Friday, January 26, 2024

Stacking 20 Meter Yagis: 2 Long vs. 3 Short

Only a fraction of hams have stacked yagis. They are common in both VHF/UHF and HF big gun stations. There are still lessons about antennas to be learned for those who do not and will never deploy a stack. There is a question about stacks that I'd like to explore in this article that comes up from time to time. It may be of interest to those with and without stacks.

The question is this: which is better, 2 long boom yagis or 3 yagis with more modest boom lengths? I am going to focus my analysis on 20 meters since that is a band where long boom yagis are very large and expensive. Many contesters instead choose to stack three or more yagis with shorter booms. There are more of them in the stack but each is less difficult to build and raise.

There are advantages to using 3 smaller yagis:

  • More pattern possibilities by selecting combinations of 2 of the 3 yagis
  • It is easier to rotate the side mounted yagis, offering more directions with stacking gain
  • The main azimuth lobe is wider, which can be a benefit for contesting

There are disadvantages as well. These are primarily narrower low SWR bandwidth and lower gain. Unless the ham has unlimited resources, the stacking of smaller yagis is a popular choice. 

It also helps that there are suitable yagis on the used market that can be purchased inexpensively and, where needful, optimized for gain, pattern and SWR. The Hy-Gain 204BA is a common choice. The optimized version of that antenna by N6TV is popular. Performance and construction details can be found in the ARRL Antenna Book.

I chose two long boom yagis for my 20 meter stack, and similarly for 15 and 10 meters, although those are smaller antennas. I kept the expense down by designing and building them myself, and I got a lot of satisfaction from the project. Most contesters would rather buy or modify so that they can get a big signal with minimum fuss. Not everybody has the same interests and priorities.

The breadth of this article is narrow in that the baseline for comparison is my antennas. I am most interested in alternatives to what I've built and the scope for future improvement. I will not do a broad comparison of various stack configurations. That said, lessons from this brief analysis have broader application.

The antennas

I will compare my 20 meter 5-element yagis on a 41' (12.7 m) boom to the N6TV 4-element yagi on a 26' (8.1 m) boom in the ARRL Antenna Book. Despite a 50% longer boom the gain of the 5-element yagi is not that much higher. Many big guns with 5-element yagis put them on a 48' boom for more gain. I chose an intermediate length boom as a compromise between performance and mechanical difficulty.

There are diminishing returns as the boom get longer. Keep in mind that the boom length, not the number of elements, is the determining factor for maximum gain. Elements are added to a long boom yagi to achieve the required level of mutual coupling for maximum performance.

The 4-element yagi is blue on the above charts. The gain difference ranges from 1.2 db at 14 MHz to 0.8 db at 14.350 MHz. The pattern comparison was done near the top of the band where the gain difference is small. Although the gain advantage for the 5-element yagi drops at the high end, the SWR remains very good while that of the smaller yagi rises to over 2. 

For a 5-element yagi on a 48' (14.6 m) boom the gain is higher by 0.5 db at 14 MHz and rises to 1 db at 14.35 MHz. At the time I designed my yagis I decided not to make the boom longer to keep the weight, cost and maintenance to within bounds that I was comfortable with. I will continue the analysis with my antennas since that is my primary interest. Tack on the extra gain if your interest is a 48' boom

These comparisons bring up a common point of contention: does 1 db make a difference? Yes, it does, though perhaps not in the way most think about it. Except for weak signals riding the noise level, you will benefit little from the difference on receive. It is different at the other end of the QSO. More stations will hear you because your signal is more competitive with their QRN and their QRM. You don't often notice that for daily operating, but it makes a difference in DX pile ups and during contests. A seemingly small signal improvement can improve contest scores.

Comparison of 2 × 5-element and 3 × 4-element stacks 

For model simplicity, the yagis are directly driven with a source placed at feed point of each driven element. There are no matching networks since there is no model penalty for an impedance mismatch and the patterns are unaffected. All yagis experience mutual coupling with the others, which is unavoidable and the reason that stack gain is not the 3 db that one might expect.

Now that we've set the baseline, let's move on to the comparisons. We know at the outset that stack gain is nominally 3 db. It can vary ±1 db or so due to yagi separation and height, and there may be effects of unequal power division when the impedances of the yagis are different. I think most will agree that 2 to 4 db does make a difference in on air results. In my experience the impact can be surprisingly large.

The heights of the 20 meter 5-element yagis are 140' (42.7 m) and 70' (21.3 m), which is approximately where I have them on my tower. I placed the upper and lower optimized 4-element yagis at the same heights and inserted a third midway at 105' (32.0 m). The one in the middle is approximately at the height of my lower 15 meter yagi. 

I believe that this a fair comparison. A third 5-element yagi does not easily "fit" because it's too close to the existing yagis. I exclude that case for now, but I will return to it later. Hence the comparison of my 5-element stack to a 3-stack comprised of the shorter 4-element yagis.

There are several interesting points that can be seen in the elevation plots:

  • The gains of the full stacks are nearly equal.
  • The 5-element yagi, as a stack and as individual antennas, have poor coverage of elevation angles between about 30° and 35°. There are no gaps with the 4-element yagis.
  • Other than the full stack, the 5-element yagis are individually always better. That is perhaps most important for the upper yagi on long haul DX paths with the lowest elevation angles.

The 4-element stack does pretty well in the comparison. The azimuth pattern (see above) is broader and that can be an asset during contests where you want to reach the maximum number of stations while running. However, the beam width difference is small. Vertical stacking narrows the elevation lobes but not the azimuth lobes.

Although you need 3 yagis instead of 2, the mechanical advantages of the smaller 4-element yagis is enticing. I know many contesters that have gone that route. 

Additional combinations of the 4-element yagis

There are 3 combinations for the 4-element yagis (not including BOP -- both out of phase) that are not available with the 5-element yagis. Those are the three combinations of two yagis.

  • Upper + Middle
  • Middle + Lower
  • Upper + Lower

We now have 7 total selection possibilities. The question is whether so many is beneficial. Compare these elevation plots with those above. The full 3-stack is the primary (black) trace.

It isn't surprising that the elevation pattern of the last combination -- upper + lower -- looks very similar to that of the 5-element stack. The only significant difference is that the gain is lower by about 1.3 db. That closely matches the difference between single 4-element and 5-element yagis.

The other combinations of two yagis are more interesting. Both do well in the lowest elevation angle lobe, with only a small difference in the elevation angle where they peak. The gains are down only by about 1 to 1.5 db from the full 3-stack. This is about what to expect in general between 2 vs 3 yagis in a stack; the difference between 1 and 2 yagis is of course approximately 3 db. There are diminishing returns. You'd need a fourth yagi to get close to 3 db more gain than a stack with 2 yagis.

Another advantage of the upper-middle and middle-lower combinations is that the middle elevations are well covered. The individual yagis in a stack of 4-element yagis achieve that as well (see above) but now we do it with increased gain. The high angle radiation is also reduced in comparison to the upper-lower combination. That may be useful if you don't have a separate low yagi or you wish to avoid BOP (both out of phase) configurations. The latter adds complexity to the stack switch. 

Challenges and benefits

The many combinations of a stack with three yagis add complexity on the tower and in the shack. There are 7 combinations compared to 3 with a two yagi stack, not counting BOP. At right is an example of a controller for a 3-stack system sold by Array Solutions.

Impedance matching is, perhaps surprisingly, less of a problem. There are several stack switches for three yagis that employ one network for feeding two or three of the yagis; the network is bypassed when selecting an individual yagi. 

A common solution is a TLT (transmission line transformer) wound on a large (2.4") ferrite toroid. There is a low insertion loss design whereby the transformation ratio is approximately 2.25. The net SWR isn't perfect but it is still pretty good for both cases. For a 50 + j0 Ω load, the SWR would be 1.1 for two yagis and 1.3 for three yagis. Since no yagi has a perfectly flat SWR, the mismatch due to the TLT may be dominated by antenna's SWR. That is, you might not notice it most of the time.

I could do the same with my home brew stack switches by altering transformation ratio of the L-network. It is also possible to switch a capacitor by relay to improve the match when selecting either two or three yagis. My stack switches are single band only while the TLT network is broadband, typically covering 40 to 10 meters. You need the latter for multi-band antennas such as tri-band yagis.

What I've learned

There are no big surprises in this analysis and comparison, nor did I expect any. The benefit comes from being able to put numbers to the scenarios rather than make broad assumptions. It was a useful exercise. I'll briefly list several of my thoughts from this modelling exercise:

  • A stack of 4-element yagis works very well. The gain of a 3-stack compares favourably to my 2-stack of 5-element long boom yagis.
  • There are more stacking options with 3 yagis. You can split the stack to point the rotatable yagis one direction and still have a 2-stack in another. Smaller yagis are far easier to rotate on a side mounted swing arm (or ring rotator) than my 5-element yagis.
  • When the 4-element stack is split, typically the upper yagi would be used for a long haul path such as Asia while the middle and lower yagis can be pointed to Europe. The gain to Europe of this combination is about 1.5 to 2 db lower than the full 4-element stack. That can be a reasonable sacrifice during contests if done only occasionally. It is superior to the choices I now have.
  • The many combinations that are possible with a 3-stack entail complexity. During a contest there is no time to play with all of the possibilities or to explain it to guest operators. There is also little advantage since the elevation angle and other propagation factors vary from one QSO to the next. They additional combinations may be have greater value for DXers.

One way to reduce the complexity of the stack is to permanently bond two of the 4-element yagis. If I were to do it, I would bond the middle and lower yagis. That entails bringing the transmission lines for those yagis to a common point at 0° phase shift (in phase) and feeding them in parallel with a network to transform 25 Ω to 50 Ω. Coax is run from there to the stack switch, also with a 0° phase shift, between the bottom pair and the upper yagi.

The stack switch can be same one as for a 2-stack since its operation is identical. When you select the "lower" yagi you are actually selecting a 2-stack.

I have no intention of replacing my 5-element yagis. They are excellent antennas that do wonders when stacked. However the stack only works towards Europe because the lower yagi is fixed. It would be nice to have another yagi in between so that there can a middle-lower 2-stack to Europe when the upper yagi is pointed elsewhere.


I do not want another 5-element 20 meter yagi on the tower for several reasons. It also fits poorly since the separation between yagis would be less than the boom length. That's a pretty good heuristic for spacing the yagis in a stack since it addresses the bulk of the mutual coupling issues. A side mounted 5-element yagi is difficult and expensive to rotate due to its weight and wind load. I won't even try.

This is what it looks like by the numbers. The gain of the three 5-element yagis is only about 0.6 db better than my existing two yagi stack. Even if that small boost is gain is acceptable, notice that the gain for the upper-lower combination (middle yagi not fed) is significantly reduced relative to my existing stack. Gain is compromised by interactions among the yagis -- they're too close together. The combinations of two yagis are, like the 4-element stack, equally useful, though gain is limited by those interactions.

There is another possibility: place a small yagi in the middle. The separation between yagis is greater than the small yagi's boom length though still less than the 5-element yagi boom length. Since the 4-element yagi is centred on the tower, the driven element is offset from that of its larger cousins. That can be compensated by a delay line to the middle yagi -- it is "ahead" of the others.

The  optimum delay line was found in the model to be 40°. That is larger than the expected 36° due to the 83" (211 cm) offset of the driven element. Mutual coupling is once again the culprit. The length of the delay line will also be sensitive to the matching network at the feed point, such as a gamma or beta match, since they will impose a different phase shift (reactance) compared to the larger yagis. To avoid model complexity, I included sources for each yagi without concern for impedance mismatches. You can do that in a model but not for a real antenna.

Even that doesn't help us. The gain of the 3-stack is almost exactly the same as my existing 2-stack of 5-element yagis. The degradation due to mutual coupling becomes very apparent when the middle 4-element yagi isn't fed. The currents induced on the inactive antenna elements isn't large but more than enough to disturb the stack's pattern. The currents can be inspected in the model.

Gain is about 1.5 db worse than if the 4-element yagi were not on the tower. The upper-middle and middle-lower combinations certainly have utility but for the reduced gain. The middle-lower combination can have higher gain when the upper yagi is rotated to a different direction.

If you are enamoured of the additional combinations made possible with a 3-stack, you must either use 4-element yagis or increase the tower height to achieve wider spacing of the 5-element yagis. A taller tower is not in my future!

This is useful information. While I have no serious plan to redo the 5-element 20 meter stack, the alternatives are worth pondering. If a 20 meter stack is in your future, detailed modelling should be done before planting a big tower. HFTA is another useful tool to optimize stack configurations for the local terrain before beginning construction.

Sunday, January 21, 2024

The Intensity of NAQP

Although I call myself a contester, there are times when I don't enjoy it. Most of what I dislike are intensity and the duration. NAQP (North American QSO Party) has intensity. At 10 hours of operating time it is at least brief. I can survive it even if I'm not always having fun. Despite that, it's a superb opportunity for honing one's contest skills.

The power limit of 100 watts tends to even out the competition. Modest stations can do well in these contests if the operator is skilled. The playing field is not truly level since antennas, location and propagation play large roles. The latter is somewhat balanced by propagation that favours western stations on the high bands and eastern stations on the low bands.

Despite the pressure I put on myself to do well, I dove in at the opening bell and did my best. As we'll see, I did better than in previous NAQP CW contests. That's promising.

This article might not be of interest if you're not a contester. That's okay. Even if no one cares, I benefit from writing the article since it helps me to think about what does and doesn't work, and then consider what I might do differently in future contests.

Team competition

The team competition isn't taken too seriously by most participants. You can tell just by scanning the list of irreverent team names. CCO (Contest Club Ontario) enters teams in NAQP according to member interest and participation. 

Despite not being a top-tier competitor, I do well enough that I am usually included in the CCO #1 team. That alone puts me in under pressure to do well since I get put on the same team as two WRTC gold medallists (VE3DZ and VE3EJ). I know them both and I'm sure they would have a good chuckle to hear that. The pressure comes from within, not from my fellow team members.

A little pressure to perform well is good. In past years the pressure of friendly competition made me a better runner and cyclist, whether it's a group sprint to the top of a mountain or not letting a friend pull ahead of me during a half marathon.

One peculiarity about the team competition in NAQP is that mixes assisted and non-assisted operators. Obviously teams with more assisted operators will score higher. Our team had at least two in the assisted class.


I don't practice SO2R very much, and 2BSIQ even less. You must do it in NAQP to have a competitive score. There are always stations to work so if you keep to a single "stream" you cannot be competitive. Of course, none of this matters for those in the contest just for fun. 

Many top contesters train with MorseRunner, RUFZ and other training aids leading up to major contests. I've tried offline training and hated it, so I no longer bother. Performing well is nice but it is not imperative. I get my practice on air. I know other (and better) contesters that do the same and for the same reasons. It's "real" radiosport.

I pick second tier contests in which I have no interest in placing well and that have enough activity to enable long runs and that have many stations and multipliers to hunt. For NAQP my practice took place in the RAC winter contest. I usually enter it just to hand out 10-point contacts to participants. This time I did it SO2R with a lot of 2BSIQ, unassisted and running 100 watts.

SO2R and 2BSIQ are more difficult in RAC, CQ WPX and other contests that include a serial number in the exchange. You cannot rely on the call history file for the contest. In contests like NAQP with fixed exchanges, all I do for most contacts is listen to ensure the name and state match the pre-filled data, and only type when they do not. It saves mental and physical energy when operating two radios. It's more stressful with serial numbers because you must listen and copy the unique exchange. That makes for good practice.

2BSIQ technique

For SO2R, I use N1MM+,  two keyboards and the SO2R Mini for controlling radio audio. It's what I'm use to but there are many alternatives. I am definitely a fan of two keyboards since I find it easier to mentally associate typing with the radio. When I need to focus on the audio of one radio, the "~" key in N1MM+ signals the SO2R Mini via its OTRSP interface. There are simpler and more complex (and expensive) products to manage receiver audio. 

N1MM+ has a software interlock so that you never transmit on both radios at the same time. That makes it easy to comply with the rules. For this contest I was powering two rigs from a single DC power supply. Since there is never a two transmitter load on the power supply you can get by with one 25 amp supply for both rigs

Synchronizing the QSOs on two radios can be difficult. The other operator may delay their transmission, send very fast or very slow, repeat the exchange, fail to respond the first time, send superfluous information (e.g. their call, again, or my call before the exchange), and so on. You must be prepared for surprises during every QSO.

There are many techniques for keeping the QSOs in sync. I am still learning but I know enough to do reasonably well. Sure, I flub a lot as well. It's important not to become embarrassed or despondent, and slink back to SO1R with head bowed. Keep at it and focus on getting back in sync.

Consider these alternative CQ messages (you can substitute "TEST" for "NA" in other contests):

  1. VE3VN NA
  2. NA VE3VN

Which is better? In some circles it is actually a point of contention. For SO2R, in my opinion, you ought to use the second. When the station you are in contact with on the other radio transmit longer than the CQ on the other radio it is a simple matter to tap F4 (or other function key depending on the logging software) to repeat your call to extend the CQ. You can't do that in the first case. 

I will also interrupt a CQ when I must transmit on the other radio, usually when I'm S & P on it, so that the other station doesn't think I've disappeared. Interrupting a CQ has a low cost while delaying an S & P transmission has a relatively high cost.

There are many more tricks that help to sync and re-sync the QSOs. Since this is not an article strictly about SO2R, and I'm not expert enough to be giving advice, I won't delve deeper. You'll figure out most of it on your own, eventually, if you keep at it. The better you get the less stressful it becomes. Your scores will increase and that will motivate you to stick with it. Always keep in mind that when you make SO2R flubs you are still providing a benefit for all participants.


In many contests, when you run you tend to do so for a long time. That is unusual in NAQP except for those with big signals from a rare multiplier. Most stations are hopping from band to band, so that when a run slows it is best to switch as well. You must both run and hunt, switch frequently and often hop from band to band. 

If you stick to running for too long, you will not work others that are running. The opposite is true for S & P. For every QSO, one of the stations is running and the other is hunting. It has to be that way. For those operating SO2R, at least one of the radios should be running. Dual S & P is more difficult than 2BSIQ since you often need to copy stations on both radios most of the time. That's a rare talent.

I am less agile than I ought to be. I stick with runs longer than I should, whether the rare drops or the rate remains high. The former case should be obviously true. The latter may be puzzling. By running for too long you miss activity and multipliers on other bands, and that will hurt your score no matter how good the run. Stop the run and hunt multipliers or work other bands, especially 10 and 15 meters, when they're hot. When you return to the band where you had been running. the rate will soon resume.

To be agile you must be attentive to propagation and hunt stations at high speed. If you are assisted, take advantage of that to rapidly work through the available multipliers and then other stations. But always do it while running on the other radio.

I was not as attentive to the agility practiced by others. When I had difficulty working a multiplier due to many callers, I would quickly move on and try to work them later. Often I delayed for too long and the station was no longer running -- they're practicing agility! That cost me multipliers. In many contests they stick around for longer, but not in NAQP.  

I have enough antennas that I don't rotate the yagis during the contest. I set them up before the contest begins, typically pointed south, southwest and west on the high bands. For the limited number of multipliers to the east I rely on backscatter or the yagis' minor lobes. On 80, the inverted vee is used for nearby stations and the vertical yagi to reach the Caribbean and west coast. On 160 meters I mostly receive on the southwest Beverage, and switch to other directions when necessary. All switching was done with mouse clicks using my station automation software.

High bands vs low bands

VE and W population is higher in the eastern half of the continent. That gives an advantage to western stations on the high bands and to eastern stations on the low bands. The high bands were so good this year that eastern stations delayed moving to 40 meters until well after sunset. In previous years there was lots of activity by late afternoon.

A common tactic of many of us in the east is to take off times during daylight. That leaves more time to work the low bands late into the evening. I took two 30 minute off times so that I could be active until midnight (0500Z). The rate was still high when I had to quit so I may have benefitted from more off time early in the contest.

The typical approach is to sweep up as many multipliers as possible on 10 and 15 meters, work as many other stations as we can and then move lower. 20 meters was my best band in this contest rather than 40 meters. Runs were ineffective on 10 and only intermittently on 15 meters, but 20 meters was very good until well into the evening. I failed to effectively use my time on 10 and 15 meters by trying to generate runs that never materialized. I should have hopped among the high bands more often and targetted multipliers.

The low bands were terrific as well, but only after stations moved down. It was pretty easy to work out to the west coast on 80 meters, and even on 40 meters well before their sunset. Later in the evening the same occurred on 160 meters. Had I been able to operate longer my multiplier count on 160 would been higher.

Multipliers vs QSOs

There are 60 to 70 multipliers available to work per band in any given NAQP contest. Not all states (50), provinces/territories (13) and other North American countries are active. That adds up to almost 400 multipliers that can be found across all 6 contest bands. Propagation limits your ability to reach the maximum due to skip zones or a low MUF on the high bands, and distance on the lowest bands.

The ratio of contacts to multipliers in NAQP is lower than in many other contests. In this contest my ratio was 4.8. It can be below 4 for those using assistance. The ratio is higher for the those with the highest score since they run out of multipliers to work. Look at the claimed scores at 3830 or the results of past contests.

A friend (who is a far better contester than I am) recently told me that he did an experiment in a previous NAQP. He operated 2BSIQ close to 100% of the contest. The number of contacts was higher than usual but his multipliers were lower. That may be due to stations in rare sections doing so well by running that they stick with it. A VE3 has to be more agile.

Getting fills

I had a peculiar problem in this contest that I haven't seen to the same extent in others. When I would ask for a fill, such as "name?", there was often silence or they'd send their call again. It took two or three tries to get the desired fill.

There was an even worse problem. In most cases when I copied a partial call, I would send the partial back one or two times. That usually worked well. Several experienced contesters would reply with only the part I was missing, whether the prefix or the suffix. That also worked well. The trouble came when I replied with the partial (or incorrect) call followed by my exchange. This is a common technique to save time and have both of us move on to the next QSO more quickly.

Few would correct an incorrect call. They either didn't care or didn't notice, though I am hoping it was the latter. Similarly, many did not provide a full call in response to a partial. As long as I sent my exchange they would reply with only their exchange. When I would repeat their call appended with a "?" or ask "CL?" or "CALL?" there would be silence or they'd repeat their name or the full exchange. In a few cases this went on several times. I don't understand it.

When all I received was silence after a few tries, I had to assume they'd left the frequency. I'd send "NIL" or nothing at all, and erase the incomplete QSO. I can understand why many contesters will not send their exchange until they've received the full correct call of the other station. I might have to start doing the same.

Holding a run frequency

I was surprised by how many times other stations would jump onto my run frequency and start CQ'ing. No "QRL?" or any announcement of their presence preceded a rapid succession of CQ's. I've never seen this happen so much in major contests like CQ WW. It happened to me more than a dozen times in this NAQP.

In about half the cases the station realized their error and vanished. The rest persisted. Having a fight over the frequency only wastes time so I take action. A small QSY of 50 to 100 Hz often solves the conflict. In other cases I find another run frequency, or I switch to S & P or try another band, depending on where I think I'll be most effective.

I note their call signs, and many are well known contesters. In several cases they would call me a few minutes later when they, too, quit running. It was funny in a way. All you can (or should) do is shrug your shoulders and move on. Don't let incidents like these derail you from your primary objective of scoring well.

Another way of putting it: "Contesting means never having to say you're sorry."

Errors, call history and spots

In December I contacted the keeper of the SCP (super check partial) database (W9KKN). I requested that "VE3UN" be deleted from SCP. It's a valid call but not one active in contests. After investigation he deleted it. While I can't stop others from confusing U and V, at least there will be a "?" next to the wrong call rather than a check mark. Busted calls get into SCP because multiple contesters make the same copying error.

It did no good in NAQP. My call was regularly busted as VE3UN. I suppose that it's all those dits. Not everyone regularly updates their copy of the SCP database or it be in the call history file they're using. It's also possible that they ignore or fail to notice the "?". Once they log the wrong call, it will show up as a valid option when they hear me on other bands. Assisted operators often believe spots and fail to listen. 

There is little more that I can do to avoid the inconvenience of being called by those I've already worked; I already send CW slower than most to help others. For the few that repeat my (incorrect) call before their exchange, I try to correct them. Even then many don't listen. I may be among the first to apply if we convince our regulator to issue contest friendly call signs as in done in many countries.

I am responsible for many of my own errors. I have yet to achieve an error rate below 1% when operating SO2R, and it is higher when also doing 2BSIQ. That isn't surprising. All I can do is practice more. I rely on call history to save unnecessary typing since that distracts me from successfully managing two QSOs. It is imperative to listen at all times since the call history may have no pre-fill. Names and locations are also frequently different. Hams move (and keep the same call sign in the US), alter their names slightly (e.g. ROBERT vs. ROB) or honour a recent silent key by using their name.

Too many don't listen and simply accept the pre-fill. I do listen and yet I still make mistakes. When uncertain or the station is weak, I will route that rig's audio to both ears for better copy, even when that means I miss critical info on the other rig. I can catch up and re-sync within 10 to 15 seconds. It's worth the effort. It isn't enough to have a high rate and multiplier count if you lose them after log checking and are docked an additional penalty.

Don't be lazy. Take the time to listen carefully and copy accurately. Your contest results will immediately improve. If you need CW practice to do it well, then put in the practice time. This applies to everyone, not only those operating SO2R.

How I did

Once I overcame the initial shock of diving into SO2R and 2BSIQ during the first few minutes of the contest, I settled down and did pretty well. I made mistakes, but I have enough experience to deal with them and get back on track.

I was unhappy with my rate over the first half of the contest and wondered whether I could equal previous scores. That changed as activity moved to the low bands. The rate increased and with the great conditions the multipliers filled the log. As usually happens, running provided the majority of the multipliers. Occasional spins of the VFO are used to hunt down the rest.

My raw results were 1234 contacts and 258 multipliers. That is a little over 100 contacts and 30 multipliers less than the typical top contester in this region in the same SOAB LP (unassisted) category. The best do even better than that.

Since no two years are the same with respect to propagation conditions and activity, the real improvement is seen in the rankings. I've definitely moved higher. Compared to the previous two years, my raw numbers are improved by 10% to 15%. That is mostly due to the increased time I spent doing 2BSIQ.

Looking forward

I don't know how much better I can do when I am unwilling to practice more to improve my ability with 2BSIQ. It would be enough to improve my accuracy and operating strategy. I have no ambition to climb to the top of the single op standings in NAQP or any other contest. 

Somewhere on that path there is a fuzzy boundary between the fun of challenging and improving myself, and aggravation. I won't cross that line.

Wednesday, January 10, 2024

Reversible Short Heliax Beverage Antenna

I have a lot of scrap coax. What to do with it? Sure, I could throw it out but most of it still works pretty well at low frequencies even though a full spectrum sweep can look especially ugly. I persist in trying to come up with a use for it all. There are hundreds of meters of the stuff.

At left is an SWR plot of a 40-year old 40 meter length of LDF4 terminated with 50 Ω. It has seen some rough handling over the years. I have 3 of these rolls in my scrap pile. They take space that I'd like to reclaim, but I haven't been able to talk myself into hauling them to the local landfill for disposal.

The plan

I would like a second set of receive antennas for multi-op contests. The existing 6-direction Beverage system can only be used by one station at a time since only one of the 6 directions can be selected. It can be fed to both stations if the operators are happy to use the same direction, but that's unreasonable. All I could do for the recent CQ WW contests was to switch the system to one station or the other. The one without had to make do. 

That isn't so terrible since the 80 meter yagi provides pretty good RDF (receive directivity factor) on receive. Unfortunately the yagi only functions between 3500 and 3650 kHz. That isn't enough for a phone contest. Extending the yagi's range to 3800 kHz may be done this year, but is more likely to be delayed until 2025.

I have a need and I have a lot of junk coax. I decided to use the coax to make a reversible short Beverage pointing east and west. It's short so that the azimuth pattern is broad, close to 90° in each direction, which covers half the compass, and with a low but useful RDF -- I can add a south Beverage or other small directional receive antenna later. 

I am basing the antenna on my experience with a short, 90 meter long uni-directional Beverage that I had for a short time a few years ago. It worked very well. In fact, I put the new antenna in almost the very same place, along the fence and tree line that separates two hay fields. To make it reversible, I used the same design as for the reversible north-south Beverage made from 150 meters of RG6. The only difference is in the transformers to accommodate the change from 75 Ω to 50 Ω coax.

I picked the two best of the 40 meter lengths of LDF4-50A. The low frequency SWR sweep of both are nearly identical. The third roll (wide sweep shown further above) is decidedly worse. I measured both lengths and then dug into my piles of short Heliax scraps to make up the difference to reach about 90 meters of total length. 

The two lengths were placed on top of the fence line with the help of a friend and joined them with an N barrel connector. I needed his help to thread them through the trees without kinking the cable or damaging the jacket. For half the distance the bushes are thick and thorny so it wasn't much fun. 

To keep the cable from drooping between supports (the log fence zigzags), rope was tied on at both ends, pulled taut and the ropes tied to conveniently placed trees.

That was in early fall. There it languished until mid-December when I had the time to resume work on it. Unfortunately it could not be prepared in time for the CQ WW contests. We made do with switching the existing Beverage system (6 directions) between stations. I would like to have the new Beverage ready for the ARRL DX contests.


Before proceeding to wind the transformers and build the switching system I turned to modelling. Although 90 meters is a good length for a short Beverage, it is unusually low and "fat". I expected these factors to affect the optimum length, and I was right.

I tweaked the length until the F/B was best. That was 86 meters. I selected one of the scrap lengths of Heliax pictured above and added it at the east end of the Beverage to make it that length. Of course the NEC2 model likely has some inaccuracy due to the ground proximity and largely unknown composition, but it doesn't hurt to at least try to get it right. 

If it turns out not to be optimum the impact is small since the RDF is unaffected by small length differences, just the F/B noticably changes. The RDF in the EZNEC model can be calculated from the difference between the gain (-15.1 dbi) and the average gain (not shown) of -24 db. Therefore the RDF is approximately 9 db. That isn't great but it is better than almost all compact receive loops like the pennant, EWE and others.

Although the 90° azimuth beam width seems poor, in my use case that's an advantage. The objective is to keep it simple for the operator for the second station in a contest. This is not my main Beverage system where better performance is needed for both contests and DXing on top band. The RDF is fine for cases where the reception is poor on the omni-directional 160 meter transmit antenna. It is less helpful on 80 metes due to the narrower beam width though, as we'll see, it is still useful.

In time I would like to supplement the east and west coverage with a short south Beverage. It would have to be a winter only antenna since it almost certainly have to be run across a hay field. There would be no point in making it reversible to the north because there's little for us to work in that direction. There is the long north-south reversible Beverage in the main receive antenna system for those brief periods when we look north towards Asia.


The transformers are the key to good performance. I wound the transformers before building the rest of the electronics. I used the same binocular Fair-Rite transformers as in the past, and are typically used by pretty much everyone else building Beverages. This time, rather than use Teflon liners, I used insulated wire salvaged from scrap Cat5 cable for the winding with the fewest turns. The insulation served as a protective bed for the second and longer winding made from coated magnet wire.

The annotated diagram from ON4UN's Low Band DXing book shows the transformer turns for this implementation. The same book estimates that the surge impedance for this Beverage should be approximately 350 Ω. The reflected signal (west direction) travels through the 50 Ω Heliax and the feed line 75 Ω, made from a combination of old RG59 and new RG6. I used the handy table in the ON4UN book for winding turns for the various transformation ratios I needed.

All of the transformers were tested on a VNA using a suitable termination resistor. I didn't bother testing the insertion loss since it was certainly better than -1 db in all cases. It is not critical for a receive antenna as long as there's enough gain that atmospheric noise can be heard in the receiver. Beverages rarely require auxiliary amplification. Use the rig's pre-amp if necessary, and a BPF if there's a strong broadcast station nearby. In my remote QTH there are no nearby broadcasters so the only strong signal is from my second station during contests. I haven't yet needed a BPF to deal with it.

I selected enclosures for the head end electronics and for the reflection transformer. I reused a box from a retired Beverage head end for the new one. I enlarged the hole for the F connector to install an N connector and added a stud for the ground wire. For the reflection transformer I chose a very small plastic box. It is almost dwarfed by the N connector that barely fits on its surface. But it was cheap and the transformer is small.

The completed head end demonstrates that sloppy construction is usually acceptable at low RF frequencies. I like that since I'm a disaster waiting to happen when working on circuitry. A small proto-board loosely secured supports all but the GDT assemblies for lightning protection. There is generous wiring to the connectors to ease removal for service. There is no need for metal enclosures that will complicate construction since the coax connectors don't share the same ground.

I made mistakes: one cold solder joint, one no solder joint and one transformer installed backwards. All were easy to fix. I'm prone to carelessness when working on circuitry, whether it's commercial equipment or my own projects. Bedlam usually ensues when I open up a transceiver.

For testing, I built a bias-T interface on a proto-board to inject 12 VDC to energize the reversing relay in the head end. It consists of a 0.1 μF capacitor and an RFC. Although, as mentioned above, sloppy wiring is acceptable at low frequencies, you can see the rising SWR at the right of the analyzer screen (7 MHz) due to the inductance of the long leads used for testing. Resistors (330 Ω and 50 Ω) represent the Beverage loads. The nominal transmission line impedance is 70 Ω or 75 Ω, so an SWR of 1.5 is what to expect on a 50 Ω analyzer.

The head end was installed at the west end of the Beverage. I used RG59 for the feed line into the house since it was the right length and I had no other use for it. I tested it beforehand to ensure it was still okay, at least at low frequencies. For the rest of the run into the shack I used RG6. I used F twist-on connectors and F barrel connectors between coax segments. The RG59 was laid on the ground at a right angle to the Beverage to minimize interactions. I'll lift it onto an aerial messenger cable later this winter or in the spring to get it off the ground.

The tiny enclosure for the reflection transformer is dwarfed by the Heliax it plugs into at the east end of the Beverage. Both ends are grounded via 4' copper-clad ground rods for the terminations. These have proved adequate for all of my Beverages even though their ground impedance isn't great. Beverages are pretty tolerant, which is one reason I like them. In other installations it may be necessary to improve the ground rods or add short radials.

Despite all the below grade rocks and tree roots I only had to make 6 trials to drive in the two ground rods. I got lucky. In one case a few years ago it took twice as many tries to drive in one ground rod. You pull it out and try again a foot away. Trial and error is necessary.

The squirrels began exploring and abusing the Beverage as soon as it was pulled along the fence line. The Heliax became a convenient rodent highway that perhaps saved them the effort of jumping from log to log. The ⅛" nylon rope at the head end was soon chewed through so I replaced it with scrap insulated copper wire. 

I suspect that it was rodents rather than the usual deer that recently chewed through one of the radials on the 160 meter transmit antenna. That was easy to fix. I'm thankful that they have never (yet) chewed on the many hundreds of meters of RG6 running through the bush to the various Beverages.

When I first connected the antenna it didn't work. After some frantic troubleshooting I discovered that the ground wire to the head end had fallen off. Once I screwed it back on the Beverage worked as expected in the east direction. The SWR curves are hardly perfect and the scraps of feed line didn't help. I've found that Beverage antennas are very tolerant of impedance matching challenges like these.

The impedance centres near 75 Ω (SWR of 1.5), which is per the design. The cycling is most likely due to a surge impedance that differs from the design objective of 350 Ω. There are many factors to consider, though the most likely one in this case is the ground connection. The ESR (equivalent series resistance) of these ground rods in my soil is typically about 100 Ω. I could have wound the transformers for the higher net impedance of about 450 Ω, but that isn't necessary. 

The impedance in the reverse direction displays more anomalies. Those are almost certainly due to the poor quality of the Heliax. It is only in the reverse direction that the Heliax is used as a transmission line to transport signals coming from the west via the reflection transformer at the east end of the antenna.

I made a switch-operated bias-T to inject 12 VDC onto the coax for the reversing function. The F connectors are for the Beverage systems and the BNC connectors are for the receive antenna ports of two radios. At the moment the new Beverage is switched manually. The switch on the left, not yet operational, will be used to manually swap Beverage systems between the two radios. The rightmost F connector is for a possible south Beverage to be used in conjunction with the new east-west short Beverage.

Assuming that the system works well, a PCB with relays will be installed for software control of system swapping and direction control of the new Beverage. It will be point and click as for the main Beverage system. Implementation is straight forward but it is not a priority. I'll have more to say about this project after it is built.


I compared the new Beverage to the higher performance Beverage system on 160 meters. I used two receivers for the test so that I could easily listen to both antennas concurrently. Comparing the reception of signals was interesting.

Signals from Europe (northeast) were about the same on the new Beverage as on the longer east Beverage. The long east Beverage has a sharper beam width so its gain falls off to the northeast. The long northeast Beverage is, unsurprisingly, the clear winner for European signals. 

Signals are stronger on the long Beverage since Beverage gain increases with length. However, that does not indicate quality of copy since both signal and noise increase. Direction and RDF are what matter. Use the receiver pre-amp if necessary to raise the antenna noise level above the receiver noise floor.

Testing the F/B and the west direction had to wait because at first the antenna didn't work in the reverse direction. Troubleshooting found that the N panel jack on the enclosure with the reflection transformer had a broken centre pin, the ground lug was loose and the transformer was wired backwards. So many mistakes in such a small box! Well, that's not unusual for me.

When I did get it working the F/B was tested on 160 meters with stations in Europe and W7. It works very well in both directions. Performance to southerly directions was unpredictable, depending on where the signal fell into the off-the-side nodes and nulls of the Beverages being compared.

I next turned to 80 meters. It is interesting to compare the patterns of the 3-element vertical yagi and the short Beverage. There is of course a large gain difference but that is not entirely relevant. It may matter when switching from one to the other since it may also require turning the receiver pre-amp on or off. 

I live with it even though I could install an external amplifier for the Beverage to better equalize signal levels. I don't because it is common for a pre-amp, even one with a BPF in front of it, to be overloaded by a nearby kilowatt transmitter. That's only a concern for SO2R and multi-op contests, which is different than for most low band operators.

In my brief testing on 80 meters the short Beverage works well. The RDF of about 11 db, which is 1.5 db better than the yagi, may prove useful for digging out weak stations during contests when the main Beverage system is being used on 160 meters.


With this antenna completed, that's one more check mark on my long list of winter projects. It is unlikely that I'll pursue manual or software swapping of Beverage systems during this contest season. I will instead turn to other projects.

If you have the space and one or more old rolls of retired coax, consider a project like this rather than tossing them into the garbage bin. It's a simple and inexpensive way to improve low band receive performance. The improvement can be especially impressive if your main antenna is not directive, such as a vertical or inverted vee. A 90 meter (300') long antenna will fit within many urban fringe or rural properties where a full size Beverage twice that length will not.

Thursday, January 4, 2024

Article Popularity Over 11 Years

I'm quite surprised to still be blogging after 11 years and to do so while sustaining the same pace of articles. This is article #580, which is an average of about one article per week. Blogging is falling by the wayside in comparison to those who have taken to YouTube and similar media. Each has its place. I don't have an audience anywhere close to that of the popular YouTube ham channels. That's not my goal yet I am always surprised to learn how many are reading my blog.

Most of the traffic comes from search engines rather than regular "subscribers". That isn't surprising. Typically we search for help when we need information or when something breaks. Let's say your Hy-Gain rotator needs work. You type in "how to repair a hy-gain tailtwister" and my blog shows up high in the results. That's how most readers end up here. However, I often find that videos rank higher than blogs in the results. 

I'm not chasing eyeballs so I stick with the medium that I prefer. There are no ads and I earn no income from the blog. I am not motivated by money or attention. I see the blog as one way I pay it back to the hobby that has done so much for me. It helps that I enjoy doing it. Words are how I best express myself.

Statistical imperfections

I have enough experience with statistical analysis and mathematics in general to be wary of simplistic interpretations of raw page views. There are many confounding factors that skew the results. The popularity of an article does not necessarily measure its quality or value.

  • Bias to older articles: Articles published long ago have a higher probability of being searched for and read simply because they've been around longer.
  • Blogger statistics: I am reliant on the statistics kept by the Blogger platform. They aren't very deep or informative and since Google pretty well abandonned Blogger, there are unlikely to be improvements.
  • Robots skew the page hits: Like everyone on the internet, my blog is regularly plagued by robots that repeatedly hit articles, seemingly at random, that upset the statistics. A longer sampling period reduces the numerical affect of robots, since they active for only short periods and their targets shift.
  • Bias to my interests: You will find no articles on my blog about VHF repeaters and handheld radios. That does not mean that the subject is unpopular! The statistics are only meaningful for subjects that I write about.
  • External site bias: Search engines are not neutral. When a search on a subject does or does not list one of my articles near the top of the list the statistics for the article are affected because people will click on the link. That does not necessarily indicate popularity. There is a similar effect when another site links to articles on my blog. Article hits are inflated by the interests of that site's owner and that site's popularity with other hams.

Those are the confounding factors that came to mind when I gave it a few minute's thought. I'm sure you can think of others. Keep that in mind as you read on. This article is more of an entertainment than a valid scientific analysis due to the poor data quality.

All time top 10

Contesters love making the top ten. I first did so in Sweepstakes back in the late 1970s. Let's look at the all time top 10 articles for this blog.

  1. 40 Meters 3-element Wire Yagi (2014)
  2. Stacking HF Yagis - The Basics (2014)
  3. 40 Meters Wire Yagi - Inverted Vee Elements (2013)
  4. Adjust a Yagi By Pointing It Up (2016)
  5. 40 Meters 4-element Wire Yagi (2014)
  6. Hy-Gain Trap Repair (2019)
  7. 3-element Coil-loaded Yagi for 40 Meters (2016)
  8. Overhauling a Hy-gain Tailtwister Rotator (2016)
  9. Air Core Coax Chokes: Good, Bad and Ugly (2020)
  10. Making the Move to FT8 on 6 Meters (2018)

Recall what I said about statistical analysis up above before taking the list at face value. It is strongly slanted towards older articles, as we should expect. Since they've been around longer they've had more time to be searched and read, or read by following links from later articles. Nevertheless there are insights to be gained.

Notice that there are 3 articles about wire yagis for 40 meters and one for a yagi with short (loaded) elements on the same band. I've long noted their popularity. Yagis for 20 meters and up are fairly easy to buy or build, and raise. Not so for the lower bands. Most hams have no possibility of directional antennas on 80 and 160 meters, but 40 meters is often within reach, if one accepts a few compromises. 

I believe that is what motivates the interest in those articles. I wrote them for pretty well the same reason! Long ago I had a wire yagi on 40 meters and I loved it. Exploring lightweight yagis on 40 meters was of great interest to me, in the hope that I could repeat my earlier success. Of course I have moved on and I now have two large rotatable yagis for 40 meters. My interest in wire yagis has waned, but not so for many others.

I'm surprised that the article about stacking basics made it to #2. I had thought the subject to be well covered by others. My exploration of the possibilities and alternatives was more of a selfish interest. Clearly others disagree and appear to welcome my addition to the knowledge base. I hope that the information is helpful.

The two articles on repairing Hy-Gain products is worth a chuckle. Again, the statistics have to be considered in context. It might be that Hy-Gain products are prone to fail. On the other hand, more may fail or need maintenance simply because they have a large market share. A product with 10% of their sales would, all things being equal, have just 10% of the interest in similar articles. For example, I've written several articles on prop pitch motor repair that are not very popular, and that may be for no other reason beyond the fact that few hams use them as rotators. Hy-Gain is dominant in the rotator market for ham antennas.

#9 and #10 are different. Common mode chokes are poorly understood by many hams. Coax chokes are inexpensive and commonly used despite their limitations. I thought it worth a few words on their proper selection and use, and apparently others agree. There is ample high quality information out there (and referenced in the article) on common mode chokes. Is that information too esoteric for many so they come here? Perhaps, but I have no way of knowing.

The popularity of digital modes is undeniable, whether or not you are a fan. My use of FT8 and similar modes is limited. I reluctantly began to use WSJT-X on 6 meters several years ago when activity migrated to FT8. Since then I've become an enthusiastic digital operator on 6 meters. My reason is the many advantages it has for DXing on the magic band. I have given talks on the subject to various clubs as well. The interest is there and I believe that's a good thing.

2023 (12-month) top 10

Change is inevitable. Whether it is the march of technology or the operating interests of the amateur radio community, the hobby is changing. You can be a curmudgeon about it but that only serves to isolate yourself from others. That includes technology as diverse as digital modes, tubes vs solid state equipment, software vs hardware, and much more. 

It was therefore of interest to me to compare the recent popularity of articles to that from the past 11 years. Again, the statistical factors at play skew the results. By restricting the measurement period to the recent past there is less skewing towards older articles. Only articles published late in 2023 are disadvantaged by the shorter sampling period. 

I have only provided links for articles that do not appear in the previous list. That also helps to highlight the differences between the two sampling periods.

  1. 40 Meters 3-element Wire Yagi
  2. Hy-Gain Trap Repair
  3. Air Core Coax Chokes: Good, Bad and Ugly
  4. Stacking HF Yagis - The Basics
  5. Reversible RG6 Beverage Antenna (2020)
  6. Notes on Gin Pole Mechanics (2014)
  7. 160 Meter Shunt Fed Tower (2020)
  8. Overhauling a Hy-gain Tailtwister Rotator
  9. Adjust a Yagi By Pointing It Up
  10. CW Switching With PTT (2016)

There is a large overlap, especially at the top. Many older articles are of greater current interest while others are read less. While that's expected, the specifics are what interest me.

Only one of the 40 meter wire yagi articles remains in the top ten. However it remains at #1. The interest in achievable 40 meter gain antennas continues. Coil-loaded yagis and wire yagis with more elements are certainly less practical. On the other hand, the articles contain information of value to anyone considering these types of antennas. Perhaps more hams prefer construction articles than discussion about theory and models.

Hy-Gain antenna trap repair has moved up to #2. I suspect this is due to the article being relatively recent and not due to increased interest. I doubt that trap yagis have suddenly starting falling apart in 2023.

Low band antenna articles fill two of the top ten slots. Again, this may be due to their recency. I began my focus on low band receive and transmit antennas in 2017 soon after I moved to this rural QTH. It was then that the blog content shifted from small station antennas to big station antennas. I have written little about small station antennas for the past 7 years. The blog reflects my current interests.

The rankings of articles about gin poles and CW switching are unexpected. In the latter case it appears to be due in large part to a robot that was hammering that article for a while. However there has been a steady trickle of interest in both of those articles. I guess that the trickle of interest adds up over time.

I'll finish my commentary with a cautionary note about the article adjusting yagis by pointing them up. I don't do it that way any more. Big HF yagis are difficult to stand upright high enough for the tuning to be accurate. It is also quite difficult to access the feed point when the yagi is in that position. It is also easy to confound tuning due to interactions with towers, antennas and other obstacles. I now prefer to raise them horizontally to a modest height that is sufficient to stabilize the feed point impedance. Of course VHF and UHF antennas have always been tuned this way since even head height can be indistinguishable from free space.

Wrap up

I decided to ease into 2024 with this lightweight article. Hopefully some readers will find it of interest. There are several technical articles in the pipeline that should be published in the coming weeks. But I needed a break, hence this article.

I can't promise that every article will be of interest to every reader. I speak to my interests, my observations, my experiments and my experiences. I try to do it in a way that makes the articles useful to others. Many articles strike a cord with others and become popular. Most are duds, finding little interest. That doesn't concern me. I would only be concerned if nothing I wrote was of interest. That may be the day I stop writing.

Unfortunately the year has begun with several station problems that are weighing on me. Not to mention my obligations to others that are adding to time pressures. I have only turned a rig on once so far this year. The lull is temporary. Many contests and DXing opportunities are coming up.