Sunday, October 29, 2017

Basic Tram Line

Raising a yagi onto guyed towers requires moving them over or between guys. There are alternatives that are often impractical or expensive. These include hiring a crane or lifting the boom and elements straight up and assembling them in the air. For most hams a tram line is used since it is economical and not overly complicated. Details matter, however, since doing it wrong can cause real grief, from lost time fixing mistakes to complete loss of the antenna or injury.

Work on my big tower has been progressing apace such that I am now able to attach antennas. I have raised the first antenna and did it with a tram line. This is a side mounted yagi at ~120' (35 meters) fixed on Europe (northeast). Since time is pressing as the weather grows colder I am relying only on antenna I have on hand. Therefore I am using my Hy-Gain Explorer 14 short boom tri-bander. Next year I will switch to higher performance antennas.

I previously raised this antenna onto my 15 meter antenna in Ottawa, also using a tram. That tram had the antenna sliding up two ropes. That is impractical for my new tower. Instead I am using a more traditional tram line. I'll step through how I did it in enough detail that you could do it yourself.

In fact I did this operation entirely on my own. Since there were numerous tasks necessary to get everything working properly I did not want to call anyone out here to sit around while I fussed. When the bigger antennas are trammed to the top of the tower I will be relying on friends to help out.

Side mount bracket

The tower came with several items that were used for side mounting yagis. From these I selected what I needed to make a simple bracket suitable for this antenna. I will replace the bracket next year, but for now I saved time by using what I have on hand.

The bracket is comprised of two lengths of angle stock. One bolts directly to a tower girt while the other uses pinch clamps which allows it to be placed at any position. The weight bears on the lower bracket by means of a bolt, not the cheap muffler clamp you can see. The upper bracket holds the upper end of the pipe. A pipe substitutes for a mast to enable use of the antenna's stock boom-to-mast clamp and to allow some directional flexibility for pointing the yagi.

Tram line components

Rigging for the tram line had just been installed when the picture was taken. A large shackle anchors the aircraft cable used for the tram line itself. Below the anchor a pulley is affixed to the pipe mast. The rope is used to haul the antenna along the tram line. The cable for this operation is ~180' (55 meters) long. More than 300' (90 meters) of rope is required. Although it is possible to haul the antenna from the tower (with a shorter rope) it is far easier to do it from the ground. As a general rule every task is 3 times more difficult on the tower than on the ground.

There is a lot going on in this picture so I'll step through all of it. First I needed an anchor for the tram line. My lawn tractor was ideal: it is portable. heavy and comes with a tensioning device: reverse gear. There are three positions from which tramming can be done on a guyed tower, between each sets of guys. This area happens to be the only one without trees nearby; trees can be excellent tram line anchors. Unfortunately I had to use the treeless area to achieve the correct orientation.

Orientation is critical and requires careful planning. The position of the side mount bracket is no accident. It is the only one compatible with the bracket and pointing this particular antenna towards Europe (the antenna in the picture is oriented exactly in that direction). Notice that on this 3-element yagi the driven element is forward of the boom centre. The bracket (as we'll see) ensures that when pointed northeast the elements all stand well away from the tower.

The boom half of the mast clamp had to be reversed so that it faces the tower, for the same reason. This was easier than flipping all the elements so that the trap drain holes point down. The flat side of the clamp faces the tower, ready to be bolted onto the other half of the clamp when the antenna is lifted.

"I can fly! I can fly!"
The rope securing the boom to the tram line pulley and the haul rope must be at the antenna balance point (centre of gravity), which in this case is right where it should be: the boom-to-mast clamp. Each rope must attach at two symmetrical points either side of centre so that the antenna cannot rotate on the tram line, twist or waggle up and down.

Getting it right is very important. I fussed with it for over an hour and had to reverse the lift a few times until I had it perfect. The basic process is to do all the rope work with the antenna on the ground (supported off the ground itself), with the tram line slack. The tram line is then placed under tension, which will lift the yagi off the ground. Make sure the haul rope is tied off or the yagi will roll backward!

The ladder you see was used to inspect and adjust the ropes and pulley as the yagi first lifted off the ground. The elements are pointed slightly upward to assist with clearing the guys immediately below the bracket. A tag line is attached to the boom so that the elements can be steered around the tower and guys, if necessary.

The tractor made this stage of the operation easy to repeat several times as I fixed problems with the rigging. Remember to chock the wheels when the tension is set!

Raising the antenna

Hauling the antenna up the tower is perhaps the easiest task. Setup takes the most time, and is well worth the investment of time and efforts. Should the antenna spin out of the correct orientation while hauling I strongly recommend immediately lowering it and fixing the problem. It's far easier to correct problems on the ground than while the yagi is dangling 30 meters in midair.

The Explorer 14 weighs only 45 lb (20 kg). Hauling the antenna up the tram line by hand is quite easy. It is made easier by the mechanical advantage the tram line affords. This is because the antenna is travelling up a slope rather than straight up. The trade off is a longer hauling distance. I attached a rope cleat to the bottom of the tower so that I could rest during the haul and to secure the antenna while working on it on the ground or in its final position.

In the next picture the antenna is beginning to straddle the tower. I didn't even need to use the tag line to achieve this perfect orientation. After all the trouble with the setup the antenna raising proceeded beautifully. If you are not so lucky do take the time to ensure the elements each go where they should. If the tag line in insufficient do it from the tower. Yagi element tips are fragile! This is where having a friend along to assist is very welcome.

What you can't see in the picture is the wind blowing. The wind was 20 to 30 kph perpendicular to the tram line, with gusts up to 50 kph above the tree tops. It wasn't a factor. Although I was concerned about the wind there was a storm coming in followed by a forecast of several days rain. So I went ahead. When the tram is properly rigged a stiff breeze is not a serious difficulty.

Attaching the yagi

Once the haul rope bottoms out on the pulley the hauling is done. Done properly the boom-to-mast clamp will rest very close to its intended position. Before climbing the tower the tram line should be made slack. When you do this the haul rope will relax and allow the antenna to rest against the mast. Bolting on the yagi is made easier when the tram line and pulley don't offer resistance. The vertical position of the yagi can be adjusted after it is clamped on and the tram line system is detached. Don't delay climbing the tower when the tram line is slack since the antenna has more freedom to move in the wind.

In the adjacent picture the yagi has just been bolted to the bracket mast and the tag line (green) and haul rope (white) removed from the antenna and tied off.

The picture shows detail that was missing in earlier pictures. There are a few items to note.

I used the boom half of the clamp to achieve the two symmetrical tie off points for the haul rope and tram line cradle.

There are two shackles connecting the cradle to the pulley. With just one shackle the yagi would twist to one side.

To slip the pulley on and off the tram line I used one with a removable wheel (sheave). To get it off the tram line I knock out the axle retaining clip, remove the axle and then separate the wheel from the body. It goes back together the same way. This is quick and easy compared to detaching the cable anchors to slide the pulley off the end of the cable.


I did not take an antenna analyzer up with me. With the conductive tram line present I would not have gotten good impedance measurements. I'll do that the next time I'm on the tower. I don't anticipate any problem. My modelling of guy interactions with respect to the orientation of this antenna promises no difficulties. We'll have to see if that is indeed the case.

The bottom of the tram line was tied off at the tower but left anchored at 120'. It will next be raised to the very top to raise larger yagis to the rotating mast. This small lift was good practice.

The antenna was raised on the Saturday of the CQ WW SSB contest. The weather was about to turn ugly and I was in any case unable to effectively compete due to my temporary lack of good antennas during construction. I expect to do better when the CW contest rolls around in several weeks.

Monday, October 23, 2017

Pile ups: 3 Basic Methods for Getting Heard

In my previous article I mentioned putting up my old multi-band inverted vee as an interim measure to get me on 17, 30 and 40 meters while the big tower project is ongoing. My immediate goal was 3C0L. I did work them on several bands though not as many as I'd wish since I gave priority to tower and antenna work while the weather continued to be pleasant.

In the process of cracking the pile ups on 3C0L and others I thought it interesting that I was using 3 distinct operating techniques depending on the pile-up depth, propagation and the competitiveness of my signal. They can be used by anyone, from little pistol to big gun, and they are used.

The purpose of this article is not so much to reveal anything novel other than to categorize them in a way that can help the DXer choose how to approach each pile up. If you've followed this blog for awhile you'll know that in my QRP years I wrote several articles on cracking pile ups with a tiny signal. It seems worthwhile to add this one to complement what I've written earlier.

#1: Predict where the DX is listening

This is the most common technique and is widely understood and practiced. There is no need for me to repeat here what everyone knows. If you use it you'll know that sometimes it works well and other times not at all. The difference in results often comes down to whether your signal is competitive with others in the pile up.

Competitiveness is not only about antenna and power. With the best station in the world you will be beat out if propagation favours another region of the world. For us in eastern North American that is most often Europe. For example, with a low solar flux north-south paths are better on the high bands. That puts North America at a disadvantage compared to Europe for working 3C0L. Even small stations in Europe will outgun you.

However if you are competitive in the pile up and you are good at predicting the DX operator's pattern you will soon have the QSO in the log. Prediction works well much of the time.

#2: Call where others are not

When you are not competitive your skill at predicting where the DX is listening will most often lead to frustration. Many others can predict as well as you and your signal will be underneath theirs. You'll end up frustrated as you fail to be heard. Those with little signals know this feeling all too well; it's a part of the game. Another strategy is required.

In the past 24 hours I used the following technique twice: to call where others are not. The first case was 3C0L on SSB. They chose to work stations by numbers. I'm too busy to sit near the rig to wait for them to call for 3's so I kept missing an opportunity to call. When I was able to call the pile up was huge and in the few minutes they worked 3's I was unsuccessful.

Catching them one last time on 20 meters before they shut down (14.190 MHz, and listening up 5 to 10 kHz) I did the prediction thing for a couple of calls before realizing this was unlikely to work in the few minutes remaining. So I listened to learn where others were calling. The vast bulk of the callers were on 14.195 MHz, the frequency of the previous QSO -- there are lots of predictors out there! There were a several callers on 14.200 MHz and only a few in between.

I picked 14.1975, right in the middle of the pile up range, and made my call. No one else was heard on that frequency. It took 2 or 3 calls until he QSY'd and found me. Into the log he went. The mass of predictors then made their call on my frequency.

The second example was FT5WQ/MM on 40 meters CW. This is not a country, just an opportunity to practice pile up technique. With the inverted vee rather than a yagi, and no amplifier, I was not competitive for the size of pile up. Prediction didn't work for me. So I delayed a second when he solicited callers and tuned the VFO to where I heard silence. Again, it took 2 calls to put him in the log.

This technique works because even the most dedicated DXpeditioner gets fatigued from constantly trying to pick a call sign out of dozens or hundreds of overlaid signals. Eventually they make an unpredictable turn of the VFO to avoid the predictors. When that happens they'll usually stop at the first isolated signal they find. That signal can be yours.

#3: Uh oh, where's the pile up?

The first two techniques can be succinctly stated as calling where he's listening and calling where others are not transmitting, respectively. But what if you can't hear the pile up at all? This happened to me with 3C0L on 10 meters CW. He was working mostly Europe and a few in North and South America. Evening was crossing Europe and the propagation gradually favoured this hemisphere.

From VE3 I heard not a whiff on any of them, not in Europe and not in the Americas. Prediction was impossible. I didn't know where he was listening or where others were transmitting. This is a dilemma. This brings us to the final technique: to call blind and hope for the best.

Despite the lack of signals there was one source of information, marginally useful though it was: the DX spotting network. Occasionally the DX will be spotted with the frequency where he was worked. I saw one of these timestamped a few minutes earlier. That makes the information old. Yet it was all I had to go on. That one said listening up 3 so I called up 2.5 kHz.

Despite calling blind I actually got through within a few minutes. I was monitoring the spots and would have tried a new offset if someone mentioned one, but no one did and I stayed where I was. I returned the favour by spotting my offset to work him.

Although a poor strategy in most cases don't hesitate to use it when all else fails.

Sunday, October 22, 2017

Where DQRM Comes From

With all the station work going on here I have been mostly inactive this month. First the TH7 had to come down for service, and my only other HF antenna -- 80 meter inverted vee -- was taken down in preparation for the move to the big tower. This became a problem when several attractive DXpeditions appeared on the bands.

Soon after the TH7 was back up, although not well cabled or fed, I had 3C0L in the log on two bands. But I had nothing for the lower bands. As at least an interim measure I decided to resurrect my old multi-band inverted vee and installed it on the Trylon at an apex height of 18 meters. Now I have a resonant antenna for 40, 30 and 17 meters. It isn't a great antenna but good enough to get me by without distracting me from more important tower and antenna work. I'm glad I kept it around. It resonates higher on each band since the interior angle is less than that for which it was originally tuned. I did this to avoid interactions with the TH7 above it.

DXpeditions and DQRM

When it comes to DXpeditions we inevitably need to discuss DQRM. I am well past any feelings of angst or anger when I encounter it. More often it leaves me sad. It's a part of our hobby and a part of the challenge of working rare DX. Like others I work around it with a combination of technology and skill. I leave the anger to others while I go about trying to work the DX.

Deliberate QRM (DQRM) is not a recent phenomenon. It has with us almost as long as amateur radio has existed. Indeed it is not restricted to our hobby, with DQRM too frequently on various commercial, police and other services dependent on radio communications. By DQRM I am restricting the definition to non-commercial interference, not the kind where governments and commercial interests get involved as a matter of (bad) policy. It affects not only DXpeditions but also contests and perhaps most perniciously on emergency traffic.

This post is not about dealing with DQRM when it occurs. There are many ways of doing that, good and bad. My own approach is to ignore it. Although DQRM affects my enjoyment of my amateur radio pursuits I often have a greater worry about the health and mental well-being of the perpetrators. It makes me sad, not angry.

Acting out against the perpetrators, whether on the air or pounding on the shack table, achieves little except perhaps to relieve stress. A better approach is to better understand who these people are and what motivates them. Put aside the hate and the anger for a moment to consider that the perpetrators of DQRM are as human as you and also have wants and needs. It is not a short term solution but if followed through can eventually have a positive impact.

DQRM hits close to home

Once in my life as a ham I was well acquainted with a couple of DQRM perpetrators. I didn't know it was them until they were caught by some dedicated ham sleuths and subsequently busted by the authorities. It was horrifying. Since I knew them well many friends asked me how this could have happened. I had no good answer, and that bothered me.

Perhaps I was too young at the time to understand this type of behaviour and to recognize the human traits that drive it. Immaturity undoubtedly played a role; we were all young at the time. With maturity I can retrospectively begin to understand.

I won't give any details even though these fellows are sadly long dead. It serves no purpose. Those who know me from that time will know the names, call signs and circumstances.

While I mentioned immaturity as a contributing cause that is a wholly unsatisfactory explanation. It permitted the DQRM to begin and continue due to poor judgment but was itself not the underlying cause. It was a toxic mix of disrespect for others and a disdain of operating interests that were far different from their own.

Some of the disrespect was the ordinary kind that young adults feel toward the previous generation as they begin to make their own way in the world. It is the rare family home where this doesn't occur. Unfortunately I've found that many adults are adults in age only, never shaking off their youthful arrogance, impulsiveness and reactionary disrespect for others. They grow older but not wiser. Look around and I think you can find examples among those you know.

Combine that immature attitude with impunity and trouble can begin to brew. Most people, even adolescents, will not cross the line, or perhaps only dip a toe across when they have these feelings. There were no inhibitions at all in those central to my story. Some of that was driven by unfortunate circumstances in their own homes which I won't get into.

They dared each other and crossed the line arm in arm with smiles on their faces. The DQRM went on for some time despite knowing that they were being hunted and that the hunters were closing in. It became a challenge to them to evade capture. In their minds it was little different than driving over the speed limit when the police announce a campaign against speeding. They didn't care, fearing neither consequences nor the impact they were having on others.

There was no escaping the consequences. They were assessed fines and withdrawal of operating privileges for a time. To the best of my knowledge they did not re-offend after regaining their licenses. I am less certain that they truly learned their lesson, only that they felt foolish to be so incautious at what they were doing. That is, they regretted getting caught, not what they did.


When someone behaves in a manner that affects us negatively or of which we disapprove, regardless of the law, it is easy to slip into easy explanations and stereotypes. Looking deeper into what the DQRMer is thinking is difficult and messy. They may not know either. Ultimately the reason they do it is because they enjoy it or because they enjoy the reaction of others.

Usually there is no evil intent, just righteousness. They disapprove of the activity and feel justified to take matters into their own hands. They can't leave others to enjoy their choice of operating activity.

Even this is inadequate. Most of us have these feelings in certain circumstances and we do not lash out. If we do it is episodic rather than an obsession. For example, imagine you are in a pleasant QSO with a friend that is rudely interrupted by the appearance down the band of a rare one who says he's listening up 5 to 20 kHz. You may stand your ground for a time, perhaps go so far as to try to get the others to QSY or briefly DQRM the DX. Two wrongs don't make a right, and in any case it doesn't work. Better to (correctly) abhor what occurred and QSY. The DQRM doesn't recur.

Instead let's restrict our DQRM appraisal to the serial perpetrator. The ones who listen for the DXpeditions, super-station contests or individuals they simply dislike and wage a recurrent campaign of DQRM. They either dislike the person or the activity and use that as justification for their actions. They understand what they are doing is wrong, or at least illegal, so it is the rare DQRMer who identifies. The same technology that makes finding the rare ones easy is used by them, so when they are motivated they are difficult to avoid.

The role of unhappiness

I became a ham as part of the great wave of baby boomers, so we were all young. What used to be called the "generation gap" in the 1960s applied to hams as well. And we were active! Being young and having many ham friends of the same age meant there was bound to be trouble. I got into my own share of it but never DQRM or similar operating misbehaviour. That line I never crossed. I can't say whether it was good sense or just good luck considering some of the bad company I kept.

The vast majority of hams today are older. That is, our generation grew older and fewer young people joined the hobby. Youthful exuberance and bad judgment are no longer significant factors causing DQRM. We have to look elsewhere for explanations.

Unhappiness is one. While some people are perpetually unhappy everyone goes through unhappy phases in their lives. It's the human condition. Unhappiness often spurs us into action to change our lives to either remove the cause or to undertake activities that can make us happy again.

Isolation is a common cause of unhappiness. We're social creatures and need companionship. What far too many people discover is that isolation creeps up on you as you enter your senior years. Many of my older friends have discovered this unfortunate fact of life. The children are gone and even the grandchildren no longer look forward to visits. They have other interests and responsibilities. Retirement quickly separates you from long relationships with coworkers and customers. Friends and family members of similar age relax and then withdraw from many social activities or become infirm and finally die. Marriages often end. The trend of single person homes is growing in North America at least.

Curmudgeonly behaviour is one outcome, as is a desire to connect with others or to be simply noticed. The reason for being noticed doesn't have be a good one. Indeed misbehaviour can be an excellent path to immediate and widespread notice. For hams DQRM beckons.

Old people tend not to care what others think of them. There is a passing similarity in behaviour to teenagers despite the underlying cause being very different. It is like a forest in a drought, vulnerable to a single spark. They may not care about the pain they cause or possible consequences to themselves. Indeed they may see it as harmless fun and laugh at the reaction of others. Some people like poking an anthill with a stick just to watch the ants scurry about. It can be a welcome distraction from the terminal unhappiness they feel.

DQRM arises

There are technical solutions to DQRM, including deep data analysis and DF (direction finding). DF, which can be terribly difficult on HF, has worked well for many on VHF and UHF. Underfunded regulatory and enforcement authorities will do the latter but rarely the former. For the most part hams are on their own for HF DQRM. Successes are elusive yet do occur. Most initiatives fail when initial enthusiasm falls victim to the difficulty and time involved.

Psychological remedies can have more immediate results. It can take substantial discipline. These include ignoring the DQRM, thus denying the need for notice, operating technique and even strategic avoidance. Idle speculation of what motivates the perpetrators may prove interesting for a time, if unfruitful.

Data is better than speculation. Our desire to dislike the DQRM perpetrator often leads us to false conclusions. They are unlikely to conform to the evil caricatures we tend to gravitate towards. Often they are sad and lonely hams that in other circumstances would elicit pity rather than scorn.

Consider my discourse on unhappiness above and the impacts of age and isolation. Most people who have been involved in any activity or pursuit for most of their lives grow at least a little weary of it. Hams become less active or settle into ruts of repetitive and unfulfilling activities.

I can think of numerous examples of HF operators with great stations who appear to spend most of their time making endless short QSOs. They're active yet I doubt whether there is any true enjoyment involved. They've won contests or achieved DXCC Honor Roll and are running out of motivations to operate while having more time to operate than ever before due to their age and isolation. But they aren't causing DQRM.

On FM you probably can name several calls of those who always seem to be near the rig and ready to answer anyone willing to chat. Call them directly and they invariably answer. There is some utility to it since when help is needed there is someone listening and ready to respond. But are they enjoying themselves or filling the hours of their lives?

These are benign if sad examples. I seem immune since I left the hobby for many years only returning when the time was right for me. My enthusiasm was refreshed. Hopefully it will last. Some of my contemporaries who never stopped operating are now becoming fatigued and questioning the point of it all. Some become inactive. Yet there are others who are as enthused with the hobby as when they were first licensed decades ago. Most are somewhere in between these extremes.

When fatigue, age and isolation come together in select individuals we see a turn to curmudgeonly behaviour and among those a few who will lash out. Whether this is a common cause of DQRM I cannot say. Among those who are caught this is a not uncommon reason. Mostly, as I said earlier, these examples come from VHF/UHF FM rather than HF due to the relative difficulty of finding them. I have to think that HF is the same despite the paucity of data. Anecdotes are not data so I could be wrong.

I ask you to follow along with me to imagine a scene. An elderly ham sits at the controls of a very good station. Plaques are on the wall celebrating a lifetime of operating achievements. He's alone and has been for years. He believes there is little to look forward to in the hobby or in life. Unlike some others he sees no point in working stations for no clear objective.

He tunes the band or has an eye on a Telnet window. Rare DX appears. He listens to the pile-up, the mad pursuit of a new one by countless hams. He envies their enthusiasm, a commodity he depleted a long time ago. He worked this country dozens of times and on every band and mode, the first time decades back. There's no point to calling that he can see. Yet he has a good station and is a skilled operator with nothing better to do if should tune away or turn off the rig. He may hear calls in the pile-up of those he knows but has not spoken to them for years. He feels annoyed and wronged by that negligence. He honestly doesn't notice that connection is a two-way street and he is equally to blame for the silence.

He stares at the rig. What will he do?

In rare cases you know that he will turn to DQRM. Although his identity will remain undiscovered he will be noticed, spoken to (shouted at) and message boards will fill with comments expressing disgust and irritation. He has found a scapegoat for his unhappiness and a way to hit back and even become enthusiastic about operating again, even if it's for a dreadful purpose. Evil can be enjoyable.


Do you know such a ham? I don't mean a DQRMer. I do mean a elderly and accomplished ham who has seems to have gone inactive and doesn't show up to club meetings. You know he is alone. Perhaps a phone call or a visit would be a good idea. Hams like this have stories to tell and few to tell them to. They want connection yet are too proud to reach out or are not comfortable doing so.

Hams who have active connections to their peers are less likely to turn to evil. Of course few do in any case. Reaching out to one or two can enrich you and him. The cloud over their heads blows away, for at least a little while. The few who are prone to evil are less likely to act on it when they know and like the person behind only one call in the pile-up. Maybe they'll even reach for the key to call the DX to try and beat out their friend.

If we're lucky we will be old one day, and when it comes we may be alone. Wouldn't it be nice if someone reached out to you in that situation? Happy hams don't DQRM. Reach out and maybe, just maybe, there will be less DQRM on the bands.

Thursday, October 12, 2017

Bad Vibrations

When we think about fasteners for antennas perhaps the most common questions are about stainless steel and yield strength. There is more to it than that. This was brought home to me recently when I went up my Trylon 70' tower to remove a wire antenna, to do a general inspection and to plan coax routing improvements for the Hy-Gain TH7 and the Cushcraft A50-6.

That's when I saw the following on the TH7. Can you see what's wrong?

The splice bolt holding the boom sections together has lost its nut and lock washer and had worked itself halfway to freedom. The one on the other side of the boom was not quite as bad since the nut had loosened but not yet fallen off. Left uncorrected the boom would soon be held together only by the tension of the boom truss. I put other projects on hold since this called for an emergency repair.

The bolts were out of reach and the antenna could not be easily rotated due to its weight and the 6 meter yagi stacked above. A closer visual inspection uncovered other problems. The antenna had to be lowered to the ground for a full maintenance overhaul despite having been up for only 4 months.

Obviously I had made mistakes. I was in a rush at the time and took a few shortcuts. Nothing serious, or so I thought. Or at least nothing that couldn't be remedied before winter, which was my plan and why I did this inspection climb.

I had several days leeway since I had to wait for helpers to resume work on the big tower. Once the weather was cooperative I rigged the tower for lowering the antenna with my lawn tractor. It came down surprisingly well considering I did it myself. I was able to handle the tag line while the tractor rolled forward.

Once on the ground I gave the antenna a thorough inspection. The number of problems was depressing. Just because I write a blog about towers and antennas does not mean I do every job perfectly. Far from it. I make mistakes and I take shortcuts like any ham.

First about those boom splice bolts. There was an interior start pattern lock washer on the one bolt that had not yet entirely unscrewed itself. Presumably the other had the same. Lock washers on round surfaces, especially small diameter tubes (2" in this case) don't bite well. I redid the bolts using the pattern for the Cushcraft XM240: lock washer under the bolt head and nyloc nut on the other end.

Before undertaking repairs I went to my favourite fastener store and stocked up on ¼" stainless lock washers and nyloc nuts. I had an interesting conversation with the clerk helping me out. He pointed out the labels they stuck on the stainless steel fastener bins: "beware of galling!" They'd gotten weary of dealing with irate customers who would try to return stainless fasteners that were over-tightened (excessive torque) and not lubricated. Careless handling can ruin a stainless steel fastener in an instant. I lubed the boom splice bolts before firmly applying torque.

Lubrication of fasteners

Lubricating the threads of a bolt (or nut) before use is often good practice. Aside from prevention of galling of stainless steel fasteners there are other benefits. One is that non-stainless, non-galvanized fasteners succumb to rust far slower when coated with grease, and grit has more difficulty being driven into the threads by weather. Later removal of the fastener is easier. Common grade 5 bolts and nuts fall into this category.

The second benefit is setting the correct torque. When nuts are tightened on a bolt some of the applied torque is due to friction in the threads rather than axial force of the thread surfaces. This results in increased risk of insufficient torque leading to future loosening due to vibration or thermal cycling. A thin film of grease reduces this risk by eliminating friction, without increasing risk of the parts "sliding" apart.

There are unique lubes available for every imaginable fastener alloy. Those are the best though not always necessary. A thin coating of a non-optimum lube is better than none at all. Most often I use white lithium grease. Over many years I've had good success with it. It's cheap and widely available.

Lock washers vs. double nutting

Writing about lock washers on round tubing reminded me of a conversation I had with a tower pro. He said that they are increasingly skipping lock washers entirely since they have had too many instances of lock washers failing in service. That is, they break in two. Whether this is due to the rigours of weather and stress cycling or washer quality wasn't made clear to me.

The alternative they and many others often use is to start with a flat washer rather than a lock washer between the work surface and the nut. After applying the required torque they then put on a second nut. The first is held with a wrench as the second nut is tightened. The claim is that the locking action is excellent and due to the nut being thicker than a lock washer there is less chance of fatigue failure or loosening.

I cannot vouch for whether this is indeed superior. It is a technique I've used in other applications with good effect but never on towers and antennas.


Most hams have experienced or are aware that yagi tubing elements are prone to high frequency oscillation when the wind blows. The sound may be audible and thence comes the name of the phenomenon.

Damping can be used to reduce singing, and eventual element failure from metal fatigue. Old Hy-Gain mono-band yagis are especially notorious in this regard. Rope inserted in the elements is a common method of mechanical damping. Newer Hy-Gain element tips are roped. This may be inadequate.

15 meter reflector (second element from the end of the boom) singing in the wind

I mention this since during my inspection of the TH7 I discovered that the 15 meter (mono-band) reflector was singing, even though the tips are roped. After lowering the antenna I reconfirmed that the ropes were in place. None of the other elements was singing at the time or during a later climb. I find that the trapped elements are more immune from singing, likely due to the tube diameter transitions from small to large to medium around each trap.

I decided to leave the damping alone for now. The singing was intermittent rather than continuous so it may be that the tip ropes alone keep metal fatigue under control. I will check again next year.

More problems

There were additional mechanical problems with the TH7 that I had to address. Several of the boom-to-element clamps were inadequately tightened, and some bolts lacked a lock washer. They had not loosened: I didn't tighten them enough. A few of the elements had rotated on the boom a few degrees. This is not enough to be a problem, but it would surely become one in future.

I carefully tightened all the clamps and realigned the elements. Or perhaps not so careful since I managed to miss one of the driven elements. The driven elements are close to the tower so this oversight was easily remedied.

When the TH7 first went up in June I noticed that the SWR minimums were at higher frequencies than expected (per the assembly instructions) on 15 and 10 meters. I rechecked all measurements. I discovered a few small (< 1") errors and that the first 10 meter director was 3" off its correct position on the boom. By placing the antenna 6" higher on the mast I was better able to route the rotation loops of the this and the 6 meter antenna above it so that they ran orthogonal to the boom and driven element phasing harness rather than parallel.

The SWR problem did not go away. I tested it with an analyzer at the antenna. The ancient RG213 feed line show a small amount of age-related irregularity and could affect the measurement. I now suspect the balun since the pattern of the TH7 seems to be fine; that is, it is a feed point problem. I will test that hypothesis later by attaching the analyzer directly to the feed point.

While the TH7 was off the tower I measured the SWR of the A50-6. It improved a small amount. This is evidence of unwanted mutual impedance that could be affecting 6 meter performance. This is not unexpected for yagis with 20'+ boom separated only 7' on the mast. I plan to push the A50-6 higher up the mast to reduce coupling. But not right now.

The TH7 boom truss mast support that I cobbled together from spare parts was unstable and ready for replacement. I had done this because not all the original parts for the truss came with the antenna (I bought it secondhand). I constructed a better support bracket and installed it when the antenna went back on the tower.

Hopefully no more distractions

Trouble on the Trylon was not accounted for in my fall antenna and tower planning. Luckily the cost in time was not excessive. What it did was pretty well push me off the air for close to two weeks, and missed one contest I had intended to operate: the California QSO Party.

Now it's back to work on the big tower. Progress has gone in bursts depending on availability of friends for ground crew. I am gradually getting closer to having antennas nice and high.

Monday, October 2, 2017

Hanging a Top Loaded 160 Meter Vertical From the Big Tower

There is a lull for the moment in activity on the big tower. Parts are on order, metal fabrication needs to be done and I need to wait for helpers to be available. Although I hate the delay this is an opportunity to get busy on other priorities, which are numerous.

One of these is an antenna for 160 meters. So I sat down to review my options and design something that will get me through the winter season. I decided to shelve my original 160 meter antenna plan as too problematic and time consuming to be undertaken this year, if ever.

A horizontally polarized antenna for 160 meters is a poor choice even with a 43 meter tower; that's still only ¼λ, far too low for effective DX communication. So it has to be a vertical. I could shunt feed the big tower, except that for SO2R and multi-op contesting use of the tower in this fashion pretty well precludes use of any of the antennas for other bands mounted on the tower. Besides which, with all the yagis and mast on it the electrical length would be longer and therefore less predictable. Radials have to be rolled up in the spring before the hay grows and the ticks return.

The trees near enough to be useful as vertical supports are under 25 meters height and near to other planned antennas or the power line. In any case I don't have a good way to send a rope and wire that high and through dense foliage. It's a solvable problem but not expedient.

Since my long term plan for 160 meters remains unsettled I am happy to pursue a temporary solution to get me through this coming winter and contest season. Doing nothing isn't an option since I am missing too many QSOs and multipliers with makeshift approaches such as loading my 80 meter inverted vee last contest season. I worked some DX (over 30 countries) with great difficulty, and almost all were contest super-stations.

I settled on a what is a fairly popular antenna: a wire vertical top loaded with a 2-wire capacity hat. It is effective, can hang off the big tower with long rope and is efficient with a modest number of radials. The design is also popular in vertical yagi arrays since multiple elements for multiple directions can be hung around a big tower. The tower serves as the driven element.

Basic design and potential problems

After some geometry and experimentation with EZNEC I settled on a design where the vertical is 21.3 meters tall and each half of the top hat 13 meters long. It resonates at 1.830 MHz, near the centre of the band segment for CW DXing and contesting. The 'T' is at an angle of 45° so that it can be placed 20 meters from the tower and the catenary rope tied off near the top of the tower. Impedance at resonance is 27 Ω.

The choice of distance from the tower allows enough space in the hay field for 30 meter long radials without the need for an extremely long transmission line. The area is to the southwest of the tower, approaching the stone wall surrounding the yard area, and overlapping the south guy anchor. The catenary rope will be tied off to a tree or a stake in the ground, which will be determined during final layout of the antenna.

Transparent 60 m diameter circle roughly marks the extent of the antenna's radial system

The antenna is easy to model, with a few cautions. The tower is grounded for lightning safety with a 10' long ground rod (9' in the ground). This cannot be directly modelled in NEC2 so I used the MININEC ground option in EZNEC. The impedance of the ground connection must be estimated and simulated with a resistance load at the bottom end of the wire representing the tower. The tower itself is simply modelled as a 30 cm diameter wire, which is consistent for a lattice triangular structure with 20" (50 cm) faces.

I tested the model with both grounds before adding the tower to identify any modelling anomalies. MININEC ground is required in the full model since the tower is grounded. The antenna is raised slightly above ground (20 cm) so that it and the radials can be modelled in NEC2. The 27 Ω resonance impedance mentioned earlier is from the real, high-accuracy ground option in EZNEC. Switching to MININEC ground the reported impedance drops 10% and the resonant frequency moves downward an insignificant 2 kHz (-0.1%). The reported gain also shows a small change due to ground loss differences in the two ground models. MININEC reports 1.0 db gain versus 0.4 db for real, high-accuracy medium ground.

Based on this comparison the antenna is remarkably similar with both EZNEC high-accuracy ground and MININEC ground. This provides some assurance that the full model that uses MININEC ground is useful and reasonably trustworthy.

The antenna and capacity hat are 14 AWG TTHN house wire. There are 16 30-meter long radials made of 24 AWG insulated copper wire that are tentatively planned to be the individual strands taken from stripped bulk data cable. With this many radials the system begins to show the characteristics of a non-resonant ground plane, so the chosen length can work well. More radials are of course better though not enough to justify the trouble for a temporary antenna.

The major difficulty using 24 AWG wire for radials is their fragility. I²R losses are negligible at 1,000 watts since the current divides among the radials. It is quite low in each, low enough to substantially minimize loss. It works out to a small fractions of a decibel.

There is no real need for the radials to be 40 meters long since the system is non-resonant, and in any case they are electrically longer due to the adjacency to ground which lowers the velocity factor (VF). A good place to learn more about this at N6LF's site where he has extensively documented his many careful experiments on low band verticals and radial systems.

Now, about that tower...

The antenna itself is unremarkable. Many hams use this or a similar design on 160 meters. There are enough of them out there to assure that it can work quite well. My model of the antenna confirms that and it appears reliable based my explorations with EZNEC.

Now we come to what is perhaps my greatest concern: the impact of the 150' (really ~143' or 43 meter) tower on antenna performance. Notice in the EZNEC model view above that there is significant current on the tower since, at 43 meters and grounded, it is resonant at or near the 160 meter band. Worse, the distance between the tower and vertical is 20 meter (⅛λ), an ideal separation for a 2-element yagi!

With only a single antenna for 160 meters I am concerned that if the tower acts too much like a parasitic element that the pattern will discriminate against directions that are useful for DX and contest contacts. When loaded with mast and antennas it will be electrically longer and may act as a reflector which will inhibit my ability to work Europe (northeast). That would be bad. Some hams use this effect to create a directional set of verticals surrounding a tall tower. Since I will have only one an omni-directional pattern is preferred.

Of course there would also be gain towards the southwest, covering the bulk of the US. This is not a great trade off since the gain is small. F/B is the greater concern. That's what yagis do.

Exploring the landscape

To investigate the range of possible outcomes I ran the full model while varying the height of the tower. This is not exactly equivalent to a 43 meter tower with a capacity hat (top mounted yagis) however as long as the effective (electrical) length is not too much more than the physical height the modelled results will be more than close enough to gain an understanding of the tower's impact. I need insight more than I need high accuracy.

I varied the height from 35 meters to 55 meters in steps of 2 meters. At each step I used the model to measure the gain, F/B, feed point impedance and resonant frequency (X = 0). The plot is quite interesting. Tower grounding (ground rod) is simulated by a 20 Ω load in series with the ground connection.

The first thing to notice is that at a shorter height the tower acts as a director element. Since the pattern is with respect to the southwest I show that reversal as a negative F/B, while keeping the gain relative to the main lobe. At 41 meters height the tower's action as a reflector is accentuated.

The true maximum F/B is very sensitive to tower height and my chosen steps of 2 meters is too coarse to show how high the F/B can go, which is in fact more than 12 db. On 160 meter a yagi has a very narrow effective bandwidth.

Azimuth plot for an electrical tower height ~43 meters;
almost, but not worst case for high F/B
Radiation resistance of the vertical dips sharply in the tower's "yagi zone", as expected. It gets as low as 12 Ω, or half its value in isolation. The plot does not clearly show the change in resonant frequency due to the scaling. It dips down to 1.810 MHz (-1%) when the tower is an optimum reflector then slowly rises to 1.820  (-0.5%) MHz. Up to 55 meters height it never quite makes it back to 1.830 MHz, its resonant frequency in isolation from the tower.

Of most interest to me is that the gain and F/B only gradually return to normal as the electrical height of the tower increases. With a mast projecting 3.5 meters above the tower and holding two large yagis this is what I can expect to experience. That is, a loss of 2 db towards Europe and a similar gain towards the US midwest. Anecdotal data from hams with a similar antenna is consistent with the model. There is little effect in other directions.

Impedance at the greater (electrical) heights is a respectable 21 Ω, a drop of only 10%. The antenna will need an L-network to lower the SWR from slightly over 2 at resonance. This is easy to build. Most likely I'll reuse the box for the 80 meter feed of my previous tower back in Ottawa. I'll do the design once the antenna is built and I measure the actual R and X values. The antenna's SWR bandwidth is good and will exhibit a good SWR across 1.8 to 1.9 MHz with a simple L-network at the feed point, provided the tower resonance is outside its yagi zone. L-network tuning is expected to change as yagis are added to the tower since that will change the mutual impedance with the vertical.

On to construction

This antenna project will go ahead later this month. It'll be done after the prop pitch rotator shelf and mast are raised to avoid the catenary interfering with the lift. I am also waiting to see whether my neighbour will bother to take a second hay crop off the field. There may not be enough there for him to take the trouble, so I am likely free to proceed when ready.

I am looking forward to operating 160 meters this winter. Never before have I had a good antenna for that band so it'll be a new experience. Most of my 160 meter operation in the past has been contests from other stations. I expect to have some fun bumping up my DX totals and contest scores.

Once the tower project is complete you can expect a return to more articles like this one, about antennas and operating. Building support structures is important but is not my primary interest.