Saturday, May 30, 2020

Mast for the 15/20 Meter Tower

My new 140' (40 m) tower is primarily for my 15 and 20 meter stacked yagis. Recently I installed the mast for the upper yagis. The 15 meter yagi will be at the top of the mast and the 20 meter yagi at the bottom.

Last year I kept the top two sections of the new 140' tower on the ground so that the mast and rotation system could be fabricated to fit. The mast is supported by 3 bearings and bearing plates, a plate below them for the prop pitch motor and custom couplers between the mast and thrust (bottom) bearing and to the motor drive shaft.

I made sure to get it working before proceeding with installation of the tower sections and the mast. Correcting mechanical problems in the air can be extremely difficult. Time spent getting it right on the ground is well worth it. Avoid shortcuts and never imagine that a job of this magnitude will reward laziness.

There are two features of the rotation system for this tower that are different from that for the near-identical 150' tower. One is that the prop pitch motor is mounted upside down below the mast for direct drive instead of chain drive. The other is that the mast is aluminum rather than steel.

I was negligent about taking pictures of the construction and mast lifting. There are times I'm so focused on doing the work and keeping safe that the camera does not come to mind. Prose and graphics will have to suffice, complemented by pictures I took after the installation. The prop pitch motor, which isn't yet installed, will be left to a future article.

Mast size

The mast is a surplus standard 20' length of 2-⅞" OD 6061-T6 aluminum alloy pipe. My original plan was to use this as half the boom of a 3-element 40 meter yagi. Then I realized the pipe was schedule 80 rather than 40 which is heavy for a boom. The wall thickness is 0.276" and it weighs 53 lb (24 kg). It has a few holes from its previous use for a commercial antenna. The cap is welded with a spike for draining atmospheric charge.

I plugged the yagi data and pipe data into a mast stress calculator. It should support my 5-element 15 meter yagi at the top and 5-element 20 meter yagi at the bottom for winds up to 180 kph. These are the upper yagis of my 15 and 20 meter stacks. Their electrically identical and lower twins are side mounted and fixed towards Europe.

The expected maximum wind for this region is 135 kph (85 mph). The mast has a good safety margin, including an allowance for the holes mentioned earlier. Since aluminum alloy has a difficult to determine cyclical stress (fatigue) capacity the large margin is more important than for a steel mast.


One benefit of aluminum is the low weight compared to steel. Two men were comfortably able to lift the mast to the top of the 140' tower. I rigged the rope with pulleys so that my helpers could work apart and respect the 2 meter separation to protect against COVID-19. The gross lifting weight was approximately 70 lb (32 kg) including the top plate and bearing and fasteners.

There are two reasons to lift the top plate with the mast instead of beforehand. First, it shifts the centre of gravity lower. My gin pole can lift a load a maximum of 7'-8" above the tower and that is below the midpoint of the 20' pipe. The plate moves the centre of gravity 2' lower, which is almost but not quite enough. More on that in a moment.

The second reason is to ease the drop into the top of the tower. The clearance through the 75 mm bearing is tight for a 73 mm diameter pipe. The pipe would have to be almost perfectly vertical to slip through. With the bearing plate attached to the mast it drop more easily into the tower. Once the mast slips into the middle bearing 5' below the top plate can be bolted to the tower girt.

The same technique was used for the mast for the other big tower. Except in that case the mast was shorter so the gin pole had adequate reach.

Some of the alternatives for overcoming this constraint were described in the article on topping the Trylon with a 19' mast. The technique used here is better and takes advantage of having two helpers on the rope who could quickly react to verbal instructions. I had to shouted so they could hear me 140' below; none of our radios has the hands-free feature.

Absent a picture I drew a diagram. The heavy bearing plate, held in position by a muffler clamp, lowers the centre-of-gravity (CoG) ~2' below the pipe centre (C). This is 6" short of the gin pole's reach. A muffler clamp higher on the mast snags the lift rope which effectively shifts the attachment far above the CoG. The clamp isn't too tight so it doesn't crush the rope. Use the U as the snag not the sharp saddle!

The mast hangs almost perfectly vertical. The only time it leans (as depicted) is when the bottom is still on the ground. I followed the mast upward in 20' steps to guide the mast and bearing plate past the tower, guys and side mount yagis. A tag line hung from the bottom for another steering alternative and as a safety line in case the mast swung out of control during the final stage of the lift.

When I'm as high as is safe at the top of the tower the snag bolt is loosened and slid down as my friends continue the lift. Eventually the clamp bottoms out on the rope coil that grips the pipe. That's when you need to hold the pipe vertical from the bottom so that it doesn't overturn. The tag line is trapped in my gear in case I need it in an emergency. The operation went smoothly without mishap.

As the mast descends into the tower the plate stops when it contacts the tower. The clamp doubles as a stop when it contacts the middle bearing. That's when the top plate is bolted to the tower. The rope coil is slid upward a few feet as the rope is slacked and then the weight is retaken by my friends. I descend to the middle bearing, move the clamp up a short distance and the mast is lowered until the clamp again holds the weight.

The previous day I lifted the mast coupler and associated hardware so they were already at hand. It's ~2.5' of 3.5" OD 6061-T6 schedule 40 pipe. The coupler is attached to mast and it is dropped until it is sitting on the lower bearing. That bearing takes the full thrust load of the mast and antennas. All the bearings are 75 mm deep groove double sealed industrial bearings (FAG) with a capacity far in excess of the axial and radial loads of this application. This is a good fit for 2-⅞" (73 mm) pipe. A shim can be used on the top bearing to reduce chatter if that's a concern.

Whether a shim is used or not check for free 360° rotation. The bearings will likely require some adjustment to centre the mast. I have a small misalignment that I will correct later.

Mast Coupler

The coupler I fabricated has a few functions:
  • As a mast collar it transfers vertical load to the bottom (thrust) bearing
  • Extends the mast to the design length, with 12' extending above the tower
  • Attachment for the prop pitch motor drive shaft, keeping it centred and free from axial and radial loads

The coupler was partially described earlier. The pictures give a closer view (sorry, I couldn't keep my feet out of the frame). Shims are needed to centre the mast and lower coupler to the 2-⅞" mast and lower coupler. Unlike for the first big tower I machined the shims so that the bolts go through them and so cannot creep out. Jam nuts are better than lock washers to secure fasteners on a round pipe.

The only critical dimension is that for the lower coupler to the motor shaft. It needs to be centred within the coupler and the vertical distance to the motor crown gear must ensure full engagement but without placing load on the motor. The raw motor without an adaptor plate and thrust bearing is not rated for significant axial and radial loads.

The shaft is 1-¼" steel schedule 40 pipe with a 1.66" OD. The coupler ID is 2.469". A grade 8 bolt transfers torque and two ⅜" bolts in tapped holes centre the shaft. The design is fully adjustable and permits easy removal of the drive shaft for maintenance of the system including motor removal.

The shaft came with the motor and I decided to try it out since it is well made, if a little rusty. Downward flowing water is shunted to the side and away from the motor. If the shaft is unequal to the job I will take it to a machine shop and make it stronger.

Although the bearing plates are ¼" steel they will deflect under load. To simulate the effect I used a winch to put several hundred pounds of load on the system when it was still on the ground. The deflection of the bottom thrust bearing was no more than ⅛" yet this is enough to be worth the effort to compensate for in the design.

Adapting antennas to the mast

The boom-to-mast clamps and boom truss are home brew and not adaptations of commercial clamps. The design takes account of the softness of aluminum alloy in comparison to steel.

The upper 15 meter 5-element yagi of the stack is mounted at the top of the mast. For this reason the boom truss support is integrated with the boom-to-mast clamp. This way the mast does not require extra height for the truss support and installation and service are easier.

On the downside all the weight bears on the boom and mast clamps. For a truss support on the mast -- the conventional method -- the weight on the boom-to-mast clamp is reduced.

There is provision for 4 saddle clamps to grip the mast. By distributing the load over more than 2 clamps they each don't need to "bite" as deeply into the aluminum alloy mast. Cold flow is reduced so that the grip force holds better over time. The pipe wall is so thick that marring by the clamps is not a structural risk. I have not yet decided how many clamps to use: I can start with two and add more later.

On the other hand this antenna is not terribly heavy. The 20 meter antenna that will be at the bottom of the mast is much heavier, but that force is reduced by the boom truss being mounted on the mast in the conventional manner.

Many of you will recognize the clamps from the DX Engineering catalogue. I have had good success with these "Cycle 24" galvanized saddle clamps in other projects. I prefer them to the stainless saddle clamps for their ease of use (special lubricants not required) and textured band for improved grip.

The mast clamps are offset 1" from centre to fit the truss support clamps beside it. The completed boom-to-mast clamp fits nicely on the yagi. If all goes well it will be raised before the hay grows too high. Otherwise it must wait until August. The larger 20 meter yagi is scheduled for lifting later this year.

Working on the mast isn't safe until the motor is installed since it is otherwise freewheeling. With the first yagi lift planned before motor installation a temporary solution is required.

The anti-spin grip is comprised of a muffler clamp and perforated angle stock. When the arm is tied to the tower the mast will not spin. The grip is easily removed or loosened when the motor is installed.

Next steps

I hurried to install the mast so that I can experiment with the 15 meter stack. The phasing and switching work is yet to be started. With the hay now at knee height and the easing of the pandemic lock down I have a brief window before work must be delayed until August.

My plan is as follows during the haying season:
  • Raise the 15 meter 5-element upper yagi and ensure that it works
  • Build the coax phasing harness between the yagis and connect them to the main transmission line
  • Design and test the stack switch
  • Install the prop pitch motor and test that the mast and yagi rotate properly
In the adjacent photo some of the hardware for the 15 meter yagi tram line can be seen on the mast several feet above the tower. Once the yagi is tested and mechanically adjusted it will be raised to the top of the mast. This last step is not urgent since the stacking work can proceed regardless.

If all goes well, after the hay is harvested I will assemble the 20 meter 5-element upper yagi, tune it and raise it to the top of the tower. The phasing harness and stack switch can then be constructed and installed. With a little luck my 15 and 20 meter stacks will be ready for the fall contest season.

Saturday, May 23, 2020

I Hate Logging Software

Keeping a log has not been legally required for most hams for decades yet we almost all do. The only common exception is VHF/UHF FM. We keep logs for awards, to remember and greet new and old friends from conversations past, for future reminiscences. Until perhaps 2000 logs were mostly kept on paper and now it's almost all by computer.

Those who are forced to use paper during PC-less operating such as on mountaintops computerize their logs after returning to civilization. Yet there remain holdouts, sticking with paper, usually for aesthetic reasons.

My first experiment with computer logging was for contests in the late 1970s. Other than a bit of playing with computer contest logging with CT in the following decade my log was paper up until my long QRT began in 1992. When I returned to the hobby in 2013 my logging was solely done by computer.

There are plentiful alternatives from which to choose, free and commercial. Back in 2013 I looked at N3FJP, Log4OM, DXLab, HRD and a few others. All have their pros and cons. There is no one right answer for everyone. Free software was desirable for a first choice since I suspected I would want to migrate to something better. I am not averse to paying for good software and I did trial a few of those products.

I settled on the (then) non-commercial version of HRD (Ham Radio Deluxe). For me it had the best mix of usability, DXCC tracking, spot display and ancillary data. Also important to me was the ability to put the daily log and contest logs (imported after each event) in separate data bases and have all data bases contribute to DXCC tracking. Entering rapid-fire QSO data is not great but tolerable.

Several months ago the performance of the old HRD began to suffer gretly under Windows 10. It seemed that every update from Microsoft creates backward-compatibility problems, which is not unusual. So far as I know the newer commercial HRD does not suffer from these problems because they update the product as necessary to stay current with Windows.

After 7 years of being reasonably happy with the old HRD it was time to move on. I revisited products I first looked at in 2013 and a few others that appeared to be popular. Here is a partial list of what is important to me in daily (non-contest) logging software. Your priorities may not be quite different.
  • Continuity and support: Will there be support and updates for years to come? Too many niche products die when the developer dies or loses interest.
  • Rapid QSO entry: Outside of contests my QSOs tend to be short. I need to be able to enter start/stop times, reports and perhaps name with a minimum of keystrokes and mouse gestures.
  • Band map of DX spots: Spotted calls graphically arranged by frequency tells me what is where at a glance. Maps and lists are poor alternatives.
  • Automatic log lookup: Did I work the station before? When, where and name are wanted.
  • DXCC tracking: Is a station a new country or band-country? Is the country correctly derived from the call sign? DXCC needs per band tied in with spotted calls.
  • Ancillary QSO data: IOTA, QTH, free text comments for antenna and power, etc.
  • Performance: I want everything to happen instantly. Processing delays for large data bases of contacts are a problem.
I am flexible rather than rigid in regards to logging software requirements. Not only is perfection unattainable most hams find that their requirements evolve as they become accustomed to a product and their operating preferences change. You think: if it can do this why can't it do that? Your thinking evolves, software products evolve, and indeed everything in our hobby evolves.

In short, I will make no recommendation. Indeed I rarely find recommendations useful. Perusing online reviews of logging software is more likely to confuse than enlighten. Reviews are typically made by those either very happy or very unhappy, and those eager to declare "me too!" Of the products I've tried the reviews are unlikely to agree with my experience.

Rather than making a recommendation I'll talk more generally about what to watch out for when investigating logging software. That is far more likely to be useful. Making a lazy choice can lead to frustration. Consider what is most important to you and then play with a few of your top candidates before making a decision.

Customization and the user experience

Beware software that is infinitely customizable! This is typically promoted as allowing each user to create a unique experience by adjusting, well, just about everything. What it instead screams to me is: "we don't know how it should work so you figure it out."

Creating an effective user experience (UX) is difficult. I've had to do this myself in my professional career and I have closely worked with those whose job was to improve product UX. You might think that a ham who produces ham software would be ideally placed to get it right. Regrettably this is often not the case.

Mostly what we have is users adapting to the peculiarities of the application or customizing it to the point that only they can use it. Once you've reached that point it is difficult to change. Instead it is our nature to rationalize and to defend our choices vociferously.

Of the products I've tried I think the worst in this category is DXLab. It has a large base of enthusiastic users. I've now come back to it for the third time and I still find it impossible to like. Window management is weird, the UI obsolete, customizing it to point of usability is long and difficult and there are simple bugs that seem to persist.

It's not all bad, of course, just not what I am comfortable with. Many like this type of software so perhaps you will as well.

Feature creep, or "bells and whistles"

Mature products frequently run into this problem. Whether in a bid to differentiate from competitors or to meet the needs of diverse and small numbers of users feature count increases with time. Obsolete and rarely used features are not removed. As features increase there are more things that can break and interactions among those features can decrease usability and have deleterious interactions.

Ham logging software is no exception to this rule. Perhaps the product adds an interface to a vintage rig, adds tracking for the "Worked All Podunk" award or supports Windows XP machines. Continue this for several years and the software can begin to collapse under its own weight. The majority who stick to the basic features can find their use impaired by features they never asked for and don't want.

In fairness developers are often doing no more than responding to requests from their customers or keeping up with new technology. But when a feature is added to a mature product rarely is the total UX reconsidered. It is usually left to the user to decide which features to enable or disable and to decide how they ought to interact (see previous section). Adequate testing becomes difficult to nigh impossible since feature interactions grow faster, often far faster, than the feature count.

There is one logging software product that has become so bloated with these bells and whistles it is jokingly said that for every 5 bugs fixed there are 6 new bugs introduced. Those bugs can become increasingly troublesome and software updates a source of user angst.

Oftentimes less is more.

Real-time application interfaces

The more sophisticated logging software support real-time interfaces to other amateur radio applications. These include:
  • CAT for transceiver control
  • Rotator control
  • Serial interfaces for antenna, amplifier and filter switching and related contest peripherals
  • UDP broadcasts to send or receive QSO data for storage and further processing
  • Software API to receive QSO data from digital engines, including FT8, PSK, RTTY and CW
  • Online databases to retrieve biographical data by call sign
  • Upload QSOs for electronic QSL (confimation)
This is not a complete list. Not even close.

I prefer to use the absolute minimum of these interfaces. CAT is obviously needed and I am planning automation for antenna and filter switching. I am making progress with SO2R switching, including keyer and mic control. All the rest I am avoiding.

It takes time and effort to properly implement these interfaces and to keep them working. Even when done well problems will arise due to software updates. Communication glitches result in database synchronization errors that can be difficult to discover, track down and correct.

I prefer to transfer QSOs manually at month end between logging applications and to LoTW. Many hams enjoy fiddling with these interfaces and features. I am not among their number. Simple is good and good enough is good enough.

I go further in that I prefer software that does not support unwanted interfaces since that can lead to bugs in the features I use (see above). Where there are optional modules for these interface features I don't install them, and if the features have configuration switches those switches are set to off.


Products built and maintained by a sole developer tend to have a limited lifetime. When that person retires or dies the product goes into stasis and will eventually become unusable, whether through changes to unrelated software that it uses or no support for future equipment and services. I have been very lucky that the old HRD has continued to work for me for 7 years. Over the past year I have endured increasing occurrences of software glitches.

Support and product improvements take time and effort that users must compensate, and payment is deserved. There are many free alternatives if the willingness to pay is low. Of course those who pay expect good support and should get it. HRD was a free product that now has a license fee to pay for support and new feature development.

A few products are both free and well supported by a team. N1MM Logger+ is an excellent example. Despite contests being its primary application it has been successfully used by DXpeditions and by many users for daily logging.

When you choose logging software how confident can you be that it will be there tomorrow? To protect yourself make sure the application can export the QSO data base in ADIF format, and test that it can by making periodic backups. In future you can import the data base into another logging application. Insist on that to insure yourself against future obsolescence.

What I'm doing now

My current daily logging software is N1MM Logger+. It meets most of my criteria and I am most familiar with it since it my contest logging software of choice. Where it misses my criteria, especially with regard to DXCC tracking, I transfer logs to HRD monthly at the same time I upload to LoTW. It was easy to import my log from HRD using ADIF.

The QSOs are kept in a separate database from contest logs. I have a "Contest" database in HRD to which contest logs are imported after every event. FT8 logs for 6 and 160 meters are directly uploaded to LoTW from the WSJT-X log but not exported to N1MM and HRD. While most hams want digital and non-digital QSOs in the same database I prefer the separation. LoTW does all the category assignments that matter to me.

The screen capture shows which N1MM windows I use for general logging, using the DX "contest" selection. There is the band map with both self spots and cluster spots, the Telnet window for the cluster and a map with the terminator and spots. The log window includes past QSO lookup. A tally of QSOs and countries per band and mode is in the summary window

CW and phone messages are easy to program and use. All are keyed from the entry window or in F-keys. This is superior to using the Winkeyer buttons. I keep CW speed under keyboard control rather than configuring that option only for contests.

Since I have more than 10× as many contest QSOs as non-contest QSO the use of separate databases is helpful. I generally do want to see when and where I've worked a station before but not if it was in a contest. To me they are very different and unrelated activities. I like that this is natural to N1MM Logger+ as it is for HRD. Most logging software has support for just one database.

Before and after contest several windows and options must be configured. That is a downside of using the same application for contests and daily operating. There are ways to smooth the changeover which I have not bothered with. I haven't even decided whether to stick with N1MM Logger+ for daily operating.

I may yet decide to try something different. For now it works well for me and my style of operating.

Monday, May 11, 2020

Keeping Busy During the Pandemic

In addition to no availability of helpers during the pandemic lock down the weather has been anything but springlike. The temperature has been very cold, so cold that it's been snowing. In May. We experienced high daily temperatures that are below the normal high for this time of year. The combination of cold, high winds and snow is delaying many antenna projects.
Recent visitor walking past the towers

Even so quite a lot has been accomplished on the ground, some of which I've related in recent articles. While not the most interesting of items to relate, in this article I'll describe the many projects that have kept me busy. During these challenging times there is still much that can be done.

Antenna decommissioning

From the 150' (43 m) tower I completely removed the 80 meter inverted vee and my seasonal 160 meter antenna. As I've previously reported the 80 meter inverted vee has proved less useful than expected. The 160 meter antenna radials are in the way of farm equipment for haying season and must be removed for a few months.

I have no firm plan to put the 80 meter inverted vee back up except possibly at a lower height where it was originally installed. I also have to give thought to 30 meters since this was the only antenna that worked well on that band. When the 160 meter antenna goes back up in the fall I have a plan to improve its effectiveness with regard to efficiency and directivity. More on that later in the year.

160 meters on the 80 meter vertical yagi

When I last mentioned the addition of 160 meters to the 80 meter array the matching network was temporarily attached. The shunt capacitor has been moved inside the weatherproof box and the match has been improved. To do this the values of the shunt capacitor and series coil were adjusted.

The 2350 pf capacitance calculated with TLW is very close. The addition of 4 × 100 pf 1kV capacitors to the 2000 pf mica transmitting capacitor brought the SWR very close to 1. Coil turns were squeezed and spread to put the SWR minimum at 1830 kHz and then taped to the form to prevent movement. Due to its large size the coil remains exposed to the weather and that may be a problem.

It isn't perfect but it gives me year round access to 160 meters. There is activity through the summer months though far less than the winter. I mainly expect to use it in the few contests I operate in the warmest time of the year.

80 meter yagi

The 80 meter yagi itself requires repair. The galvanic corrosion noted previously was repaired by soldering tinned lugs to the wires that attach to the galvanized tower struts. This should be sufficient for years of service.

The northwest/southeast pair of directions is not working properly and the problem needs to be diagnosed. There was a broken control cable I knew about but that repair didn't solve the problem. There is no rush since the low bands are not a priority during the summer and these are the least used directions. Perhaps I'll look at it during the summer if I'm brave enough to hazard the ticks! I use a ground sheet to reduce the risk.

Trench warfare

Another consequence of the pandemic is the difficulty and expense of renting equipment. The fellow I usually rent from appears to be shut down for now and in any case he no longer has the trencher I used in the past. This is the trench to my most recent 140' tower. During the winter I had two runs of Heliax on the surface for the recently raised bottom yagis of my 20 and 15 meter stacks.

With the arrival of haying season I had to do something and fast. So I picked up a shovel and pick axe and went at it. Manual digging of a 170' (50 m) trench about 20 cm to 30 cm deep and wide enough to accommodate several runs of LDF5 and rotator/control cable is not a lot of fun. But as with contest operating and BIC (butt in chair) being methodical and persistent with SIH (shovel in hand) the job does not take too long.

The trench is shallower towards the far end and hugs the stone wall to avoid the roots of the beech trees lining the inside of the wall. The roots of the (currently) small spruce tree go deep rather than shallow and were no impediment.

Cables are bundled with those from the other big tower at the far end of the trench and follow the same overhead run to the switching system at the base of the 70' tower near the house. Total distance is ~230' (70 m).

The pictures provide perspective on the scope of the challenge. This is one time that ugly cold weather is advantageous. You don't overheat in the springtime sun and the black flies and ticks won't come out to play. You need only prepare to get wet and dirty. Overexertion is not recommended so I did it in stretches of no more than 1 hour at a time. The first day I broke the sod and set it aside. The next day I expanded the trench to the required depth and width.

Industrial electrical suppliers are open for pickup orders so I ordered the cable I needed and within a week the trench was ready for covering. That went faster than the digging. I put the Heliax at the bottom and the control cable on top, maintaining enough pressure to keep all of it flat on the bottom as I back filled the trench. The field is now ready for haying.

Tower maintenance

All the towers required maintenance and their annual inspection. Tasks including the antenna removal noted above. Nothing too serious was amiss though some things require repair.

On the Trylon (21 m) tower the only important task was to aim the yagis. The Tailtwister mast clamp is not the greatest and wind storm action on the 40 meter yagi occasionally give the mast a turn. This time the high wind (90 to 100 kph) moved the yagis out of alignment by 20° in late winter. The XM240 beam width is so broad that it didn't matter much however with the arrival of sporadic E season correct aiming of the 6 meter yagi is better than having to constantly remember the azimuth correction.

On the new 140' (40 m) tower the mast bearings developed surface rust despite being painted before installation last fall. I will remove the bearings and paint them properly with several coats. That's easier than painting them on the tower. This is only possible because the mast hasn't yet been installed. Although the double sealed bearings are silky smooth rapid rusting could become a problem as the years pass. While up there I completed the rigging to tune the upper set of yagis for the 15 and 20 meter stacks.

The TH7 on the 150' (43 m) tower was misaligned by the same amount as the XM240 and 6 meter yagis during the same wind storm. The direction pot was easily aligned at the control unit but an inspection was warranted. The saddle clamps were less tight than they should be. The antenna was turned and the bolts torqued.

Unfortunately the turnbuckle screws on the boom truss support were bent when the wind hit because the mast side of the turnbuckle screws are bolted to the mast clamp rather than freely pivoting in open eyelets. I was easier to do at the time with the material on hand so I took the risk. The turnbuckles are inexpensive and the TH7 is slated to come down later this year so I decided to leave it alone. It'll certainly last the summer.

Tuning the upper 15 meter yagi

The upper yagi of the 15 meter stack has been sitting out in the hay field over the winter. There was no rush to get it tuned and prepared for raising since I could not be ready until spring and better weather. The mast has yet to be raised and the bracket to be fabricated. In the hope that I can get that done before the hay grow too high I proceeded to tune the yagi.

This went far quicker than the first time. All the gamma match dimensions were recorded and replicated on the upper yagi. It is better to keep good records than to redo the work! Element length adjustments were done on both yagis at the same time so that their performance is as identical as possible.

It took only one tweak to achieve the excellent SWR curve shown. The yagi is too low for proper tuning. My intent was to check that the tuning was about what it should be and the mechanical work on the gamma match. It is back on the ground for remedial work on the gamma match before it is readied for final adjustment. The boom is stronger and heavier than for its lower twin since it will be rotatable and up almost 150' (46 m).

Due to the lock down the yagi likely won't be raised until August. It will be placed out of the way for the interim. The upper 20 meter yagi will not be assembled and tuned until just before it is raised in late summer. It is too large and heavy to be stored except in pieces.


It's a funny thing that despite staying close to home during the pandemic lock down my enthusiasm for operating has been lower than usual. From what I am hearing from others this is quite common. I will not force myself to operate since that would make it a chore rather than the pleasure it ought to be. The absence of DXpeditions and major contests doesn't help.

I have not been entirely inactive although I've done more listening than operating. Low solar flux has not stopped the polar path summer openings as 24 hour daylight returns to the high north. UA0, BY, JA and more southerly east Asia stations are heard on 20 meters almost every night.

On 160 meters there are morning openings to VK, ZL, JA and other distant locales. For a few minutes before and after sunrise (which is very early in the morning) stations come through with good signals. Unfortunately almost all the activity I've heard has been FT8 and not the CW I prefer. Since I am not an early riser I rarely catch these openings.

If nothing else it is an opportunity to experiment with the new Beverages and switching system. The great circle route to west Australia, which is near our antipode, is very different than east Australia and New Zealand. ZL is best on the southwest Beverage while VK5 and VK6 are off to the side on that antenna and are only heard on the north Beverage (VK5 is northwest and VK6 is north-northwest). The east-west reversible Beverage planned for next winter is needed.

With the 160 meter antenna removed the port on the antenna switch was reassigned to the 6 meter yagi. The end of 160 meter season is the start of sporadic E season VHF. I have already heard my first European and EA8 stations and worked stations in South America, Caribbean and Central America.

No new countries have yet been worked although a couple were copied. My hopes are high for the season which peak at the solstice in late June.


The Snowbirds are the military aerial acrobatics squadron of the RCAF. Their home is at an air base about 150 km to the west in FN14. With the arrival of spring they have begun a series of countrywide tours as part of the government's plan to keep public morale up during the pandemic. Although my remote rural QTH is not on the schedule I am on the flight path to between their base and Ottawa and Montreal. I have seen them in the vicinity once or twice before.

Several days ago while I was down on my knees in the muck laying cables in the trench I heard the unmistakable roar of many engines approaching from the western horizon. Guessing what it was I stood up and pulled out my phone. Seconds later they made their appearance, flying low and fast and in formation headed east.

Realizing the rare opportunity I noted their flight path and ran back about 20 meters in my mud-caked work boots. I took several shots in quick succession and picked the best for display. I sent it around to a bunch of local hams and our contest club and it was well received. I'll end this article with that shot. Enjoy!

Monday, May 4, 2020

Beverage Remote Switch

With two reversible Beverages for low band receiving -- north/south and northeast/southwest, and more planned -- I need a way to select the direction. I chose a remote switch with a DC control cable back to the shack. This is the more economical and convenient than multiple bringing coax from each antenna back to the shack.

The switch is uncomplicated to design and build. I brought the project forward due to the COVID-19 lock down even though the low bands are not a priority during the summer atmospheric QRN. Without access to helpers and the rapidly approaching peak hay and tick season the big antenna projects must be delayed a few months. While that's unfortunate it is no reason to slack and I am having no trouble keeping busy.

The remote switch is located at the edge of nearest hay field close to the feed points of two Beverages. Some separation is required to reduce risk of pattern degradation from conduction between grounds at each feed point and the switch.

To reduce the work I decided to use a buried and unused Cat5 cable (8 conductors) terminated at the 43 meter tower. The tower is about 25 meters from the Beverage switch so a trench across the field was dug with a shovel and pick, a Cat5 cable buried and the trench refilled. It took about 3 hours of manual labour. As exercise goes it isn't ideal but it'll do to keep me active and in shape.

In the picture but you can see that the trench is not particularly straight! It doesn't need to be and I wasn't careful about it. The post for the remote switch is just left of centre near the tree line. Near the right edge is the feed point of the 175 meter long northeast/southwest reversible Beverage. 

The cable is already connected through to the house so all I had to do was make connections at each end and at the tower junction box. Another Cat5 cable from the basement patch panel puts control of the Beverages on the operating desk.

The switch is so straight-forward a schematic isn't necessary. Indeed I didn't draw one; I had the circuit imagined in my head and went with that alone. I chose the smallest sealed metal box from my inventory that would fit the components. The layout for the holes was done on masking tape and then drilled. The mechanical fittings were installed and wiring proceeded.

Unlike the plastic boxes for the Beverage and its ports kept at different RF ground potentials this box must be metal and with no conductivity gaps. The purpose is to route common mode current on the Beverage connections to ground and allow none of it to seep into the interior. The ground lug on the left wall connects to a 4' ground rod below the box. Common mode at each Beverage feed point is similarly managed.

Control signal DC ground is tied to the Beverage antenna ground. DC ground and all signal lines have RF chokes for RF isolation from common mode currents from nearby transmit antennas. Other than the 1000 μH choke on ground line 'G' the chokes are the smaller 100 μH size to better fit the available space. Construction is dead bug style, with rigidity by dint of solid wires throughout.

The barrier strip may seem an odd choice for such a small box. Using a connector would require a larger box for the switch and soldering connector pins out in the hay field. The screws of the barrier strip make it easy to wire the Cat5 cable in the field and disconnect for maintenance or upgrades. The barrier strip does double duty as a mechanical anchor for the chokes.

The relays are SPST reed relays with integrated protection diodes. The coils use the inner 2 pins, with positive on top. The diodes make the coils polarized so orientation matters. One relay is powered at a time to select one Beverage. No antenna is selected without power. One SPDT relay can be substituted if an unpowered selection is desired. The SPDT relay must be energized (the default antenna deselected) when a different antenna is selected. Port-to-port isolation is good despite the back sides of the relays being tied together. This technique is only advisable for low frequency applications.

When two receivers use the Beverages they share a common feed line. There is no provision to have each receiver connected to a different Beverage direction or for diversity reception on a single receiver. Indeed the reversible Beverages have one feed line rather than the two required for sharing. Splitting the signal will result in a -3 db level reduction, or worse depending on how splitting is done. For my station I expect the Beverages to be used primarily on 160 meters and only occasionally on 80 and 40 meters when directional antennas for those bands need an RDF boost for the weakest signals.

An amplifier is a future consideration to equalize the signal level with the transmit antenna, recover gain lost by splitting or to equalize receive antennas. The longer a Beverage the higher the gain. There is a small difference between the 150 and 175 meter long Beverages. Other antennas may exhibit greater gain differences.

The 'R' control line places DC on the Beverage coax to power its relays for direction reversal. Because only one Beverage relay is powered at a time only that antenna receives reversing current. A choke and capacitor keep DC out of the feed line circuit. If a Beverage antenna is not reversible it requires a capacitor on its output transformer to prevent a DC short in case the 'R' line is inadvertently powered.

The F-jacks for the RG6 to the Beverages require a ⅜" hole and spaced far enough apart to provide room for a wrench (nuts) and for fingers (attaching coax). The hole for the feed line jack is ½" to accommodate plastic spacers (with a raised inner lip) that isolate it from the box -- more on this below. The hole on the far left is the minimum size to pass the Cat5 cable. The several small holes are for drainage. From experience some tiny insects can get inside. If the holes were any smaller drainage would be poor.

The feed line is isolated from the chassis and Beverage coax by the aforementioned spacers on the jack and with a 1:1 transformer. The antenna winding is between the selected Beverage (capacitively coupled) and antenna ground. The transmission line winding is between the RG6 shield and centre conductor. The extra bits of wire were snipped after the picture was taken, and tape was placed under the capacitors for additional shorting protection.

Here's the switch at the installation site with the control lines connected and partially dressed. The wire debris you can see was removed later. Although there are connectors for 4 Beverages antennas all 6 selector lines are connected. Other receive antennas could be added in future by knocking holes on the right wall of the box.

After testing with clip leads in the shack to confirm that the switch works as it should I added wiring and switches to my manual antenna control box on the operating desk.  The toggle switch selects the normal (top) or reverse (bottom) direction of the rotary selector.

I am planning a software controlled ergonomic receive antenna selector as part of my migration to station automation. As with some other projects it may be pulled forward if I cannot make progress this spring and summer on big antenna jobs due to helpers being kept away by "social distancing".

For now I am very happy with the instant direction switching, even it is just 4 directions. It is enough to be exceptionally useful. The small number of directions is only a significant problem on 40 meters where the Beverage main lobes are narrow. This will be remedied when I add more directions, as soon as late this fall. All I need to do is add the Beverages and plug them into the now existing switching system.