Sunday, December 30, 2018

Year End Retrospective

My station building plan for 2018 was very ambitious. Too ambitious, as it turns out, so I had to walk back my expectations and prioritize projects. Even so I did accomplish quite a lot, although some of it has yet to bear fruit.

Here is what I managed to accomplish:
  • Build the 3-element 80 meter vertical yagi. The switching system, the final component, is now under construction. Assuming I sustain my energy to work in the cold weather it should be complete in January. Until then it is fixed on Europe.
  • After several iterations the prop pitch direction indicator seems to be working well. The next step is to improve the usability of the home brew control unit.
  • My planned second tall tower (140') was planted and is now more than halfway up (80'). Depending on weather and ground crew availability I will get to 100' this winter and complete it in 2019. It is not absolutely needed until late summer when I expect my long boom 20 and 15 meter yagis to be ready.
  • I gutted all the temporary coax and control cabling and rebuilt it from scratch. That project is nearing completion. When done I will be ready for SO2R and M1 and M2 multi-op low power, optimized transmission line performance and cabling ready to go for complete station automation. That final big step is a 2019 project.
  • Physical and electrical design and initial construction of long boom yagis stacks for 20 and 15 meters. These are slated for the new tower. Over the winter I will purchase enough aluminum to determine the optimum physical design for the elements. Two of the booms are built and I have the aluminum on hand to built the booms for the top (rotatable) yagis of the stacks.
  • Electrical and physical designs for high performance 40 meters yagis is underway. It is possible that I'll build a prototype element this winter and raise it on the tower to test its weather performance.
With respect to operating achievements there is much to be satisfied with:
  • Competitive contest performance in the low power and QRP categories. Three #1 plaques were added to my collection.
  • Exceeded my 6 meter DX objectives with FT8 during the summer sporadic E season.
  • 160 meter DXCC.
  • 300 DXCC entities, starting afresh from my return to the hobby in 2013.
  • Experimentation with additional shack automation features for contests.
I even found time to have a life outside of amateur radio and assist others with their towers and antennas. My 2019 plan will be finalized in the new year. It will still be ambitious but more doable since a lot of the advance work was done this year.

With respect to the blog I see that the article count in 2018 is comparable to previous years. That's a good sign that my enthusiasm for keeping it going hasn't declined. What does concern me is that there appear been fewer antenna articles than I'd like. From reviewing web site statistics most readers would probably agree. We all want more articles about antennas!

I do have a few antenna articles in the pipeline so that lack will at least be partially addressed early in the new year. Unfortunately for antenna articles my energies have been in part deflected elsewhere this year, so that is what I write about. Despite this I hope that there is enough variety and food for thought to keep you interested in coming back.

My regular audience is not exceptionally large. Although it seems to be slowly increasing it is not my objective to increase readership at all costs. I could do that easily enough by writing about politics! By continuing to focus on topics that interest me -- towers, antennas, DX, contests, etc. -- there is a natural limit to the potential audience. I'm okay with that.

Blogger is not the greatest platform for blogging these day. I find it difficult to make it easy for readers to comment without inviting a deluge of spam. Features are lacking and Google has pretty much abandoned the service with respect to bug fixes and new features. It isn't enough of a problem to incite me to make on the effort to move the blog elsewhere. I work around the problems and suggest that readers contact me by email when leaving comments is too difficult.

With that I will close off the blog for 2018. On the air I closed off the year with two contests: RAC Winter contest and the Stew Perry Top Band Challenge. The latter delivered some spectacular 160 meter DX for my QRP effort. Score details and soapbox can be found on 3830.

See you next year, on the blog if not on the air. I wish everybody a happy new year.

Wednesday, December 26, 2018

Choosing L-network Capacitors

Anyone who works on high power amplifiers and antenna matching networks know that suitable capacitors can be expensive. They must be stable, highly efficient and withstand high RF voltage and current. Choosing lesser components will only result in failure and replacement. Air dielectric capacitors, whether variable or home brew with a fixed value, work well but are large, usually far too large for where we want to fit them.

In my junk box I have a modest quantity of capacitors that are rated for high power RF applications. Of course one never has enough or of the desired values if antenna experimentation is to be done. Because I have been using no more than 200 watts since returning to the hobby several years ago I have often taken the easy way by using unsuitable capacitors in matching networks, knowing that they would most likely survive at these power levels. So far I've had no spectacular failures or excessive heating.

Since my plan is to run QRO eventually, probably next year, taking a shortcut on RF capacitors is no longer an option. I have done some reading and research to find alternatives that are not expensive and will do the job. This is important because I do like to experiment with antennas, which requires a stock of capacitors covering a large range of values.

As already stated, variable capacitors are too big. For the low bands fixed padding capacitors are needed in any case so variables are no panacea. Years ago variable capacitors were commonly used because there were few affordable instruments to measure antenna impedance and design a network to convert complex impedances to 50 Ω, and the math is difficult for most hams.

My 160 meter antenna L-network

We have made progress. Now I measure the feed point impedance with an accurate analyzer, plug the values into software tools and -- presto! -- out pops a matching network. I design coils again using software, pick one more capacitors and measure their value and built the network. It is now quite easy to get a near perfect SWR in one pass of this procedure. An example is my article on designing and building the L-network for my current 160 meter antenna.

For that network I needed a capacitor of around 2150 pf. From my junk box I pulled out an ancient 2200 pf disk ceramic capacitor. It worked well despite being of uncertain voltage rating and RF efficiency. But it was not without problems. There was a noticable temperature rise during extended contest operation on 160 meters, which in turn altered the capacitance and SWR.

To compensate I preset the rig's ATU for the "hot" capacitor. When the SWR started its inevitable rise I would switch in the ATU and continue operating without further problem. Happily the capacitor suffered no catastrophic failure as I feared.

This fall I attempted to improve the situation. The original capacitor (see above) was replaced by a chain of higher value disk ceramic capacitors. Power handling of small capacitors can be increased by connected higher value capacitors in series or lower value capacitors in parallel by decreasing voltage across or current through each capacitor, respectively.

It didn't work as expected. Although the photo is fuzzy you may be able to make out the "Z5U" rating symbols. I foolishly paid no attention. When put into service the heating effects were far worse than with the the original capacitor. Within 15 seconds of CW transmission at 200 watts the SWR swung wildly upward. Wait a minute and the low SWR returned. It was almost impossible to keep the SWR low without frequent re-tuning of the ATU.

Not all capacitors are equal

After a month of this I did what I should have done at first, which was to find out what Z5U means. In brief, the dielectric properties are such that the capacitance is acutely sensitive to temperature and efficiency is poor. These capacitors are suited to RF bypass usage where the capacitance value isn't critical. It was time to find something better.

For those who want a ham-oriented introduction to RF power capacitors I highly recommend an online article by I0JX. The technical depth is just enough to explain capacitor design and construction that the average ham should be able to understand. He surveys the variety of capacitors in the market and how to identify which ones are appropriate for high power RF applications, and how to pick the right capacitor at each point in a QRO amplifier. This is directly applicable to antenna matching networks.

It turns out that the 500 pf doorknob capacitor I used in the L-network of my short 80 meter vertical in Ottawa several years ago is not rated for carrying QRO. Rather it is only adequate for RF bypass. Fortunately it is big enough that the 100 watts maximum I ran at that time let it run cool. Not all of those large ceramic doorknob capacitors are the same.


While visiting a friend in early December he regaled me with the woes he's had with finding replacement capacitors in the pi-network of his Eimac 8877 HF amplifier. These are switched in for 160 meters because the air variable capacitors for the plate and load control need padding. Unfortunately the capacitors he had that were properly rated were too big to fit in the small space where the existing ceramic "doorknob" capacitors are situated.

My eyes lit up. I calmly asked to see these overly large capacitors that he can't use. He pulled out a cardboard box full of large and ancient mica capacitors. It was a treasure trove for a scrounger like me. Having done him a few favours he let me go through them and find what I needed. I was fortunate to find one with a value of 0.002 μF, which is 2000 pf. It measures 2300 pf, near perfect for my 160 meter antenna.

A week before Christmas I cut out the problematic chain of disk ceramic capacitor and popped in the mica capacitor. As you can see it's quite large. The screw holes turn out to be the same size as on my stock of doorknob capacitor, making it easy to attach to the existing fitting on one end. On the other end the screw holds the severed lead of the removed capacitor.

160 meter bliss

Back in the shack I turned on the transceiver and tested the modified L-network. The SWR was back to 1 at resonance, and less than 1.5 from 1800 to 1840 kHz. After 10 minutes of hitting it with 200 watts of CW the impedance was rock steady. In subsequent operation it has continued performing beautifully.

I am hopeful the capacitor will work well with 1000 watts. There is some reason for doubt. These ancient "sandwich" style mica capacitors are considered unreliable over long use due to the mechanical construction. New mica capacitors of equivalent rating are extremely expensive. My hope is based on the RF stability of all varieties of mica capacitors despite my failure to locate specs on the internet of this specific capacitor type. It's just too old, I guess. What little I could learn tells me that the RF current rating should be over 10 amps, more than enough to handle 1000 watts in an L-network designed for a moderate impedance transformation.

One further note on L-network design as it relates to capacitors. For every impedance transformation there are typically four topologies: shunt L or C and series L or C, with the shunt placed on either the generator or load port. The one I am using places a shunt C across the load port, with the L in series between the ports. Tools such as TLW, which comes with the ARRL Antenna Book, allow you to select the network topology.

I chose this topology because it produced values of C and L that were convenient to implement. Topology choice also determines whether the network rejects harmonics (low pass filter), an important consideration for SO2R and multi-op contests. At this time I did not bother to do so. I will when I decide on a permanent 160 meter antenna. My L-network designs for the 80 meter vertical yagi use a low pass filter topology.

Going forward

I continue to keep my eyes open at flea markets for high power RF ceramic capacitors. You have to get there early because they go fast! That is, the ones with high voltage and current ratings, and those with high capacitance values. The electrical boxes I use for matching networks have enough room for putting a couple of mica or doorknob capacitors in series or parallel to get the values I need. I can probably get a few more of the large mica capacitors from my friend to add to my stock.

For the two L-networks in my 80 meter vertical yagi I will conduct another experiment. I ordered a large number of small valued high voltage, high stability disk ceramic capacitors that I can add in parallel to get the values I need. These capacitors are very cheap when bought in bulk so the financial risk is negligible.

We'll see how they do in practice, first with 200 watts and later with 1000 watts. If it doesn't work out, well, it may be back to hunting for surplus mica and ceramic doorknob capacitors.

If you've never given much thought to the capacitors needed for building matching networks I hope this article has given you the incentive to learn about capacitors and encourage experimentation. For those who enjoy playing with HF and MF antennas you will see the difference when the proper capacitors are used.

Saturday, December 22, 2018

Inferior Tools and Their Uses

Not enough hams understand, appreciate or recognize high quality tools and hardware. I have been handed sockets that shatter when torquing a grade 5 bolt, knife blades that dull and notch when touching steel and screwdrivers whose tips break or bend. Recently a few low grade bolts were mixed in with my purchase of grade 5 bolts sets for splicing sections of my new tower, which I discovered when the threads stripped while leaning on the wrench.

Paying for quality makes good economic sense since you won't soon be shopping for replacements or left cursing at the top of the tower with no recourse but to come down and replace a failed tool or part. You know the saying: you can pay now or you can pay even more later. Over my long career as a ham I have learned the lesson through painful experience and I can now say that it is in my bones.

Despite this good advice there is a place for tools of lesser provenance. I'd like to cover a few of these as they relate to tower work.

Multi-sized ratchet wrench

When I first noticed these tools on the shelves of hardware store several years ago I turned up my nose at them. Ratchets are by nature prone to failure and the more features they sport the more unreliable they become. A fantastic sale price convinced me to give them a try. Now one have one or two of these with me on every climb. Each wrench has 4 sizes, two on opposite sides of each head.

The set I have hasn't yet suffered a failure. Considering how much use they get that's impressive. The tool encourages me to check bolts more often and make it easy to tighten them well. An important feature is that the ratchet can be reversed with a flick of the thumb of the hand holding it. Tools that allow one hand operation are wonderfully convenient when you're hanging off the side of a tower. Because the large head makes it impossible to fit these wrenches into small spaces such as splice bolts on triangular leg towers, read ahead to the next section.

Adjustable wrench

Can you remember the size of every fastener you have on top of your tower: tower attachments, antennas and electrical connections? Do you keep a record of each one use it to select the wrenches to pack for your climb? I do neither. It's tedious, prone to omissions and errors and you can never find the document when you most need it.

In addition to a selection of good quality open ended wrenches I usually pack a small adjustable wrench to avoid having a tool roped up the tower or, worse, having to climb down to get it. This tool is far from ideal but in a pinch you'll become a believer.

Utility knife

These are cheap, fit easily into a tool bag pocket, can be operated with one hand and despite easily dulling a fresh sharp blade is had in seconds. You can use them to sever tie wraps and tape in one motion, strip wires in a pinch and for other odd jobs. There are far better knives out there, ones with longer lasting blades, more ergonomic and sturdier construction. I avoid the cheapest ones that do not take replacement blades or provide a means to lock the blade position. The latter can prove dangerous.

Years ago I used a multi-blade camping style knife such as the venerable Swiss Army Knife. Despite their ubiquity the steel quality is not up to hard use and the blade can jackknife on your fingers with an injudicious motion.

Multi-tip screwdriver

Many small electrical connection screws on antenna feed points, baluns and control lines have a screwdriver head, not a hex head. The variety of tip styles is the dilemma. I always pack proper screwdrivers for the work I am planning, but too often I don't know which tip styles I'll need, or I need to work on a connection other than the ones planned.

A stubby multi-tip screwdriver such as that pictured is cheap and takes up little room in a tool pouch or pocket. The steel quality is better than I would expect for the price; I haven't yet ruined a bit. When not up the tower I keep it in a kitchen drawer for routine household repair jobs.

Old guying hardware

In my garage and outdoors I store an inordinate quantity of old and rusty guy hardware. These include thimbles (as shown), turnbuckles, guy grips. guy strand, shackles and much more. It finds occasional use when pulling and adjusting guys, lifting jobs, messenger cables and tram lines.

I would never use them to permanently guy a tower since they do not have enough service life remaining. Just be sure to inspect old hardware before using it. I am blessed with lots of space to store stuff that others would (sensibly) discard.

Cheap vinyl tape

For coax connectors and other critical electrical splices I use high quality sealing and protective tapes and covers. A roll of moderate quality vinyl electrical tape is usually in my tool pouch for less critical tasks. These include securing cables to towers, masts and yagi booms. Several wraps of vinyl tape holds well and doesn't risk excess compression from cable ties on expensive and fragile cable. I also use the cheaper tape to weatherproof temporary connections. Just be sure temporary doesn't become permanent.

On the ground it can be a handy way to secure coils of guy strand, coax and other long cables into tight, easily handled packages for transportation and storage. The tape can later be cut without a qualm since it is so cheap. Do watch for tape that can't be easily worked in cold weather or that leaves a sticky residue when removed. Cheap tape also has a habit of unravelling when exposed to weather.


I drop things. Dropping tools from 150' can easily destroy tools, whether cheap or dear. It's comforting to know that if I drop a cheap tool I have lost little except time. But do make sure your friends below are wearing hardhats! When I drop a good tool I pull out one of my cheap tools.

Good tools can sometimes surprise. After going through a series of "lifetime guarantee" ratchet socket wrenches over the years that spontaneously disassembled I chose to invest in an expensive tool that I purchased in a shop that caters to professionals. A friend dropped it from 75' directly onto the concrete tower base.

The socket and wrench separate on impact. I never did find that socket, so it must have bounced a considerable distance. I expected the wrench to be junk. To my surprise it had only a small scratch on it and it worked perfectly. Two years later it's still working fine.

Spending money on good tools can pay dividends. Even so there is a place for cheap tools when doing tower work. Choose wisely and tower work can be proceed on schedule and without undue stress.


Tower and antenna work is hard on gloves. Thin work gloves are inexpensive and I discard them when they are too worn for safe use. Gloves suitable for use in cold weather, of which we have an abundance, is another matter.

There are good products on the market, for a price. I try these from time to time. But for daily use I have another solution.

I participate in a variety of sports, including winter sports. As a matter of course I buy well insulated gloves with leather palms and that allow excellent finger flexibility. Eventually they wear out, sporting tears and other defects. When this happens they become tower gloves.

They are usually good for one winter season of tower work. Tears that expose the insulation can be patched with electrical tape with only a small loss of flexibility. Your hands stay warm and protected from abrasion and bruises at almost zero cost. You can typically find excellent sales on ski gloves of this type in late winter.

Even if you use good gloves be sure to keep a pair of cheap gloves with you. Otherwise you'll have a cold and painful descent when you drop one. And you will.

Saturday, December 15, 2018

First MSK144 QSO on 6 Meters

I have a decent antenna for 6 meters, 200 watts and WSJT-X. I used WSJT-X extensively during this past summer sporadic E season with great success. On this basis it should be a simple matter to try out meteor scatter on 6 meters. And it is! The recent Geminids meteor shower provided ample opportunity to learn how to do it.

After going through the manual and making the various adjustments to my setup to use MSK144 on 50.260 MHz I proceeded to monitor and make test transmissions. Within an hour I was comfortable enough to call someone without any real risk of messing it up. Soon I had my first MSK144 contact in the log.

Unfortunately this small accomplishment did not excite me. Indeed, I really don't know if it was meteor scatter or sporadic E, which is now reaching its wintertime peak. While monitoring activity with headphones I certainly heard the unmistakable signature of meteor trails on a variety of signals. It is less easy to determined what transpired during my QSO, or in fact in any specific case. It may have been a mix during the three minutes it took to complete the contact.

I have experience monitoring meteor pings in the 1980s and early 1990s when I was very active on both 6 and 2 meters . In the latter case it is easy to be sure that it is meteor scatter since sporadic E is so rare at the higher frequency. However, even then I never did overcome the hump between monitoring and participating. It seemed to require a lot of power and my plan to build a kilowatt amplifier was delayed then abandoned when I exited the hobby in 1992.

I like the new digital technology that makes meteor scatter so much more doable than with the CW and SSB procedures of the past. Perhaps if I were to try MSK144 meteor scatter on 2 meters I could become more enthusiastic. That will have to wait for at least another year. But I will give it a chance. Perhaps my present disinterest is due to the lack in the potential of achieving something unique and interesting that I can do the same or better on sporadic E. It isn't always easy to internally reflect on what motivates us.

Speaking of ennui, I ought to mention that my enthusiasm for winter sporadic E is muted, as it always has been. After monitoring the FT8 watering hole at 50.313 MHz for several hours there was not a single station that I have not already worked. In other words: same old, same old. As much as I delight in the technological and operating challenges of amateur radio I still want some novelty. DX possibilities in December are at best modest.

I'll put the digital modes aside for awhile. For sure I will be back for the summer sporadic E season, perhaps with a few improvements to my 6 meter antenna situation. The main one being to replace the RG213 with Heliax. Beyond that I will at some point return to 2 meters DXing, with a suitable antenna and power. When that happens I am sure that I'll try meteor scatter one more time.

Monday, December 10, 2018

Customizing Guy Hardware

Deep in my pool of partially finished blog articles is one about how one goes about calculating the guying requirements for tower and antenna loads. I may eventually finish that one, maybe. I've been reticent since I am not a structural engineer and I want to be sure to give reasonable practical advice that will not mislead. We'll see how that goes.

Instead I'll focus on a narrower topic in this article: customizing guying hardware for my new 140' guyed tower. When you buy a used and obsolete commercial tower and you want to be economical (that is, cheap) there may be components to be fabricated or improvised. Whether original or replacement, all components must be up to the demanding loads such a tower will be subjected to.

My choices are not necessarily the choices others would make. That isn't important. What does matters is to design and build components that are up to the demanding requirements. Many choose to overcompensate with excessively heavy, strong and expensive solutions. Having some understanding of what is going on can lead to more moderate solutions. That is my approach.

Anchor rods

Wandering through my local tower company's stock of surplus parts several lengths of steel that made good anchor rods were spotted. These are galvanized angle stock 10'-6" long and ½" thick. There are pre-drilled holes suitable for attachments top and bottom. The larger ⅞" holes are the ones I used.

Although I neglected to take a picture of the completed anchor rods bottom end what I did is easy to describe. Approximately 3' lengths of ⅞" steel rod (which I got as part of the deal) were inserted through those holes. These are the load bearing members that couple to the reinforced concrete anchors previously shown.

I used two rods to double the load bearing surface. Using the bottom hole alone is a poor choice due to the small amount of steel between the hole and edge; guy tension pulls towards the top of the picture which puts the load on the bottom of the holes.

A typical commercial anchor rod for this application is 1" round galvanized stock. Since strength is largely in proportion to the cross-sectional area of the rod ½" angle stock of this size works well, and can be stronger if correctly adapted. I have seen ham towers with two ¼" angles back-to-back, which is roughly equivalent. One difference between round and angle stock is that the round stock behaves more predictably if the rod is not installed at the correct angle, both lateral and vertical. So if you do use angle stock, which is usually less costly, oversize angles are not a bad idea.

Guy attachment plates

Commercial anchor rods have at least a closed eye at the upper end for attachment of guying hardware. Mine have a few holes that I put to use. Those holes are symmetric with those on the bottom end. It was up to me to come up with a suitable attachment plate.

What I do have is the original L & R equalizer plates for this tower. There are 5 holes for ½" turnbuckles with U terminations (similar to shackle pins) and one large 1" hole for attachment to the anchor rod. My challenge was to design a simple and effective method of coupling the equalizer plate to the angle stock. The alternative is to weld the back of the plate to one edge of the angle, similar to what I did for the existing LR20 tower.

First, it helps to get a little bit lucky. I was able to find ½" galvanized plates of the perfect size in those aforementioned surplus bins. Again, the price was unbeatable. All I had to do was machine them to fit. That is, once I calculated the required load capacity. Let's start with a brief discussion about shear.

The diagram comes from a Fastenal technical reference on a variety of load applications for structural fasteners. I highly recommend it. It shows the correct way (on the right) to use a bolt to link three plates under double shear load. You can imagine that the upward load is the equalizer plate (with the guys) and the lower loads the previously mentioned use of two linked angles as an anchor rod. Notice the importance of ensuring the load bears on the unthreaded surface of the fastener.

In my case there is only one angle. Coupling them in the simplest fashion is a case of single shear, which places a large shear load on the bolt shank, head and nut. This can be done but is not ideal. Double shear keeps the full load on the shank, leaving the bolt head and nut to merely keep the plates in position. You'll see an application of single shear in the next section, and the fastener requirements.

The existing ⅝" holes in the link plates were widened to ¾" to accommodate the calculated diameter of grade 5 bolt to comfortably exceed the load requirement. The unthreaded section of bolt under the head is 1-½", perfect for 3 × ½" plates (the equalizer plate is ½").

For the calculation I assumed a peak load of 3× the pre-load of 1100 lb on 4 guys (30% of 5/16" EHS guy strand breaking strength). The Fastenal technical reference provides excellent information about the strengths of various fastener types and grades. Indeed it provides far more detail than most of us would ever want to know.

To confirm my calculation I asked a friend with an almost identical tower what he uses. He has the same size ¾" grade 5 bolt. Although he opted for an A325 bolt, which is not really necessary for double shear applications.

During construction the upper bolt is not fully tightened to allow the equalizer plate to freely rotate. It will be snugged up a little when I'm done to ensure the three plates cannot twist.

Notice that I used holes on the link plates and the anchor rod far enough back from the ends to ensure the maximum amount of steel surrounding the stress points. This left barely enough room to fit the turnbuckle pins.

Tower guy yokes

The tower came with only two sets of the original LR20 guy yokes. I need four sets. The guy yokes are unique items that, like the tower, have been out of production for at least 20 years. In the photo below I show one set that I used to temporarily guy the bottom section until the first permanent guy station at 30' was reached.

The are made of ½" hardened steel with 9/16" raised threaded ends for extra large bolts that prevent pull out from the purpose-made holes in all tower girts. The girts are designed for this purpose. I add washers under the nuts to reduce the potential for stress risers and bending of the girt steel, which is not uncommon with LR20 towers.

The yoke design is a good fit for guy termination thimbles. The method of tower attachment allows the yoke to pivot to accommodate the wide range of angles across all guy levels. Because the steel is so hard it takes a bit of muscle to hold apart the arms of the yoke for insertion into and removal from the girt.

The custom yokes I designed and had made in a machine shop are shown above. This was the second attempt after the ¼" galvanized plates I provided to the machinist were bent at a greater angle due to miscommunication. He made new ones from ⅜" plates, which I painted since they are not galvanized. Machining was completed in my workshop once I decided on how to attach the guys.

Look closely and you'll see a few features of interest. First, the ½" bolts and nuts that splice the tower sections are not the same as the ½" fasteners on the yoke. The latter are A325 bolts. These structural fasteners are described in detail in the referenced Fastenal document. The bolt heads and nuts are larger than standard fasteners. The required wrench size is ⅞" rather than ¾".

The greater bearing surface is needed to withstand the shear force between the tower girt and yoke plate. Again I refer to that Fastenal document for a diagram demonstrating such single shear loading. The bolt head and nut experience stress risers and the shank has bending stress. A325 bolts and nuts reduce that stress. The stress is further minimized by keeping the plates -- tower girt and yoke plate, in my case -- tightly bound by approaching the maximum torque.

Another A325 bolt binds the yoke plates. Without it the guy tension would gradually bend the plates and allow them to tilt downward, both actions will weaken the plates and reduce guy tension. You should also notice that the original bolt (left) isn't long enough to allow the nut to fully thread onto the bolt. This was corrected (right) before the guys were pulled tight. When the picture was taken there was 700 lb tension on the guy.

I could have used shackles to connect the guy thimble to the yoke, but I don't have enough of the appropriate size. The shackles I planned to use have a pin opening of ½", which is not enough to accommodate back-to-back ⅜" plates. They would have fit the original set of ¼" plates. Instead I drilled the holes out to ¾" to fit a heavy duty thimble and guy grip.

The custom guy yokes are used at the lower two guy levels -- 30' and 65' -- where the guy angle is closest to horizontal. Considering that these yokes cannot pivot this is the best place for them.

Bearing plate

The tower bearing plate is indirectly related to guying. Its function is to transfer the vertical tower load onto the base pillar without creating point stresses while allowing the tower freedom of movement (rotation and tilt). The force involved is substantial, of which the largest portion is due to the combined vertical component of the total guy force vector. The tower itself weighs less than 2000 lb (0.9 tonnes) yet the vertical force can exceed 10,000 lb (4.5 tonnes) under severe wind load.

The opening in the base section is 1-⅝". The pier pin is ~1.3"; it doesn't have to be a precision fit. The bearing plate is a surplus ½" galvanized steel plate that was pierced in a machine shop to slide over the pier pin. The plate is approximately 7" × 7".

The dimensions of the bearing plate are not critical; L & R recommended 8" × 8". For the design load the ½" thickness is close to the minimum size. Thinner plates will curl over time, reducing the effective contact area. A plate wider than the 12" diameter of the vertical rebar cage is not well utilized. Over the years there will be some grinding of the plate due to the rotational load of the yagis. This is preferable to rigidly attaching the tower to the base.

The bearing plate is grouted to the pillar to improve mechanical coupling and to ensure the plate is level. It is difficult to perfectly level the concrete pillar when the concrete is poured and wet. Downward pressure is placed on the plate while the grout is partially. The plate is adjusted with a level. Excess grout is scraped off the sides of the bearing plate.


You'll have noticed my emphasis on using galvanized steel and fasteners for all components. Corrosion protection at these critical points is mandatory. Rust weakens the tower and replacement of corroded parts will eventually be necessary. This can be done but it is not easy.

Where I wasn't able to use galvanized steel the parts are painted with good quality steel paint or with cold galvanizing compound. I do the same with old turnbuckles. Even the tower itself which is hot dip galvanized and painted was cleaned and given a fresh coat of paint, using a compatible primer over bare galvanizing where the paint has worn off.

Anchor rods of any type must be galvanized or use another ground-rated coating because corrosion due to soil chemistry can severely shorten its lifetime. It is a good idea to dig down a foot every couple of years to check the rod's condition.

I'll close with a picture of the tower raised to 70', using all the custom guy hardware described in this article. As one might say about winter tower work: sure it's cold, but there are no bugs!

Thursday, November 29, 2018

CQ WW CW Recap

What a wild weekend that was. Overall I am pleased with my result though I know I could have done better. While my memory is fresh a recap is in order. There are lessons to be learned. Not only for me, but for others as well, even those with better or worse stations.

I will not dwell on my score or my competitive placement. You can visit 3830 to find that. Keep in mind that any comparison must take into account location, category and the difficulty comparing US and Canada scores due to the CQ WW rules. I find it more useful to compare multipliers -- zones and countries -- with those in comparable locations.

Station recap

My new contest station is incomplete, and the gaps showed in how I did. If you ever wondered by 3 db makes a difference, well yes it does. Even 1 db can put several multipliers in your contest log. In several case I am down more than 3 db than where I plan to be, and in comparison to the best single op stations.

160: T-top vertical with 8 x 30 meter radials, suspended by catenary from 40 meters height.
80: Low inverted vee at 19 meters and 3-element vertical yagi fixed northeast. When complete the yagi array will be switchable in 4 directions and omni-directional.
40: Low inverted vee (fan combination with 80 meters) and XM240 up 46 meters.
20/15/10: TH7 at 21 meters, TH6 at 43 meters and Explorer 14 at 32 meters fixed to Europe. I used tri-banders for expediency (already in my stock).

160 meters

I struggled on top band more than I expected, especially since conditions were good and a large amount of DX was heard. Despite being able to hear them my 100 watts wasn't good enough. I had more luck the second night when signals were slightly stronger and I recovered some ground. For general DXing my antenna works very well and I can often win in pile up over those with more power and less antenna. This weekend it simply didn't make the grade.

After importing my contest log into my general logging software I was pleased to discover I had at passed 100 countries on 160 meters. It took almost exactly 12 months, dating from when I put up the 160 meter antenna, the first full size antenna I've ever had for top band.

80 meters

Similar to 160 my first night on 80 meters was dreadful. The band was filled with DX but few could copy me. Again, the second night was far better when I had no trouble running to Europe both before and after their sunrise. Even so my multiplier count is poor. Lots of what should be easy shots were heard, but they did not hear me.

Much of the trouble will go away once the 80 meter array switching system is built since the inverted vee did not do well, yet it was all I had for directions other than northeast.

40 meters

This is one of the two money bands (the other is 20) when the sunspots don't come out to play. Doing well on 40 meters is critical to a competitive score. But the competition and QRM are fierce. You need a signal that will not only stand out above others but also allow you to successfully run. I am not truly there yet but I am certainly getting closer.

The first night was difficult. Running was near impossible, especially considering that the European path is already diminishing when the contest starts at 00Z. It was discouraging. The sunrise opening produced fewer multipliers than I hoped for. The next night was significantly better, though running was not as productive as hoped. That all changed with sunrise when several double multipliers (zone and country) came with an over-the-pole opening with good signals. But not all fell to my low power signal. A small 2-element yagi can only do so much even when it is up so high.

My best result was Sunday afternoon. After picking off stations on the high bands I was able to fully move onto 40 meters at 3 PM (2000Z). For the next 90 minutes I had a great run, almost all Europe. Many needed countries, and even zones, came calling.

20 meters

You must do well on 20 to produce a good score. My result was good though not great with respect to DX QSO and multiplier totals. As usual it was the early morning path to Europe that produced the most productive runs. I moved there as soon as the possibilities on the low bands faded after sunrise. With my current antennas I really want to turn the prop pitch rotator to bring the high TH6 to bear on Europe, and that also moves my 40 meter yagi away from multiplier hunting to the north and west. That's a problem that will be solved next year.

I only used the slightly lower Explorer 14 when I needed the TH6 elsewhere since, although good, it does not deliver the same result. Since 15 meters is open to Europe at the same time and the higher antenna is far superior there is no question that 40 meters must be sacrificed. Later in the day I used the lower TH7 for shorter paths, leaving the TH6 to pick off distant multipliers in South America, the Pacific and Asia, and the Explorer 14 to catch any Europeans in the anomalous afternoon opening (late evening in Europe).

15 meters

Only brief runs to Europe were possible since 15 meters was marginal. Mostly I spent my time multiplier hunting, or working US stations when little else was workable. Normally strong signals from South America were not. Some easy multipliers in the Caribbean were missed due to the brief midday window for this fairly short path.

10 meters

This one's easy. I worked nothing. Despite regular checking and some CQing when the band was most likely to open no signals were heard. It appears others in this northerly region had similar luck. I did not ask any locals to move for me. That would be an easy two multipliers: zone 4 and VE.

Problems encountered

The weekend was largely free of equipment problems. The major difficulty was the direction indicators for both rotators: T2X on the 20 meter tower and prop pitch on the 43 meter tower. In part this appears to have been due to moisture getting into the prop pitch pot and into the T2X control cable. The latter has several splices. The prop pitch direction indicator resumed working once the rain stopped and it had a chance to dry.

Better weatherproofing for the prop pitch pot is called for, though not this season. The T2X cable is already slated for replacement, and I may get it done this winter. 

There is some RFI with the computer display when using the TH7 and 80 meter inverted vee on the short tower. They are close to the house. Occasional weak RFI was present when yagis on the big tower were turned west, which is towards the house. This is tolerable now but will be a serious problem when I get an amplifier. I'll have to deal with it sooner rather than later.

Aside from a few software glitches that was it for technical problems. On the personal side I suffered no ill effects from operating over 40 hours (out of 48 possible). I do notice that when I get really tired I have more typos when running. Most were corrected while the keyer was playing provided I typed faster than the other's call sign was being sent. That's a challenge at 32 or 34 wpm!

Strategic options

My strategy was strongly constrained by my power level and antenna capabilities. It was often better to hunt for multipliers on less productive bands than run where I ought to be but could not do well. Sometimes the situation was reversed, when it was better to run, if only to the US, than hunt for multipliers that were not very workable.

Everybody's situation is different, so there is no need to go into particulars beyond the broader strategic choices implied. I will just say that running, when possible, is almost always the best choice. Most contest logging software will calculate and display the number of QSOs that are needed to equal one multiplier. If the number is 5 and you have a good run rate it is usually safe to continue.

But if there's a short opening expected to several needed multipliers it may be better to move and try that for a few minutes. It might be your only chance to work them. Of course if you are SO2R or multi-op you can do both! Indeed for most of us in non-rare areas that is the primary motivation to do SO2R. Secondary objectives are to work stations in general on another band or, for the mutants among us with super-stations, try 2BSIQ (two bands synchronous interleaved QSOs) to concurrently run on two bands.

Regrettably (or not) I am not a mutant and although my station is getting nice and big it will never be a super-station. I am content to aim for run of the mill big gun status and do SO2R. My station is very close to being SO2R compatible, low power CW only for now. I will finish the build mid-winter and then practice. In next year's CQ WW contest I should be able to improve my multiplier count.


Do you truly want to easily and quickly improve your contest scores? You must run, even if you prefer not to do so. Most of the little gun contesters of my acquaintance won't do it. Either they find the prospect intimidating or simply assume that it not possible for a small station. This is never true. A big factor in my two world #1 QRP plaques in CQ WW SSB (and a #2 on CW) were only possible by running. Although that was when we had sunspots and there were excellent opening on 10 and 15 meters where 5 watts can be very effective. If a QRPer can do it so can anyone.

Unless I'm specifically looking for certain multipliers I will try to run. I resort to S & P only when that isn't possible, or late in the contest when I must find those big guns who seem to run all the time leaving no other way to work them. While scouring the bands for stations to work I find a clear frequency I will frequently try a bit of CQing. If nothing happens in a minute or two, or it does but after several minutes the rate is poor I'll resume S & P. Eventually it'll stick, whether due to a change in propagation or my chosen frequency is nice and clear over in the target continent.

Big guns run the majority of the time. You might think multipliers might be missed by doing this, but that would be wrong. Try running you will be surprised by who calls you! Soon you'll understand the value of running even if you're a little gun. To do it well you want to be quick, both in speed and procedure, so that callers you don't answer immediately will stick around rather than fret over time wasted and QSY.

As an example, consider my woes on 160 meters. After having no luck calling numerous DX stations for multipliers I parked low in the band and started CQing, hoping to work a few US stations. Within a few minutes I had several Europeans logged! It just goes to show that many stations who can hear you are S & P, and if you run you can work them.

On CW many callers will not be zero beat and for crowded band conditions where you must use a narrow filter you will have to become good at quickly adjusting the RIT. Logging software such as N1MM Logger that I use have convenient  keyboard shortcuts to control RIT. I then clear the RIT using a macro key after the QSO. It is better that multiple callers not zero beat since it can be near impossible to pick out one call sign. As I said, be quick, so don't shy away from CW speeds over 30 wpm even when you run QRP.

Once you find a good run frequency don't be surprised that you may lose it. Another station in the skip zone might not hear you and will start running on what appears to be a clear frequency if you experience a lull in callers. Unfortunately some big guns are less than ethical in their operating and will deliberately steal your frequency, relying on their superior signal to drown yours. If you're a big gun yourself you'll have to make a judgment call whether to stay and fight or QSY.

Whatever you choose don't become angry and act on emotion rather your rate. I can be better to move. When I operated CQ WW SSB at VE3JM a month ago, where clear frequencies are rare, many times others tried to move in really close and run. They nearly always failed. That's one advantage of running a kilowatt and stacked yagis: you tend to win, and do it by simply continuing to do what you're doing.

The mighty decibel

There an old joke among contesters: would you risk your marriage for 1 db? How about 3 db? Contesters' spouses are not always fans of big towers and antennas. What is it worth to you? Should you take plunge will your score noticably improve when you go from a 4-element to a 5-element yagi, or stack two of them (or three)?

For general operating, perhaps not so much. Contesting is different. As an example, my small tri-bander fixed on Europe up 32 meters shows little difference on the S-meter compared with the larger tri-bander up 43 meters. Yet the higher one consistently delivers more callers when I run. The difference is certainly less than 3 db.

What more often makes the difference is not what you hear but what others hear. In a band crowded with loud, closely-packed signals a few decibels will make your signal stand out above the bedlam. Of course if everyone does this there is no advantage, but not everyone does and so it works. A small absolute increase in received signal strength is not the issue; S9 and S9+2 are both solidly Q5. Consider the mix of all signals being received and the threshold effect of one signal rising up has an outsize improvement on readability.

It's the same if your signal is close to the noise level, especially on 80 and 160. That readability entices callers. That's why a few decibels can greatly improve run rates. The same is true of QRO, but almost all big guns use QRO so antenna gain is where the focus needs to be.

On 40 meters I can get 2 to 3 db with a full size 3-element yagi. That is still in my plans, though perhaps not in 2019. It is slated for the top of my current tall tower at a height of 43 meters (where the TH6 currently resides). But I would like something powerful for the European path. I am eyeing a multi-element wire yagi fixed on Europe that could net me 2 db more than the planned full size yagi. That will be possible once the new tower is up. First I will have to address potential interactions with yagis on the two towers since this one will in between and in line towards the northeast.

I estimate that the mono-band yagis I am planning for 15 and 20 meters will be 2 and 3 db better, respectively, than the TH6. Add another 3 db (approximately) for stacking two of them. That's a huge difference that is well worth the time and expense for those with a passion for contests. I hope to be in that position this time next year.

Completion of the 80 meter vertical yagi is coming along, and that is as far as I'll go through at least 2019. Getting more decibels on 80 will be difficult. I can perhaps gain 1 db by doubling the radials. On 160 I have the possibility of using my big towers as yagi parasitic elements to get some badly needed gain. Again, probably not until after 2019. I am deferring 10 meters two years until we get a few more sunspots.

Operating improvements

I plan to start doing SO2R early in the new year. It will take time become effective. To begin it will be with CW, low power and the second radio for S & P only. By late 2019 I expect to be ready to try QRO on at least the run radio and SSB as well. Thus I will initially focus on boosting my multiplier count rather than total QSOs. The latter will come later once I become proficient.

Antenna, filter and switching automation is in the pipeline. The intent is to facilitate fast band changes to catch those multipliers. I expect to develop my own software and control hardware to suit the unique objectives I have for my station. Commercial solutions are very expensive and from perusing what's available none of it does quite what I want. The potential for experimentation by going my own way is another motivation.

There are features in N1MM Logger and other software that I do not use despite the potential value. Although I like to keep it simple that is not really consistent with improving my effectiveness as an operator of a big gun station. I'll have to push myself to do more. In the same vein I need to script my contests to remind myself where I need to be to run or catch those elusive multipliers. At present I tend to improvise depending on how I feel at the time.

The point of this long dissertation is to show just how much more I can do to improve my result in CQ WW, even though my category placing now is excellent. If done right it will be fun rather than a chore.

Thursday, November 22, 2018

Early Winter Interlude

This year has not been as productive as originally planned. I could have done more during the warmer months, but life is more than amateur radio. Now that contest and DX season is in full swing on the HF bands and my energy to progress various projects is high we get this:

So far we've gotten ~30 cm of snow and temperatures that keep it on the ground. In the photo you see my new tower project abandoned in the hay field amidst 60 kph wind, blowing snow and -10° C temperature. It's only up 40', so there's till 100' to go. Overnight the temperature dipped even lower, to -20° C, which is in record low territory for November.

Ordinarily this time of year is perfect for raising towers, with cool temperatures and no hay or bugs to worry about. I have in the past raised towers in winter and I would happily do so again. It is not so easy with a tower this size since I use a vehicle for lifting muscle, and the only vehicle that can deal with snow pack is a tractor, which I don't have. Although a winch will work I only have a manual unit and that takes a lot of work to lift 130 lb tower sections up high. I am also reluctant to ask friends to work in these conditions.

While I wait for a thaw that may not come my thoughts turn elsewhere. In particular, preparation for the CQ WW CW contest this weekend. One good thing about the deep snow is that it is far easier to navigate the bush to maintain the long northeast Beverage receiving antenna. I've been waiting to do that since it has been not been performing at its best recently. On reaching the termination I saw that the ground rod clamp was loose. Tramping out for needed material and back in again I made the repair and tested it last night. It's much better now. Later I'll buy a suitable clamp and make the repair permanent.

For the contest the 3-element vertical yagi has been fixed towards Europe. Although I now have all the parts I need to finish the switching system and critical components have been prepared -- switching matrix and identical coils -- it has been delayed to focus on the tower project while the weather cooperated. The switching system can be worked on in winter conditions. Setting priorities this way has the unfortunate outcome that the yagi switching system is not ready for CQ WW.

There are other maintenance projects to be done when the frigid weather relents, even if just a little. These include cable organization, SO2R control lines, rig-controlled switching among many others. For the present it's all on hold. Despite all these issues I am pretty well set up for the contest. My preparation for the next contest will be better.

I think it's time for another cup of coffee. For the Americans out there, have a Happy Thanksgiving. I hope to work all of you in the contest. The warm shack is very inviting right now and there are lots of VE3s and others scattered across the Caribbean to be worked as they, and I, warm up for the contest.

Monday, November 19, 2018

XM240 and 17 Meters

The station I have built, and continue to build, is primarily focussed on HF contesting with a secondary focus (though a very close second) on HF and 6 meter DXing. Due to time, budget and other practical considerations the so-called WARC bands -- 30, 17 and 12 meters -- have gotten limited attention. While my attention is indeed elsewhere these bands are not forgotten.

I have been happy to use my 80 meter antennas on 30 meters with the help of a tuner to bridge the small disparity between 10.1 MHz and the actual third harmonic. Having a choice between a horizontal and vertical antenna is beneficial. Building a gain antenna, one with two or more elements, is not at all in my plans and may never be due to the size, cost and effort involved.

The minimum of a solar cycle does not turn 12 meters into a hotbed of activity though there are sparks of interest, such as when I worked VP6D on both CW and SSB a few weeks ago. On 12 meters I use a tuner on one of my high yagis and hope for the best. This is usually good enough because extreme height makes up for many flaws.

Which brings us to 17 meters. This band remains very useful for DXing even during a solar minimum. Yet all I have for this band is my XM240, which performs similar to a dipole at 18.1 MHz and is resonant not far above the band. The moderately high SWR is managable with a tuner. Again, height is my friend.

Of these three bands it is 17 meters that is best positioned into inducing me to consider a better antenna. It is not urgent. What it does is make me conduct a few thought experiments on how I can achieve improved performance at little cost and effort. One of these thoughts was to turn the XM240 into a 2-element 17 meter yagi. The concept of adding a 17 meter reflector to the antenna is theoretically sound so I built a computer model to see what could be done.

Before we proceed I will be very explicit regarding the limits of this exercise. I have not built this antenna and I may never do so. I don't know how well it would really work. The greatest danger is that the XM240 cannot be properly modelled by the NEC2 engine; only NEC4 is up to the task and I don't have it. My EZNEC model of the XM240 is at best a proxy of the real antenna that allows me to explore its behaviour, but not to accurately derive physical dimensions. I'll have more to say about this later.


When I purchased the XM240 it was placed in storage until it could be raised at my new QTH. At that time I developed a "naive" EZNEC model of the antenna using straight tube elements along with coils and capacity hats with the same values as the actual antenna. Because NEC2 cannot accurately model elements with loads (EZNEC 6 can with its NEC2 enhancements, but only somewhat) the element lengths are not correct. The model nevertheless permitted me to explore the antenna's behaviour.

My current exploration of 17 meters uses that same model. I added a reflector element, tuning its reactance and spacing to the driven element to optimize performance at 18.1 MHz. As with the rest of the model I used straight tubing rather than a taper schedule. That can be added later should I decide to build it. The model's value is not affected by this doing this, it's just that the element length will be different with tapered tubes.

Notice that the XM240 40 meter reflector has almost zero current flowing on it. This is one key to understanding why a 17 meter reflector can be added to the antenna so simply. Indeed it the same reason why a yagi can be correctly tuned close to the ground by pointing it upward. When the 17 meter reflector is correctly tuned there is effective cancellation of the fields from it and the driven element towards the rear. The 40 meter reflector is spaced far enough that it has low mutual impedance with the other elements at 18 MHz, and therefore has negligible effect on the 17 meter reflector and driven element.

The other key to understanding the design is that the tuning of the driven element has essentially zero effect on yagi performance, that is, gain and F/B. Whatever phase shift mistuning introduces does not affect the phase relationship to the reflector. It is only a concern for matching. However this can only be relied upon if the length of the driven element is not too short or long, which would affect the mutual impedance with the reflector. You can see above that current on the driven element is low beyond the 40 meter loading elements, which keeps its electrical length on 17 meters close to that of the reflector.

Some improvement in 17 meter performance could be gleaned by reducting element spacing. I decided against that in favour of placing the reflector close to the boom centre to minimize torque imbalance. The 3 meter spacing is 0.18λ at 18.1 MHz.


The width of the 17 meter band is only 0.5%. It is therefore good enough to tune the antenna for the centre of the band and have close to optimum performance across the full 100 kHz, despite the narrow gain and F/B bandwidth typical of 2-element yagis. I used 18.1 MHz to keep to round numbers, and because I favour CW.

It is possible to raise the gain a little higher than 6.2 dbi by narrowing the element spacing and centering the frequency of maximum gain within the band. This would come at the expense of poorer F/B, and matching challenge due to the drop of radiation resistance at peak gain. I chose not to do so in this design due to the aforementioned torque imbalance and because the F/B is already quite poor, though as expected for the parameters of this 2-element yagi design. For me these are reasons enough to sacrifice 0.4 db of additional gain.

When fed without the reflector the pattern of the XM240 on 17 meters is similar to that of a dipole, with a bidirectional gain of ~2.4 dbi. On the air I do not notice any F/B so the model may be reliable in this respect.

The question to ask is whether 4 db of gain and modest F/B is worth the trouble. It can be easily argued that a separate and better performing 17 meter mono-band yagi is preferable. In my situation a separate yagi would not be placed as high as where the XM240 is currently located: 46 meters up. I am undecided. It's food for thought until the time comes that I decide to do more on 17 meters.

I have not reported on the SWR or feed point impedance because the straight tubes model of the antenna is unreliable on 17 meters. The best I can predict, based on exploring the model, is that the R component of the impedance is in the region of 25 Ω. I will not predict the reactance other than to note that it should be comfortably low.

A switchable matching unit, such as an L-network can be employed for 17 meters if an SWR of 2 or 2.5 is problematic. The network can be mounted at the mast to avoid adding weight at the end of the boom, and the network designed to match the impedance measured at that point.

Of some concern is that the Cushcraft 1:1 common mode choke operating at 18 MHz, a kilowatt and a mismatch at the feed point. A better balun is advisable or the network and switch should be located at the driven element and the balun switched out of circuit when operating 17 meters. But this is all a lot of bother for a modest improvement of 17 meter performance.


As said, this is purely a thought experiment to consider my future alternatives for improved 17 meter performance. I don't know if anyone else has tried to do this with an XM240 and I didn't research the question.

Computer modelling makes these types of analyses easy to do in the comfort of our shacks. It's a lot easier than modifying the antenna, especially an antenna of this size, and measuring the results. The analysis will now be shelved. Time will tell whether I return to it in the next couple of years.

Tuesday, November 13, 2018

Ode to the Nyloc

The TH6 on top of the 150' tower had become increasingly intermittent over several months. At first I suspected a bad port on my antenna switch. With the switch repaired the problem continued. The next time I climbed the tower I noticed that the rotation loop connector to the LDF5 Heliax main run was slightly loose.

I didn't repair it just then since I didn't have the tools and weatherproofing material to open and close the connection. I tied it off more securely to the tower because I saw that the coax was just stiff enough to transfer a small torque to the connection when the antenna turned, which was likely responsible for the loosening.

That seemed to help. Then I became busy and my next climb was far in the future. Again I let it be. As you might guess the problem worsened to the point that the antenna could not be used at all. Of course by then the weather turned unseasonably cold, windy and wet, making a climb that high difficult and unwelcome.

A one day break in the weather combined with a dire forecast forced my hand. I packed all the material I would need and climbed the tower in cool, partly sunny weather with a stiff breeze that was thankfully at my back (as on many commercial towers it has only one climbing face). I terminated the bottom end of the coax with a small 50 Ω load and brought the antenna analyzer up the tower. This arrangement allowed me to test the antenna side and the transmission line so that I wouldn't be left guessing if my prognosis proved to be wrong.

After cutting through the layers of sealing tape and unscrewing the rotation loop I tightened the loose N-to-UHF adapter and attached the analyzer. Luckily the transmission line tested good. Going the other way so did the antenna side. All done? Not so fast.

Just to be sure all was well I ran the analyzer in continuous mode and wiggled the rotation loop. The analyzer jumped around like crazy. Reaching up and around blindly with one hand so that I keep my eyes on the analyzer I wiggled the all along the coax and then the balun connector. It got worse. When my fingers moved to the other side of the balun one of the wires was found to be loose.

Craning my head around I saw that a retaining nut and lock washer on the antenna side of the balun were missing. I my mind I thought: oh no, not again! At least this time I had found the root cause, and there was an easy fix.

Yagis vibrate in the breeze, and there's a lot of breeze that high up. Elements on Hy-Gain yagis are particularly prone to singing even when roped per the manufacturer's instructions. Eventually element tips fatigue and break. I wasn't too worried about breakage since the antenna is very old and temporary. Well, maybe not so temporary since my plan to replace it this year has been delayed.

Vibration also loosens fasteners. Lock washers are not as reliable as one might think, especially not on round aluminum tubes. I know professionals who avoid them in favour of flat washers and jam nuts or double nuts. The referenced experience (link) with the TH7 was not the first time and the current problem is not the second time. It happens too often. In the interests of minimizing maintenance at a station with multiple towers and antennas it helps to spend a few extra pennies on better fasteners.

This is a job for a Nyloc nut. I have lots of the right size ever since I stocked up on them to fix loose bolts on my three Hy-Gain tri-band yagis and other devices. But I didn't bring one up the tower with me. As a temporary fix I looked around and noticed that the studs on the Balun Designs balun are the same size as the bolts on all the Hy-Gain clamps: ¼" NC stainless.

I liberated a stainless nut and lock washer from the refurbished TH6 boom-to-mast clamp and fixed the balun connection. The analyzer gave a thumbs up sign as I wiggled everything in sight. I redid the weatherproofing and called it a day. It was cold up there! Weather for the next week looks horrendous and I can only hope it gets better after that. When it does I will be replacing the nuts with Nyloc nuts.

As I slowly build my next set of yagis (for use next year, not this year, unfortunately) I am making liberal use of Nyloc nuts. On long boom yagis this is especially important since, unlike a "small" TH6, the feed point is not accessible. When a nut falls off a balun far out on the boom there may be option other than taking the antenna down for repair. That's a lot of work! Better to spend a little extra on better fasteners.

This is my ode to the Nyloc. I've become a believer. So should you. While building my station I've learned about other specialty fasteners that will likely make appearances in future articles.

Friday, November 9, 2018

Contesting Big and Small

Unlike some contesters of my acquaintance I am happy to contest in most any category. Most often the categories are relevant to power -- QRP, 100 watts and maximum legal limit -- but there are also categories for numbers of operators and simultaneous transmitters, wire antennas or reliance on skimmers and spotting networks. For CQ WW SSB my category was high power multi-two (HP M2). Then QRP (SO QRP) a week later for CW Sweepstakes. It's quite the contrast!

Soon after I got into contesting and DX as a teenager I was all for more and more power. As with fast cars, power was more than I could afford and there could be undesirable consequences. An example of the latter was irate neighbours during contest weekends. Even 100 watts caused problems with televisions, telephones and stereos in the 1970s. In response to a firm suggestion from my parents I stopped inviting over friends to multi-op with their amplifiers.

When I got a real job and saved up for a house up went the tower and antennas, and a Collins 30S-1 entered my ham life. That was a big beast with a 4CX1500B (replacing the original 4CX1000A) and Peter Dahl plate transformer. It was capable of putting out a lot of power.

This was the late 1980s and all the above problems with power returned. Some of the neighbourhood problems could be fixed with a few toroids, but not all, and I never broached the idea of opening up anyone's appliances to insert RF bypass components. So the contests I entered from my home station were in the 100 watts category. I wasn't happy about it. The amplifier only saw action when DXing or on the low bands where there were few RFI difficulties.

Older and more mature when I returned to the hobby in 2013 I decided to start small, with QRP, and see where that led. DXing and contesting with 5 watts were a lot more fun than I expected. When I bought a 100 watt rig two years later I continued to enter many contests in the QRP category. Part of it was worry about keeping the peace with the neighbours (who were mostly the same ones that experienced the woes of living next to a kilowatt 20 years earlier), and also because I was more competitive in the QRP category with my modest antennas.


Which brings us to the last full weekend in October and the biggest international contest on the calendar: CQ Worldwide SSB. Over a chat about towers early this fall Vlad VE3JM invited me to operate from his contest station an hour's drive east of Ottawa. If you contest his big signal should be familiar. Vlad has several towers with stacked yagis on the high bands and gain antennas on the low bands.

This would be my first foray into high power for many years. I had some trepidation about whether I'd remember all the tricks of QRO contesting, which is very different from low power and QRP. You might think it gets easier. It doesn't. In fact it's far more intense and competitive, and in many respects more challenging. There are no excuses in QRO: you are competing against the best contesters and the best equipped stations around the world.

Team: I have to say this was perhaps the most laid back and easygoing multi-op team I've ever been part of. We followed no schedule and no grand strategy. Operating as Multi Two we kept both stations going the full 48 hours, except for a few hours the second night when there was just one operator. In addition to myself there was Chris VE3FU/VO2AC, Rich VE3KI and, of course, Vlad VE3JM, all of whom are experienced contesters.

We were so polite that on wandering into the shack one of the operators would inevitably lift his headset and ask if you wanted to operate, even when they were in the middle of a big run. Someone always seemed to be cooking or heating up food, or cleaning the accumulated dirty dishes. When you wanted to sleep or take a short break there was rarely a problem recruiting a relief operator.

Strategy: The strategy we followed was simple: run, run, run, but keep an eye out for multipliers. When you have a dominating signal running is really the best way to score high, including multipliers. Where we perhaps fell short was on multipliers since without one operator scouring the bands many can be missed because on SSB there is no skimmer, only human spots. But to do this properly we'd need a third station for listening and another operator.

It wasn't always possible to run. Even though we can work Americans for points there were long periods overnight when we had to S & P for DX and, where possible, multipliers. This is entirely due to being at the bottom of the solar cycle. For example, with the high bands closing early the QRM on 40 meters is intense and even a big signal like ours is difficult to hear in Europe. Then 40 fades on the productive European path and everyone migrates to 80 and, if they can, 160. SSB is a big challenge on the low bands due to the intense QRM and higher noise level.

Learning curve: I was the only member of the team that hadn't operated at the station so my learning curve was the steepest. Although I've been to Vlad's station before that is very different from sitting down and operating. For one, the logging software was new to me. Before the contest I downloaded a trial version and familiarized myself with it as much as possible. It was important to focus on a small set of critical features that would be regularly used. A list of common commands was taped to the computer display.

Antennas and antenna sharing/switching are unique to every station. We went through it all on Friday afternoon and practiced. Tri-banders were shared, with their own custom switching software between stations. Rotators controlled yagis for multiple bands so you need to be aware of what the other operator was doing even when they weren't using the tower when you wanted to turn your antenna. Communication among operators was key to making this work. There were gain antennas on all bands, 160 through 10 meters. Directional receive antennas are shared by both operators.

For the most part we successfully navigated the software and hardware controls, though mistakes were occasionally made. It was necessary to learn the stacked yagi configuration that worked best on every path. Some of this was complicated by precipitation static (snow!) that affects the top antennas the most. On the low bands you have to flip through the directions quite a lot to cover the compass or to better copy weak callers.

Weak signals: Perhaps the most challenging aspect of operating a station with a big signal is that you are regularly called by much weaker signals. Many callers, and most on the low bands, are difficult to copy. It's a struggle, and one I had to relearn after being out of the kilowatt game for so many years. They hear you easily but you must play with antennas and filters and ask for repeats and fills to put them into the log. It can be mentally fatiguing but necessary to scoring well. All callers are appreciated despite how much work it can entail. At times I had to encourage callers to keep trying.

On the other hand, no matter how weak the DX station you find when doing S & P you can call them and expect to work them. That aspect of weak signal copying can be a real joy. All those years of "the one that got away" are forgotten. You hear them, you call them and they're in the log. Pile ups on the rare ones are quickly dealt with. You work them and move on to the next.

Problems: It is a rare contest where everything goes right. Our weekend included noise of unknown origin, loose rotator clamp, receive antennas among other problems. Certainly our score was impacted though not greatly. We were able to find workarounds for most by being smarter about using what we had and avoiding, if only temporarily, certain bands or antennas. That is perhaps one measure of a good team: that we found ways to do well despite the problems.

Not the biggest signal: Several times during the contest I was complimented on the dominance of our signal on the bands. We did indeed have a great station and it showed in our score. Yet it was not the best. As with anything, it seems no matter how much you've done there's always someone, or many someones, whose stations are bigger.

Many times we were beat in the multiplier pile ups by well known call signs of super-stations and had to wait our turn. On paths and bands with marginal conditions we missed out on multipliers that would have given our score a big boost. No matter how big your station there will be the ones that get away.

Despite everything we had fun and made a competitive score. The weekend was a success.

CW Sweepstakes

Operating QRP in Sweepstakes was quite different. My trusty (and much neglected these days) KX3 was dusted off and patched into the computer, antennas and other accessories. This is my only good option for QRP because my main rig, the FTdx5000, has a minimum power output of 10 watts and I don't have a 3 db outboard attenuator.

QRP gave me a relaxed way to enjoy the contest. QSO rates would be modest and stretched out over more hours. With higher power Sunday can be a real drag once all the most active hundreds of stations have been worked. Recall that in this contest you work each station just once, regardless of band.

Being in the eastern region of the continent in a solar minimum I knew that the low bands would deliver most of the contacts, and that is just how it happened. Despite running 5 watts my most productive band was 80 meters. I had no trouble running on Saturday evening. The 3-element vertical yagi fixed to the southwest delivered many west coast QSOs, some of whom answered my CQ. That was fun.

I sometimes joke with friends that the less power you run the bigger your antennas need to be, and that's why I am putting up big towers and antennas. There is indeed some truth to the antennas compensating for low power, though not as much as might be thought. It takes a lot of antenna to bridge the 23 db gulf between 5 watts and 1,000 watts!

Not only could I run it was also possible to crack a few pile ups on multipliers and the fresh meat (participants who only show up briefly late in the contest) on Sunday. A few stations seemed to doubt that my class was really 'Q' since my signal was S9+. That, too, was fun.

Overall this was a low intensity operation. I relaxed, ran when I wanted and hunted when I wanted, and I kept to regular mealtimes. Despite operating 3 and a half hours shy of the full 24 hours allowed I placed well in my category, at least with regard to self reported scores on 3830 and in advance of log checking. I know of a couple of QRP entrants with high scores that are not reported on 3830.

How I'll ultimately place I don't know or care. It is entirely possible I would have won had I stuck it out for the full 24 hours. I achieved my objective of having fun and seeing what QRP would do with my current crop of antenna. This is a very different sort of fun compared to CQ WW SSB a week earlier.

I know contesters who always operate QRO or QRP, and who are always serious or casual. For me any approach to contesting can be fun. In the future I will continue to mix it up from contest to contest. That's what works for me.

Wednesday, October 31, 2018

Lurking, Waiting and Scheduling: Circumventing the Pile Up

Now that the Ducie island VP6D DXpedition is wrapping up I thought it worthwhile to review a few of the less competitive techniques for working the rare ones. I used all of them for at least one band slot to work VP6D. I call them "non-competitive" since none involves pile up busting skills, antennas, power or propagation prognostications.

These are complementary to those competitive skills, many of which I've discussed numerous times on this blog, though admittedly not for a while, and mostly in the context of QRP and modest antennas. Just do a search to find those articles. I prefer competitive skills since they are a path to improving my operating and contesting, and it's lots of fun to mix it up in the pile ups with the world's best stations and operators.


My timing and luck were not with on 40 meters CW in the early days of the DXpedition. They got on 40 meters close to their sunset, which is prime evening operating time in eastern North America. The pile ups were fierce. Despite having a 2-element yagi up 46 meters my 200 watts could not compete with the mass of kilowatt signals.

According to their band plan they transmit on 7.010 MHz and listen up. One evening I set the receiver on this frequency and programmed a transmit split of 1.02 kHz. I then unplugged the headphones and reduced the volume on the speakers low enough that the noise wouldn't be objectionable. With that playing in the background I concentrated on non-ham tasks that I could do in the shack; my shack and home office share a converted bedroom.

Some time later I distinctly heard a high speed "VP6D up" emanating from the speakers. By the time I stood up and took the two steps to the desk with the rig the message repeated. I punched the memory button to send my call, waited a second and punched it again. My eagerness caused me to double with him. I waited and a second later I heard "VE3VN 599". With a "599 TU" I had them logged on 40 meters CW.

There were a couple of other lurkers but I got through first. To be courteous I waited a few seconds for one more lurker to work VP6D before spotting them. Within a minute the pile up was roaring.

Lurking is boring but it can work to circumvent the pile up. Unless you have a excess amount of time on your hands I suggest you do as I did by scheduling some useful tasks you can do in the shack while you wait. Many times the DX does not show up and you'll be disappointed.


If the DXpedition is long enough and you are very patient most pile ups can be entirely avoided by waiting. Eventually all pile ups thin or disappear as most everyone has worked the DX on a particular band and mode.

This is how I worked VP6D on 30 meters. I had tried a few times to break through the pile up early in DXpedition but for some reason I had no success on this band. Waiting was not entirely voluntary because for numerous reasons I often could not get on the air when conditions were favourable. Other times they were not active on 30 meters or were on FT8 rather than CW.

The day after I got home after operating CQ WW SSB from another stration I worked them first call when heard on 30 meters CW. They were calling CQ with few takers. Waiting can work.

The danger with waiting is that DXpeditions can be wrapped up earlier than planned due to weather and other logistical problems. If you wait you lose. Consider the recent TT8KO DXpedition that lasted one day before the authorities shut it down. Wait if you must but don't be surprised when you miss the rare one because you waited.


I was only able to reinstall my 160 meter antenna the day before CQ WW SSB. Since the DXpedition was slated to end a few days after the contest and I would be unavailable during the contest I chose to schedule time to find and work them on 160 meters. It is typical that DXpeditions start dismantling antennas a couple of days in advance of the DXpedition's end and they usually start with the low bands. Waiting to work them on 160 meters after the contest would be risky.

Lurking on 160 meters isn't quite as reliable as on 40 meters since the noise is high and I don't yet have a low noise receiving antenna to the southwest, towards VP6. Instead I lurked at one remove by monitoring their DXA page on the shack computer. I would glance over from time to time to see if the 160 meter activity button was lit. Since I did not have have on 30 meters either I was watching for that one as well.

When it was midnight I became impatient. I needed to rest up before the big contest. So I tuned to their frequency and connected to the spotting network. Lo! There they were. DXA was not updating properly and I missed their first appearance on the band. By this time they were slowing working Europeans, which is a very difficult path. After listening for a few minutes I could see this would continue for some time. I reluctantly shut down and went to bed. However I had not given up.

I decided to risk contest fatigue by getting up 15 minutes before sunrise. Their fantastically strong signal was peaking towards S9 as the sun crept up to the horizon. At 5 minutes before sunrise they were in the log despite a good sized pile up. Perhaps I had the advantage due to a sunrise enhancement, or perhaps I was a little bit lucky. I didn't stick around to monitor their signal strength as daylight flooded through the windows.

Scheduling can feel like work rather than a hobby. But if you want to bag the DX it is something you will need to do occasionally even if you have a big signal. Knowing the schedule of rare DX and planning your schedule on the air to match has a long tradition. In the decades before DXpeditioning was common and spotting networks were non-existent this was a tried and true technique for the serious DXers. If you'd like to read more about it I recommend W9KNI's venerable book The Complete DX'er.