Friday, February 24, 2023


I decided to write up my experience in the ARRL DX CW contest this past weekend because I learned a great deal by putting in a more committed effort than I planned for. My early hope was to make this the first multi-op contest from my station. That plan foundered because I hadn't completed work on the shack in time. 

Instead I took the opportunity to install my new operating desk and temporarily assemble the two operating positions for SO2R. I didn't even bother to move it back against the wall. Access for cable work was more important than having it look pretty. I finished one hour before the contest started. Despite the haphazard wiring, the only RFI was to the SM5000 on top of the FTdx5000. I don't use the speaker so I disconnected it. 

I took lots of breaks, short and long, on Friday evening. Most of the time I was running stations on 40 meters and hunting multipliers on bands from 160 to 15 meters. Conditions were fabulous. I stayed up for the European sunrise then slept for several hours. 

Every band but 10 was open when I got up an hour before dawn. From there it only got better. Runs on 15 and 10 were phenomenal. It was difficult to keep the rate high due to the difficulty of extracting a call sign from the roar of the pile up.

Well, that's not of interest to most readers since everyone had the same experience. From here I'll deviate from the standard contest narrative to provide insight into the challenges I was dealing with and how I dealt with the best DX contest conditions we've seen for nearly a decade. I think this approach is more interesting to readers.

The arrangement is only a little different from before. I wanted to try a few changes to see how I'd like it. The biggest change is the monitor position. I like the monitor to be low to minimize eye movement as my focus shifts between the keyboard and N1MM entry windows. I was using WSJT-X, when the picture was taken. Imagine that the N1MM entry windows are positioned at the bottom of the monitor. 

The 24"gaming monitor has an adjustable height. Should the change to the layout become permanent, a short shelf will be built and the monitor placed on that. Rotator controllers or other devices can be placed underneath. That is difficult do with this monitor since the pillar gets in the way. For the contest I instead moved the FTdx5000 inward for less reach to the controls. Like many contesters, I prefer keyboard controls to twiddling knobs, and I don't need the rig in front of me. That said, I did find a benefit in this contest of having the bandwidth control and a few others up front.

My preference is to place the amp on top of the rig, as is done for the FT950 and L7 on the right, but that isn't possible for the heavy Acom A1500; the L7 power supply is on the floor. Auto-tune amps don't need much attention so, whenever I acquire those, they can be placed out of the way.

Rotator controllers on the left are ideal for the right handed, such as myself. For multi-op contests they'll be moved to between the operating positions. I ran into a last minute technical issue while wiring the BPF for control by my automation system so they had to be within reach for manual control. The BPF can be moved under the desk when the automation is complete. 

Until I convert commercial controllers for prop pitch motor control I will continue with the ugly one I inherited. All I did before the contest was wire the breadboard direction circuits via the direction rotary switch so that you see the direction of the selected prop pitch motor on the outboard meter.

Weather and results

Weather was a problem. Several hours of freezing rain before the contest had yagi elements drooping and misbehaving. The upper yagis of the 15 and 20 meter stacks were severely affected and were pretty well useless until late Saturday afternoon. By Sunday morning they were back to normal and my signal into Europe was full strength. For some reason the 40 and 10 meter yagis and the TH6 were fine. 

High SWR on the 80 meter vertical yagi limited my power to about 400 watts for the duration of the contest (amp protection fault). As a result I did poorly on 80. After the contest the 80 meter vertical yagi did not recover. It switches normally and the antenna pattern appears to be normal. Further investigation will wait for warmer weather. 

As few days earlier, I once again installed my trusty old 80 meter inverted vee at 100' (32 meters). I couldn't use because I have no free ports on the 2×8 switch (more on that antenna in a future article). I would have swapped it for the vertical yagi had I known that the fault wasn't due to ice.

Despite the various technical problems, my raw score includes over 3300 contacts and close to 400 multipliers in 36 hours of official on time. I am pleased with how I did despite my score not being competitive. Had there been no ice and had I put in a longer effort, it is likely my QSO count would have been close to 4000. 

My skills at SO2R put a limit on how well I can do. 2BSIQ (running on two bands at the same time) is difficult under ideal conditions and far more challenging when faced with large unruly pile ups now that propagation is so good. I will get better at 2BSIQ but I have little motivation to become highly skilled. I might not be capable of it even if I was interested. I'd rather focus on preparing the station for multi-op contests and enjoy myself with less intensive efforts the rest of the time.

I took notes after the contest about propagation and station performance. I'll now look at the points that might be of interest to readers, or at least the contesters among you. Everybody know propagation was great so I'll say less about that and more about how it affected my operating tactics.


This is the second contest for my home brew station automation system. This time it had an intense workout because I was SO2R and frequently changing bands and antennas. None of that was needed when I first used it in the CQ 160 contest. I am happy to report that the software worked very well. It ran the full 48 hour contest period, including off times, without interruption, proving its reliability.

I'm showing the GUI again to illustrate design flaws I discovered while operating the ARRL DX contest. This is apart from the ugliness of the current layout. It comes done to how it communicates critical data during a hectic contest like this one. Imagine you have to switch the stack mode for the left radio (R1) to gain a few decibels to copy an Asian station calling over the pole while running Europe. Which button do you press?

The answer is obvious but try to do it instantly in the heat of the contest. During the contest I often pressed the wrong button. The association of the many antenna mode buttons to each radio is not obvious from a brief glance. Reading the numerals on the buttons to figure it out is prone to mistakes when you need to do it instantly. It is surprisingly difficult to recall what band you're on while focused on a deep and unruly pile up, or two.

Another problem was knowing whether an alternate antenna is available before pressing the radio's adjacent antenna button. That's slow and confusing. It most often occurred with sharing the TH6 on the high bands. What would happen is that I'd press the antenna button to call a station where the TH6 is pointed and then find it can't be selected because the other radio has it. Of course I could read the other radio's antenna button but it's easy to miss that in the heat of a contest. 

I have ideas for a new GUI layout to alleviate these and related operating issues. The redesign is likely months away since I have higher priority tasks. It works as it is and that will have to do during the upcoming late winter and spring contests. Other planned feature development will also be paused since the GUI redesign will affect everything. The hardware is under the desk, invisible and relay clacking is barely noticable with headphones.

My immediate task is to finish the electronics and wiring for automating BPF selection. That topic is interesting enough that I plan on dedicating an article to it.

Run, run, run

When a band is wide open to Europe there is only one word of advice anyone needs: run! The volume of available contacts is enormous and it cannot be ignored. No matter your station, you are almost always better off running than hunting. Many casual operators find running intimidating and avoid it. It is well worth making the effort, no matter how clumsy you might be at first. Single band rates of 3 to 4 contacts per minutes add up fast! 

Rare multipliers often call you when you run, avoiding the time needed to hunt for them. I was unassisted in this contest so finding multipliers can be very time consuming, and that's expensive when the runs are so good.

The large number of callers with stacks and a kilowatt makes running especially challenging. It is a problem that is nice to have. I have had to learn techniques to get at least partial calls and make it clear that others should QRX. I am getting better at it while maintaining rate. 

This is the one time when I raise my CW speed closer to 40 wpm and signing my call once every 2 or 3 contacts since it communicates to callers that I am doing all I can to serve them quickly. When the rate slows, so does my speed. I don't want to scare off casual operators.

When my speed goes up so do the bad spots. It is easy to know even though I was unassisted. Suddenly the pile up would increase in size and most callers are dupes. In almost every case I was spotted by a human as VE3UN. Skimmers tend to make different call sign errors. It is a consequence of point and click contesting. Spots and skimmers drive the multitude to the runners and the net benefit is strongly positive despite these challenges. When it happens there is really no good escape other than to QSY. Fighting the inevitable only wastes time.

Getting the most from the stacks

For most of the first day of the contest the upper yagis of the 15 and 20 meter stacks were next to useless due to the ice. Ice is a dielectric that lowers the VF (velocity factor) of the elements, lowering their resonant frequency. The effect is uneven across the elements. The result is high SWR and severe pattern impairment. I mostly got by with the lower yagis until the ice load loosened when the temperature rose. They are effective antennas when used alone to work the Europeans.

With all the yagis working, there are many strategies to their use and I exploited all of them in the contest:

  • Stacking gain to Europe during prime time European openings
  • Turn the upper yagi to high production directions and to hunt multipliers
  • Spray in two directions while running to pick up multipliers from marginal paths

With my lower yagis fixed on Europe, Europe is the only direction I have stacking gain. I would like to have the 10 and 15 meter lower yagis rotatable for stacking gain to Japan and elsewhere. I may eventually do that and I have preliminary design plans. For now I must to work within the constraints of those fixed yagis. Often I'll use the rotatable TH6 to hunt multipliers when I need the stack for Europe, or the upper yagi is in use for working Asia and the Pacific.

Spraying was very effective on 15 and 20 meters. In the early morning I would aim the upper yagi about 10° to 20°, almost over the north pole. This positioned it between Russia and east Asia, while still offering some stacking gain towards Europe. There were few callers from Asia during those European runs, but many who did call were multipliers. These included VU, E2, VR2, BY, among others. 

Pointing the upper yagi to the east in the late afternoon attracted long path Pacific stations, including ZL and VK. Again, that also provided some stacking gain towards Europe. But I couldn't do that for long since it was sunrise in Japan, followed by the rest of east Asia. There were good runs to Japan on 10 and 15 meters.

Sharing the 10 and 40 meters yagis appropriately was a challenge. The 40 meter yagis are not stacked, and there is conflict when Europe comes blasting in well before sunset when Japan starts pouring in on 10 meters. Having every band open at once is welcome but difficult for a single operator to maximize contacts and multipliers.

Luckily the lower XM240 works better than the high 3-element yagi to Europe before sunset. So I turn the upper 10 meter yagi to Japan and the big 40 meter yagi goes along for the ride. Once the 10 meter opening fades an hour or so after sunset, the 10 and 40 meter yagis are turned back to Europe. After our sunset the high yagi pays big dividends on 40 meters.

More yagis and more rotatable yagis are common in the biggest stations to exploit solar maximum propagation. I will never do that. What I've built is about as big as this station will get. Rotating the lower yagis is about as far as I'll go. The TH6 helps fill the gaps and, as I've noted, I hope to improve on it this year or next.

Overnight strategy

The high bands lose productivity at night even during a solar maximum. Daylight at this northern latitude is limited in winter and that closes the high band sooner than further south. After Asia and the Pacific fade after sunset there is little more to work than a few stations to the south. The low bands continue to get a lot of love during contests.

The faulty 80 meter vertical yagi kept me off that band when I needed to be there. It was frustrating to be unable to work many wanted multipliers because they couldn't copy me. Partial contacts don't count, and I had lots of those. I didn't need a high rate, just multipliers. 

Others followed the same strategy, though with more success than I had. There was little reason to try to bulk up on contacts on 80 and 160 meters when so many stations preferred to stick with the high bands.

As sunrise sweeps across Europe, the low bands open in sequence: 160, 80, 40. Unlike during a solar minimum, the openings are shorter. I can remember back a few years when I was working Europe on 80 meters a full two hours after their sunrise, and for longer on 40 meters. This year one has to be more agile and avoid lingering too long in one place.

The compensation was 20 meters. After 40 began to fade, 20 meters opened to Europe both nights. That doesn't happen during a solar minimum. Since it's been a while, I was tardy to recognize the pattern the first night, and I was early to bed in any case. The second night I arrived on 20 earlier and got the best from the opening. The run on 20 meters was tremendous. What a novelty at 2 AM local time. 

The propagation fades after a while since we don't have a high enough solar flux to keep the path open on this end. Then it's back to 80 and 160 meters or, in my case, a few hours sleep. I got up before dawn to find Asia and Pacific stations on 80 and to hunt Asian stations on 40 meters. Few distant stations were heard during our 160 meter sunrise openings.

By the time the sun is a few degrees above the horizon, the high bands come to life and it's back to running Europeans. I would keep the big 40 meter yagi northwest for a while longer to hunt Pacific and Asia countries. That kept the upper 10 meter yagi out of the action for the start of the opening.

20 meters during the day

If your peruse the claimed scores on 3830, you might notice that the 20 meter QSO counts of many are below those for 40, 15 and 10 meters. This is typical of a solar maximum. Low level solar flares are constant and keep the D-layer absorption moderately high on the sunlit half of the globe. Absorption peaks at noon and when the Sun at near the zenith. What ordinarily only blocks signals on 40, 80 and 160 meters, now also blocks signals at higher frequencies.

Those who chose to enter as 20 meter single band saw a major impact on their scores. There is more at play than signal absorption. With 10 and 15 open, contesters abandoned 20 meters. This is particularly true for those with smaller stations. Sure, you must operate 20 meters to have a competitive entry but, like with 80 meters, there is little reason to stay there for longer than necessary. Since a minority of contesters operate SO2R, 20 meters lies idle when they're having fun on other bands.

Operating desk

This first trial of the new operating desk did not go well. My penchant for home brewing everything caught up with me. There are several design flaws that I must deal with. The answer will be either my own selection of modifications or to find a suitable replacement from an office furniture surplus outlet.

The plywood is only ½", but there are two bonded layers inside the frame. The area is 8' × 30", enough room for two operating positions. There are no cross-members other than the one at the rear, and there is a diagonal strut mid-span. It's strong enough to support the heavy equipment seen earlier in the article. 

There is a lower back shelf for power supplies, the station controller and other items. The old desk had the same feature. I bolted on power bars and there is another lower shelf at the far end for the internet modem and other items.

The structure is strong but more flexible than I'd like. The mid-span strut allows a small amount of sag, which I didn't account for. The wood frame, though strong and diagonally braced, bends only a small amount. 

While not a problem, it gives me pause. I have to wonder whether the various screws will hold it together properly for the long term. Desk top flexing is already causing the hard, furniture grade paint to craze. It looks good and is holding up well except for those hairline cracks in the finish where I lean and pound the keyboards. 

The greatest miscalculation is in the ergonomics. The 30" depth is perfect for an operating desk, however the several inches overhang at the rear means that knees can connect with that mid-span strut and shins can bump the shelf. Although the dimensions are the same, on the old desk the rear of the top is aligned with the frame. Those inches make all the difference. I was trying to maximize support for the amplifiers and rigs, not realizing the impact on the operator. Now I know better.

These are correctable problems. What I have to decide is whether to modify the desk or to find a commercial alternative. Modular office furniture uses steel channels and panels to give it both rigidity and strength, with a laminated surface for durability and appearance. Perhaps I'll see what the used office equipment stores have in stock. An 8' long tabletop may be difficult to find. In the meantime I'll use what I have.

Follow up

There really isn't any specific action to take after this contest experience other than to proceed with my 2023 plan. It may sound as if I'm griping about many little things, yet this assessment is needed if I am to improve myself and the station.

Propagation makes up for many ills. A low tri-band yagi and wires would have performed very well indeed this past weekend. With my now large station I merely have an extra edge. The bigger obstacle to a competitive score is me. My station has grown to become better than its owner-operator! With a more skilled operator it is now possible to compete for the top spot in a contest.

Friday, February 17, 2023

3Y0J and the Age of Entitlement

No one who is active on HF could be unaware of the recent 3Y0J DXpedition to Bouvet Island in the south Atlantic Ocean. Maybe you were in the pile-ups, maybe you were annoyed or inconvenienced by the activity and attention, or perhaps you were in the small minority who saw it as an opportunity to showcase the darkest corners of your soul. There was something for everyone.

Their poor location for propagation to much of North America (behind a mountain), low power and simple wire antennas, combined with the enormous appetite of DXers worldwide was a recipe for chaos. And chaos there was. Some of it intentional but much of it unintentional. Mistakes, confusion and an inability to actual hear 3Y0J made a mess of their transmit frequency and within the pile up. The team improvised tactics to mitigate the problems, though with limited success.

During the DXpedition I was amused to notice that the page hits on a years old article on my blog started climbing. Nothing viral, just well into the 3 digits. That article was a heartfelt attempt to see into the lives of the hams responsible for the DQRM (deliberate QRM). The referral URL told me little and a brief experiment with a search engine did not enlighten me. All I know for certain is that the topic was on the minds of many hams the past two weeks, DXers or not.

Can you find the common trait of the many kinds of hams acting out during the DXpedition?

  • DQRM'ers
  • Team isn't tough enough! I could do better in those extreme conditions.
  • They're idiots! Wrong FT8 period, behind a mountain, losing equipment in the water, shortage of food, fuel and water, etc.
  • Why aren't there immediate log uploads? I want confirmation now!
  • I'm in Upper Slobovia with a wire hung off the back deck and I can't hear them. What an awful DXpedition!
  • They don't do enough CW/SSB/FT8 (maybe even SSTV) on 160/20/12/10/etc.
  • $800,000 divided by 19,000 QSO (10,000 uniques) is a ridiculous number. I shouldn't have given them money, or I didn't donate but I'll complain as if I did anyway.

What do they have in common? Entitlement. This is more concisely stated as: Me! Me! Me! 

Everything is about them and for them. The challenges and priorities of others are of less or no concern. They know what they want and they want it now, no matter the circumstances. The behaviour is perhaps more on display nowadays because the internet gives them an ideal channel to express their grievances.

While these hams do not appear to be anywhere near a majority, they do form a significant minority. You may know one. It is possible that you share one or more of the above sentiments, even if you did not express it in a public forum. It's human nature, though most adults keep those urges under tight control. The ones who act out are like small children who have failed to mature.

DQRM? It's a call to world saying: look at me! I can't work Bouvet? Someone must pay for that injustice! The team isn't perfect? I'll tell them how to get things done (despite zero expertise and experience)!

Do you need more evidence? When you have time to kill I suggest scrolling through the multitude of comments on the DXpedition's public Facebook page. The entitlement reeks off the screen. It comes from every country and in many languages. The grievances and criticisms are universal. Although they appear with greater frequency from those in richer countries, that may only be because there are few hams in poorer countries. Non-hams likely have no views on the matter.

Some of the DQRM was quite funny. I could tune to any frequency where they were known to appear and there would be regular squawks and beeps from would be DQRM'ers. But 3Y0J wasn't there and hadn't been there for hours. That's quite astonishing. You just have to wonder what (or if) they're thinking. Although I didn't chase them on FT8 it was amusing to hear from many that the pirates were often using their own grid squares in CQ's from the supposed 3Y0J. 

There may be a market for an online course to be tentatively titled: Introductory DQRM'ing. Of course that's unrealistic since DQRM and competence are incompatible attributes.

When the team asked that everyone only work them once for an ATNO (all time new one), hams with better equipped stations worked them on several band and mode slots, and even duped them on the same band and mode. Like FT8WW they spent a lot of time on FT8 to give smaller stations a fair chance. From what I've read, that appears to have worked. 

Me? I'll confess that I worked them twice. I'll explain why, below the screenshot of my confirmations from their logs uploaded to Club Log.

I did work Bouvet back in the 1980s. Even though I didn't request a QSL (as usual for me!) I didn't want to overreach despite restarting my DXCC count when I returned to the hobby a decade ago. I've stated my personal feelings about DXCC and awards before and I'll direct you there rather than repeat myself.

My excuse for working them twice is that I didn't think that I'd successfully worked them the first time. The WARC bands are difficult for me since I have, as yet, no antennas for 30, 17 and 12 meters. I load whatever antenna seems to work and hope for the best. It was a struggle to get their attention on 30 meters CW. My call and report were clearly received from them before DQRM obliterated them for 10 seconds. I sent 599 and my call a couple more times. When the interference relented, I heard 'TU UP' as they moved on to the next QSO.

About two days later their CW and SSB logs were finally uploaded. My QSO was not there even though the period included when it took place. I guessed that they'd miscopied my call when I resent it and I didn't hear them send the incorrect call before it was logged. That isn't uncommon. In fact it happened to me recently, twice, with another DXpedition.

I got lucky on 15 meters CW the last day of their activity with my large and high mono-band yagi that helped me to punch through the competition. That QSO was completely in the clear and I was confident that it was good. To get there I had to wait until conditions faded to Europe so that those of us in North America had a chance. Luckily European DQRM was not a factor because they are heavily attenuated off the side of yagis pointed at Bouvet.

All the logs were uploaded when they were back aboard the Marama. To my surprise, both contacts appeared. I was aiming for insurance and instead I earned two band slots. Logged time of the last uploaded QSO is often misleading because there is more than one station and each has its own log. There's no way to know whether the upload is partial or complete.

Our shacks are more automated than ever. Our SDR radios and software skimmers can let us know what is happening on any ham band in real time. We rarely need to touch the VFO knob to earn DXCC. I recently heard of software that will decode CW pile-ups and highlight the last received instance of  '5NN'. You can use that information to improve your chances of working the DX.

No matter how sophisticated our shacks and how modern technology eases our DXCC quest, and ultimately DXCC Honor Roll, someone has to actually travel to the country of our desire. They must invest time, effort and expense to carry a radio to a distant part of the globe, put up an antenna and call CQ. Without those hardy souls all of our DXCC counts would be far lower than they are. No one could aspire to the DXCC Honor Roll. For the rarest entities there is no expectation of native hams; we need DXpeditioners to fulfill the need.

If working rare DX was easy, what would be the point and where is the challenge of achievement? I know that's cold comfort to those not in 3Y0J's log, but it is part of the game. Don't be disappointed by failure. We can use the experience as motivation to hone our skills as DX'ers and do what we can to improve our stations. 

I salute the team members of the 3Y0J DXpedition and I wish them fair winds on the cruise to Cape Town, South Africa. Eventually I expect to thank one of them in person. That would be fellow 6 meter enthusiast Cezar VE3LYC. I bet he has a tale to tell.

If you didn't work 3Y0J, you can bet that there will be another attempt by a future team of enthusiasts. Where there's a demand there's sure to be a supply. Unfortunately it isn't likely to happen soon. Extreme DXpeditions like this are neither easy nor cheap.

Monday, February 13, 2023

Bushing Protection

Often it's the simple things that can ruin your day. In a station as large and complex as mine, I expect things to go wrong, but I tend to worry more about towers, antennas, cables and complex electronics.

Immediately before the start of January's NAQP CW contest (North American QSO Party), I ran into one of these small and unforeseen problems. The TH6 on the rotatable side mount wouldn't turn. At a moderate height (22 meters) and 130° coverage from VE7 (west) to the east coast (south-southeast), it sees a lot of use working stations within North America on the high bands and for hunting multipliers in South America and the Caribbean.

NAQP was about to begin so there was no time to diagnose and resolve the fault. The tri-bander would therefore be fixed west and I had to use the 5-element mono-band yagis at twice the height to cover south and southwest directions. That's far from ideal because they are too high (40+ meters) for short paths. My usual strategy is to have the high yagis point to the more distant west coast and use the TH6 for the shorter distance stations in the US south, southwest and midwest.

It's impossible to know how the problem affected my score. I doubt it was significant. I came in last of our highly talented 5-member team, but there were other reasons to account for that. It is by design that I have enough antennas to be flexible when problems like this arise.

What happened? The 50-year old controller for the Ham-M rotator, which I plan to replace soon, was working properly. There appeared to be no cable faults per resistance tests. When attempting to rotate the antenna the direction indicator bounced a few degrees, as if the motor was struggling against resistance. Nothing obvious could be seen by looking at the side mount system and antenna out the window with binoculars. 

Hy-Gain Ham and Tailtwister rotators have low torque motors. The reduction gears multiply the torque so that they can turn moderate size arrays. Without their strong wedge brakes, the wind induced torque on large yagis can easily overturn the motor. Indeed, it is possible to stop these rotators with a strong hand grip. I've done it myself, just to prove to myself that it can be done.

The motor run capacitor, a common maintenance issue, is mounted at the rotator, with weather protection, so it could not be tested. Many hams mount the capacitor at the rotator to save on cable (two wires are eliminated) and reduced torque due to the resistance of those long wires. Most motor capacitors are rated for winter temperatures, and so is mine, which is not a Hy-Gain part

I didn't suspect that was the problem since the rotator behaved normally the day before and these capacitors typically deteriorate gradually rather than suddenly. They will last for many years. When they weaken or fail, they are inexpensive and available from MFJ or any local electric motor shop.

I could not climb the tower to check the capacitor or anything else because the contest was about to start and a couple of days of light rain followed by freezing rain and a temperature drop covered everything, including the tower, in a layer of ice. 

Even as I operated in the contest, I continued to think about it. I had a hypothesis. To test it I had to do nothing but wait. Two days later the weather warmed to a few degrees above freezing. This time when I tried the rotator, as I had done periodically during the contest and after, it turned. There was no hesitation and rotation speed was normal.

Perhaps you can guess what happened. By all means follow the link provided at the top of this article to the one describing the rotatable side mount. You can inspect the mechanical design from the pictures.

What almost certainly happened is the following. Rain water ran into the gap between the mast and bushing. Then it froze. Bare metal surfaces are often not the same as the air temperature. In the dark or under clouds, the metal temperature is colder than the air. When in bright sunshine, the metal temperature is hotter, sometimes much hotter. Putting your hand on the body of a car that's been out in the Sun will remind you of that. Conversely, as the old tales warn, don't lick a metal post in wintertime!

The reason is the low specific heat of most metals. They hold little heat and that heat is easy to lose (by infrared radiation) and to gain (by sunlight, torch or other source of radiant heat). Water on the mast and bushing will freeze quite readily.

Ordinarily this isn't a problem since it simply runs out the bottom of the open bushing before it can freeze. The ambient conditions cooled and froze the water quicker than it could exit out the bottom. The gap between the 1.5" (IPS Schedule 40) galvanized mast and 2" (IPS Schedule 80) 6061-T6 bushing is only 0.019" (0.5 mm). That's a good fit for a bushing but not when faced with freezing rain.

The weather warmed to a balmy 5° C under bright sunshine this weekend. Once I had 3Y0J in the log I climbed the 150' tower with the material I had prepared in advance. Adding a weather cap to the bushing was one of several jobs I did during that climb. As you see it's still deep winter. The trail of indentations on the snow is the from the tread of my snowshoes.

The solution to the problem is simple. I cut two strips of thick flexible plastic to fit around the mast pipe (found in my junk box) and compressed them with a hose clamp. Little if any water can pass this seal to enter the bushing.

There is no easy way to test the seal and I see no reason to do so. Whatever wind driven water does get past the seal will be a fraction of what an open bushing is subject to. I consider the problem solved.

While this may seem a trivial matter to justify its own article, I can only respond that it is often the simple things that can incapacitate your station. That can be devastating during a major contest effort, a public emergency response or when one of the rarest DXCC entities comes on the air for a few short days. 

Details matter. Don't overlook or dismiss small vulnerabilities in your station. You should have a backup plan at the very least.

Tuesday, February 7, 2023

Skewed Path vs. Antenna Polarization

Radio signals are not always propagated on a direct great circle route between two stations. When it happens it can be surprising and so we remember it. Yet it occurs less often than what we might believe. The ordinary act of determining direction (azimuth or bearing) by where we point our antennas to maximize the signal can be misleading. 

This is particularly true when we determine direction by comparing antennas with different polarities. We are misled because antenna patterns depend on the polarity. For HF antennas these are the linear polarity modes -- horizontal and vertical -- referenced to the ground. Other than local effects such as ground loss, Faraday rotation ensures that antenna polarity is often not terribly important. A received signal can have any linear polarity, no matter the polarity of the transmit antenna, and it can change quite a lot in mere seconds.

A good example of a polarity-dependent antenna pattern, and how it can be misunderstood, or exploited when properly understood, is the lowly inverted vee. Yagis have a similar behaviour, as shown above. Off the sides, there is substantial vertically polarized radiation at high elevation angles. The elevation plot is for a 3-element 20 meter yagi up 15 meters at 85° to the side. I didn't take it to 90°, directly off the element ends, because the horizontal component is too small to see. There is never infinite signal rejection under real world conditions.

With some antennas the effect of apparent direction and polarity can be even more surprising. This is common on the low bands when we use different transmit and receive antennas. We use directive receive antennas to better copy stations that can hear the signal from an omni-directional transmit antenna.

These are the 1.8 MHz azimuth and elevation patterns of a terminated 150 meter long Beverage antenna 2.5 meters high. Radials are added in the NEC2 model to emulate the behaviour of ground rods -- NEC2 doesn't permit direct ground connections. The elevation pattern is for the centre of the forward lobe where the horizontal component is nil. The main lobe is vertically polarized, which is exactly what is expected of a Beverage. The gain peaks at 40° elevation. The lobe is narrower and the peak elevation lower when the antenna is longer than 1λ, as a 150 meter long Beverage would be on 80 meters and up.

The 160 meter patterns for the Beverages in my station are little different since they are no longer than 175 meters. Notice the substantial horizontal polarization 45° off the forward direction. At an elevation angle of 40°, in some directions the gain is higher for horizontally polarized signals. As we'll see, that is relevant to the main thrust of the article.

From this discussion of polarization and antenna patterns we proceed to consider why hams might believe a path is skewed when it is not. Skew propagation is relatively rare because it requires a horizontal ionization gradient in the lower ionosphere to refract or reflect the signal to the side. 

Active aurora is responsible. There is a narrow area adjacent to the active aurora region, between where E-layer absorption is high and further distant where the gradient is low. It's a transient phenomenon.

There is an ordinary horizontal gradient in the ionosphere since solar insolation is latitude dependent. It is too shallow by itself to significantly skew signals from the direct (great circle) route. Forward and backward scatter are common, but the scatter signals are very weak and, although useful at time, are not skew propagation.

My choice of speaking about Beverage antennas is no accident. I am regularly presented with the appearance of skew path when using my Beverage system on 160 meters.

The occurrence of apparent skew path that motivated my exploration is the sunrise opening to Japan and the Far East. Since it is common when geomagnetic activity is low, the auroral mode of skewing is unlikely. With the Sun conveniently rising around the time I normally wake up -- 7:00 to 7:30 AM -- there are many mornings that I turn on the radio to see what propagation there might be to Asia and the Pacific.

As many have lamented, this has not been a great season for top band. With increased solar activity the absorption of the D-layer and polar regions has increased. Unlike during solar minimums, signals from the Pacific and Asia before and after winter sunrises have been far weaker or totally absent. With limited CW activity, or at least other than that from a handful of regular operators, I most often flip to 1840 kHz and monitor FT8 activity. That way I can easily check propagation while having breakfast.

The Beverage directions of note in this case are the north and west selections of the north-south and east-west reversible Beverages. It has been quite common this winter that signals from JA, HL, HS and a few others are strongest or best copied when pointing west. This is interesting since the great circle bearing for those countries ranges from 330° to 0°, which is right in the centre of the north Beverage's forward lobe. The north-south Beverage points a little west of north, at about 350°. The west Beverage points almost exactly 270°.

Very often this winter the signals from the Far East are best with the west Beverage. About half of the time the north Beverage is best. Pacific and west coast stations are always strongest on the west Beverage. KL7 and VE7 are often a toss up because the bearings to both are in between and the main lobe of the Beverages is pretty broad on 160 meters.

Is it skew path? The question is often asked by those with directional antennas on 80 and 160 meters. The answer is not obvious in many cases. What I am about to present is not novel, but it is worth taking the time since many hams fail to consider the interplay between antenna polarity and ionospheric behaviour.

First, I think it appropriate to reiterate a fundamental rule of antennas and propagation.

The ionosphere, not the antenna, determines the propagation path and its apparent azimuth and elevation direction. Our job is to choose and use antennas to best exploit the path or paths that are present.
Solar irradiation on the D-layer causes it to absorb lower frequency signals. The lower the frequency the higher the absorption. On 160 meters the process is rapid and begins before sunset when the high ionosphere sees the Sun many minutes before its rays strike the ground. Propagation, if it exists, must have a higher elevation angle so that absorption is minimized; at low elevation angle the path through the D-layer is longer and therefore radio waves are more attenuated.

If there is no high angle path, signals will be very weak or absent. At high angles our vertical and vertically polarized antenna patterns are a poor fit. Let's have a closer look at the pattern of the 150 meter long Beverage on 160 meters.

The pattern at an azimuth of 0° was shown earlier and it the polarization was entirely vertical, as expected for a low travelling wave antenna such as a Beverage. The horizontal component grows as we turn away from the main lobe, becoming equal to the vertical component at around 45°. Keep in mind that the antenna itself is, of course, firmly affixed to the ground; it doesn't rotate! That's why we must have several Beverage antennas for 360° coverage.

The great circle route to Japan and Far East falls between 60° and 90° off the side of the west Beverage antenna. In those directions the horizontal component is stronger than the vertical component, although 5 to 20 db weaker than the vertical main lobe. As we approach 90°, directly off the side of the Beverage, the vertical component is particularly weak at all elevation angles.

It is not enough that we must aim high at sunrise for the west Beverage to perform better than the north Beverage. The polarization must also be horizontal, and close enough to being exactly horizontal for the high gain vertically-polarized main lobe to appear deficient at high angles. 

Much has been observed and written on polarization of MF signals that travel through the ionosphere. There are effects, especially the electron gyrofrequency, that favour vertical polarization in most areas of the globe and horizontal polarization in other areas. I am in the majority of hams that live where vertical polarization is dominant on 160 meters. On HF, including 80 meters, Faraday rotation is more dominant and thus polarity has a strong time variability. Faraday rotation is slower on 160 than on HF.

Assuming the path is not skewed, it must be the case that the signals are horizontally polarized. Only that way will the weaker minor lobes compete with the main lobe. In the example of the Far East that I am highlighting, there has been little difference between north and west Beverages this winter, on average; sometimes west is superior and sometimes north is superior. I don't remember this happening as often last year. The east-west Beverage hasn't been up long enough to compare to earlier years.

Either way the signals have been weak and marginally workable with a kilowatt to my full size vertical. A vertical antenna strongly favours vertical polarization in all compass directions. Receiving a horizontally polarized signal well on the west Beverage is no assurance that I'll be heard since the path may favour horizontal polarization. For skew path, when using the Beverage for the apparent direction, reception should be full strength and vertically polarized. A successful QSO becomes more likely. 

A vertical directional antenna for transmission and reception could help to answer the question since these antenna have no more than a tiny horizontal polarization component at all azimuth and elevation angles. An example is my K3LR array on 80 meters; there are a number of these "big gun" antennas and 4-squares on 160 meters. They are huge antennas and I'll never have one; my aspirations are more modest. An alternative is extensive testing with a suitably equipped partner in the Far East. For me, these are both unlikely. I may have to remain ignorant on the matter.

Where this leaves me...

After this long-winded analysis, what should I conclude? Nothing definitive I'm afraid. The path is likely direct and the polarization is more horizontal than what I'm accustomed to experiencing. The signals may be weak for no greater reason than the off axis horizontal component of the west Beverage has a gain 10 db lower than the vertically polarized main lobe. 

Whether skew path or not, there is a valuable lesson. It helps to have more than one antenna, with a selection of horizontal and vertical polarization. That is impossible for most hams but there are alternatives. For example, a low band dipole can be an effective receive antenna on 160 meters. After lightning took out my Beverage system last year I could often get by with the XM240 as a receive antenna. The few decibels of relative gain it has in the forward and reverse directions can be enough to make copy an otherwise unintelligible signal.

When we cannot get directivity or polarity diversity from our low band transmit antennas, it is very worthwhile to install a receive antennas or use a low band dipole or yagi, even though they are far from ideal. Be flexible and try what you have. You might be in for a pleasant surprise. As the saying goes: You can't work 'em if you can't hear 'em.

You may have noticed that several of the links in this article go to K9LA's 160 meter page. If you have the time, it is worthwhile to browse the site. There is a collection of articles by him and by others that delve deeply into top band propagation and antennas. ON4UN's Low-Band DXing book also contains a lengthy discussion of low band propagation.