I'd seen it all but I was wrong. There is a new kind of bad behaviour. Perhaps I should not have been surprised that digital modes, with the need for different tactics to work the rare DX, breeds new forms of poor DXing behaviour. 

My own operating on digital modes (and by that I primary mean FT8) is limited. I do it on 6 meters where it does wonders, a little on 160, when CW activity is absent, and on other bands only as insurance contacts when I have not yet successfully worked a DXpedition on CW or SSB. It may be that I've been slower to notice these digital antics than some others.

I won't bore you with multiple screenshots of what I've seen even though a lot of it is amusing. Some of these antics include:

• Wrong call sign (e.g. 3Y0J and 3YOK): These were obviously entered manually. This wouldn't happen if they clicked on an actual message from 3Y0K. Presumably they can't copy 3Y0K yet they insist on calling.
• Transmitting on the wrong period: The DXpedition is on the first (even) periods (00/30) and the callers are on the opposite periods (15/45). Callers on 00/30 aren't copying 3Y0K or carelessly override the convenience feature of letting the software choose the correct period.
• Passersby calling the callers: Amazingly a few of the called answer. I guess those pile ups are where the "work everybody" crowd goes to hunt fresh meat.

Now let's look at the one screenshot I did take. I chose it since it captures several kinds of odd behaviour. The frequency is 1836 kHz, which I have been periodically monitoring since 160 meters is the one remaining band where I'd like to work 3Y0K. Call signs of the callers have been obscured.

The first two messages are pretty innocuous. These appear to be stations legitimately calling the DXpedition. However, while there was concurrent evidence that they were being weakly heard in Europe it was very improbable that they were heard in my part of the world (I'm in FN24). I have an extensive system of Beverage receive antennas with which I hear very well and I didn't copy 3Y0K at all. The station in FN31 is one I don't ever recall hearing on top band.

These may both be examples of blind calling. While this may seem pointless it does have one possible benefit. That is, if 3Y0K is not actively CQing but the operators are monitoring 1836 kHz for signs of an opening, successful copy of these transmissions would get their attention. 

The number of stations doing this sharply increases as sunrise in Bouvet approaches later in our evening -- their sunrise is approximately 0525Z. Successful stations have noted that their signal peaks about 10 to 15 minutes before then if it appears at all. I am not aware of a northeast NA station hearing or working 3Y0K early in our evening, 5 hours before their sunrise.

Another surprisingly common sight is stations sending an R-nn message seemingly out of the blue. Did they really copy a signal report from 3Y0K? That northeast NA station is very unlikely to have heard them when I and other well-equipped top band stations have not. I see the tactic done by many stations when 3Y0K is weakly heard (on all bands, not just 160) and few if any are heard by the DXpedition.

What is going on? I have heard opinions that it is a harebrained tactic to illegitimately slip into the log. Pretend that you received their report and hope that they copy one out of the multitude of R-nn messages sent by the station. The hope is that the DXpedition op clicks on it to send the RR73 and thus you magically appear in the 3Y0K log without every copying them. Unbelievable! Yet many persist.

Any DXpedition, and indeed almost every FT8 operator, uses auto-sequence. Therefore the tactic does not work. Even were they not using auto-sequence it would take a particularly dim DXpedition operator to click on that message to send an RR73 and then log the QSO. On 160 this is even less likely to happen since if you're having that much difficulty it is very unlikely that the R-nn message would ever be copied by them.

You may have also noted that this station did not actually copy the DXpedition and typed an incorrect call. That will certainly not work! It takes a especially shallow intellect to believe that DXpedition ops are so incompetent.

The last example from the screenshot is of a station responding to a phantom decode. That isn't uncommon. With stations configured for automatic responses, operators that don't pay attention or lack an understanding of international call sign prefixes and structure, regularly fall into this trap. It is more interesting in this case since that station was not CQing or blindly calling 3Y0K. How did it come about, and on 1836 kHz which is not the designated FT8 waterhole? It's a mystery, but an amusing mystery.

I have to wonder how these hams perceive DXing and the technology. Don't they think they ought to be able to copy the station they're calling? On CW or SSB this can be difficult due to weak signals or DQRM but not on FT8 -- the signal is decoded or it's not. Is getting in the DXpedition's log more important than legitimately working them? If that's all you want, send them a "donation" and thank them for working you on 160 meters at such and such a time. While that won't work with 3Y0K it is unfortunately that a few DX operators will confirm those donations.

As I type these words I have heard 3Y0K only once on 160 meters. First on CW and then FT8, at the anointed pre-sunrise opening. They switched to digital when they had difficulty copying the CW callers. Unfortunately I failed to get their attention on CW and I decoded them just once on FT8 before the brief opening faded. Oh well. I'll have to keep trying. With the switch to daylight time last weekend it has gotten harder since 0525Z is now 1:25 AM local time. I can't (won't) do that every night.

As the DXpedition continues the DQRM has subsided. I guess the perpetrators got bored. From my QTH they have mostly been off the side of the beam (Europe) or inside the skip zone (eastern NA). Frustrated callers continue to vent on the DX spotting networks to little effect since the DXpedition doesn't monitor spots. Better to send an email to the pilot for your region.

With a little luck (and sleep deprivation) I may yet work them on 160. Even if I don't I've done well and have nothing to complain about. I can claim an achievement rarer than a QSO with Bouvet: an email! This came to us from a friend on the DXpedition. It was great to hear from him and it put a smile on my face. I hope that the rest of their stay is without drama and that they all get home safely. Many hams are now one step closer to DXCC Honor Roll.

3-element 20M Yagi (Constrained) Optimization

I am designing several small mono-band yagis to replace the TH6. The venerable tri-band yagi is fixed south at an intermediate height (~25 meters) for working the southeast US, Caribbean and South America. It's deficits are that it is narrow band (high Q), high loss (traps) and not sharable during multi-ops. It's also very very old.

A no-trap tri-band yagi like the Skyhawk fits the bill when combined with a triplexer and set of high power BPF. However that is a very expensive solution at >$4,000 if the equipment is purchased new. They are not often found on the used market. I am fortunate to have purchased a used Skyhawk far below the new price. It is rotatable at about 21 meters height.

A few small (smallish) yagis are not expensive to build since I have ample aluminum in my stock. I also do not anticipate difficulty side mounting these yagis where they can be effective without significantly interacting with the stacks for the high bands. Additional switching hardware will have to be built and fit into the station automation, but that isn't difficult. Low loss transmission lines are mostly already in place.

I decided to abandon my attempt to design a 2-element 20 meter yagi with the attributes I want. Performance of every 2-element variation, including Moxons, have been poor in some respect. These include gain, gain bandwidth, SWR or mechanical robustness. My revised objective is an ordinary 3-element yagi. I have all of the material on hand, although I'd have preferred not to use so much of it. Hopefully I can replenish my stock through more scrounging.

Even for such a simple antenna there are many interdependent parameters. For the design process I have fixed the boom length to 7 meters (23') since I can build a boom that length from available tubes and it is sufficient for good performance. I have further fixed the position of the DE (driven element) at 40 cm (16") behind boom centre: closer to the reflector than the director. It is a position that is conducive to achieving good performance that is used for most yagi designs.

Fixing certain parameters simplifies the design and optimization but can omit some high performance solutions. Based on my experience these choices are acceptable since excellent designs are readily obtainable by fixing these particular parameters. 

Since this is a design exercise rather than a construction plan, all of the elements are constant diameter 25 mm wires. A taper schedule can be added later with negligible change to the yagi's performance. Using EZNEC, I compared NEC2 and NEC5 then decided to stick with NEC5 for the remainder of the design process. Gain is virtually identical between NEC2 and NEC5, with small variations in F/B and feed point impedance.

The modelled feed point matching network is a beta (hairpin) match. The length of the DE is shorter than resonance to provide series capacitive reactance. The length and impedance of the shorted stub determine the shunt inductance. These parameters are easy to adjust in the model and in the field. A beta match requires the DE to be electrically isolated from the boom, unlike the gamma matches I typically use. Mechanical complexity is traded for tuning simplicity, but either is acceptable. A CMC (common mode choke) is advisable for any feed system.

With the selected fixed parameters we have the following degrees of freedom in a 3-element yagi:

• Lengths of the director and reflector
• Ratio of director to reflector lengths 

Really, that's about it. Only a 2-element yagi is simpler. Yagis with 4 or more elements are more difficult to optimize since there are so many more variables. Luckily there are numerous published and optimized yagi designs so that in most cases you can look them up in the ARRL Antenna Book and elsewhere. But beware of unverified designs based on boasting, poor methodology, old myths that refuse to die and opinions not backed up by engineering.

Even for a simple 3-element design like this one there are a several things to keep in mind:

• Maximum gain is largely determined by boom length, not the number of elements. Once a boom length is selected, we choose the number of elements needed to ensure sufficient coupling among them to enable the performance objectives to be attained.
• The length of the DE is irrelevant to performance. It only needs to be close enough to the lengths of the parasitic elements to effectively couple. Modest shortening of the DE to transform the feed point impedance to 50 Ω has negligible performance impact. 
• For a 3-element yagi, gain rises with frequency and is typically maximum beyond the operating bandwidth. For 2-element yagis maximum gain is below the operating bandwidth. Yagis with 4 or more elements are similar to those with 3 elements in this respect but with more variability. 
• Smaller reflector to director length ratios give higher gain and narrower SWR bandwidth. Too small a ratio can result in an antenna gain that cannot be effectively matched and requires large diameter elements (not wire) to avoid ohmic loss in the elements. This is due to the low radiation resistance where gain is maximum. That is expected and not a coincidence.
• High reflector to director length ratios can in extreme cases be fed without a matching network since their feed point impedances can be close to 50 Ω. However, that feature comes at the cost of performance. 

For this design exercise I modelled a 3-element yagi with a parasitic element "spread" of 6%. That is, the reflector is 6% longer than resonance for the operating bandwidth and the director 6% shorter. I then adjusted the DE and beta match for an SWR of 1 at mid-band: 14.175 MHz. That was my baseline. From that baseline I increased and decreased the reflector to director ratio to bracket a reasonable range of performance metrics.

To demonstrate the results I will only present 3 of those spreads: 5%, 7% and 10%. Outside that range the performance metrics are not to my liking. Others could perhaps justify alternative designs for specific applications. My primary objective is as follows:

• Maximum gain for an SWR lower than 1.5 across the 20 meter band: 14.0 to 14.35 MHz. 

I am not concerned with optimizing F/B, since the antenna is primarily for contests in which I am happy to hear and work stations off the main lobe. The low SWR objective is to be compatible with solid state amplifiers that have no ATU. This is an objective to enable maximum operating agility. The TH6, like any loaded or trapped yagi, performs poorly in this respect.

Well, that's a long preamble to set up what will be a brief presentation of my modelling results. So let's have a look.

From this graph it should begin to become clear why I selected the spread values that I did. Above 7% the 1.5 SWR is too narrow, and is indeed little better than the TH6. The SWR bandwidth at a 10% spread seems enticing until we consider performance.

To display F/B and gain on a single chart I expanded it vertically. The colour scheme may be a little confusing but good enough to convey the data.

There is a significant gain difference among the three designs. As already described, gain rises toward the top of the band and narrower spreads have higher gain. The range varies between 1 and 1.5 db. 

Is that a significant difference for on-air performance? Many hams will say no. However, for contest use there is a demonstrable difference. It may not be immediately evident in use since QSB obscures the difference. Even 1 db will get you through the pile ups faster and when running you'll attract more callers.

For me the lower gain for the 10% spread is undesirable. At 7% gain is only 0.5 db below that of the yagi with a 5% spread, and the SWR objective is met, just barely. The parameters of the beta match (not shown) are easily achievable without compromising construction or efficiency.

While F/B is not strongly favoured for my intended purposes, the relatively poor F/B with a 10% spread is concerning. It can be somewhat improved by adjusting yagi parameters that I fixed for this modelling exercise, though not by much. A 10% is too wide. Yet it is interesting that many commercial designs within this range. Perhaps the full-band low SWR is effective marketing. 

F/B for 5% and 7% spreads are different but comparable. Considering full band performance, the 7% yagi is perhaps marginally better. It isn't worth fussing over since the difference will be difficult to notice in practice and even small interactions with the tower, guys and other antennas near and far will alter both performance charts such that it would be hard to prefer one over the other. 

Unlike gain and SWR, the overall pattern is acutely sensitive to interactions. This is because of the exact balance of amplitude and phase to substantially cancel radiation in those many directions.

My hope is that this deliberately constrained analysis of 3-element yagis helps to clarify necessary trade offs in any yagi design. There really isn't anything new in this article. Despite this, the analysis has clarified how to proceed.

My choice is a 7% spread. I have already begun collecting the material and construction will proceed this spring. Replacement of the TH6 with the new yagi may be delayed so that I don't lose 10 and 15 meters until yagis for those bands are ready. I want all three yagis ready for the fall contest season.

I am planning construction features to achieve more than the basic objectives. For example, managing interaction with the nearby 40 meter Moxon. I'll report on those after the yagi has been completed, tuned and tested, along with a detailed description of the antenna. It was brutally cold this morning but the sun is shining and spring is not far off.

ARRL DX CW 2026

Once again we did M/2 from the station of my friend Vlad VE3JM. His station is similar in size to mine and he does extremely well from there. He is also a better contest operator, especially 2BSIQ, so he almost always beats me when we enter contests in the same category. This year we have a full complement of 5 operators; last year there was just the two of us when the others cancelled due to a ferocious snowstorm. This year's storm didn't impede travel even for those driving up from the Toronto area.

This edition of the ARRL DX CW contest made it clear that we are past the peak of cycle 25. Our score was lower with 5 operators than with 2 of us in 2025. Geomagnetic disturbances are up and the sunspot count is down. The latter was actually zero (0) on Monday. We are unlikely to see many contest records broken for the next half dozen years.

Although I didn't remember to take a snapshot soon enough after the contest the Sunday K-index chart tells the tale. It wasn't good. Not terrible, but definitely not good. That said, there was a lot of DX on offer and many fantastic runs. 

Although conditions affect everybody, which ought to burden competitors equally, opportunities do not skew equitably when you move a few hundred kilometers near the auroral zone. That noticably affected us, though to what degree is difficult to say. Of course our challenges pale in comparison to those even farther north. This is not an excuse but an explanation for regional variation.

This is the setup we used. From left to right are Dave VE3KG on the in-band station, Nick VE3EY on one run station and Les VE3NNT on the other run station. In the background you can see that Vlad has an outstanding set of high power filters and triplexers from VA6AM. We still had interaction issues, especially harmonics that regularly plague CW. You will regularly find yourself near those harmonics due to simple arithmetic. 

The in-band station has no filters other than what the receiver can provide, and by the separation and polarity of the antenna. The in-band antenna is a multi-band (no trap) 40-to-10 meter vertical about 100 meters from the various towers. The in-band station has no amplifier since the proximity of the antennas does not allow use of higher power without impacting the run stations. Interference in the other direction is acceptable but often problematic.

This was my first experience operating with an in-band station and I was impressed despite the inter-station interference and limited power and antenna. Many contacts and some multipliers were logged. This is important since many stations mostly run so this may be the only way to work them. It also allows the run station to keep running, and eager operators can get in there and contribute. 

The interlocks worked well (DXLog) and it was easy for the operators to learn how to coordinate. I'm tempted to add this capability to my own station. Techniques to reduce interference were discussed among the operators.

In-band capability is not a universal solution. The run stations, with higher power and superior antennas, did a lot of the work. Also, the in-band station could not be manned full time. One reason was that the in-band station had no antenna for 80 or 160 meters. The worse conditions on the second day further limited its effectiveness due to weaker signals. Working spotted stations on the run radios risked loss of the run frequency and wasting time with busted spots, both human and skimmer generated. There were a lot of busted spots that wasted our time.

Propagation played a critical role in our competitiveness. We were at a disadvantage compared to those to the south and therefore farther from the auroral oval. That's not a complaint, just a feature of where we live. It happens whenever conditions are disturbed or marginal. 

The following is a brief description of several interesting propagation factors that we experienced, both pro and con:

• On Sunday morning when 10 meter propagation to Europe was poor, one of our operators (VE3EY) turned the 7-element yagi east, and then a little further south. Signals from Europe strengthened and the rate shot up. That was a smart move. I've known that this can happen for more than 40 years yet never suspected skew path this weekend. It is a common occurrence during solar minima years that Europeans on 10 meter peak towards the sun. Whether scatter or true skew path it is worth turning the yagi to check for this phenomenon. More southerly areas get more sunlight and therefore have a higher MUF.
  
• This weekend provided another lesson in paying less attention to SSN (sunspot number) and more to SFI (10.7 cm solar flux index). On Sunday the SSN was 0. Even so the high bands were open. SFI is a better proxy for ionospheric MUF.
• The first night and to a lesser extent the second, 40 meters stayed open to Europe until long after their sunrise. This often happens when geomagnetic conditions are quiet and the solar flux is low. Signals get weaker as the sun rises in Europe but remain workable. Unlike in CQ WW they stay on the low bands rather than moving to the high bands since they can only work North Americans. My rate was very good for longer than one might think possible.
• 20 meters opened for about one hour overnight to Europe at the same time 40 was still going strong after their sunrise. Sometimes it happens and sometimes not, so you must pay attention. After that hour the band died and didn't reopen until a little before our sunrise.
• 80 meter conditions to Japan and the north Pacific were better than expected. Overnight we worked quite a few stations. Signals were weak but many stations were workable. We usually can't work east Asia until our sunrise enhancement. Several welcome multipliers were logged on 80 this way. 

Despite excellent activity our results were down. That mirrors the experience of others. Propagation played a part as did participation. CW in particular is less popular with younger generations, especially in North America. Outside VE/W there is less interest in this contest since it is more of a QSO party than a global contest. For those on the other side of the globe there is little to work, so why would they bother. We should be thankful to those that participate and make the contest what it is.

It must also be noted that not everyone taking part is familiar with the rules. We had many US callers and even a few from Canada. They are of course worth zero points. As for dupes, it is better to work them than to try to explain the rules to each caller or to ignore or admonish them. I would never want to discourage their enthusiasm. If they encounter rudeness these casual operators won't call you in the next contest when the points they give you will contribute to your success.

As usual, we used the online scoreboard. I rarely use it when I operate alone, but it was interesting to see how our nearest competitors were doing. In ARRL DX we are on an equal footing with US participants so the comparisons are meaningful. In some respects watching the scoreboard was discouraging since there was little we could do about what we witnessed. We were already motivated and working hard on our score as I am sure were the others. 

I consider the scoreboard a needless distraction which is why I have yet to use it for my single op contest efforts. It wouldn't change what I do. Many others feel differently. However I see its value to non-participants that want to follow the competitors. In the future I may post my score even though I am unlikely to look at the scoreboard during the contest. Perhaps my opinion will change in the future.

I'll close with a note about technology and training. Most of us don't use DXLog in our own stations. I only use it when operating at Vlad's station. As I have with N1MM, his station automation systems are tightly integrated with DXLog. There is a learning curve. A crib sheet with common commands isn't really adequate since these software packages are feature rich and can behave in ways that neophytes can't predict or deal with. All we could do was fumble or call out for help when in trouble.

The only solution is pre-contest training. That means using and studying the software before the contest weekend. That is in addition to learning about the antennas and selection process in a large station. There is a lot to digest and use effectively, or at least with minimal friction. It is worth consideration in advance of your next multi-op contest, whether at your station or elsewhere.

Another Bad N-connector

After a lengthy bout of frigid weather, the sun came out and the temperature soared to 3° C. The snow was melting into puddles and it felt tropical outside. I was briefly tempted to wear a t-shirt. Of course my thoughts soon turned to tower work. Several issues have been languishing over the winter and this was an opportunity to deal with some of them.

One of those was the malfunctioning TH6. When I last mentioned it, the balun enclosure was full of water. Removing the water didn't help. From the ground the coax measured as an open circuit. My intent was to pull the coax from the balun and test the antenna, balun and the long run of Heliax. I pulled the coax jumper from the 2×8 switch to attach a 50 Ω load. That way the Heliax could be tested at the same time as the antenna with an analyzer. Preparations made and analyzer in hand (kept warm inside my parka), I stomped through the deep snow out to the tower and up I went.

To my surprise the antenna and balun passed the test. However, when the analyzer was connected to the coax I again measured an open circuit. I really didn't expect that outcome due the trouble I've had in the past with either the antenna and balun. The antenna in particular is an antique at well over 50 years old!

I reconnected and sealed the coax connection to the balun and descended. There is an RG213 jumper from the balun to the Heliax but I decided not to fuss with it just yet. Until now I'd only done an SWR test and I wanted to do a TDR (time domain reflectometry) test from the ground of the full system.

I visually inspected the jumper between the switch and the Heliax and manipulated them to check for looseness. So far so good. I connected the analyzer to the coax and set the analyzer to plot R and X from 1 to 51 MHz.

Notice the peak R and X on the right of the plot. The approximate frequency is 47 MHz. For the 0.66 velocity factor of RG213,  ½λ is approximately 2.1 meters. That raised my suspicions. I disconnected the RG213 jumper and took it indoors. I measured its length: 2.1 meters. What a coincidence! No, not a coincidence.

Modern analyzers have a TDR feature, but I don't have that on my relatively old RigExpert AA54. However it is pretty easy to achieve the same by plotting R and X and doing a little calculator math. I could have zoomed in (narrow frequency plot) for better accuracy but that was hardly necessary in this instance. 

At right is a picture looking into the N-connector on the end of the jumper that connects to the female N-connector on the Heliax transmission line. The problem is obvious: the male pin has pulled inward. It does not make reliable contact with the female receptacle on the Heliax connector. It had been intermittent for some time before failing completely a few months ago.

This is a common fault with N-connectors on coax similar to RG213. I didn't expect it to happen in a short jumper that wasn't subject to stress or weight. This is a connector where the pin is soldered to the coax centre conductor. I prefer N-connectors with a captivated centre pin but those are not available for coax with a stranded centre conductor.

I tried to pull and wiggle the coax while holding the connector and did not notice any appreciable movement of the centre pin. I have yet to open it up for a closer inspection. My priority was to bring the TH6 back online.

I happened to have a short RG213 jumper already prepared and tested. It has UHF male connectors on both ends. I keep an ample stock of N-male to UHF-female adaptors --whenever I see one at a flea market it comes home with me. 

Since I have to deal with N-connectors on most of my Heliax runs the N-to-UHF adaptors come in handy. The pins are mechanically stable so the pins cannot creep. That is critical for N connectors. They have become my preferred choice for transitioning between N and UHF terminations. They let me exclusively use the more positionally stable UHF connectors on RG213.

The new/old jumper and the adaptor were attached to the Heliax and the antenna system swept with the analyzer. The antenna was back in service. I cut off the old bits of tape and sealant and then weatherproofed the connection. It took more material that most coax connections due to the added length of the adaptor. 

Have I told you (again) that I hate N-connectors? Hate and N-connectors show up several times in the blog, as a search will demonstrate. Had I less restraint the subject would appear 10× as often in the blog! 

My thoughts on the matter are well summarized in the linked article. It accrues well above the average number of hits for articles in this blog. N-connectors should be avoided whenever there is an alternative, and there almost always is, especially for HF systems.

You might think that I am relieved to have the TH6 back in service since the ARRL DX CW contest is only days away. You'd be wrong. Yes, I'm relieved but not for that reason since I'll be joining a multi-op team elsewhere for the contest. However it's one less worry for forthcoming contests.

Although I plan to retire the TH6 this year the Heliax run will be needed for whatever antenna, or one of the antennas, slated to replace it. The balun itself requires service to prevent water ingress whether or not it is needed for the replacement. With the immediate problem dealt with that job can wait for warmer weather. Although tower work in winter isn't always difficult or uncomfortable I prefer to avoid it if I can.

Self-assessment: LCR (Log Check Report)

The LCR (log check report) for the 2025 CQ WW SSB contest have been distributed. This is an opportunity to see what specific mistakes were made. I know, that can be painful! Nevertheless it is a mandatory exercise if you want to improve. I set a personal error rate target of less than 1%. That isn't easy when operating SO2R and 2BSIQ.

It may be of interest to learn how I read these reports and use them. I'll take you through my analysis. Other contesters may draw different conclusions or focus on different items. Either way, there is more to the analysis than thinking "oops!" when you look at each error. Understanding how errors are made can lead to future improvement. We go to a lot of trouble to make a big score and the competition is fierce, so every point removed from the log is worth attention.

The LCR for this contest is a little different since it was a multi-op (M/2) with 5 operators, including myself. Due to the high rates and perhaps the inclusion of less experienced operators I was expecting a higher than usual error rate. It was a pleasant surprise to learn that we did pretty well despite my worries.

The Cabrillo does not contain the operator call signs. This can be found in the logging software database and in the ADIF that is usually exported after the contest for upload to LoTW and other applications. I deliberately did not make the association, leaving it to each operator to do it themselves. It is an individual responsibility to self assess. There are multi-op teams that produce reports for each operator.

************************** Summary ***************************
    7999 Raw    QSO before checking (does not include duplicates or missing exchanges)
    7889 Final  QSO after  checking reductions

   21766 Raw    QSO points
   21005 Final  QSO points

     170 Raw    zones
     170 Final  zones

     626 Raw    countries
     625 Final  countries

     796 Raw    mults
     795 Final  mults

17325736 Raw    score
16698975 Final  score

    1.4% error rate based on raw and final qso counts
    3.6% score reduction
     30  (0.4%) not in log
     60  (0.8%) incorrect calls
     21  (0.3%) incorrect exchanges
      0  (0.0%) missing exchanges
    175  (2.2%) duplicates removed
     24  (0.3%) calls unique to this log only (not removed)

Logging and log checking is not an exact science. Our log showed 8003 QSOs yet 4 seem to have disappeared. It's a curiosity that is negligible so I didn't delve into it. The 1.4% error rate is acceptable considering the team and circumstances. We only lost one multiplier. So far so good.

Not in log (NIL)

You work a station yet you don't show up in their log. What is going on? There are several possibilities, some your fault and some the fault of the other operator.

• Optimism: Contesters are optimistic. That can lead to over-enthusiasm as we hover over the keyboard to log that new multiplier or hard won contact. QRM, QRN, did they really copy me? Despite any lingering doubts, we log the contact. It's worth taking a few seconds to get positive confirmation that the contact was logged by the other station.
• Overlap: On a crowded band it is surprisingly easy to believe that you worked a station that you did not. This happens more often while running since the other station doesn't send your call. If another station in your skip zone starts running on your frequency you may not notice at first. Doubt may arise when the other station's timing is off from your own. Delays and overlap can also be due to SO2R, while waiting for a transmission to end on the other QSO. If it happens twice in a row, listen closely. Someone else may be there. 
• OOB: This is a problem that is mostly only experienced by those of us working Americans. Here is an example from the LCR:
  
   7099 PH 2025-10-26 0015 VE3VN     4   K*****   04 
   7099 PH 2025-10-26 0032 VE3VN     4   K****    05 
  
  Do you see what happened? How about if I explain that OOB stands for out of band? Outside the US most countries, including mine, have no regulated mode sub-bands. We abide by voluntary band plans. It is easy to click on a spot and not notice the frequency. We don't know the details of US regulations and we don't know where various license classes are permitted. We might take the time to ask if they are indeed OOB, or log them and keep running to save time, just like for dupes. Later they scrub their logs to erase the evidence of their transgression. I obscured the call signs in the LCR extract to protect the guilty.
• Oops: It is quite easy in the heat of a contest to forget to log a QSO when hunting at high speed. You type in the data and spin the VFO or click a spot to move on to the next. But you didn't press enter and the QSO wasn't logged. You soon forget the call sign and see it again, so you try to work them. They may tell you "b4" or "dupe" but you say no and try to complete the contact. Now it's the other station making a mistake and they will get a NIL if they won't work you. That's another good reason to work dupes and avoid time wasting arguments.

Modern log checking software is able to detect copying errors and still correctly match QSOs. That is rarely the reason for a NIL. You're not in the other station's log and you must try to do better.

I have to admit that NIL errors annoy me since they are largely avoidable. I've discussed them in this blog going back many years, here, here and here to give a few examples. I am not exempt from my own advice to do better.

Incorrect calls

It is easy to get a call wrong, either by a copying error or typo. If the other station is running and doesn't send their call every QSO or two you might not notice the error. Human and skimmer spots are also frequently wrong, which is why it is highly advisable to rely on your ears before logging the contact.

 14121 PH 2025-10-26 1954 VE3VN     4   HB9      14  incorrect call 

While running it is quite common for the other station to not really listen to you announcing their call or even caring whether you said it correctly. You get the penalty, not them. By not offering a correction they save precious time. It is your responsibility to confirm that the call sign is valid. In case of doubt make it clear to the other station that they are not being logged until they confirm their call. Do it explicitly or by sending their call with a "?" (on CW) to elicit a repeat.

An important tool to assess the validity of a call sign is the Check Partial window of the logging software (N1MM, DXLog, etc.). It will show matches and near misses to the SCP database (super check partial), call history and your current contest log. If you see a question mark instead of a check mark next to the call ask the station for confirmation. Non-contesters who call you often won't get a check mark, so verify. Even you are certain that you copied the call correctly they may have made a mistake. This can easily occur when sending CW by hand.

Unique calls are variants of incorrect calls. These are calls that are not found in other participants' logs. That's suspicious since it's very unlikely that you'd work a station that no one else has. But it does happen if you have a big signal and there isn't much action. Non-contesters will call you to say hello and try to help with your score. I see a lot of these callers on 40 meters phone when CQ'ing above 7200 kHz. If you sound friendly and welcoming casual ops are more likely to call. 

Even so it is likely that many uniques are indeed calls incorrectly copied. There's no easy way to tell so if your log hasn't been artificially stuffed with them you'll be allowed credit. There are contests in which these contacts are removed from your log without penalty. Again, the lesson is to be certain, so verify.

Incorrect exchanges

For the majority of contacts CQ WW there is really no exchange to log. The zone is determined by the call sign, and logging software will pre-fill it for you. Call history will pre-fill the exchange in cases where the zone cannot be derived from the call sign. However, it is your responsibility to verify the pre-filled exchange.

US calls are the greatest risk. Hams in that country can keep their calls when they move to a different district. Few contests decree that they sign portable; e.g. KX9XXX/6. Whether or not the correct zone is pre-filled, you must check the sent exchange. Enter the correct exchange if it differs from what was pre-filled. 

Many contesters become negligent when they get tired in a long contest or they lose focus while operating 2BSIQ. But there are no acceptable excuses for exchange errors.

 7086 PH 2025-10-25 0005 VE3VN     4   VE2DXY   05  correct     2
 7086 PH 2025-10-25 0014 VE3VN     4   S51CK    14  correct    15
 7086 PH 2025-10-25 0027 VE3VN     4   YP3A     15  correct    20
 7220 PH 2025-10-25 0120 VE3VN     4   K4RXH    08  correct     5 

A common error is to forget to correct the exchange after making and correcting a call sign typo. Depending on the logging application the exchange may not be automatically updated after correcting the call. 

Unless the exchange is very long (e.g. ARRL Sweepstakes) it is usually faster and more accurate to wipe the QSO and reenter the entire call. The corrected call sign then pulls up the correct exchange to pre-fill. Tabbing back and forth when running a pile up, especially while SO2R, is a guarantee of busted exchanges. 

Duplicates and the other guy's mistakes

Back in days of yore when logging wasn't done by computer and we actually sent call signs and exchanges by hand, duplicate contacts were penalized. They had to be found and removed from the log either during the contest (dupe sheets, anyone?) or after. It was a tedious process that was eventually automated by computer logging.

Contest sponsors eventually saw the light and recognized the value of leaving dupes in the log. It made log cross-checking easier and more accurate and put an end to the practice of on-air arguments about whether we've worked before. Dupes were henceforth removed without penalty. Indeed you were encouraged to leave dupes in the log. However, some never lost the habit of scrubbing their logs.

Always always always work dupes. Don't waste time arguing. Perhaps the other station miscopied your call on the current or previous QSO. By not working them again you risk a NIL. 

We had a 2% dupe rate. That's high but not unusually high. It's bound to happen with 8000 contacts in a single contest. Our LCR showed how often our call got mangled. Most were either typos or poor copying, while a minority were due to bad spots. 

 ************* Stations Copying VE3VN Incorrectly *************

 14156 PH 2025-10-25 0000 ***ON    11   VE3VL    04 
 14156 PH 2025-10-25 0001 ***LY    20   VE3WN    04 
 14000 PH 2025-10-25 0054 ***PLL   11   VE3VL    04 
  7000 PH 2025-10-25 0342 ***FKW   15   VE3VW    04 
  7070 PH 2025-10-25 0406 ***DOF   15   VE3WN    04  

Do not simply ignore this section of the LCR. I study dupes to think of ways to improve how we enunciate our call sign, choice of phonetics, CW speed, etc. Every mistake, ours or theirs, is an opportunity to learn and improve. The same goes for busted calls and exchanges. How can you make it easier for others to log your call and exchange more accurately. Again, calls obfuscated in the LCR extract above.

Changing your operating practices can result in fewer dupes. That frees up time to work new stations and earn more points.

How to improve?

Perusing the LCR there are several lessons to me and my team that can lead to improvement in future contests:

• Watch for bad spots! They'll appear on the band map exactly at your operating frequency. Don't simply shrug and plow onward. Send your call more often and more slowly so that stations drawn to the bad spot will recognize the mistake and not waste their time or yours by logging dupes.
• Operators may accidentally speak their own call sign instead of the one used for the multi-op station. Train yourself and your ops to used the pre-recorded messages. For some reason in phone contests many operators unnecessarily speak rather than push a function key. I like to save my voice and make fewer mistakes. Accurate, clear messages are superior to scratchy and negligent voicing when tired.
• QSY when a bad spot draws too many dupes. We are loathe to abandon productive run frequencies yet sometimes we must to avoid wasting time on dupes, QRM and other annoyances. With spectrum displays it doesn't take long to find a new run frequency even on the busiest bands during a popular contest.
• Never react to the pile up. There are more stations waiting in the wings and you don't want them to leave if you take too long to get to them, but that is never an excuse for busted calls and exchanges. Take the time to get it right, and ask for repeats if necessary. With practice you'll get better and the rate will naturally rise. Don't force it. Accuracy comes before speed.

There are contests where QSOs are deleted from both logs if either operator made an error. That can be helpful since it makes operators more careful. I sent your call incorrectly? You have an incentive to try again rather than shrug and let me lose the points. I have mixed feelings about those contests. Rather than dive into that here I'll direct you to an article I wrote about it several years ago.

One feature you should become familiar with is X-QSO. If you are uncomfortable with the accuracy of a call sign or exchange and you are unable to quiz the other station, or you're not sure they logged you, you have the option of marking the contact using the X-QSO feature. 

By marking the contact as an X-QSO you are claiming no credit for the QSO and will not be assessed a penalty (if there is an error) while allowing the other station to be awarded points if the QSO is correct in their log. The most popular contest logging applications, N1MM and DXLog, support this feature. Marking the contact is a judgment call. Make your decision quickly and move on.

One final note about log analysis in a multi-op. Most contesters want to learn from their mistakes, but not everyone. I gave the operators all the data they need to correlate errors to their activity. I leave the rest to them. My primary objective was for everybody to have fun making a big score with a big station. In that we succeeded, spectacularly.