Wednesday, November 29, 2023

Improving (maybe) the 160 Meter Shunt-fed Tower

My shunt-fed 140' tower works very well on 160 meters. But it can be made better. With the winter top band season underway, the time has come to do so. While it may seem odd to put the effort into 160 meters when the high bands are consuming the attention of most hams, there are two strong reasons: contests and DXpeditions.

I would eventually like to achieve additive gain and directivity by shunt feeding both of my big towers, that is a project for another year. Making each of the verticals more effective are beneficial on their own and for when I proceed with the phasing project. It is time to make the existing vertical better. By better I mean the following:

  • Higher efficiency: lower ground loss
  • Match: broaden the SWR bandwidth
  • Permanence: replace the "temporary" construction with a more robust system
  • Arc elimination: lower the voltage across the gamma capacitor

Lowering ground loss is perhaps the easiest: add more radials. I increased the radial count from 8 to 16. SWR bandwidth and gamma capacitor voltage are both dealt with by increasing the gamma "rod" diameter. Permanence, well, we'll see how I've done. Let's look at each item in turn.

For convenience of construction and radial placement, I previously placed the radial hub at the base of the gamma rod/wire, positioned ~2 meters from the tower base. I have now moved it to the tower base. 

Radial hub

I wrapped the tower with a band of aluminum flashing and stainless ¼" studs to attach radial wires. First I had to move the heavy aircraft cable wrapped around the concrete pillar with a small one on the tower's pier pin base. I have these on both big towers to serve as anchors for antenna work.

The new radial hub is pretty flimsy, so permanence remains elusive. It is a cheap and easy solution until I see how well the new design works. Tripping on a radial (not uncommon!) bends it out of shape, but it hasn't broken, yet. 

Assuming it works out I'll replace it with a copper band next year. I could easily wrap the base with copper wire and solder the radials on, except that the radials must be removed each spring for the farming season. Mechanical connections makes that activity more convenient.

The new radial hub consists of a 2" (5 cm) wide strip of aluminum roof flashing (~0.015" thick). It's cheap and I have a lot of it, but it is not very strong. Tripping on a radial puts quite a kink in it. 

I am not too concerned by that weakness. As I said earlier, it's a temporary measure until I am satisfied with the overall design. It'll do for this winter.

There are a dozen ¼" stainless bolts with the heads on the inside of the flashing. A nut secures each to the flashing and a set of washers and another nut are for attaching the radials. In the picture you can see that I have two radials per bolt.

To support the radial hub, there are several short lengths of scrap ½" aluminum tubes screwed to it. That keeps it above grade but not so high that the radials are not too exposed to mishaps. A narrow trench has been dug around the concrete pillar that I plan to fill with stone. That's to discourage growth so that I can trim the hay around the tower base without damaging the radials. Yes, I have accidentally cut a few over the years.

Feed point

When I first built the antenna several years ago I used a margarine tub to hold the gamma capacitor. The intent was that it would be temporary. Of course it became permanent, as these things always do. As you can see the elements were not kind to it.

For the experiment with a cage gamma rod I used another margarine tub. Of course it'll also be temporary. Or so I hope. 

The new one has one added feature: a coax connector. It beats the wire nuts covered in plastic and tape that I used to connect the coax and jumpers to the radials and gamma wire. The picture below shows the inside, with the gamma capacitor I ended with after tuning (more on this later).

Seriously though, I do have a permanent feed point system half built that uses proper components. I can go ahead and finish it now that both CQ WW contests are behind me.

One curious effect on the feed point impedance is worth mentioning. When I had 8 radials the resonant frequency measured in the shack was about 15 kHz higher than that measured at the feed point. That's because outer conduction of the buried Heliax transmission line, when connected, becomes the ninth radial.

With 16 radials the frequency shift is negligible: what I measure at the feed point is very close to what I measure in the shack. The transmission line has less effect on resonance when there are more radials. That is not a surprise since it was what I expected.

Radial wire

Each bolt on the radial hub terminates two radials: one of the 8 original and one of the new 8. All are 30 meters long. The original radials are AWG 18 insulated solid copper purchased new. Of the new radials, two are the same and one is stranded. For most of the rest I used wire that I bought at flea markets at bargain prices. They range from AWG 20 hook up wire to AWG 16 electrical wire. When I ran out of wire I used AWG 17 aluminum electric fence wire left over from Beverage antenna construction. 

It's a hodge podge approach that's cheap. Cheap matters since the radials require 500 meters of wire. I was not concerned with wire gauge since the more radials you have the thinner they can be. The reason is that the antenna current is evenly divided among them. However, do not make that assumption for a low radial count such as 4 since they are susceptible to imbalance due to variations in the ground composition and therefore the velocity factor in each. Too thin should be avoided since the wire is easily damaged.

Power lost due to ohmic loss in the radials declines faster than the radial count increases. That is true due to the power equation P = I²R. When you double the radial count, as I have, the current in each is halved and the ohmic loss is ¼ what it was. Ohmic loss declines with the square of the radial count, all else being equal.

Of the 16 radials, 3 had to be bent near the end because they ran into the stone wall that surrounds my yard and house. For this many radials the impact on current balance and performance is small and is not nearly as important as having the radials.

Gamma rod

I perused ON4UN's book and I made an initial trial with two AWG 12 wires spaced 40 cm (16"). The model (see below) suggested that it would work well to broaden the 2:1 SWR bandwidth to 130 kHz. I went ahead and built it with wire scavenged from a 40 year old 40 meter delta loop. It was a great antenna but I have better ones now.

The upper cage support was made from junk box metal. The brackets that hold the aluminum tube are more than adequate to handle the dead load and the tension to keep the cage taut. I added a support rope as insurance. The pre-drilled galvanized angle is found in almost every hardware store. The multitude of holes ease experimentation with wire spacing.

Another bit of scrap tube and hose clamps keep the wires in position at the bottom. Rope and brick weights provide tension. Despite the high RF voltage at the bottom of the gamma rod there is no risk of arcing because both wires are at the same potential. This arrangement was to be temporary until tuning was completed but it works well enough that I'll keep it for at least this winter.

The top of the gamma rod is at 55', 5' lower than the previous 60'. According to ON4UN the tap point is slightly lower with a cage than with a single wire. The model confirmed that but the difference is so small that lowering it was unnecessary. During tuning (see below) I raised it back to 60'.


The tower is loaded with yagis which make the modelling process difficult. Since including them results in a large and unwieldy model, I substituted a single wire that is the electrical equivalent length of about 58 meters based on an earlier measurement of the tower monopole. The measurement was partly swamped by the ground ESR via the lightning ground rod (~75Ω) but gave a clear signal of resonance at about 1200 kHz. That is, the tower plus yagis is approximately an electrical ⅜λ on 160 meters. The physical height of the tower plus mast is 43 meters.

⅜λ is an excellent height for a vertical but it is difficult to match. The impedance is quite sensitive to the frequency. For that reason the SWR bandwidth is narrow. It was 70 kHz for the original gamma match. Further, the high inductive capacitive reactance requires a low value capacitor to cancel it and that results in a high voltage at the gamma match feed point. Increasing the bandwidth and taming that high voltage go hand in hand. 

Zooming into the feed point illustrates how the cage gamma rod is modelled. The top of the rod is the same but without the loads. MININEC ground is specified to simplify the model for the purpose of impedance matching; at this point I was less concerned with efficiency. The load in wire #1 is the estimated ESR (equivalent series resistance) of the soil and radial field. The load in wire #5 is the gamma capacitor. The source (feed point) is the circle in the bottom segment of the tower.

I adjusted the model parameters until I had a 50 Ω impedance. They were closely in line with the tables published by ON4UN. The gamma rod spacing to the tower was 0.7 meters (28"), with a 20 meter high tap point and the aforementioned 40 cm spacing between the cage wires.

The SWR bandwidth closely matches the 130 kHz predicted from the tables in ON4UN's book.

At 1000 watts the gamma capacitor voltage for the cage gamma is about half of what it was with a single wire. It is still high -- that's unavoidable in this situation -- but far safer and easier to construct with components found in my junk box.

When I reached this point I was sufficiently confident to proceed with building and installing the cage gamma rod. Before we turn to that let's first discuss an alternative model of the antenna.

In addition to the basic model, I also built one that includes additional detail. The 20 and 15 meter yagis at the top were modelled as single wires that are about 30% longer than the booms. That brings the tower resonance in accord with the measurement of about 1200 kHz. The lower yagis of the stack are not included since they typically contribute little to the total capacitive loading. I may add them later to confirm that considering that the lower 20 meter yagi is not far above the gamma rod tap point.

I constructed radial systems with 8 and 16 radials over EZNEC real medium ground. To keep them out and off the ground (not allowed with NEC2) they are positioned 10 cm high. The difference is slight in comparison to on-ground radials. It is a common workaround for modelling radials with NEC2.

The efficiency comparison is interesting because it is less than 0.1 db. However, this is likely not really true. NEC2 is really not up to the task of accurately modelling ground loss and I've run into this discrepancy many times before. 

The experiment measurements by N6LF and others for 160 meter radial systems suggest that the expected gain improvement is between 0.5 and 1.0 db. That may seem tiny but it can make a difference on marginal propagation that is routine on top band.

I am not equipped to measure field strength. Instead I measured the feed point impedance. In the initial configuration for the cage gamma rod, the impedance dropped from about 40 to 30 Ω. Although significant, the true improvement in ground ESR is not 10 Ω because this is the impedance as transformed through the gamma match. I did not reverse the calculation in an attempt to pin down the actual change.


At right is the tuning setup for the cage gamma. When the picture was taken the tap point was at 55' so the cage wires reach almost to the ground. I was using a large capacitor since, as discussed above, the model led me to expect the voltage to be about half that as before. That corresponds to a low capacitive reactance: Xc = 1/(2πfC)

After several iterations of adjusting the gamma rod spacing I achieved a 50 Ω match.

There are two possible reactions to this beautiful SWR curve:

  1. Wow! Mission accomplished.
  2. No way! The antenna physics don't permit this.

I was suspicious but enough of an optimist that I was leaning towards the first reaction. I constructed the prototype high voltage gamma capacitor in the margarine carton and hooked it up. That evening I gave it a try. None of the European stations I called could hear me or could not hear me well enough to copy my call. Yet they were not weak and I usually have no trouble working them. It was then that my reaction changed to the second one and I began searching for answers.

It didn't take long to discern the likely problem. The next morning I looked over the antenna and confirmed my suspicion. When I connected the radial hub to the ground rod I forgot to reconnect the wire from the tower to the ground rod. The only path for antenna currents to complete the circuit from the base of the tower to the radials and coax shield was via the soil. The loss was therefore excessive. In other words, the ground loss dominated the feed point resistance.

When I restored the missing connection the beautiful SWR curve vanished. To cancel the inductive reactance the capacitance had to be greatly lowered. The impedance was approximately 21 + j0 Ω. That's far lower than what's acceptable.

Unfortunately I could not raise the impedance to 50 Ω. The best that I achieved was in the vicinity of 30 Ω. It was after several fruitless trips up the tower to adjust the spacing between the tower and gamma rod that I restored the tap point to its original 60'. That, too, helped very little. Worse, the further outboard I placed the gamma cage the capacitor value declined and the SWR bandwidth narrowed. What I ended up with was little better than what I had before.


The impedance at 1850 kHz was 41 + j0 Ω and 2:1 SWR bandwidth of 80 kHz. With contests coming up and many other projects on my list I reluctantly stopped work on the antenna. It's good enough for this winter. The extra radials give my signal a boost and the SWR is easily dealt with by the amplifier. The rig's ATU is not needed across the DX segment of the band. It is needed when the I go outside that narrow range during contests when I don't use the amp.

I returned to the model to try and discover what might be happening. I can't say for certain despite learning a few new things about the antenna's behaviour. 

The first thing I learned is that a gamma match on a ⅜λ vertical does not react the same way as on a vertical that is closer to being ¼λ. The reason is that the impedance decreases as you move upward because the current node is ⅛λ above ground. That is about 20 meters in this case. With the tap point at that height, moving up or down increases the impedance. It is then transformed by the transmission line formed by the tower and gamma rod to what is measured at the tower base.

I confirmed the impedance behaviour with the simple model shown at right. The vertical wire is 57 meters long and is directly connected to MININEC ground. Peak R of more than 140 Ω occurs at 20 meters height. It is about 100 Ω at the base. I then performed a sensitivity analysis by varying the height in 1 meter steps. A 1 meter change in either direction changed R by ~10%. That's a lot!

Changing the antenna length by 1 meter in the model with the gamma match and cage caused large swings in both R and X components. Clearly the tuning is critical. It is possible there's a tap point further up the tower that will result in a 50 Ω match. Unfortunately that will bring the cage gamma rod close to the lower 20 meter yagi, and the possibility of the gamma rod threading between the elements. I'd like to avoid that if possible even though interaction ought to be minimal.

Clearly this antenna is more difficult to match with a gamma match than I expected. What I measured is not what I discovered in my cage gamma rod model or what I read in ON4UN's book.

That's all the time I have for the 160 meter antenna this season. I was already irritated that I missed the W8S Swains DXpedition appearances on 160 meters while I was in the midst of trying to resolve this mess. I likely would have been able to work them.

Planning for the next round

I am not so committed to the gamma match that I wouldn't throw it away and try something different. My options are limited since the tower is grounded. 

The only one that might work is an omega match. An extra capacitor is needed, and the best it can do is shift the impedance match from 40 Ω to 50 Ω. The bandwidth will not be improved and the voltage will remain high.

The alternative is to insert a switched L-network for the higher frequencies. I could then optimize the gamma match for 1810 to 1860 kHz (SWR better than 1.5). That addresses 90% of my needs. For contests where the activity runs up to 1900 kHz or higher, a switched L-network can lower the SWR up to at least 1900 kHz. The enclosure I plan to use is large enough to accommodate the gamma capacitor, an L-network and more.

To be completed

With the ARRL 160 meter contest coming up fast, I limited myself to an improved connection between the gamma rod and capacitor. It's cumbersome due to the 3 meter gamma rod spacing at the base (it's 2 meters at the top of the rod). 

Using an aluminum tube makes it easy to adjust the spacing without have to cut or add wire. The ABS pipe on the tower isolates the high gamma match voltage while allowing easy adjustment of the gamma rod spacing.

After the contest I'll take the antenna offline to move the gamma capacitor to its new enclosure. I will also take the opportunity to "rough in" the components for an L-network to lower the SWR higher in the band. Although I have no plan to add it this year, I want to make it easy to do next year.

I'll continue to contemplate and research the conundrum I ran into with gamma tap point and gamma rod spacing. I'd like to understand the problem better regardless of whether I install a switchable L-network.

Tuesday, November 21, 2023

On Becoming a Big Gun

Over the years I've operated from all kinds of stations: big and small; QRP and QRO; portable or mobile; wire antennas or stacked yagis; noisy urban environment or quiet rural. But until recently I've never really built and operated a so-called "big gun" station. I've operated the big stations of others in the past, mostly in contests, but never before could I wake up in the morning, turn on the rig and be able to put out a big signal. It's convenient and it has become routine.

I don't have the biggest station. It's big but there are many that are bigger. That said, there's little doubt that I'm now a member of the 1% (on HF). Many hams love to visit or look at pictures of big towers and antennas even though they'd never try to do it themselves. It takes a lot of commitment and is wildly incompatible with the lives of all but a few. You have to be in a position to do it and you must really really want it. 

Even then it's a big decision. You not only have to build the station, you must also maintain it. There are also improvements to be made to retain your big gun status, if that's your objective. It's a long term commitment. Most are content to get a vicarious thrill from the efforts of others while enjoying the stations within their means and that don't interfere with their lives.

Now that I've built this station it is interesting to see how it affects me and my operating style. There are differences and similarities; some things change while others do not. Consider this a newly minted big gun's perspective on what it's like being one.

Overwhelming force

This is perhaps what first comes to mind when thinking about big gun stations. There are pile up and contest techniques that I need less. Very often I can jump into a pile up on a rare DX station or contest multiplier, send my call once and log them. That certainly requires favourable propagation and that the called station infrequently changes their listening frequency. It doesn't matter how powerful your signal might be when they're listening elsewhere. You must still find the sweet spot to make your call.

In a major contest it can be difficult to find a clear frequency to run. When you find one there will be others trying to "muscle in" from time to time. In rare cases it's a deliberate attempt to steal the frequency. More often another big guns clicks on a temporarily blank spot on the spectrum map (while I'm listening, not transmitting) or doesn't hear me because we're in each other's skip zone.

In the past I would find it difficult to defend the frequency. Now I can. To use a hockey analogy, when you get in a tight spot you put up your elbows to keep others out of your way. Instead of having to QSY it is usually sufficient to keep CQing. They will soon disappear. Although I don't use my muscle to intentionally steal another's run frequency, unintended conflict can occur anyway. For example, when I get no reply to a "QRL?" I wait a few seconds and launch a CQ.

This next point is you might not expect. I sometimes feel shame when I jump into a pile up and push through with my big signal to quickly make the QSO. Yes, I still do it but outside of contests I feel a little uncomfortable jumping to the front of the queue ahead of many others who have invested more time and effort into making that contact. It doesn't seem fair.

Attracting pile ups

Many hams are attracted to the strongest signals on the band. The weak signals are passed over because they're more difficult to copy and there is less prospect for a conversation. Yet those weak ones may be rare DX or contest multipliers.

When I call CQ on any band open to a populated area -- most often Europe -- I will quickly attract many callers. That happens on any day, not just in contests. There are many big guns who love the attention and thrive on it. I do not. Pulling call signs out of a pile up can be hard work and there's pressure to work them all. Of course I can't because I don't spend all my time operating. Without exercising discipline, you will find yourself constantly running. That's necessary in a contest, so I do it despite not liking it that much.

For ordinary non-contest operation I tend to call others rather than CQ. I find it more relaxing because there's less of a time commitment. Even then I will often sign off from the QSO with a quick note that I am QSYing. When I don't there is a good chance that several stations will call me. They don't know it isn't my frequency.

When I choose to run, the pile ups can be immense. VE3 may be one of the most common prefixes on the planet, yet they still call. Since I don't do it often outside of contests, non-contesters, especially on SSB, are occasionally surprised to discover that we've never worked before. It is unusual to hear a ham with a big signal that they've never met before. We tend to stand out. 

Most hams just want to talk and a big signal is very conducive to that. Those with simple antennas and low power have learned from experience that it is easier to contact a big station than a small one. I try to accommodate them because I know what it's like. I've been there. I honestly enjoy pulling their weak signals out of the noise and making the contact. When they're QRP it's even more fun.


A surprising number of North American hams are wealthy or have ample funds to fund their hobbies. That is not too surprising since the majority are boomers and they (we) are the wealthiest generation in human history. I am not wealthy but I am free to spend what I have on what I want. For me that means a big gun station.

When you have the money it is a simple matter to contract out the work to build the towers. You pay someone else to do the hard physical ground work and then buy antennas, shack equipment and all the peripherals. That is, if you have a family or professional situation that allows or indeed supports your big gun aspirations. Many will spend less than their means to do the best they can with their retirement property and leave the bulk of their money for other things and to support their families.

When you hire others to build your dream station, does that lead to satisfaction? For many, the answer is yes. The business of aluminum, steel, concrete and silicon is a chore that must be overcome before the fun of operating begins. There is nothing wrong with that, but that approach would not satisfy me. I feel satisfaction when I've done the work: planting and building big towers; designing, building and raising large antennas; and designing and building control systems. 

Many big guns must feel the same way. They stay involved in building their stations to the extent of their abilities and resources. It is rare that no professional help is hired for part of the build. For example, excavation and cranes. On the Bell curve of personal involvement I'm at the tail end where my involvement is maximized. That puts me in the minority of big guns. It's a fat tail so the minority is quite large. There are many station builders that labour behind the scenes because only those closest to them know what they've done. Others garner the recognition by winning contests from their stations.

Guest operators

Which bring me to guest operators. Builders gain satisfaction from building -- I understand that well. They may also enjoy the achievements from operating the station. It just doesn't have to be them doing all the operating.

I am a middling contester and DXer. Despite my enthusiasm, I am not especially talented and I rarely strive to win. I practice the skills needed to excel and fully exploit my station's capabilities. However, I'll never be a great contester, nor do I particularly care. As I said in an earlier article:

"It is not enough to put up big towers and antennas to do well in a contest. You not only have to know how to use them to best effect, you must also be skilled at running, SO2R, hunting stations and have a keen eye on DX openings that can be marginal at best with small antennas at a lower height. I have much to learn and relearn."

I track the countries that I've worked and confirmed but I've never applied for DXCC. For anyone who has been reading this blog for a while it should be obvious that I get most of my satisfaction from building the station. A further satisfaction is inviting others to operate, whether it be for a contest or just for fun. 

It came as a surprise that many of my friends who have helped me the most with building this station decline the invitation. They prefer their own stations, even if they're small ones in a crowded and noisy urban or suburban setting. I have come to understand that: there is more satisfaction from operating from one's own station, no matter the circumstances.

Many big gun stations outside of the US and Canada are club stations. The clubs may be associated with institutions, a property owner and a group of supporters/operators, or a club of peers. Here the big gun stations are almost always privately owned, like mine. Guest operators may come and go but station building and maintenance is solely the responsibility of the owner. 

There are also big gun stations that can be rented for on-site or remote operating. Many partake of that opportunity. As long as you don't overdo it, it is less expensive than building your own. You pay to operate from a station someone else built and you avoid major commitments. It's a business transaction.

A private station rarely has a padlocked gate. Guests operators are regularly welcomed to join a team for contests or for single-op contests and events.

I recently held my first multi-op contest and there will be more. They get to enjoy operating the station and I get the satisfaction of building a team and seeing them enjoy themselves. I get a lot of satisfaction from it.


Every ham operates at the whim of propagation. No amount of steel and aluminum is enough if  nature doesn't cooperate. A 10 db edge over other stations can't compete against 100 db or greater swings in signal strength due to the vagaries of propagation. Big guns and little pistols share the same fate.

As I've discovered many times, lesser stations that are not far away will often have a large propagation advantage over a variety of paths throughout the day. That, too, can render a big gun station impotent. I am far enough north that even stations near Toronto (300 km to the southwest) regularly beat me in the pile ups. The difference is greater just a little to the south in the northeastern US. 

I really can't complain too much. When I started in this hobby half a century ago I was a VE4, and that was a dreadful location from which to DX and contest. The propagation to Europe and most of Asia had to pass the gauntlet of the auroral zone. 

Not long after moving to VE3 over 40 years ago I often considered moving back to VE4 for reasons of friends, family and culture. Had I done so there would have been little incentive to build a big gun station. You can't fight propagation. Since DX propagation is far better here the incentive exists.

Retro operating

With a large antenna system I often don't need or use an amplifier. The amplifier is turned only in certain circumstances: difficult DX pile ups; some contests; for contest practice; and challenging propagation on 6, 80 and 160 meters. I typically leave the amp on after its intended use in case I decide to make further use of it even when it isn't strictly necessary.

Not only do I leave the amplifier off, I will often increase the challenge by operating QRP in contests. It's good ongoing practice to ensure that I don't lose my DXing skills. Besides, I still love low power operating. It always puts a smile on my face when I make a difficult DX contact or I do well in a contest with QRP. Of course the antennas have something to do with that! Nevertheless, it is a lot of fun to work DX while putting 5 watts into a big antenna.

That's what I mean by "retro" operating. When being a big gun becomes too routine or easy, I deliberately challenge myself. Other than QRP, I may use one of my smaller antennas or an antenna pointed in the wrong direction to increase the challenge in a pile up. Although I no longer want to be limited by low wire antennas and QRP -- since I'd have to operate that way all the time -- I like variety and challenges. 

Having it easy all the time diminishes one's skills and interest. To be blunt: being a big gun can be boring if you don't watch yourself. I'm a big gun now but don't be surprised if the next time you hear me on the air that you can barely copy my signal.

Thursday, November 9, 2023


At long last I've fulfilled my plan to host a multi-op. The occasion was CQ WW SSB, which is arguably the most popular contest of all. I was not keen to do it single op since phone contests are not my favourite, and I was so close to being ready to host a multi-op. I recruited a few friends living nearby -- Dave VE3KG, Vlad VE3TM, Greg VE3PJ -- and circled the weekend on my calendar. The deadline spurred me to deal with several critical items on my to-do list:

  • New rig
  • New computers
  • Updates to the station automation software
  • Upgrade the 160 meter antenna
  • Move and raise yagis to improve effectiveness on the high bands
  • Arrange the operating desk to accommodate two operating positions
  • Clean the house and stock the fridge and freezer with food

My main objective for the contest was for all of us to have a good time. From my friends' feedback it seems that I exceeded that objective. Incrementally building this stations over a 7 year span I had lost sight of what it's like for those with average stations to discover that they've become a big gun and can have endless runs of DX. As one of them told me after the contest: "I had a blast!" 

Although we had just 4 operators for a 48-hour contest in the M/2 category, there was never an empty seat. It was difficult to pry an operator out of the chair to give one of the others a chance. Log statistics show that I had the lowest number of contacts: 1100 out of 7000. It was my plan to be available to guide the others to familiarize them with the station and to use the antennas effectively. I can't do that while I'm operating.

Our placement among the M/2 raw scores is quite good. We'll see how we did after log checking is complete and the results announced next year. I'm hoping we didn't make too many logging errors. Typos and more are a worry when the focus is on serving the pile up and keeping the rate high.

Not all of the experience was positive. On the way to running up a pretty good score we encountered a variety of difficulties. However, none dampened our enthusiasm and the impact on our score was modest. I should be thankful that so little went awry.

Photo credit: VA3UMM

The good

I suppose the most notable good thing is that nothing went terribly wrong. There was a lot that could have gone wrong that didn't. That's a success. Here's a sampling of what didn't go wrong:

  • No power outages
  • No equipment failures
  • No empty seats due to operator fatigue, disinterest or other issues
  • Propagation was excellent on the high bands and average on 80 and 160 
  • Very little inter-station interference

That's quite good since so much is out of our control during a contest. I have some spare equipment but there is no backup electrical generator to run two high power stations and associated devices. The utility (Hydro One) seems to have been getting better at keeping the power on in this rural area. They also respond well to reports of noise due to faulty equipment. We can hear a pin drop on the other side of the world, and that's great for pulling out the many small signals responding to our big signal.

Multi-ops require one computer per station. Since I use N1MM+ those computers are Windows PCs. Inexpensive refurbished Win10 PCs are widely available and I now have 3 of them. Since they use SSD for non-volatile storage they boot quickly and perform well. All PCs have Wi-Fi, built-in or with a USB dongle. 

For the PC running the antenna selector UI (user interface), I plugged in an ancient display and mouse from a defunct XP machine. This is a workaround until I have a touchscreen for each operator. I tried it with two mice (one per operator) so shorten the reach but the PC didn't like that for some reason. You can see the full multi-op desktop in an earlier article.

Networking was a breeze. I worried about it unnecessarily before setting it up. A friend told me how easy it was with N1MM+ and so it was. It was so easy I thought I'd done something wrong. Within minutes I had the station PCs communicating with each other and synchronizing logs. 

A third PC hosted my home brew antenna selector UI (user interface). I placed the (ancient) display and mouse for it between the operating positions, along with the controllers for the 5 rotators. I connected two mice to shorten the reach for the operators but the PC didn't like that. The mouse is a workaround until I have a touchscreen for each operator. I was not surprised to discover a few bugs in my software when I turned on N1MM+ networking for the first time. They were quickly resolved.

The bad (where there's room for improvement)

I can summarize the problems in a very short list:

  • Antennas
  • Amplifiers
  • Control
  • Multipliers

The biggest problem with the antennas is that there are so many. I am used to them but the others were not. There are 3 antennas on the high bands, and really 4 when you split the stacks. Some are fixed and some are rotatable. Further, the two tri-band yagis must be shared and each may be unavailable when the other operator is using it. The problem was worst during times of day when we could not run Europe or the US and it was necessary to try various propagation paths in the hunt for stations and multipliers.

Surprisingly it was the fixed direction high band yagis that caused the most confusion. It was very common for an operator to turn a rotatable yagi where it was wanted rather than click to select a fixed yagi pointed to the desired direction. I didn't anticipate that. From their feedback I learned that it was easy to "forget" about an antenna when there was no associated rotator. Similarly, splitting the stacks to maximum effect or using them to "spray" in different directions was a difficult concept to quickly master.

Antenna selection was easier on 40 meters since there are only two yagis. On 80 meters we usually kept to the vertical in preference to the inverted vee since we were primarily hunting DX. I say vertical rather than vertical yagi because the yagi modes are only functional up to 3650 kHz. The array is optimized for CW. For most of the phone segment the array is only usable as a simple vertical. Yagi operation up to 3800 kHz has long been on my project list. Maybe next year.

Mastering the Beverage receive antennas on 160 took practice. It was easy to understand but not necessarily easy to remember when and how to change direction. Since the Beverages can only be used by one radio at a time, despite having a choice of 6 directions. I have begun construction of a second receive antenna and I hope to have it ready by the end of the year. 

For the contest I placed a manual antenna switch on the operating desk to connect the Beverage system to one radio or the other. I programmed the Icom 7610 to always use the receive antenna port on 160 meters. On 80 meters it had to be manually selected in the Antennas menu. The FTdx5000 has a front panel switch.

The next big problem was the amplifiers. Mine are manual tune tube amps: an Acom 1500 and a vintage Drake L7. At their own stations, the other operators either use no-tune solid state amps or do not currently have amps. They all know how to operate them, in general, but none had done so recently. That became a problem.

My attempt to be helpful wasn't as helpful as I'd hoped. Before the contest I made a tuning chart for the A1500 by tuning and documenting the Tune & Load settings across the SSB segments for every antenna. It got ridiculously complicated due to the many antennas.

Although precise tuning isn't necessary it does help to keep the amps running smoothly and it also maximizes tube life. Errors were made. No, many errors were made. When you haven't used an amp for a while it can be intimidating. It is also very inconvenient when changing antennas or clicking to work a multiplier 200 kHz away, and the tuning is very wrong. 

Either the power output would be painfully low or the protection circuits would place the A1500 offline. Often the operator didn't notice until I pointed it out. Setting the drive level too low or too high was another common error. I jumped in to do a quick tune whenever necessary.

Another confusion was the pair of foot switches for the FTdx5000: one for PTT and one to generate a carrier for tuning. Guess what happened more times than I care to think about!

The L7 is more forgiving since it uses 3-500Z triodes rather the tetrode in the Acom. For that reason I didn't bother with a tuning chart. However, it must still be tuned. Too often it wasn't and the power output was little better than running barefoot. Without a foot switch, the only way to generate a carrier was to use the CTRL-T function of N1MM+. 

This is why many contest stations now use broadband solid state amps and broadband antennas such as OWA yagis and 4-squares. There are tube and solid state amps with built in ATUs, but those are expensive. One reason I like my amps is that they're cleaner than almost every solid state amp with regard to IMD and harmonics. I don't use BPF or stubs on the amps so that is important. We'll have to live with the hassle since I am unwilling to spend $20,000 for two new amplifiers with built in ATUs.

Which brings us to antenna control. For reading ease I've copied the original UI (user interface) from an earlier article. It's almost unchanged. You can read that article for detail on how it works. 

Despite my misgivings, I didn't think it would fail as badly as it did. It was barely comprehensible to the others. I have a plan to make it much better, but I've had no time to work on it.

I was frequently guiding the operators on its use. Part of that was due to the poor design and part was their lack of familiarity with the antenna and rotation options (see above). The contest raised the redesign priority and I will get down to work this winter. In my defense, the first priority was getting the automation system working and the UI was rushed. It was never intended to be a final design.

The system itself glitched several times which it has never done before. It was always at night when we were active on the low bands, so it is likely due to RFI. Intermittent faults are difficult to track down so all I can do is add more RFI protection like toroids and bypass capacitors for every wire touching the Arduino controller and the cables to the PC. Transitioning from USB to Wi-Fi will help.

On the bright side, recovery was quick and easy. When it locks up the status bar turns yellow or red. The UI is shut down, the Arduino power cycled and the UI restarted. One time the PC required a restart to clear a COM port fault. It takes 30 seconds to restore service, or twice that when the PC must be restarted. SSD storage makes for very fast Windows restarts.

Call: VE3VN
Operator(s): VE3KG VE3PJ VE3TM VE3VN
Station: VE3VN

Class: M/2 HP
Operating Time (hrs): 48

 Band  QSOs  Zones  Countries
  160:  116    10       14
   80:  470    15       58
   40: 1451    26       99
   20: 1586    36      119
   15: 1863    35      116
   10: 1462    32      130
Total: 6948   154      536  Total Score = 12,442,770

With regard to operating strategy, I believe our greatest shortcoming was multipliers. The runs were so good and the operator enthusiasm so high that it was difficult to interrupt and suggest spending more time hunting multipliers. Not all of us were experienced or comfortable with clicking those spots or using the N1MM+ AMQ window

It takes practice and a sharp eye to click on a spot, call the station and resume running. Both radios have dual receive so it is possible to listen on two frequencies concurrently. I try do it when one or two CQs go unanswered. Timing is key. Multi-single teams have it easier since only one station can run; the other (or others) can only work multipliers on other bands. In M/2 we must carefully weigh the options.

That is not to say our multiplier count was dreadful; we did pretty well (see above). Improvement will come with time. We could afford to lose a few multipliers since they were partly compensated by the high QSO points. I was more concerned with 80 and 160 meters since the runs were relatively weak and more time could have been spent hunting multipliers overnight. The rules allow us 8 band changes per hour, yet we never came close to the limit. I suspect that part of the problem was operator avoidance of frequent amplifier tuning (see above).

The future

We'll do this again, with the same team or with others depending on availability and contest mode (SSB vs CW). I made a list of station improvements that I'll work on over the coming months. My objectives are to rise higher in the standings and increase operator enjoyment and engagement. I have an incentive to stick with a core team who will become familiar with the antennas, equipment and station features.

I may gather a team for CQ WW CW at the end of November. If that occurs it will involve few if any improvements to the station. There have been other priorities in the waning weeks of fall while the weather is not yet very cold. The next likely opportunities are the ARRL DX contests early next year.

For the present, the operating desk has been reconfigured for SO2R, which I used for a casual effort in Sweepstakes CW. I will also need to spend time exchanging the IC7610 and FTdx5000MP so that the former becomes the primary operating rig for everyday operating.

Accommodating guests in my small house is a challenge. There is a guest bedroom and an adjoining bathroom and shower, but that's it apart from my own space and a couple of sofas. Old people tend to be finicky about these things but that didn't seem to apply to this fine group of contesters. We made do with few problems or complaints. That might not be the case with a larger team. It is something to think about for future contests.

The past

I am not a fan of nostalgia. Tube rigs and paper and pencil logging are history and they have no place in my shack. The fondness I feel about the past involves people. So bear with me as I finish this article with an old scanned photograph and a story.

The picture was likely taken in 1982, which is 41 years ago. It would have been at the end of one of the CQ WW or CQ WPX contests. Our multi-op call sign was VE3PCA. The station was owned by Doug VE3KKB (top centre) and located at his parents' rural home near the town of Perth. Those were good times. I was a lot younger then (left), new to VE3 and without a station of my own. I had yet to trim my 1970s hair. The others are Dave VE3KG (top right), Brian VE3CRG (lower right) and John ex-VE3EL (bottom, SK).

I have always enjoyed the energy level of multi-op contesting. I hate being alone in a room for 48 hours for single op contests and I hated it more when I was young. Joining a team at the moderately large station that Doug built was a great joy. Conditions were good, the camaraderie infectious and we sumptuously hosted by Doug's parents Mary and Jim (ex-VE3KJG). Both have long since passed.

By 1984 VE3PCA was no more. I had few opportunities to do a multi-op contest since. Later that year I bought a house and built my own modest station. In 1992 I exited the hobby entirely. When I returned to amateur radio 10 years ago, it wasn't long before I resumed contesting. First casually and then with enthusiasm. With my contesting interest rekindled I developed a long term plan to build a station that could do well in contests and host a multi-op. Mission accomplished. 

The 4 surviving VE3PCA members in that picture remain friends. Brian VE3CRG continues to be very active on HF though not in contests. Doug VE3KKB has downsized his station and no longer has HF capability. Dave VE3KG, like me, continues to be very active. He was on our team for CQ WW SSB (see the pic near the beginning of the article). It is almost exactly 44 years since we did our first multi-op together. 

Amateur radio, and contesting in particular, breeds long lasting friendships. We may not stay in frequent contact but when we do the good times return. My longest and firmest friendships are with fellow contesters. On the air you may hear little more than "59 4" but behind that brevity lies a rich culture, full of friends, pizza and smiles. Contesting, in my experience, is an extraordinarily social endeavour.

Thursday, November 2, 2023

Rapid Tower Decommissioning

Hams with towers are growing old. Many young hams are content with simpler HF antennas that don't require a tower or a long term commitment. Lifestyles have changed over the decades. When a tower comes on the used market there is often little interest. Many are free for the taking, if you take them down. Few are willing.

What do you do when the ham passes away? Small towers can usually be taken down, and I've done that. They are then given away or sold by the estate. Home buyers prefer not to see a tower when shopping. Bigger towers are a greater challenge. The estate incurs the expense of professional removal, and that may be the only option. The cost can only be recovered if there's is a buyer once it is on the ground.

A friend (Dave VE3KG) has been helping the widow of a silent key (Ajmal Rahman ex-VA3ZQ, and formerly VE2ZQ and AP2ZQ) to dispose of his station. He had a dilemma: a 110' guyed tower that no one wanted. Without a buyer, it wasn't worth the trouble and expense to dismantle it. Due to the illness of the owner preceding his death, it was in a state of disrepair. 

I previously showed a picture of the tower on this blog, along with the antenna parts that had broken and fallen to the ground. At right is a full height picture taken this past summer.

I knew Ajmal a long time ago. When I dropped out of the hobby I did not stay in touch with many ham friends. The last time we spoke was at least 30 years ago. I visited his country home when his family was young and he was eager to build an effective HF station. The tower was raised soon after.

Following my inspection, I decided that the tower was safe to climb despite several issues. But to what purpose? There was little of value to salvage. A lightning strike several years previous had disabled the rotator and likely destroyed some or all of the cables. With fatigued elements having fallen to the ground, the antennas were little better than scrap. The house was being sold and the tower had to go. We decided it would have to be cut down.

That is easier said than done. There are many things that can go wrong in that seemingly simple operation. Risk of injuries to people and property should not burden the family. Despite the large size of the property there were several complications due to the property layout and guying. 

We considered options while waiting for a neighbour to drive over with his bush hog to clear the field around the tower. There was lots of time on our hands since he didn't show up until two months later. Luckily the house hadn't been sold in the interim.

The tower and property are annotated on this Google satellite view. The yellow dots are the approximate location of the guy anchors, the orange letters are hazards and the red arrows are the directions the tower is most likely to fall when the opposite anchor is severed. The gray circle is the approximate 120' fall radius (tower height plus mast and yagi measured on the ground from the pier pin base).

There are a few general concerns about felling a tower in this manner:

  1. The fall radius is the minimum distance where debris will land. Tall towers can bounce. Their forward momentum can take them beyond the marked circle. Although that isn't likely for a tower of this size it must be taken into account.
  2. Debris from the tower top can be dispersed well beyond the fall radius. Impact velocity and momentum are very high. Mast, antennas and other attachments can break off and take flight to damage property and injure unprotected people in the vicinity. Spectators must keep their distance.
  3. Towers are most likely to fall in the direction opposite of the cut guy anchor. However they can fall in any direction in which the remaining guys are slack. That covers a lot of ground. Steps must be taken to ensure the tower falls where you want unless there are no hazards in the path of the tower or the two intact sets of guys.

We are now in a position to discuss the three fall directions and their hazards. 

The south anchor is inside the edge of the bush. Only a little vegetation had to be fought to access it. By dropping the tower to the north it would likely fall across the eastern edge of the lawn. That's undesirable but in this case was permitted. 

The problem is the northwest anchor and hazard C. I won't draw a diagram so you'll have to visualize  the scenario. C is a mature hardwood about 30' to 40' tall. When the tower topples forward the guys attached to the northwest anchor would wrap around the tree. That would severely injure or kill the tree. Worse, the tangling would cause the tower to veer left into the lawn and towards hazard E, the house. 

The first is very unwelcome and the second is unacceptable due to the risk of flying debris and lawn damage. I've seen the effects of a yagi striking a house when a 120' tower unexpectedly collapsed. It wasn't pretty.

The northwest anchor we just discussed has bushes growing all around but they were easily removed to reach the anchor. By cutting that anchor the tower would fall to the southeast. No matter how it falls there would be no risk of damage to anything of value. That sounds wonderful but for two things.

First, a tower falling into a forest typically will not reach the ground. A tower hanging overhead amid a tangle of broken tree limbs is not easily or safely removed. Neither is it easy to reach since the bush in front of the trees is dense and more than head height. I tried to get in there for a look and quickly decided it wasn't worth the trouble, both for the aforementioned problem and because of hazard D. That's the property line. We were told that it wasn't acceptable to fell the tower into the neighbour's patch of forest.

The northeast anchor was easily accessed once the bush hog levelled the field. The open field seemed an ideal landing area and the guys from the other anchors would easily cut through the light bushes on their west sides. Which brings us to hazards A and B.

Hazard A is utility pole supporting a transformer and hazard B is the distribution line and includes the telephone service cable. The fall radius comes almost exactly to the pole's guy anchor that stretches a short distance to the east (barely visible in the satellite photo). The distribution line at southwest corner of the property is 200' from the tower and well outside the fall radius. Potential debris set flying from the impact is at risk of hitting the anchor, pole or distribution line.

The red X marks the desired fall target.

"A ham's got to know his limitations"

It was at that point I recommended calling in the professionals. I was not comfortable taking on the job using a crew of hams who understood even less about the procedure than I did. I received good advice and an offer of tools from someone of my acquaintance in the commercial business in case I decided to take it on. 

He agreed with me that the best option was to cut the northeast anchor. When the anchor was cut, a rope tied to near the top of the tower has to be pulled hard within 2 seconds of separation to direct the tower to fall where we wanted. That's a precision operation. I considered the options and the procedure details and I decided it was outside of my comfort zone. Although I believed the chance of success would be very high, the cost of failure, low risk that it was, was too high to bear.

The firm I called on, Ontower, is very familiar to me and they are located a 30 minute drive from the site. The owner stopped by the site and agreed with the level of risk. A simple "cut and run" felling was out of the question. The recommended options were a crane to lay it down or bring a full crew to manage a precision fall to the target in the southwest area of the property. Cranes are expensive so we got the widow's approval to do the latter. Since the firm is fully insured, the risk of failure was covered.

Felling a tower

The appointed day was the Tuesday morning following the CQ WW SSB contest. It was a hectic weekend in which our team of 4 did pretty well. I'll have more to say about the contest in a future article. 

One of the multi-op team members, Dave VE3KG, was there with me. He knew Ajmal far better than I did and took the lead helping his widow dispose of the station. All the pictures and video in this article were taken by him. I was going to do it but after the first picture my phone battery went dead. I forgot to charge it.

The first job was to expose the guy anchors. All were galvanized angle stock, with two being ⅜" and the northeast anchor was about 3/16". One extended above grade, one was at grade and one was below grade. Use of angles is unconventional but perfectly fine if sized appropriately. What was very unusual was the use of shackles to tie the turnbuckles directly to the angle, spread onto the two faces of the steel. That's awkward. A header is preferred.

The picture gives you an idea of the anchor style since I don't have a picture of the northeast anchor that was cut. They dug deeper than I did during my inspection to expose over a foot of it. The gas powered cut off saw needed space to work. The safeties had to be cut since, for reasons unknown, they appeared to be tied into the (presumably) concrete anchor further down. 

All guys are often loosened before cutting the anchor. In this case they decided against it, using the tension of the other guys to start it falling in the approximately correct direction. The cut anchor and its guys recoil violently towards the tower when it is done this way. 

Click to view on YouTube

A rigger tied a rope about 80' up the tower. The other end extended to the southwest corner of the property. One of the two most experienced crew cut through the northeast anchor while the other maintained tension on the rope. The fall happens very quickly. 

Once the tower starts moving, the forward momentum becomes too high to direct the tower. There would have been less than 2 seconds to pull the tower while it was near vertical. That's why the person on the rope maintained tension throughout the cutting -- there was no time to communicate over the almost 100 meter distance at the moment the anchor was severed. The person on the rope can feel when the cut guys go slack and do what's necessary.

I'm sure many of you are expecting a video. We have one! Dave pulled out his phone and recorded the cutting and the fall. It's short and 95% of it is the cutting. The tower falls fast. We were of course told to stand well back. The falling tower hit the bullseye. It was a neat job. Professionals make it look easy. It isn't.


With the tower on ground, our thoughts turned to salvage. The disposition of everything was not yet decided as I write this article. The crew separated all the sections while we inspected and disconnected the rotator and mast. The foreman brought the saw over to speed the work by cutting both steel and aluminum jammed into the ground. 

He then inspected every tower section and cut through one leg of the sections that were damaged. This is a smart way to discourage hams from the temptation to reuse them. An hour later they were done. They were on site for little more than 2 hours.

There are aluminum bars that can be reused, but the the guys are scrap other than, perhaps, the porcelain insulators. The short fibreglass rods that electrically decouple the tower from the EHS guys are old, likely damaged from the fall and partially delaminated. While tempting, they must not be reused.

The only prize I left with was a Tailtwister rotator. Although damaged by the fall it might be reparable. I can use it for parts if not. I'll open it up for inspection later this fall and if it looks interesting I'll write it up for the blog.