Building & Tuning the 3-element 20 Meter Yagi

There was no rush to build the new 3-element 20 meter yagi since it can't be raised until the fall for several reasons. I worked on it over the summer as time permitted. It is now largely complete, tested and tuned. This fall I'll take down the TH6 and replace it with this antenna. I also plan a similar antenna for 15 meters. Both are to be fixed south, just like the TH6. They will be more efficient and less prone to multi-station interference than the TH6. Another for 10 meters can wait since the solar cycle is waning.

Although a 3-element yagi is a common directional antenna there are a few factors worth discussing. Those will make the article longer than you might expect. The details may prove useful to others, including how construction choices affect performance. No matter our experience and knowledge there is always more to be discovered even in antennas that we believe to be thoroughly understood.

Element taper and K-factor

The ratio of wavelength to wire diameter (λ/D) affect the SWR bandwidth of an antenna element. The higher the ratio the greater the change in reactance for a given change of frequency (dX/df). Therefore an antenna made from wire has a narrower SWR bandwidth than the same antenna made from tubes -- fat is good! The effect is greater at longer wavelengths (lower frequencies) for a given wire diameter. The effect is noticable at 20 meters, but small enough that it can usually be safely ignored.

Antenna modelling engines readily calculate the effect. It influenced my choice of a 7% spread for the parasitic elements of the 3-element yagi. For contesting I want a low SWR from 14.000 to 14.350 MHz. However, the model utilized fixed diameter elements, while the real antenna uses tapered elements. It is not obvious what the effective ratio is for tapered elements.

The steps for each half element are as follows:

• ~1.5": 3" long, calculated for the boom-to-element clamp, where director and reflector are electrically isolated from the boom; the estimated diameter for the DE (driven element) is not critical since it is accommodated by the matching network
• 1.315": 9" long for DE and director, and 21" for the reflector
• 1": 51-¼"
• ⅞": 51-¼"
• ¾: 51-½"
• ⅝: 21"
• ½": 24" (R), 13" (DE), 4" (D)

Small deviations of actual tube lengths were accommodated during construction so that the half-element lengths are 224" (R), 200" (DE) and 191" (D). The tubing from 1" to ¾" came from 20 meter yagis built by a long-gone Canadian firm almost 50 years ago and I saw no reason to take them apart to change their lengths.

When I ran the model with this taper schedule there arose a problem. The effective λ/D ratio was higher than that of the initial model with fixed diameter elements. The change of SWR at the band edges was enough that I increased the 7% spread to 8%. That achieved the same SWR bandwidth while sacrificing about 0.2 db of gain. Since this is a "multiplier" antenna pointed south the gain difference is not too concerning.

The lesson is that element taper is a significant design factor. The effective wire diameter more closely resembles that of the outermost thin tubes than the average or the large diameter found at element centre.

Boom

I was fortunate to have all the aluminum and attachments in my stock to build this antenna. That includes the boom. With the pieces I had there were several alternatives to make the boom. I finally decided to use a couple of length of 2"×1/16" tubes that came from old yagis. Hy-Gain used the same size tubes but neither of these appeared to come from a Hy-Gain yagi based on the wear marks.

To join the tubes I used a scrap 2' length of 2-⅜ OD schedule 40 6061-T6 pipe. Aluminum flashing fills the small gap since the ID of the pipe is a little more than 2". They are held  together with ¼" stainless (304) bolts and nylocs. Lock washers are not effective on round surfaces so it was nylocs or jam nuts. I've used both techniques in my various antenna projects.

One end of the longer 2" tube has a press fit galvanized tube (left picture). Clearly this was the original boom's coupler to another 2" tube. I intended to use it to join the tubes but I couldn't make it work. There has been enough oxidation over the decades that making it fit would have taken a lot of tedious preparation of the surfaces. It wasn't worth the effort. I cut the steel flush to the end of the tube. 

When I was done the boom was 282" (23'-6" or 716 cm). I reran the model with the slightly shorter boom (24' in the original model) and the performance difference was negligible, as I expected. The actual length of the yagi is several inches shorter, measured centre-to-centre from director to reflector, due to the boom-to-element clamps. One can be seen on the left being tested for its fit. The small clamp you can see on the right picture is one of the boom truss attachments. These were found in my junk box (source unknown).

Elements

Since the widest tubes of the old element sections mentioned above are 1", I slipped them inside 1.315" OD pipe. This is schedule 40 1" (IPS) pipe so the ID is a slightly over 1". For other antennas I've wrapped the 1" tube with aluminum flashing. The amount of flashing is easy to calculate since C = πD and D is 1" so the circumference is ~3.14". I rounded down to 3-⅛" so that the flashing didn't overlap itself.

It didn't work; no amount of forcing the pipe, flashing and tube would make them fit together. I measured the OD of one and the ID of the other with calipers and discovered that the ID of the pipe was a little less than expected. All of this aluminum was milled around 1980, so either the mill finish is responsible or it's a build up of aluminum oxide. Since I'm not equipped with a metal lathe I cut the flashing in half (to ~1-½") and it all fit together nicely.

Notice (top left) the obviously hand cut slits; most of the pipe ends didn't have slits. I didn't discriminate and all were joined in the same fashion as shown in the picture. The rear stainless screw head presses directly on the 1" tube for improved rigidity and electrical continuity (see the larger hole in the bottom left corner). Conductive grease was applied to all surfaces after sanding off imperfections and oxides.

The joints between tubes are peculiar. I don't think that was state-of-the-art a half-century ago! Metal strapping squeezes the slit tube onto the inner one. This would have required a special tool. Under tension the machine folds back and crimps then cuts the strap. It's a very solid if unconventional method of joining tapered yagi elements. I can only remember this method being used on shipping crates. A self-tapping screw further prevents slippage. While unusual I saw no reason to redo any of it. 

The ¾" tube was the tip of the original yagi elements and the elements were roped with ¼" polypropylene twist rope. Those were not a good choice so the rope and plugs were removed. I don't anticipate much singing in this yagi but we'll see how that goes.

The smaller tubes were attached in ways I've done before. The end of the smallest tubes (¾") of these sections and the ⅝" tubes were drilled for #8 stainless screws and secured with nylocs. The ⅝" tubes were slit for hose (gear) clamps to secure the adjustable ½" tips. All except the longer tips on the reflector were pulled from my junk pile. They have holes and other imperfections from earlier projects which don't matter as long as the tubes are structurally sound. This isn't an art project.

Notice the black marker rings on the ½" tubes. The element halves were precisely measured to match the EZNEC model. From experience I know that the SDC (stepped diameter correction) algorithm is very reliable. For a 20 meter yagi I try to match the model to within ¼" -- try to do even better on higher bands. A lot of time and effort goes into the design and construction of a yagi so this is not the place to be sloppy. Don't cheat yourself by talking yourself into believing that precision doesn't matter. 

Boom resonance

I've previously discussed how a 3-element yagi can behave as a loaded dipole at about half the yagi's design frequency, where the boom is the driven element and the outer elements are capacitance hats. The is a significant risk of interaction to an antenna on that lower that is close and orthogonal to the yagi. I have this problem with the 40 meter Moxon (and the XM240 before that) and the south-pointing TH6 above.

I reduced the interaction by raising the TH6 a little higher. When this yagi replaces the TH6 the problem must once again be dealt with. However, unlike the commercial antenna I have design options to nip the 40 meter resonance issue in the bud.

The director and reflector elements are electrically isolated from the boom. That prevents them from becoming capacitance hats with respect to the boom resonance. The stray capacitance between the 1.315" pipe and boom clamp is negligible in this application.

The insulators are cut from a flexible ABS pipe that was surplus to a property drainage project. They fit nicely and are strong enough to take the compression of the u-bolts to keep them in position. If you do something similar I will warn you that the insulators must be slipped on before the second half element is attached to the centre pipe, otherwise the tapered section joint hardware (screws, hose clamp, etc.) will block their passage. You'll would then have to cut the insulator, in one place if the insulator material is flexible or in two places if it is rigid. Those cuts can make it difficult to prevent insulator distortion and eventual failure.

The driven element is grounded to the boom. This is for the convenience of building the gamma match (see next section). Since an element near the centre of the boom does not electrically load it in the same way as the outer elements it is an acceptable choice.

I modelled this combination of element brackets to confirm that the 40 meter boom resonance was eliminated. Notice that placing the source at different places on the boom (top: near the DE; bottom: boom centre) effects its impedance at higher frequencies just as it would in any dipole. However, those are irrelevant to this scenario; you could feed the boom this way for real if you cared, but that is hardly typical! That peculiarity does not bear on the fact that the boom resonance on 40 meters is gone. Problem solved.

Gamma match

In the EZNEC model the impedance matching network is a beta (hairpin) while the built antenna uses a gamma match. The former is quite easy to model while the latter is not. In practice, the beta match is a good proxy for designing the driven element of a yagi with a gamma match. 

The reason is that both matching networks perform best when the self resonance of the DE includes -20 to -30 Ω of capacitive reactance, and both work well for the typical 20 to 30 Ω feed point resistance range typical of yagis. There is often no need to adjust the tips of the DE when a gamma match is used despite a beta being employed in the model.

The gamma match saved me the trouble of isolating the DE from the boom and splitting the DE at the centre as the beta match requires. That is, it's convenient and the gamma match works well, though often misunderstood. No, it doesn't cause the antenna pattern to be measurably asymmetric or promote common mode on the coax shield. A CMC (common mode choke) is advisable no matter the matching network.

The design of the gamma match differs in a few respects from those I built for my stacks of 10, 15 and 20 meter 5-element yagis. First, it is more rigid at the centre. A ⅛" thick aluminum bar ¾" wide is attached with a galvanized saddle clamp to the DE adjacent to the boom-to-element clamp. That is the minimum width to comfortably accommodate an SO-239 UHF panel connector. Hanging below it is a piece of rigid PVC that I pulled from my junk box. Have I ever mentioned that I'm a pack rat? I throw nothing out. Particularly astute readers will recognize that rectangle of PVC from a previous project.

The RG213 gamma capacitor is stripped of jacket and shield and inserted into the 7/16" gamma rod. The rod and shorting stub came from one of those ancient 20 meter yagis I scavenged so they are the correct dimensions for this antenna. When fully assembled the gamma match is stable and rigid, and should be up to the rigours of the elements. If not, since this is a 3-element yagi, the gamma match is easily accessed from the tower for service. 

One addition I may add before the yagi is raised is an aluminum jumper from the bar to the element to bypass any galvanic incompatibility due to the interposition of the galvanized saddle clamp. It is fine as it is to conduct initial testing and tuning.

Assembly

Once the boom and elements were built the antenna had to be assembled in the hay field. Although it is reasonably lightweight, an assembled 20 meter yagi needs a lot of room. I did this at the planned launch point for tramming it onto one of the guyed towers for testing and tuning. 

Of the alternatives for getting it high enough off the ground -- preferably λ/2, or at least 30' (10 m) -- this seemed most convenient since for a 3-element yagi the DE is adjacent to the tower. It is easy to adjust the gamma match with minimum fuss. For yagis with any other number of elements (2 or 4+) the DE is out of reach from the tower and other tuning arrangements are necessary.

Since the 2" sections of the boom are different lengths and the longer one has the steel insert that I couldn't extract, the reflector was placed on the short section, since it is heavier, to help balance the antenna. With the DE closer to the reflector than the director the final balance point was almost exactly midway along the 2-⅜" coupling pipe. That's convenient even though the halfway mark by distance is on the longer 2" section.

I used my usual method to weigh the assembled yagi by placing an ordinary scale on a flat surface, then measuring my weight and the weight while lifting the yagi off the ground. The weight is 40 lb (18 kg), which is quite light for a yagi of this size. It will be up to 10% heavier when the boom-to-mast clamp and boom truss are added. Neither is yet built nor needed for initial testing and tuning.

Test & tune

The yagi sat in the field for two weeks while I travelled to Labrador. Back home with August racing to a close I really needed to get this project moving. The bugs were fierce before the trip and they were likely to subside later in the month. Despite that hope being dashed I ploughed ahead.

Yet there was no real reason to do this test. From long experience, models built with NEC2 and the SDC correction within EZNEC are remarkably accurate. It nevertheless gives me piece of mind and confidence that when the yagi is raised to its final position on the tower that it will work correctly. A fault at that time would be more expensive to fix. I judged that a few hours of work would be time well spent.

I set up a tram line between my two big towers to tow the yagi up above the lowest set of guys. A height better than ½λ is more than enough for precise tuning. The tram is at a shallow angle since the towers are 200' (60 m) apart. That makes it an easy one man job. Both the tram line and haul line are ropes so that they don't interact with the antenna. The biggest hassle was unravelling the long lines since no matter how well I fold them after use they still like to tangle.

Tram lines have featured so frequently in this blog that I see no need to say a lot about it. Put the term in the search box if you want to read more. One point to mention is the yellow rope from the tower to the link between the tram line and the winch-driven cable. It is a safety line so that if the winch fails the tram can't collapse. Another point is the height of the anchors and haul cable pulley at around 45' (14 m). The bottom guys of the destination tower are at 35' (11 m).  That allows the element tips to clear the guys and place the yagi midway between the first and second set of guys to minimize interaction.

Hauling a 40 lb yagi at a shallow angle requires little effort. The penalty is that it takes a while due to the length of the tram line. It's a trade off I liked since it made the job easy to do myself. Once the yagi was up the tram line was slackened to bring the boom into the tower so that all parts of the gamma match could be reached from the tower. 

The gamma capacitor was purposely made long. By the time I was done it as almost a foot shorter. I'll make it a little longer for the final version and add the support insulator for the gamma rod near the feed point. Tuning went quite well as you can see on the left. The final SWR curve will be slightly different and better since I stopped when I was close enough. Recall that this is a test to ensure that the yagi is performing as expected. So far so good since it closely resembles the EZNEC model.

Note the connection of the analyzer to the feed point with a male-male UHF adaptor. Although this is less convenient than a short jumper cable it has an important advantage: no need to compensate for the impedance transformation of the coax while adjusting the gamma match. Without it I'd need to guess at each step or use a tool like TLW to transform each measurement to the impedance at the feed point. This way is awkward but saves a lot of time and frustration.

With a successful test in hand I lowered the yagi and parked it in the hay field. It can stay there until I'm ready to raise it to its final location on the tower. Mechanical work on the gamma match, boom truss and other items are ongoing. I'll probably reuse the CMC that's currently on the TH6 or I may make a coax (solenoid) choke for it as I've done for my other monoband yagis.

Next steps

Obviously the next step is to raise the yagi. That will have to wait until the fall. First, it will take planning to arrange for the removal of the TH6. The 40 meter Moxon, which is not far below it, will have to be navigated around. I have a few alternatives to get it done. Aside from that I have other projects and obligations to deal with. 

The second reason is that I'd like to have a 15 meter yagi ready to go at the same time. The TH6 covers  20, 15 and 10 meters, and although I can delay a south-pointing 10 meter yagi to the next solar cycle, 15 meters is more critical for the multiplier rich south. I have been assembling the parts but as yet I'm not far along. I will also need to bury more Heliax since I am running out of transmission line capacity. The 15 meter yagi will go on the tower with the 15 and 20 meter stacks, but low enough that it will not appreciably interact with the stack.

The 15 meter yagi will be a relatively easy project since the antenna is smaller. I will most likely keep it to 3 elements so that it can fit on a short boom while having similar or better performance than the TH6 which, although it has 4 elements on 15 meters, some use traps. I'll write about it when it's done.

Back to Labrador

There are times when we go the extra mile -- or 2000 km -- to help a friend in need. I joined Chris VO2AC on another long drive to Labrador to work on his remote station in Happy Valley-Goose Bay, Labrador. Unlike two years ago this time it was just the two of us. Other friends had to decline due to obligations despite their willingness.

He had a long list of jobs to be done but we were confident that the two of us could get it done. So he went ahead and booked vacation time from work. The total trip was 10 days: 4 days driving and 6 days working. On several of those days we worked late into the evening. Including driving around town he put over 4500 km on his truck. He had a full load in the bed of his F150 and a full load on the drive back. More on that later.

This article will mostly deal with the work that would most interest readers. Suffice to say that we were spoiled by the hospitality of his mother Thelma and aunt Judy who prepared most of our meals. Other relatives of Chris invited us to their houses with typical Newfoundland hospitality and introduced me to several dishes I'd never heard of before. Then there were his many friends that provided our accommodation, flew a large yagi to Labrador and much more. I'm convinced that Chris is related to half the town and the other half are childhood friends. I felt very welcome even if it was all a bit overwhelming.

What had to be done

These were the major tasks that we needed to accomplish:

• Repair the rotator, or discover what might be interfering with its proper operation
• Matching networks for several antennas
• Upgrade, repair and replace various station equipment, hardware and software
• Non-radio work on the property

The first item was why my presence was particularly useful. I came in handy for the second as well. For the rest I was just another pair of hands to get the job done. I wasn't there for just the "glamorous" work.

Rotator

The T2X (Tailtwister) rotator failed some time ago and attempts to diagnose and repair it from the ground were unsuccessful. Since that was the most important job we got to work on it the very first morning. That meant lifting the mast and yagis so that the rotator could be removed and brought to the ground for inspection and service.

There are many ways to lift a mast and its complement of yagis that ought to be the subject of its own article. It's one that I've touched on several times on the blog. For now I'll just say that I used a chain, come-along (hand winch) and a pulley attached to the mast to take the weight off the rotator. This seemed to be the most convenient approach for this job among the several alternatives I've used over the decades.

I couldn't fit everything in one photo since I was too close for a wider view. This one will do until I write that article about mast lifts. The chain wraps around tower members and attaches to the winch and a rope through the pulley to pull the mast straight up. The thrust bearings are loosened to allow the mast to slide past.

Without lateral support the yagis can spin freely despite a modest resistance to torque from the lifting mechanism. It is vitally important to put a "block" on the mast or yagis to prevent that, especially if it is windy or the mast and antennas must be left like that for hours or days. Weather is unpredictable. It is also recommended to "lock" the mast with, for example, an ordinary muffler clamp sitting on a thrust bearing so that the weight doesn't relax the rope or chain enough to interfere with reinstalling the rotator. However, be warned that almost all thrust bearings used by hams are not designed for axial loads.

Well, that's enough for what I intended to be a brief description. In this case the weight lifted was only about 150 lb (70 kg) but we had to leave it like that until the next day. I tied the bottom yagi (JK Mid-tri) to the tower with rope to keep the mast from rotating more than a few degrees. There was some rope relaxation overnight but not enough to get in the way of the rotator installation the next day.

The fault was in the rotator and not the controller, specifically the brake solenoid. This was despite the nominal resistance checks recommended for this series of Hy-Gain rotators. It failed to operate when powered and drew enough current to blow the controller's AC fuse. The solenoid and brake mechanism looked pristine and there were no apparent mechanical flaws. Chris can look into the problem at his convenience now that he has the rotator back home.

The substitute rotator also experienced a fault! After opening it up we found a wire that was cut. I say cut rather than broken because there was evidence of a wire cutter being used. We don't know where or when that occurred but it was easily repaired. The rotator was installed on the tower and performed admirably. Hopefully it'll last for years to come. 

We didn't have too many ball bearings escape us during the disassembly and both rotators were quickly reassembled using my usual alignment procedure. Neither T2X needed grease or other attention beyond that already mentioned. 

Antenna matching

The tower supports verticals for 80 and 160 meters and inverted vees for 40 and 80 meters. Deployment isn't optimal due to the wires being close to the towers and, for the inverted vees, the interior angles are not greater than 90°. Shunt feeding the tower isn't currently an option but could be in the future. For 40 meters Chris also has a 3-element vertical yagi (modified K3LR array) that can point northeast and southwest in addition to omni-directional.

The vees and verticals have fairly narrow SWR bandwidths. Adjusting the lengths of these antennas is not easy and our time was limited. Mounting matching networks at the feed points of the inverted vees was also inconvenient. Chris chose an alternative that can work very well on the low bands: put the matching networks on the ground where they can be easily maintained and adjusted. 

Provided that the SWR is reasonable the mismatch loss on the coax (LMR400 in this case) from the matching network to the antenna can be quite low. For a given length, type of coax and SWR the loss rises with frequency. The loss is easily calculated and there are formulae and charts in every antenna design book commonly used by hams, and plentiful online calculators. There is no need to get into the mathematics here. It is up to each station owner to make the calculation and decide what is acceptable to them. There is no excuse not to do the calculation; don't fool yourself.

With a set of measurements made at the base of the tower (where they plugged into antenna switches) I sat down with TLW (comes with the ARRL Antenna Book) and designed L-networks -- there are many alternatives and also online calculators such as this one that I picked at random. Chris already had the boxes built, including high-Q coils, so all I had to do was determine L and C values, and the L-network topology (there are 4). 

I experimented with different arrangements to find one that allowed a capacitor substitution to switch a narrow SWR range from CW to SSB band segments with reasonable SWR. The prepared boxes included a relay (for switching capacitors) and a coil with a clip lead to adjust L to the design value calculated by TLW. The process is easier than it sounds.

We had bags of vintage mica transmitting capacitors of every type and value imaginable. A group of us pool our resources and pick what we need for our antenna projects. Despite their age they work well. I have never had one fail.

A perfect SWR is not necessary provided that it was below 2 or, better, 1.5 over the desired range. Those are upper values acceptable to his solid state amplifiers. Careful design will usually find such a solution across a few hundred kHz on 40 and 80 meters, and less on 160 meters. Success is only limited by the Q of the antenna. A simple matching network can move the frequency of the ideal match but cannot broaden it.

For the 40 meter inverted vee I was able to find a solution that worked pretty well from 7.0 to 7.2 MHz (picture above). The L-network for the 80 meter vertical degenerated to a series C since the shunt L approached infinity. The reason is that the measured R value was close to 50 Ω. The positive reactance is cancelled with a series capacitor (see the photo). Since this antenna has a narrow SWR bandwidth and the inverted vee was made switchable between CW and SSB we opted to tune it to the CW segment.

Chris programmed his software to allow operator selection of the various network options. That went well so all we had to do was weatherproof the coax connectors and antenna feed points. A rainstorm moved in during the work so we got quite wet. Letting the connectors get a little wet is not really a problem but then we'd have to thoroughly dry them the next day before wrapping them in tape.

Antenna matching woes

Not everything went smoothly. I'll mention a couple of items that gave us grief since our experience can be educational. We dealt with them easily enough but only because we understood what was happening. 

First were the two antenna analyzers: they didn't agree. The differences were small but large enough to matter. One or both of them had to be incorrect. This could be due to poor quality analyzers or damage. I've seen too many hams using inaccurate instruments or not being aware of how they can give incorrect measurements when used improperly. 

An antenna analyzer is single port network analyzer that generates a signal at the displayed frequency and compares that to the signal that the network being tested returns. That is, an S11 measurement. In our case both analyzers are by RigExpert (AA54 and AA55-Zoom) which has a well earned reputation for reliability and accuracy. That said, they are designed for field use and are not laboratory instruments. Some compromises are required to harden them for the intended application.

What happened? The X measurements closely agreed but there were significant deviations for the R component of the complex impedance. Chris told me that the AA55 had previously suffered an accident that destroyed part of the bridge circuit. The precision SMD resistors that replaced them were not exactly 50 Ω due to availability. I tested the device with a dummy load that showed an SWR of about 1.1 at all frequencies, or an impedance of about 54+j0 Ω. The error was larger when measuring low impedances. 

I used my AA54 for measurements after discovering the problem despite its lack of features in comparison to the newer AA55. The bridge circuit in a network analyzer is critical to its accuracy and the one in mine was working perfectly.

The second problem was quite interesting, and predictable had we thought about it in advance. To improve ground loss for the verticals -- 80 and 160 meters and the 3 elements of the 40 meter array -- we tied them together at the radial plates. It's a good idea and I do it whenever I can for my antennas where the radials overlap. However, radials are an integral component of the antenna system's behaviour, not only its efficiency (protection against near field ground loss). Except in a very extensive radial field any change to the radials will impact the impedance of the antennas.

The match we had obtained for the verticals was no longer quite so good after doing the work. Realizing what had occurred we disconnected those wires. There was no time to rework the matching networks for each antenna; it was left for the future. In the case of the parasitic 40 meter array the impedance change was less concerning than the pattern changes. Element tuning in an array is critical to its performance. A slightly higher SWR in a single element antenna is easier to live with. 

Inter-station interference

Chris's station is fully SO2R and 2BSIQ capable. With so many antennas fit into a tight space there are challenges preventing harmonics from degrading reception on higher bands. This is despite a full complement of high power BPF (band pass filters) and triplexer by VA6AM, and a 2×8 switch and ancillary switches with pretty good isolation between ports. The laws of physics are not negotiable.

The addition of stubs to the BPF to attenuate the second harmonic made no discernible difference. We were pretty sure that the problem was more fundamental than that. As is typical done in many stations, the BPF are placed on the antenna side of the N×M antenna switch. Unfortunately that makes the station susceptible to the relatively poor port isolation of the antenna switch in comparison to the ultimate rejection of the BPF and stubs.

I can get away with it in my station since most of my antennas are far apart or usually pointing in different directions rather than at each other. The best approach is to place the filters on the transmitter side of the antenna switches. That is really only practical with two sets of high power BPF since you'll otherwise be faced with leakage through the relays that switch the BPF between radios. Most choose to have switchable coaxial stubs after each amplifier and leave the BPF where they are. There is no perfect solution, we do what we can with the situation as it is.

Sundry items

When a station can only be occasionally accessed for brief periods of time there are certain to be overlooked items and other mishaps. I won't go through them all, but I will mention a few related to the tower and yagis.

My usual technique for installing rotators is to loosely bolt it to its tower plate and do the same for the plate to the tower members it mounts on. That way I can ensure that the rotator and mast are aligned and only then tighten the various bolts. I do the same with antennas, only slightly tightening bolts on the boom-to-mast clamps and other mounting hardware until I am satisfied that the yagis are pointing the right direction, are level and the rotation loops have been tested.

It is not uncommon that I'll miss a few bolts when I'm done. I discover the mistakes soon enough and then make sure that all are properly tightened. For a remote station you may not get that second chance. Not only were several nuts only finger tight, a few were entirely missing! I can't be certain that these oversights were my fault but I'll take the blame regardless. I'd have discovered them quickly in my own station since I am frequently on the towers.

When you run cables to a tower you have a few ways of doing it: overhead, on the ground, or underground. The initial install used a conduit buried in the sandy soil common throughout Happy Valley-Goose Bay. Digging a trench isn't difficult, which is good since he needed another one

The new trench was short and was not for coax or control lines. Chris has cameras so that he can remotely view the tower and antennas and all the critical equipment inside the shack. He handed me a shovel and I dug a new trench to the fence that separates the tenant's yard from the antennas and tower for more cameras.

I placed the new trench directly on top of the existing conduit. It is only about 6" (15 cm) deep. Other than being careful not to damage the fabric over the conduit it was quick and easy work. Certainly I've dug enough trenches of my own. He may eventually need a deeper trench out to the tower for more cable as the station grows. 

Detours on the return drive

After passing through the town of Churchill Falls we made a couple of stops. Public tours at the generating station were temporarily suspended so Chris chose alternatives. The first was a hike to a lookout over the real Churchill Falls (see picture at the start of the article). The waterfall isn't impressive since almost all the water is dammed and diverted to the generating station. If the water gets too high they open the gates to let the excess escape over its natural outlet over the falls. It's a rare event that I am told is very impressive.

Our next stop was at a place where two westward transmission lines abut the highway. We took a close look at the towers. Well, of course we did: hams love towers! One line uses self-supporting towers with 4 legs and the other uses guyed towers. At the end of the article is a picture showing Chris standing next to the pillar base of one of the latter. Their size is impressive, to say nothing of the many megawatts on the wires the towers support.

There are 4 guys per tower and the pillar base. In that regard they are similar to the guyed towers found in larger amateur stations like mine. The towers are bolted together rather than welded. That allows lower cost of transport to the site and no need to coat the towers beyond the factory galvanizing. 

It would be interesting to watch them erect these monsters. Every tower, pillar and anchor has unique requirements engineered for the the site. 

They must work with the local soil and rock, whatever it is and no matter the lack of levelness since the tower position can't deviate far from the transmission line's path. Unfortunately we couldn't tell how the anchors were done. 

There are really only two alternatives: drill and set anchors into the rock if its tensile strength and size are sufficient, or excavate the rock for a conventional dead man anchor where the overburden resists the guy tension. 

The guy cable and hardware are approximately 1" diameter (2.5 cm) so the breaking strength must be close to 100,000 lb, with a preload of about 10,000 lb. There's a lot of force on each tower and its supports. Failure of the transmission line is really not an option; a reliable electricity supply is critical to our modern civilization.

The real reason for the trip

If you read the article from 2024 you'll see a room full of Heliax, almost all of it AVA5 (⅞"). It came from the decommissioning of a commercial site. Naz VO2NS stored it at the Labrador City club station. They eventually decided that they have no use for it and offered it to us. We had very little room in Chris's truck on the earlier trip. We did better this time.

I have no exact measurement of how much is there other than it's a lot. I don't need all of it, but I can find good homes for the rest. Many hams don't appreciate the difference low loss transmission line can have on their on-air success, especially as the frequency climbs. It's one reason I do well on 6 meters and it is absolutely essential for the long runs necessary to traverse the hay fields and climb my tall towers. The average run on HF is more than 100 meters.

I'm showing my age (on the right)! Chris VO2AC is on the left and Naz VO2NS is in the centre. This is a roll that Naz and I compressed from about 4' diameter to 3' so that it would fit inside another roll. Space in the truck bed was at a premium. Heliax this size can be wound tighter, but only if done carefully. Naz's neighbours were entertained by our (eventually successful) attempt. It was done by rolling the Heliax down the back lane into a tighter bundle while laughing over our many mistakes along the way.

Mission accomplished

For most of you, the outcome of this trip to Labrador will be an easier shot at zone 2 and Newfoundland-Labrador (NL) for DXing and contests from 160 to 6 meters. Chris wins because he has a more competitive station that is SO2R capable on HF and 6 meters, whether for daily operation or in contests. Since he'll do better so will you.

Building and maintaining a remote station that is thousands of kilometers away is not for the weak of heart. Much can go wrong, or at least fail to go right. If something fails it can be months until a repair is feasible, even if it's to reset a computer or jiggle a connector. Although it helps to build well it is inevitable that trouble will make an appearance sooner or later. 

I must also mention that the climate in FO93 is harsh and the flies are fierce. Working outdoors this time of year is unwise without an ample supply of bug repellent. There are no bugs in winter so you only need to deal with the cold and snow which are both in ample supply. Having come from VE4, I am familiar with what winter tower work is like for Chris and others in Labrador. On the other hand, the electricity supply is ample and unbelievably inexpensive due to the local generating capacity.

Chris is committed to this venture in his homeland and he will make every effort to keep it going, even when that means hopping on a plane or making a 2000 km drive each way. That is less burdensome than it seems since every trip is an opportunity for him to visit with his large family and reconnect with old friends.

I don't expect to make many more trips to VO2, perhaps none if all goes well. I leave Labrador with the satisfaction of helping Chris be successful. I can also look forward to a reliable multiplier in every contest that I enter. Of course there's all that Heliax waiting to be put to good use. That is, once I figure out how to move it the 50 km from his home to mine.

WAE Rookie

I never entered the WAE (Worked All Europe) contest until this past weekend. I could claim that the unusual QTC rule is the reason but that's really not it; only some laziness on my part to learn how it works. The bigger reason is that it takes place in the summer when I mostly avoid HF and contests.

I decided to give  WAE CW a try this year. I did it part time with low power since I didn't want to attract many callers while I learned how to do QTC. I studied the N1MM+ documentation before the contest, noted the key features needed to bring up the QTC window and send them and started calling stations. I assume there are similar features for DXLog and other popular contest loggers.

I did S & P for most of my time in the contest so that I could control the pace. My only CQing -- I hesitate to call it running, as we'll come to later -- was Sunday afternoon. In retrospect, this is an unusual contest that may be an acquired taste. I remain undecided, as you'll see.

Many contesters love WAE and may be offended by what follows. Please keep in mind that I am writing this in good humour and poking a little fun at a contest with peculiar rules that lead to peculiar behaviours.

Multipliers

Multipliers came up while briefly reviewing the rules before the contest. They seemed a little odd. I decided not to worry about the details since my score was not a concern. As I worked stations the multipliers accumulated and that was good enough.

As time went on there was a puzzle: the multipliers were growing at an alarming rate. I worried that there was a scoring bug in N1MM. Apparently not. It is actually possible to have more multipliers than QSOs in this contest. Had I only known I'd have looked for more. I ended up with 297 multipliers from 311 contacts.

With effort you could do the same in CQ WW if you restrict yourself to working only one station in each zone -- that's up to 2 multipliers per QSO. But that would cut your effective operating time, and score, since there are only 40 zones. The sky's the limit in WAE.

Endless clicking

When doing S & P while assisted it is routine to click on human or RBN spots to find stations to work. On CW the skimmer network is so good that few contest operators bother to spot stations. There is almost no need to touch the VFO.

Well, that's simple, right? Not in WAE. Far too often I found that when I clicked on a spot I would find two stations in the midst of a long exchange of QTC. Not knowing how long that would take, and it can be quite some time, I would click on another spot. Time is of the essence in a contest.

But the next station is doing the same! With some dismay I click again. And again and again. Finally I find a station either finishing a QSO or a bunch of QTC and my finger hovers over the Enter key. Then they don't sign. I patiently wait for the next caller to make their contact, hoping to hear a call sign. Then they close with "QTC?" and off I go again looking for a station to work. 

I don't think I've ever had so low an S & P rate as in WAE. Not even years ago when I operated QRP.

Polite or rude?

When I don't have QTC or too few to go to the trouble of sending them, what should I say? There are endless ways to say no: "sri", "nil", "no qtc", "later", etc. I heard them all during WAE. It matters since I had to deal with the situation quite a lot.

Not having anticipated the frequent need I did not program a function key to politely decline. I did it manually by paddle but found that at over 35 wpm lengthy and dit-laden messages could be tricky to send. Eventually I settled on a simple "no". It's not particularly polite but it is short and effective. 

That worked for me and it certainly didn't deter the eternally hopeful from returning later to ask again. Some would do it 2 or 3 times. They might have come by even more had I operated longer.

The one respite was 80 meters. Nobody asked me for QTC on 80. Let's see...summer QRN, 100 watts...hmm. Maybe that's not so surprising. I think the European strategy is to hunt for QTC on the higher bands where copy is better. That's sensible. Maybe if I want to avoid QTC requests in the future I should do a single band 80 meter entry. There are no single band categories in WAE but I don't see why that should stop me.

Sending QTC

Sending QTC is absurdly easy with N1MM+. I could read a book while doing it and still respond to requests for repeats. Other than keyboard shortcuts to open the QTC window and send the header, you just press enter after each QTC is acknowledged, or press another key to repeat part or all of the QTC. All of the real work is done by the European operator.

It's boring, but points are points. I look at the points as compensation for the sheer tedium and annoyance. This might seem to be an opportunity for SO2R ops to make use of the dead time, but you really can't since the gaps between QTC are too short to fit in a transmission on the other radio. Copy an "R" and on to the next. Many operators do SO2R in WAE so it is certainly possible, but I wonder if that is only because the rate is not so high as in other contests.

QTC are not simple message. They consist of a UTC time, call sign and serial number. There are ample opportunities for copying errors and requests for repeats. Yet it rarely occurred. The European operators are good at the WAE game. Only once out of about 40 QTC series was I asked to QRS, and I was typically sending at 35 wpm. There was one instance of many repeat requests during a QTC series, which was on a noisy and interference plagued 40 meters. I don't recall who it was but he worked hard for those QTC. Bravo!

Who gets my QTC?

Since my supply of QTC is limited and the demand is almost unlimited, I have to deal with economics of a scarce resource, a resource that I control. DX stations have this peculiar superpower in WAE. Who gets my QTC? Do certain stations deserve them more than others? How do I decide? They may care but no matter who I give them to the impact on my score is the same. The potential dynamic is interesting.

It isn't as simple as bestowing them on my friends. Each can only get 10. What do I do with the rest? If I refuse to give QTC to anyone else my score will suffer. To get the most out of my contest effort I'll eventually have to give them to anyone who asks.

The alternative is more devious. I can give them to all except stations I want to hurt. That is, I withhold those 10 QTC from certain stations. I can still send my full load of QTC while (marginally) hurting selected stations.

Is that fair? No, of course not, but it breaks no rules. With the recent controversies in WRTC about cheerleading and pirate multipliers it's a good thing that there are no QTC in that competition. The situation is ugly enough already.

I want to run!

It was all S & P until Sunday afternoon when I decided to try some running. It didn't go well. I would attract a few casual European participants and then the QTC requests arrived from those I'd worked before. It seemed that as soon as the small pile up heard the first letter of "QTC?" they all scattered to the winds. Like me they had no intention of sticking around for a lengthy QTC exchange. 

I knew they'd gone when I declined the QTC request and no one was there to call me again. I would resume CQing in an attempt to run stations but then another previously worked station would jump in to ask for QTC. It was inescapable; running was next to impossible. Imagine how much worse it would have been had I been running high power.

It was both amusing and aggravating. Again, points are points, but sending (or refusing) QTC makes running very difficult and sending QTC is boring. I didn't like it so I stopped trying to run.

Activity

Let's be blunt, it wasn't great. Having heard so much about the contest and its importance to European contesters I expected more. I was surprised how quickly I ran out of stations to call. Running elicited calls from smaller and more casual participants, however as already noted, all my runs were rapidly interrupted by QTC seekers. 

Was this simply a bad year because qualifications for the next WRTC are slated for the future? Perhaps that had an impact on a few but not the bulk of European operators. Maybe the problem is us, the non-Europeans. If we were more active in WAE maybe that would encourage more European activity. I can't speak to the activity level in Asia and elsewhere since I usually couldn't hear them at the same we had our openings to Europe. 

Going by the reported scores on 3830, we worked far more Europeans than vice versa. The QSOs on their side were especially low considering the contest duration. However the QTC achievements of the serious European competitors were very high, far higher than their QSOs.

When the roles are reversed in ARRL DX contests there is certainly more activity on both sides of the Atlantic. Is it because of the season? QTC? Something else? I don't know. Of course neither holds a candle to the activity in CQ WW and WPX.

QTC? What's a QTC?

Quite a few Europeans are happy to work DX in WAE while having no interest whatsoever in QTC. They are in it for the enjoyment, not the score. They never ask for QTC and they never accept if you offer. I can sympathize.

I wonder how many of them there are? Presumably there are some outside Europe that are too casual to post to 3830 and may not even bother to send in their logs. However it must be said that sending QTC is pretty easy with a modern contest logger, so why not do it if asked. It's easier for a European operator to avoid QTC since if they don't ask it is rare that someone will offer to send them some.

So it's possible to enter WAE and avoid QTC. But be prepared to say no a lot if you're outside of Europe.

Next year

After this year's brief experiment I just don't know. It didn't seem too exciting, just different. All I can say is that I like to go to others' parties when I'm invited since they so readily come to ours. Putting a few contacts (and QTC) in their logs is a neighbourly way to return the favour.

NAQP CW & 2BSIQ Notes

I don't practice contesting techniques. I've tried Morserunner and other tools and I hate them all. It's just too fake for my tastes. That said, they work -- ask any top ranked contester. The only "practice" I get is live, on air, in contests.

I made a last minute decision to enter NAQP CW last weekend. This is a contest where you must do SO2R and especially 2BSIQ to place well. The contest is short and fast paced. It can be very intense since there is little leeway for mistakes. Pick the wrong band at the wrong time and you can't compensate for the mistake the next day.

Despite my previous so-called practice in the IARU contest I have hardly operated HF at all recently. Summer is sporadic E season, and that means monitoring and running FT8 on 6 meters all day, every day. Outside of these contests I had only a handful of CW contacts in June and July. With most of my antennas and rotators fixed I had little excuse, so I configured the station for SO2R and went into it cold.

My biggest lack was 160 meters. With no radials on the vertical during farming season and Beverages that seem to be suffering from difficulties (probably nothing more than corroded connectors) there was no reason to stay up late. Unlike other times I did this one for a straight 10 hours, from 2 PM local to midnight. I only made a handful of contacts on 160 since I was either not heard or I had difficulty copying stations. I wasn't fussed about it.

Band  QSOs  Mults
-------------------
  160:   28    14
   80:  168    38
   40:  379    53
   20:  311    50
   15:  224    46
   10:   12     5
-------------------
Total: 1122   206  Total Score = 231,132

Despite the flaws of the station and operator I did respectably well. You can check 3830 for how my score compares to the raw scores of others in the highly competitive SOABLP category. I joined a team but our total wasn't great since several excellent operators in our club were not available and others could only participate part time. Did I mention yet that it's summer?

The contest started slow for me. It took me at least an hour to get fully into SO2R and then 2BSIQ, and to finally abandon 10 meters. I tried for too long on 10 since my neglect of it in January hurt my score. This time trying too hard hurt my score. After those misfires the contest went more smoothly with a consistent rate of over 100 QSOs per hour. Not great but okay.

As in January, I did 2BSIQ as much as possible. That raised my rate but hurt multipliers. It could have been worse because, as usual, participation is lower in summer than winter. The reason is that a lack of callers meant that I frequently scoured the bands for stations to work -- run on one radio while S & P on the other -- which added both contacts and multipliers. You have to do this anyway if you want to work others who are mostly 2BSIQ since they'll never call you. That is, unless they're assisted and the runs dry up. I didn't worry about them too much since they are more likely to click-and-call me than I am to find them. Tactics are quite different for assisted and non-assisted operators.

I envy the Europeans. Overlapping NAQP was the European HF Championship that has similarities to NAQP. Although the contests are about the same length -- more of them used high power, could use SSB and CW and were (by default) assisted -- their QSO totals were impressive. I could hear many of the European big guns off the back of my yagis. I sometimes had to QSY to avoid QRM.

We just don't seem to have the numbers on CW in NA any more. I last noted how this hurts our global competitiveness in my article on the IARU contest. It also hurts us in domestic contests.

Timing woes

2BSIQ, and also conventional SO2R, can only succeed with carefully aligned transmissions. However the process of syncing can cause unwanted behaviour in callers and others. There are many ways to "force" alignment that are acceptable to others but not always. Here are a few I dealt with during NAQP.

• Hair trigger callers: Some people just won't wait. If you delay even half a second they call again. They are constantly doubling with me. There is little I can do to work them other than by annoying someone on the other radio, which I try not to do. If there's another caller I'll pick them up instead so that I can make progress. The hair trigger guy never sticks around when that happens. Rush, rush, rush.
• Point-and-click: Other callers send their call once and if they don't hear a reply in a second or two they vanish. I don't notice until I send the exchange to them and hear silence in response. I try again even though it is pointless. They have already clicked on another spot. These callers often click and call later so it isn't a big problem.
• Click and run: A few seconds silence encourages some to grab the frequency. They are not actively stealing the frequency, just not bothering to check first by sending "QRL?". Depending on the circumstances I'll either resume my run or QSY. Many of them will disappear when they hear my CQ. They may be rude but they also don't persist when they're called out.

While SO2R and 2BSIQ are beneficial for those practicing these techniques they are also of value to others. The reason is that more QSOs overall are made and that fills everybody's logs, raising scores across the board. There are still some who don't see it that way and are too sensitive to transmission delays. It's a contest and they are understandably impatient. Whatever the reason, it is necessary to deal with callers like that.

Chris VO2AC sent me recordings of my two QSOs with MB1A, the WRTC team for which he was referee. In one case I was 2BSIQ and in the other case I was running while hunting on a different band and called MB1A. I won't include the recordings in this article since there is nothing noteworthy about them. It was interesting to hear the transmission delays as I waited for the transmission on the other radio to end.

In these cases the delay was brief, indicating smooth 2BSIQ and SO2R timing. That doesn't cause problems. Most contesters have learned to wait that fraction of a second for the SO2R operator to get to them. It would have been more interesting to have a recording where the timing goes awry. I'd find it painful listening but also instructive.

Call history fills and errors

I use pre-fills from a call history file to save typing. I favour any tool that makes 2BSIQ easier. The danger of the pre-fill is that many contesters don't check that it matches what is sent by the other station. That will earn them many errors, and they'll deserve every one of them. There's no excuse for it.

I use the call history file that is compiled by VE2FK and is easily imported with N1MM+ and other major contest logging applications. It is possible to make your own call history file from the logs of previous editions of the same contests, but I never do; I like the low effort convenience of Dub's files. No call history file can be entirely correct and it is of no interest to me whether an incorrect pre-fill was my fault or somebody else's! I watch, copy and override where necessary.

It is interesting that perhaps 5 to 10 call signs when entered during NAQP received a "?" indicating that they are not in the SCP (super check partial) database, yet when I moved to the exchange fields there was a call history pre-fill. That's unusual. I have no explanation.

However, when a call is not in the SCP and there is no call history pre-fill I question whether I copied the call correctly. Although I send the call when responding with my exchange it is a sad fact that many will not correct their call. I have to explicitly ask them to repeat their call when I run into this situation. In most of these cases I found that I had indeed copied their call incorrectly. 

A mistake I made was not to have a function key pre-programmed to send "cl?" or "call?" Keyboard and paddle CW is awkward in a contest, and with SO2R can easily be sent on the wrong radio depending on context and timing.

Error rate

It's certainly too soon to know my error rate for this contest. That will come out in due time. My hope is that I performed better than in the January NAQP CW where my error rate was over 2%. 2BSIQ is no excuse for that, and indeed there is never an acceptable excuse.

Instead I'll talk about my errors in CQ WPX CW in May this year. The result were just published and participants were sent their LCR (log check reports). Of the approximately 700 contacts in my log there were 9 errors, for an error rate of 1.3%. That's not too bad for a contest with (unpredictable) serial numbers, but still a little higher than my 1% objective.

Of those 9 errors, none were for call sign errors and 3 were for NIL (not in log). I am pleased with the former and there is no easy way to determine whether the latter were due to my error or theirs. So let's look at those 6 exchange errors; that is, serial numbers.

21048 CW 2026-05-30 1701 VE3VN  0244   G4R    0100  correct   200
14049 CW 2026-05-30 1918 VE3VN  0299   OM5MX  0129  correct   127
14029 CW 2026-05-30 2121 VE3VN  0311   SN7O   0792  correct   892
14036 CW 2026-05-31 1130 VE3VN  0453   SP4TKR 0103  correct  1034
14029 CW 2026-05-31 1941 VE3VN  0594   UW8SM  2196  correct  1196
 7018 CW 2026-05-31 2341 VE3VN  0685   DK6SP  2074  correct  2064

The copying errors were almost all due to dits. I'm not surprised. At high CW speeds, QRM and QRN, and SO2R it is quite easy to lose or add a dit. I'll just have to be more careful. Really that means more operating and thus more practice. It is not practical and is poor procedure to constantly send their number back to them with a "?" appended. That should only be done when truly in doubt. I was not in doubt, just wrong. I don't even have the weak excuse that the low bands are noisy since all but one were on 15 and 20 meters.

Of course it isn't just me. Countless time during the contest my call was copied as VE3UN. I had it removed from SCP by Bill W9KKN yet the incidence of this error has not diminished. I correct it when I hear the error but I also suffer many unwanted dupes. They hurt my rate which lowers my score. There is little I can do about the errors made by others.

Coming up

I am seriously considering operating in this weekend's WAE CW contest. I've never done it before. I've been reading the N1MM+ documentation on sending QTC, which tries really hard to make it easy. I expect I'll make mistakes anyway. Hopefully I won't confuse or slow down others too badly. If I do enter it will only be a brief effort to get a taste of how it is done. Any serious effort will wait for another year.

Choosing FT8 Frequency & Interval on 6 Meters

As the summer sporadic E season winds down there are several items to reflect upon. I'll have more to say about the season in my usual end of season wrap up article, later in August. There is one topic I'd like to address now. Although it can apply to any band where FT8 is used, there are behaviours that are unique to 6 meters due to the unique character of DX propagation.

This is a typical view of a mostly domestic (within NA) opening, taken several weeks ago. There are several strong signals in the US (via sporadic E), strong local stations and a smattering of weak DX (Europe if I recall correctly). European signals are mostly on 00/30 intervals and NA signals are on 15/45, except those working stations within NA. 

It's a mix of DXers (like me) and those that are happy to work anyone when 6 is open. There are a few poorly modulated signals which you can probably identify without me pointing them out. There was at least one robot that I am certain of. I blacklist the most obnoxious robots to keep the message pane "clean".

Notice the relative absence of signals at low and high audio frequencies. That's typical when activity is moderate, as in this case. Stations tend to cluster at the centre of the 3 kHz pass band, and quite a few will nail themselves to exactly 1500 Hz. Two of those are visible, one strong and one weak.

But why? Modern rigs have amazingly flat receive and transmit response curves so there is no reason to favour the centre. Further, by using the recommended split feature (real or "fake it") in WSJT-X and its close relatives the transmit audio is kept close the centre of the transmitter's pass band regardless of what frequency is selected. Certainly there are old or minimalist rigs used in SSB mode, including microphone equalization or fixed bandwidth shaping, but from the observed behaviour you'd think half the stations use those. That's highly unlikely. Old habits die hard.

When activity is high in a good sporadic E opening you'll see the opposite behaviour: crowding the edges. The idea is that since most hams are observed to favour the centre you are less likely to collide with others, including those you don't copy, by going high (above 2500 Hz) or low (below 500 Hz). Some will operate over 3000 Hz or below 200 Hz which may not decode in many station configurations. I set my receive bandwidth to 3300 Hz but not everyone does or can do that. I have a hard lower cut off set at 200 Hz.

This brings us to the ancient idea known as the tragedy of the commons. Put simply, one person seeks an advantage in a situation by choosing to behave counter to the crowd. They fail to realize that they are not unique or smarter than others. Many others will have the same thought and they will all choose the same contrary behaviour. The result should be obvious. They may persist even when they can see that others are doing the same and therefore negating the benefit of their "contrariness". Humans are funny that way.

WSJT-X can decode overlapping FT8 signals but not with assured high probability. The closer they match in frequency and timing the more likely it is that the weaker signal will not be decoded. However, especially with sporadic E propagation, you may not know if that distant DX station sees overlapping signals on your frequency. Maybe you can deduce it by how well or poorly they decode your transmissions, or you can skip a transmit period to listen for interfering stations, ones that may be weak to you but strong at the DX side of the circuit.

I actually do move to the edges in many openings. However, as the opening widens and more stations appear on the waterfall I start to move around quite a lot to find a reasonably clear frequency. I continuously search for an advantage if propagation favours another area within NA. I may stick to my frequency when I know that I can outgun interlopers since I have very capable 6 meter station (antenna and power) regardless of others that may camp out on or near my transmit frequency. 

Flexibility is the key. Never marry a frequency and never persist in behaviour that doesn't achieve acceptable results. Yet a surprisingly large number of committed 6 meter operators do just that. There are stations that can always be found on the exact same frequency throughout an opening on every day they're active. I never ask but I do wonder what convinces them that this negative behaviour is to their benefit. If another station happens to select that frequency they'll transmit there regardless. It's both rude and foolish.

I am equally flexible in my contest operations on HF. Running low in the band tends to increase rate. But if it's too crowded or another station moves too close to my run frequency I'll move. Struggling wastes time and doesn't get results. FT8 is no different. That is especially true on 6 meter sporadic E when activity and band occupation can cycle from low to high and back again within a minute or two. Flexibility will make you more successful at reaching your objectives.

Overlap is not necessarily evil. At right is an example of two kinds of overlap on the same frequency: same interval and opposite interval. Both have their pros and cons.

Some stations automatically transmit on your transmit frequency when they call you. WSJT-X has this option. Or they may do it manually when they perceive a benefit -- I do the same. The reasoning is that stations prefer a frequency that is clear on their receive intervals. That is, when I transmit 15/45 it is preferred that the frequency be quiet during 00/30 intervals to copy especially weak DX. Callers might otherwise have difficulty escaping the QRM elsewhere in the 3 kHz window. 

If you manually QSY to a station's frequency in order to work them, be sure to QSY afterward. Many forget and remain there to work other stations. In most cases it is a mistake, not an attempt to "steal" the frequency. Once they realize what they've done they QSY. Don't assume that other hams are malicious!

If two or more stations QSY to your transmit frequency there may be a decoding problem. Letting WSJT-X do the QSY is more problematic than doing it manually since, as noted above, the decoding algorithm can't easy separate signals too close in both time (clock accuracy) and frequency. Manual frequency selection, by being less accurate, ensures at least several Hz separation. Sloppy is good!

On the other hand, if another station is on my frequency but the opposite interval, that may be acceptable during busy openings. The practice in effect doubles the available bandwidth -- what those in the telecom business might recognize as TDM (time division multiplexing). However, in this case when callers QSY to your transmit frequency there can be bedlam since now we have both transmit and receive on the same frequency and interval instead of alternating transmissions. There is no perfect solution on a busy band. Again, be flexible.

The other type of overlap is visible near the top of the screenshot: a strong station has started transmitting on the same frequency and interval as a weaker station. At least that's what I hear, which can be very different to what they hear; the two stations might not copy each other at all. This is more common with sporadic E than what for typical propagation on the HF bands. 

Some stations, in a bid to find a clear frequency, will click on an empty spot on the waterfall without first checking whether the frequency is clear on their interval. That requires skipping a transmit slot to listen. Many hams are in a hurry and either don't care or don't realize what they're risking. Even when I'm running stations I will occasionally skip a transmit period to check whether some interloper has appeared, whether by their QSY or a change of propagation. It may be entirely unintentional, but can still be a problem.

When things get seriously busy on 50.313 MHz during a good DX opening, stations should move to the inter-continental window at 50.323 MHz. This doesn't occur as much as it should. A station will check 323 when 313 is busy, see little activity and move back to where everyone seems to be. It's self-defeating behaviour. It can be inconvenient to check 323, or worse if you decide to stay there for a while. You may be missing some juicy DX on 313 amidst the QRM!

This season I have occasionally CQ'd on 323 in a bid to increase activity by demonstrating activity. It seems to work, though not as much as I'd like. Like everyone else, I have to be where the stations I want to work are operating. I don't know if 6 meter DX'ing behaviour will ever change. 

On HF there is less formality about whether to transmit on 00/30 or 15/45 than there is on 6 meters. On 6 meters the convention is that you transmit on 15/45 when working stations to the east and 00/30 to the west, especially for inter-continental DX. When working Europe, North Americans transmit on 15/45 and the Europeans transmit on 00/30. In the other direction I switch to 00/30 for working the NA west coast, the Pacific and east Asia. The convention is widely followed and works pretty well. 

There is less consistency when working north-south. For example, from NA to South America, Africa and central/west Asia. As long as 6 meters is open to one region at a time there is not problem. Just do what others do, or switch your interval choice occasionally so that you don't overlook stations you'd like to work.

A problem can arise when 6 meters opens to more than one continent at the same time. You can be somewhat selective when you point your yagi but that may not be enough. This has happened a few times this July when we had concurrent openings to Europe and Japan.

What happens is the following. The band is open between NA and Europe before opening to Japan. A Japanese station hears an NA station and wants to work them. So they click on the call, such as mine, and transmit on 00/30 rather than 15/45 by the inter-continental convention. They have to! The NA station works them and then another JA calls. Others soon get into the same pattern as the opening spreads.

Before long all the east Asian stations are transmitting on 00/30. It like a chain reaction or the old cliche about tipping over dominoes: as one falls onto the next, it falls onto the next in line and soon all the dominoes are down. There is no way to reset during the opening. Sometimes the KH6 and ZL stations also enter the mix and find themselves having to operate on the opposite interval as well. When the band opens to Japan the next evening, after the opening to Europe has ended (or never happened), everyone resumes following the convention.

Conventions are helpful but not universally understood or followed. Even when you follow the convention it is more important to go with the flow. Like driving down a highway, it is safer and easier to match your speed to that of the prevailing traffic, whether higher or lower than you'd prefer, rather than rigidly adhering to the posted speed limit. 

Do what works in the moment and don't fret about it too much. The DX is hard enough to come by on 6 meters that you don't want to make it any harder.

Yagi on a Swing - 40 Meter Moxon Repair

Things break. For most hams making repairs to antennas is not too big a deal since most antennas are of modest size or made of wires. Perhaps I have more problems than many other hams since I design and build my own antennas. Errors creep in despite the care I take. Also, I have a lot of antennas.

When the repair is to a 40 meter yagi the process is especially difficult. Earlier this year the reversible 40 meter Moxon developed a fault that disabled one of its directions. An antenna of this size is not easy to work with. It is large, heavy and extraordinary awkward. I and a few guest ops lived with it until time and weather permitted repair. It took preparation and scheduling.

Confident as to the cause of the fault I chose to repair it on the tower rather than lowering it to the ground. Tramming this antenna down and then back up is difficult and introduces additional risk to the antenna. Also there is the matter of the hay that precludes taking the yagi down until after the harvest later in July.  Doing the repair on the tower required bringing one of the two Moxon elements close to the tower to access the switching electronics.

An XM240 was on the same side mount that the Moxon now occupies, about halfway up the 150' tower. To repair one of the XM240 elements I put the yagi on a swing with the anchor near the lower 5-element yagi of the 10 meter stack. That is about 30' (10 meters) above the 40 meter antenna. With the swing cable holding the antenna's weight, it is unbolted from the rotator mast and pushed outward to bring the faulty element within reach of the tower. In this case, about 7' (2 m).

However, the Moxon weighs about 50% more than the modified XM240 (105 vs 70 lb) and the swing is in the opposite direction. I not only had to contend with the TH6 above the Moxon but also the support strut for the 80 meter inverted vee. Luckily the TH6 didn't interfere with the swing in the planned direction. However, I had to loosen the accessible end of the inverted vee (the other is on the far side of the hay field), disconnect the coax and temporarily move the support strut out of the way. The weight and tension of the inverted vee legs and support rope made the operation awkward. 

The swing cable is ⅛" aircraft cable instead of the rope I used for the XM240. Despite being thin it is well within its load capacity. You just have to be careful with torque on the small hardware for the cable clamps -- quality counts. For the greater weight of this antenna I wanted less elasticity in the support cable. The cable was tensioned with a large turnbuckle. A chain grips the sides of the boom-to-mast clamp, which is at the centre of gravity. A couple of the following photos show the setup; I didn't bother taking a close up. Once the antenna's weight is taken by the cable the 4 saddle clamps holding the clamp to the mast are removed.

The picture by Dave VE3KG is annotated to show the arrangement which is otherwise difficult to see in a photo. The faulty switch box is circled. That's me on the right and Vlad VE3JM on the left. The cable swings parallel to the TH6 driven element. The swing cable's anchor is above the next higher guy station. At that height the cable only swings a few feet so the guy doesn't get in the way.

We used old positioning lanyards in case of disasters (swing cable failure) and to direct and hold the antenna where we wanted it. I have several of these lanyards in my toolkit that I've inherited from other hams. Despite being in reasonably good condition they have clearly seen better times and should not be used for climbing. Never bet your life on questionable personal safety equipment. But they can have other uses so don't throw them away. Don't give them to others if you don't know how they'll use them.

While I held the yagi in position at the end of its swing, Vlad tied the end of the boom to the tower. Another strap holds the boom to the mast for added safety. We then rearranged ourselves on the tower so that I could work on the switch box while he kept watch on the rigging.

As I suspected the fault was a cold solder between the coax connector and relay. The open circuit does not affect operation of the element as a reflector so that's why the antenna continued to work in one direction. The wire is already lifted off the relay in the photo. The relay pin was in good condition so I removed the wire and put in a new one. 

The temptation to simply solder the wire back in place should be resisted since you can't be certain that solder-clogged surfaces are sufficiently clean for a reliable joint. The "dead bug" construction doesn't allow a firm mechanical connection since the relay pin is short, designed for PCB mounting, and crimping the large wire onto it is difficult.

If you haven't read the original construction article you may be surprised by the ad hoc construction. Well, I'm a ham not a craftsman. It works well enough, even if I risk the occasional repair. Others might prefer to do it differently. In any case, the antenna is experimental and I expected to have to deal with issues and try alternative construction techniques.

Speaking of issues, notice the pool of water under the reflector coil. I didn't think water could get in so I didn't drill weep holes -- there's more in there than condensation can account for. There is now a hole at each of the box's 4 bottom corners and the top screws are taped. It is possible that the other element is in the same condition. Since the swing only works in one direction that will have to wait. Performance of the Moxon doesn't appear to be noticably affected by the rainwater.

Another problem I noticed is that one of the 4 hose clamps securing the capacitance hat tips to the fibreglass rod that hold the adjacent tips at the proper distance is loose. The ring of tape should be just within the ⅜" aluminum tube. With these small hose clamps there is only a narrow adjustment range between being too loose and stripping the threads. The antenna has to come down for repair, which won't happen sooner than autumn. It isn't an urgent repair since the rods are quite long it is unlikely that the capacitance hat tip will pull out.

Now back to the repair of the faulty switch box. I chose to solder in the new wire on the tower. It's more difficult than removing the box and doing it on the ground, but it would take more time and there was more opportunity to make mistakes. These include coax waterproofing and removing then reinstalling the tabs from the box that are secured to the element halves with hose clamps. It's a tight fit.

To use my trusty old Weller soldering gun I pulled a 100' extension cord up the tower and plugged it into a portable power station at the tower base. It was also used to drill the weep holes. I like the power station since I can use my many AC tools anywhere on my 50 acre property rather than acquiring battery operated tools. The old wire that I removed from the switch box is seen next to the small roll of solder I used.

Despite all the fuss the repair was as simple as soldering in a new wire and drilling a few holes. With the antenna swung back into its proper orientation I connected the antenna analyzer and control cable while my ground crew (Dave) clicked the mouse to switch the Moxon in both directions. That went well so we reattached the antenna to the mast, reconnected the coax and loosened the swing cable. 

With that I let my friends leave and get on with their day. I cleared the tower of the rigging and reconnected the affected antennas several days later.

Vlad and I took pictures of each other while we were working and I wanted to include that in this article. The view is interesting in that we were only half way up the tower! It was warmer than our clothes suggest, but we needed to protect ourselves from the bugs while we were on the ground. Compare this to a similar pair of photos we took of each other 5 years ago.

That's one more check mark on my lengthy to-do list. There are many more. It seems that each deserves an article so expect more as I work my way through the list over the coming months. Stay safe while you work on your towers and antennas this summer.