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.

Support

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.

Operating

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.

Snowbirds

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.

Monday, April 27, 2020

DXing Ethics and RR73

This winter I called a rare DXpedition on 160 meters FT8. I don't normally do this and I had already worked them on CW. It was purely opportunistic since I was there, I heard them and I had the time. I flipped on the amplifier (they were very weak) and went at it.

After several minutes of calling I received a signal report from them. I replied with the usual FT8 R-nn message. I resent it many times since I did not copy RR73 from them. Indeed perhaps no more than 10% to 20% of their messages were strong enough to be decoded. I did not yet have a Beverage antenna for their direction so I was manually switching between my 160 meter antenna (transmit) and 40 meter yagi (receive) which had a better SNR than the vertical.

I never did decode an RR73 message for our QSO. The few messages successfully decoded were directed at other stations. Eventually I gave up. There are several scenarios in which an FT8 QSO is deemed to be complete but this isn't one of them. At a minimum each station should copy a reception confirmed message and I didn't have one from them.

When I later searched their online log there I was in their log with an FT8 QSO on 160 meters. Apparently they did receive my R-nn message and responded with an RR73 that I failed to copy. For all I know they sent RR73 more than once in reply to my repeated R-nn messages. I'll never know.

My personal ethics on the matter are clear: this was not a valid QSO and I did not claim it. Not everyone agrees. I know people who believe that all I need to do is create and upload the QSO record with an estimated time. LoTW (Logbook of the World) and other QSO matching services have what I consider an overly generous latitude for timestamps. I knew this and deliberately did not note the time since the QSO was not valid.

Despite my passion for DXing the claiming of a rare country in this circumstance repels me. As I noted, there are others who would disagree. For many the DXCC "counter" is justification enough for bending the criteria for what is considered a valid QSO, especially when the DXpedition logged the QSO.

Indeed this is an inherent flaw of the RR73 message since it signals that the QSO is being logged by the sender with the expectation that the message is received and successfully decoded. That is never certain. In this respect FT8 and similar digital modes rely on the good faith of the operators.

Similar circumstances can occur on SSB, CW and RTTY but have historically been less controversial. FT8 brings the matter into stark relief because there is no muddy middle: RR73 is copied or it is not. There is no room for operator judgment.

That sums up my attitude toward digital DXing. I am not personally satisfied with a QSO that does not fulfill the minimum requirements. I take no pleasure in claiming a QSO that I deem invalid.

Friday, April 17, 2020

Reversing the Single Wire Beverage

In my previous article on the reversible coax Beverage receiver antenna I said that my next Beverage would be the same oriented east-west, and that it would be done shortly. I lied.

Due to circumstances I've put that project aside. Purchasing a 150 meter reel of RG6 became more difficult and expensive due to the pandemic lock down with delivery uncertain. Then there were unresolved difficulties along the planned route of the east-west Beverage. Some of the trees are quite large and old with rot and other challenges that would require additional effort to prepare the route.

What I did have was half the 400 meter (¼ mile) reel of aluminum electric fence wire left over from building the 175 meter long single wire northeast Beverage. All I had to do was hang it along the same route to make an open wire transmission line Beverage so that it could be electrically reversed. The switch to select direction is slightly different than that for coax due to the use of a balanced transmission line. The critical difference is the transformers, two of which are more complex to build and test.

As you read this article you may wish to refer to the linked articles for details I am not repeating in this one, especially that for the reversible coax Beverage. This includes references to other material, links to which are largely not provided here.

How it works

As before let's start with the rough schematic of the two-wire Beverage from ON4UN's Low-Band DX'ing book. My article on the reversible coax Beverage reviews the basic operation of the reversible Beverage. Here I will largely limit the discussion to the differences between a coax and open-wire line Beverage, covering both the physical construction and the electronics.


As before signals from the right don't see T3 and signals from the left don't see T1 and T2. Due to the travelling wave behaviour of the Beverage the signal is zero at the antenna's forward edge. The signal builds as it travels along the two parallel wires to in common mode: signal amplitude and phase are identical on the two wires.

Signals from right build up along the length of the open wire line and encounter T2. This signal does not appear at the secondary winding because there is no potential difference on the two ends of the primary winding. Instead they combine at the primary centre tap and are fed through the primary of T1 to ground, making that transformer functional. The impedance is stepped down to that of the coaxial feed line. T1 is identical to that in the coax reversible Beverage since the surge impedance is approximately the same.

Signals from the left are also common mode when they encounter T3. The same behaviour occurs, But this time the common mode signal from the secondary winding centre tap flows through the primary winding to ground. Signal energy is coupled back into the open wire line in differential mode so that the two wires now behave as an open-wire transmission line. This signal power couples through T2 and is transformed to the impedance of the coax feed line.

Operation is a little tricky but is understandable when you study the schematic for a few minutes and carefully trace the signal paths. The reversible coax Beverage is easier to understand since the exterior of the coax is the Beverage antenna while the interior of the coax is the transmission line. For the two wire Beverage the two wires do both tasks.

Physical design

Twinning the single wire Beverage easier than putting in a new Beverage. It took about a day's work spread over 3 days to fabricate parts, clear brush and install the wire. A few of the tree insulators had to be moved to accommodate the second wire and the higher tension. Unrolling 175 meters of aluminum wire and routing it through the bush was probably the easier task!

To simplify construction I oriented the wires vertically. Since this can introduce imbalance (relative to ground) the wire spacing is just 10 cm (4 inches). Doing it this way saved me a lot of work since the original Beverage is sometimes supported on the left side of a tree and other times on the right. Rerouting the first wire is very difficult and dealing with rotation for wire crossover has its own challenges.

I can add rotation in its vertical orientation should I suspect an imbalance. This seemed unlikely based on the reported experience of other hams. Initial performance tests (see below) appear to confirm this.


Several methods are used to support and space the wires. There is a mix of commercial electric fence wire supports and ones I made from PVC pipe. The higher tension allowed me to eliminate a few of the tree supports. They were no longer needed or they were sufficiently out of line to develop excess lateral force.

Simple PVC spacers were used on the longer unsupported spans to keep the wire spacing uniform. Small gauge copper wires tie keep the wire from slipping out of the slots. I first used this technique several years ago to build a multi-band inverted vee.

Nails are galvanized 3" straight framing nails. Since the trees grow around them to repair the damage leave some of the nail shafts exposed. The force on the nails is quite low so they won't bend or split the living wood. As trees grow and die the supports may have to be moved or replaced. Although the trees can handle the injury this is wild bush where the trees are expendable.


The terminations are more difficult than with a single wire or for the coax Beverage. Ideally we want a smooth curve down to the electronics. Unfortunately mine take a sharper angle. On the left is the feed point (southwest end) and on the right is the northeast end deep in the bush alongside the swamp.

Some improvement is required though, as we'll see, performance seems unaffected. If nothing else the boxes need to be firmly anchored to prevent connection fatigue and crossing each other. Occasional tree contact doesn't seem to affect performance. Now that testing is complete I'll proceed with the "finishing" work. The ground wires are a little long because the ground rod had to be away from tree roots and the open wire line is difficult to route downward. This doesn't noticably affect performance.

Electrical design and transformers

The ON4UN circuit for this type of Beverage is reproduced here along with annotations for the impedances and transformer turns ratios for my chosen design. There is flexibility in the selection of impedances to permit finding a good balance between physical design (wire size and spacing and Beverage height) and transformer design (turns count and ratio and centre taps).

From: ON4UN's Low-Band DXing with my annotations

The size, spacing and height of the two wires determine the surge impedance. There are two of them: common mode for the Beverage antenna (both directions) and differential mode for use as a transmission in the reverse direction. Although the precise impedance values are not important in themselves the choices are critical for designing the transformers.

What we ideally want for both is an impedance that allow for an integral number of turns on the primary and secondary windings on the 3 transformers for an exact transformation ratio. This is next to impossible and is not an absolute requirement and the common mode surge impedance will vary from a theoretical calculation. We want to get close so that performance is what it should be.

The surge impedance of the open-wire transmission line is easily calculated and with a small spacing relative to height there is no variation due to ground proximity. For my antenna those distances are 10 cm and 230 cm, respectively. The transmission line impedance is 620 Ω given 10 cm spacing of AWG 17 wire. The Beverage surge impedance depends on wire gauge, spacing, height, and in the case of common mode, ground quality.

There are equations for both in ON4UN's book: equations 7-2 and 7-3 on page 7-87. To experiment with the parameters I made a spreadsheet (Open Office). Below is a screen capture. I highlighted the cell with the common mode surge impedance equation so you can see what it looks like when coded. Measurement units are centimeters.


The ground quality is estimated as "good" based on what I know of the area. Choosing 440 Ω is a reasonable guess. If in practice the value is wrong it can be measured (procedure described in the ON4UN book) and the transformers redone.

The selected transformation ratios are not exact but should be close enough. In the performance section below I'll come back to this. The turns ratios are the square roots of the impedance ratios. The centre-tapped windings have an even number of turns so that the tap is never at a half turn which can introduce loss and makes for awkward vertical mounting of the transformers on the PCB.

To minimize loss at high impedance more turns are required. That's why I chose 4:12 for T2 rather than 6:2. Other than the low impedance secondary of T1 all windings are small gauge enamel coated copper. With so many turns the insulated Cat5 wires I like to use do not fit the binocular cores. Insulated wire is more convenient since it doesn't require the PTFE protective lining.


These are the 3 transformers built and tested, and the reflection transformer in its enclosure ready to be installed. I put temporary labels on the transformers so that I don't confuse them. Later the reflection transformer was taped to the box bottom to stop wire fatigue due to shaking by the wind.

For best performance the centre-tapped transformers must be balanced. ON4UN's book discusses the importance and gives a procedure to test balance. To be frank I found that advice less than useful. The more important thing, and which is not described, is how to achieve balance in the first place. Knowing that a transformer is unbalanced tells you next to nothing about how to correct the problem.

Regrettably I am no expert on RF transformers. I came up with a few steps to make the centre-tapped winding physically symmetrical with the expectation that will lead to electrical symmetry. Let's find out how I did.
  • Do the centre-tapped winding first. When there's another winding underneath you will find that it is not sitting flat or centred on the inside wall of those little holes. That will cause the wire of the second winding to slip into gaps or to one side on the first winding. The result is a small inequality of the length and shape of each turn.
  • Use an even number of turns and adjust the turns of the other winding to achieve the required turns ratio. Tapping at a half turn is awkward, can increase loss and routing the tap from the other side of the core can introduce stray inductance and capacitive coupling to other components. It's small to be sure but when you want to protect pattern mulls of over 20 db it can make a difference.
  • Do the winding with two equal length parallel wires, each enough for half the required turns. For example, for my 4:12 transformer the centre-tapped winding is done with two wires for 6 turns each. Tape the starting ends together. After each half-turn (one pass of a core's hole) ensure the two wires are bedded together on the inner side of the hole then, keeping the turn  radius equal route them down the other hole for the second half of the turn. Look inside the hole to make sure and use a small screwdriver to tamp down any "bumps". Don't squash the wire! Pull the wires taut to remove any slack that may be there. Repeat until done.
  • When the winding is complete check that the ends of the wires protrude the same length. If not something went wrong. Tiny amounts can be ignored, however defining "tiny" isn't easy! Use your best judgment.
  • When done the end of one wire and the start of the other are stripped, wound together and soldered. Don't rely on a manual connection since it can slip as it handled.
  • Build the second winding over the first.
To test the transformers I placed a load across the full centre-tapped winding that would result in an impedance not too far off 50 Ω on the other winding. Trim the leads of each winding to equal length. That should give the most accurate measurement by the antenna analyzer. Check that the transformation ratio is approximately correct and that the residual reactance is close to zero.

Do the same test for each half of the winding. You likely will not get what you expect for an impedance. That isn't too important. What we want is for the measured impedances to be equal, both R and X values. Following this process the impedances on both centre-tapped transformers was less than 1%. It may have been better but that is more than most analyzers, even the best can accomplish. Use an analyzer or VNA with excellent repeatability -- same result for all measurements of the same test setup.

Switch box

There is very little difference between the switch box for this antenna and that for the reversible coax Beverage. You can read that article for detail not covered here.

The major difference is the location of the external attachments. The studs for the two Beverage wires are symmetrically placed on opposite sides at one end of the box. Avoid putting tension on the studs since that will eventually crack the plastic. Use strain relief elsewhere and place the box wherever it can be at least protected from the elements. For our snowy winters I want the box at least 45 cm (18") off the ground. Even then it will get buried in the snow occasionally.

The coax feed line and ground connection stud are on the opposite end. All the attachments are in keeping with the electrical layout and allow the forces of those attachments to be as symmetric as possible.


The circuit board looks a little different due to the arrangement of the attachments. For example, the circuit to separate the RF and DC components is on the lower left closest to the RG6 F-connector. The default (unpowered) direction is northeast since that is the most used direction for my style of operating. Southwest relies on the reflection transformer and powering of the relays through the coax. The load for the unused direction (to dissipate rather than reflect signals) is a series-parallel threesome of 51 Ω resistors.

The quickly drawn partial schematic of the transformer section of the circuit matches the physical layout. I tried to centre T2 (lower right) between the two wire studs for maximum balance. I made the two wires the same length even tthough a difference of a few centimeters is negligible at low frequencies.

For maintenance predictability the default direction is at the top, the same as for the other reversible Beverage. For my operating preferences northeast is the sensible default. The relays are powered to select southwest, the reverse direction.

Debugging

Despite extensive testing the Beverage did not work when first installed. In the northeast (default) direction the SWR wasn't bad but there was evidence of poor rejection to the southwest. In the reverse direction the SWR was extreme and there was no signal at all. The switch box was brought indoors for troubleshooting.

When I assembled the unit I did not retest the RF behaviour. I reasoned that since the signal paths were good and the transformers were tested this wasn't necessary. This time I placed a 660 Ω resistance across the open-wire studs (to represent the transmission line impedance). With the relays powered I measured an RF short. That explained why southwest didn't work.

The PCB was removed and the DC resistances checked. This is difficult for the transformers since they show DC connectivity. With magnifying spectacles I discovered a solder bridge between the pads for the centre-tapped T2 primary winding. I cleared the debris with a sharp tool. Retesting yielded an impedance very close to 75 Ω. That's perfect.

Happy with my repair I rushed out into the windy and snow flurries to reconnect the unit to the feed point. Back indoors I eagerly tested the antenna. To my dismay there was no improvement. Either the unit had another problem or the reflection transformer T3 was faulty.

I retrieved both units for further investigation and repair. Before the hike to the far end I shorted the two wires so that I could test wire continuity. The open-wire line was fine. All I learned was that 350 meters of #17 aluminum wire has a resistance of about 13 Ω. As a transmission line for the reverse direction this is negligible loss since the line impedance is 620 Ω.

Again the switch box worked as it should. When I tested the reflection transformer T3 I was surprised to discover an RF short. The centre-tap and connection to the primary were teased apart with a soldering gun to allow testing of each winding. A DC test showed that the two halves of the secondary (high impedance) winding were shorted together. There was no short visible on the leads and wiggling had no effect.

The windings had to be removed. I can only assume that the enamel was thin or missing on both halves of the secondary at the same place. I rebuilt the transformer with new wire and like the first time it tested good. After soldering it into its box I again tested it to be sure that soldering heat hadn't been the cause.

More hiking and fighting with wires and cable in the blustery weather saw the Beverage reassembled and ready for its next test. This time the antenna worked in both directions. Mission accomplished, or so I hoped. It was daylight and I would have to wait until dark for a proper test on the low bands.

An interesting observation is that the differential mode transformers on an open-wire line have excellent discrimination against common mode signals. If not for that I would have heard something rather than only receiver front-end thermal noise when the reflected (southwest) mode was shorted out.

Performance

As for the coax reversible Beverage I tested the SWR after checking that signals were being received in both directions. As you can see below the match is quite good.


An hour before sunset I did my first test on 40 meters since there were Europeans stations coming in quite strong. The direction switching was remarkable. F/B was at least 20 db for both Europe and US stations approximately in the opposite direction. The same test a little later on 80 meters had the same excellent results. F/S was even better when compared to the vertical.

There was little activity on 160 meters to test with that evening. I had to check at intervals for signals, and I tried FT8. In all cases the F/B performance was excellent. There was no discernible degradation of signal discrimination in the antenna's original unidirectional northeast direction.

The 175 meter length is a popular choice since the minor lobes move away from the 180° opposite direction to give the optimum F/B (on 160 meters and harmonically related bands of 80 and 40 meters). Although the RDF is little different for slightly shorter and longer Beverages many prefer to have the best signal rejection directly off the back.

That the F/B and RDF appear to be what they should be, and about the same in the northeast direction as for the original single wire Beverage, indicates that the transformers are well balanced and that hanging the two wires vertically introduces negligible imbalance.

To change direction I used the same temporary DC injector built for the coax reversible Beverage. Notice the slight peak in the SWR near 5 MHz in these SWR plots and in those of the coax reversible Beverage. This is likely due to the 100 μH choke in the injector which has a self resonance near that frequency. Picking RF chokes with a self resonance outside amateur bands is beneficial.

Finishing up for the spring

The final task this spring is the remote switch box to select Beverage direction. That work is mostly done with completion slated within the next week. Expect to see an article on that later this month.

The remainder of the Beverage plan will wait until fall or, more likely, early winter. For the rest of the spring I will focus on the towers and yagis. There is a lot to do, most of which has been delayed by the "social distancing" of my friends who help me with these big jobs. Unfortunately there is much that will have to be delayed to August after the hay has been harvested.

Stay safe out there.

Monday, April 6, 2020

Reversible RG6 Beverage Antenna

I am on course to install more Beverages as my preferred low band receive antennas. As I mentioned in a recent article on my revised receive antenna site plan I had wavered on whether to use Beverages or vertical arrays. I have the room to do either, or both for that matter.

My plan relies on reversible unidirectional Beverage antennas plus a remote switching system conveniently controlled by the operator. Although less of a challenge than what I faced with my 80 meter vertical yagi I wanted to be sure I got it right before going further. I built one of these antennas and a rudimentary direction selector to determine whether it works, how well it works and to understand the challenges involved.

At this point I am convinced so I will proceed with one more of these in the coming weeks. The remote switching system has been designed and will be added this spring if time allows or in early autumn. All the required components are in hand.

Reversible Beverages are well covered in the amateur radio literature and there are commercial products for those who value convenience. Beyond a brief description of how these antennas work I'll focus on my choices, technical approach and installation challenges that may be less well covered elsewhere. I hope that that will be most useful to others and encourage hams to build one of these antennas. There is great satisfaction in building rather than buying.

Overview

Beverage antennas can be bidirectional, unidirectional or reversible unidirectional. Reversible Beverages cut down on cost and and land use at the price of electronics for switching and tuning. The antenna "wire" is a transmission line. Traditionally this has been open wire line or commercial ladder line. Coax is perfectly usable and can be cost effective and convenient. The electronics (transformers) are easier however the physical challenge can be greater.

A nice graphic of a reversible coaxial Beverage antenna can be found in ON4UN's Low-Band DXing book. Any coaxial cable can be used provided it can withstand the rigours of horizontal suspension over a long distance. The transformer turn counts depend on the coax impedance and diameter, as I'll discuss below. If both directions are not needed simultaneously a single feed line and a switch are used. That's how I built my antenna.

From ON4UN's Low-Band DXing

Now a few notes on the basic functioning of a Beverage antenna. It is little more than a long wire suspended a short distance above the ground. Imperfect ground is required for it to work. Without delving into details, the Beverage has gain in both directions off the ends of the wire.


For the typical unidirectional Beverage the signal energy of the unwanted direction is dissipated in the termination resistor (including resistance of the ground connection). Left unterminated the signal reflects from that end due to the high SWR and that feature makes the antenna bidirectional. Some hams see value in this though most choose unidirectional for its higher RDF (receiving directivity factor).

The wanted direction is terminated with the impedance of the receiving system consisting of the transmission line and the receiver pre-amplifier. Terminations must closely match the surge impedance of the antenna -- typically 400 Ω to 700 Ω -- or some signal will be reflected and affect performance. Transformers match the Beverage impedance to the load. Since the Beverage is a non-resonant antenna with a flat impedance over a large frequency range transformers are perfect for this job.

A bidirectional Beverage works in the same fashion as a unidirectional Beverage. Rather than a termination resistance the signal at the far end is carried by a transmission line to the receiver. It can be a separate transmission line or, in the antenna discussed here, the coax being used as the antenna. The Beverage antenna "wire" is the large diameter outer conductor (shield) of the cable, and that is true for both directions.

The reflection transformer (T3) transforms the high surge impedance of the antenna (as measured between the outer conductor and ground) to the impedance of the coax and delivers it to the other end of the antenna. There it is picked up by T2 and delivered to a load. T1 picks up the signal in the usual Beverage direction, transforms the impedance and also delivers it to a load.

A reversible Beverage is actually two unidirectional Beverages. Follow the signal paths in the schematic from the ON4UN book until you understand how it works. It can be perplexing at first glance.

Note that the signal (either direction) does not see the electronics at the end of the antenna it first encounters; the signal energy at that point is zero and builds gradually along the wire until picked up at the far end. For the same reason increasing Beverage length increases gain.

Other than a very short Beverage there is no need for an amplifier, and therefore no added risk of amplifier inter-modulation products due to nearby transmit antennas. For a multi-op or SO2R contest that can be a considerable benefit.

Physical construction

Careful consideration to the coaxial cable mechanical properties is necessary when it is put under tension and suspended horizontally between supports. It is not easy to find these specifications for a lot of the cheaper RG6 on the market. The mechanical specification of a maximum of 69 lb (31 kg) tensile strength of Belden RG6 is at the upper end of the range.

I recommend no more than 10 to 20 lb tension for most RG6. This provides an allowance for poor quality and wind and ice loads. With closer spacing of supports the required tension is reduced. A messenger wire, cable or rope, or RG6 with an integral messenger cable are alternatives. All of these can double the cost of the antenna.


Gripping small coaxial cable for applying tension and anchoring is not difficult with small diameter rope. Some pros call it a "thousand mile knot" and they use it to hang large diameter hard line from towers is the equivalent (and expensive!) commercial grips are not handy. One product is the Kellem grip. The used grips for Heliax are far too large for RG6. Guy wire grips are not recommended since getting the right size that holds well and doesn't over-compress the coax is challenging.

If you want to try this start by bending the rope into a long narrow U shape with the open end facing the anchor. Lace the cable by wrapping both arms of the U at the same time around the coax, and repeating until you have at least 6 or 8 wraps. The U must be long enough that there is enough rope left to tie a couple of knots. Done properly there are no stress points on the coax and the grip is good enough for slippery PVC jackets. The rope easily slides along the coax when there is no tension but almost impossible with moderate tension.

Notice the F barrel connector on the RG6 termination. It protected the exposed centre conductor until the electronics were attached.

I put in about a day's work spread over a week to clear bush along the 150 meter run of the Beverage. The tree line that looks tidy in the satellite image (see previous article) is thick with trees, bushes, thorns and deadwood. Despite being only 4 meters wide it is difficult work. Winter is the best season for doing this due to the snow cover, no foliage and no bugs.

I selected trees along the route for hanging the RG6 then removed limbs, tree trunks and bushes that either impeded me, the coax or at risk of damaging the coax. After unrolling the coax along the path I installed hangers on the trees and cleared vegetation along the aerial path of the cable.

The hangers are made from PVC pipe and seem to work. At first the coax sits on the nails since the hangers can grab and kink the coax when tension is applied. When the job was complete I slipped the coax into the hanger slots. The wire retainers are optional and only used where there was risk of the coax popping out.

The span between hangers ranges from 8 to 15 meters. I am uncertain whether the coax will weather the elements without eventually deforming or kinking. I may have to resort to installing a messenger cable. I'll inspect it in the fall and decide what to do based on how well it handles the abuse. Foam dielectric is more easily crushed than solid dielectric such as in RG213.

Later the cleared vegetation was cut into small lengths and thrown back into the bush where it can rot in peace. None of it is suitable for firewood.As you can see from the pictures this work was done in the cold weather with snow on the ground.

During installation of the electronics 4' ground rods were pounded into the ground at each end of the Beverage. This was difficult since there are tree roots to avoid and at the north end the bedrock was close to the surface. In the latter case it took a dozen attempts to find a gap in rock that would permit the full length to penetrate. I am not using radials and based on performance (see below) they may be unnecessary.

Transformers

Several years ago I built a unidirectional Beverage matching transformer for practice. I put it to use in my first Beverage, the 170 meter long northeast unidirectional Beverage. That experience came in handy for this project. A few enhancements are needed to wind T2 and T3 to deal with the increased number of turns and a smaller wire gauge.

Following the guidance from ON4UN's book I purchased PTFE sheet to line the binocular cores -- Fair-Rite 2873000202. The plastic prevents abrasion and shorting of enamel coated wire on the edges of the core. A lifetime supply of PTFE sheets can be found online for a few dollars. The 0.1 mm thick sheets I selected works well in this application.

I am sure that even good quality vinyl electrical tape and non-adhesive plastic sheets will suffice for low frequency use. Use what you will. A better view of the winding method can be seen in the close up of the switching unit further below.

I use AWG 24 insulated wire from scrap Cat5 cable for the low impedance winding. This wire is easy to work and provides a "bed" for the high impedance winding made from AWG 30 enamel wire. Enamel wire is easy to scrounge from old RF chokes and from power and audio transformers. I use a jeweller's screwdriver to press the wire against the inside walls of the core to make room for additional turns. Otherwise the wire quickly consumes the narrow space.

Be sure to wind the primary and secondary in the same direction (clockwise or anticlockwise). Winding sense isn't important but for the reflection transformer you must connect together the same ends of the primary and secondary windings. Refer to the schematic above.

After winding each transformer I test it with an analyzer. For a secondary load I use a 470 Ω resistor to represent the Beverage surge impedance. The ideal input impedance is 75 + j0 Ω (SWR 1.5) across the frequencies of interest. This transformer measures almost exactly 81 Ω from 1 to 7 MHz with a load resistor that measure 510 Ω -- carbon composition resistors increase with age.

Direction switching

The ON4UN book includes no explicit description of a switching system. It is not difficult although there important details are easy to overlook. The final product fits in a small box and has ports for the feed line, Beverage coax and ground wire. The hand drawn schematic should be easy to follow.

A few ideas for my design come from the ON4UN schematic above and the RemoteQTH schematic for an open-wire reversible Beverage by OK2ZAW.


Layout is not critical. At 1.8 MHz a little bit of sloppy wiring does not affect performance. The transformers wound on these binocular ferrite cores have essentially no coupling to each other or anything else. The enclosure must be non-conducting since earth ground and the outer conductors of the both coax ports are at different potentials or DC isolated. With the enclosure closed you can tell which is the antenna port since it has DC connectivity to earth ground via transformer T1 (lower right). Choose UV resistant plastic for the enclosures.

On the left DC and RF are separated by a capacitor and choke. The coupling capacitor should be at least 0.1 μF so that the impedance is small enough not to cause signal attenuation at 1.8 MHz. I am using 0.2 μF and 0.5 μF will do well down through the AM broadcast band. The choke should be at least 100 μH to prevent leakage of RF into the DC circuit. I am using a 1000 μH choke with a self-resonant frequency of 1.2 MHz, well outside all amateur bands, and a current capacity of 300 mA which is far more than the relay coils draw. Make sure the self-resonant frequency is outside the amateur bands before you buy.

The SPDT reed relays are suited for small signal applications and rated to -40° C. A better alternative is a DPDT small signal relay such as the OMRON G5V-2. It is specified for the aforementioned RemoteQTH design. I have a bunch of reed relays on hand so I used them. The 12 VDC relay coils operate in parallel to switch direction.

Some relays have a built-in reverse EMF protection diode. These don't so I used a 1N4001. My SPST reed relays do have them so it is important to apply the correct DC polarity. I did not use a diode to protect against reverse polarity since it will be located in the remote switch that feeds switching power to the Beverage..

The south signal flows through the top transformer and relay and the north signals flow through the bottom transformer and relay. The NC and NO contacts of the north and south relays, respectively, connect to the feed line via the coupling capacitor. The respective NO and NC contacts connect the unused direction to the 75 Ω load to prevent reflection.

The load resistor ought to be 2 watts carbon composition. From my junk box I wired two ½ watt carbon composition resistors in parallel to get 75 Ω and 1 watt rating. The 2 watt rating can be had with 4 inexpensive ½ watt 75 Ω carbon composition resistors. The solder terminals for the resistors are raised above the board so they are easily accessed for replacement if a nearby lightning strike destroys them.

Hardware is stainless and spacers under the bread board are plastic. The wing nut on the ground wire lug uses a wing nut so a wrench is not needed. The bread board has two horizontal rails at the centre of the long dimension. I used one for feed line ground (coax shield) and the other for the +12 VDC relay voltage.

All the DC switching paths were tested without the transformers on the board and winding continuity was tested when the transformers were mounted. The reed relays are so quiet an ohmmeter was the only reliable way to determine whether the relays were operating. The RF signal path could not be easily tested and as it turns out there was a wiring error.

Getting the bugs out

There is nothing electrically complex about this antenna. Other than ground rods all of the important components are visible in the adjacent photo. Nevertheless it is easy to make mistakes, and those mistakes can be difficult to troubleshoot.

I made one that resulted in nothing heard. It turned out to be a simple wiring mistake. I diagnosed it by looking at the photo of the switching unit. As an exercise try to discover the error yourself before reading further (see earlier closeup).

With everything connected I went back to the shack, turned on the rig and listened. Since it was daylight I didn't expect to hear much but I heard nothing at all. My antenna analyzer showed an SWR plot of a long and unterminated coax. Applying voltage to switch direction had no effect.

With an ohmmeter I confirmed that the coax was connected to switching unit by the presence of relay coil resistance. Before running out to the field to retrieve the units I studied the photograph I of the switching unit. To my surprise that was enough to fully diagnose the problem. With sunset approaching I brought the unit indoors and confirmed that my suspicion was true. A soldering gun and a bit of wire later the unit was ready to go again.

The mistake was that I had taken the wire from the relay contacts for the receive path to a bread board pad and then soldered in the DC blocking capacitors. But these went to different columns of pads. The new wire connects the capacitors to the signal path wire. This was faster than pulling the board and redoing the job properly.

With that done I tried again and had success! It was sunset so testing could began immediately. More on this below. Despite many decades of being a ham and endless antenna projects I still get a thrill when a new home brew antenna is connected and it works. There was a smile on my face as I repeatedly switched Beverage direction, compared signals strengths and contemplated how a hunk of wire barely higher than my head could perform radio reception magic.

Temporary direction control

The default direction is south, that is, the direction with no relay power applied. North will be used relatively rarely to work on sunrise openings to Asia and during other brief propagation opportunities. This is a good strategy for all directional switching systems and not only for receive antennas.

I built a temporary device to inject 12 VDC into the coax from the operating position. It doesn't get any simpler than this. I removed the resistor network from a QRP attenuator and soldered in a 0.2 μH capacitor and a 100 μH RF choke. A wires snakes around the sheet metal where it can be accessed.

To switch the antenna to north 12 VDC is applied between the chassis and wire. Polarity matters since the diode across the relay coil will short with the wrong polarity. I didn't bother with polarity protection for this temporary device.

The temporary switching system is ugly. The red clip lead is attached to the wire to point the antenna north. Two 9 volt batteries provide operating voltage of about 15 volts (one of the batteries is weak) which is well below the maximum voltage specification for the relay coils.


Some care is needed to avoid shorts. It is critical to get the cabling right otherwise DC will be injected into the receiver front end and that can be a very expensive mistake.

Performance

The first test was the SWR. When properly built and adjusted the impedance should be 75 + j0 Ω across a broad spectrum. Of course that ideal is never reached so it is fortunate that perfection isn't necessary for excellent RDF. Beverages are more forgiving antennas than driven vertical arrays.


This is very good! Some ripple of impedance versus frequency is typical. The flattening of the SWR at higher frequencies could be surge impedance variation with frequency or, more likely, due to increasing transmission line attenuation with frequency. The transmission line is approximately 150 meters of RG6 plus another 150 meters of RG6 in the south direction since that signal comes back to the feed point via the Beverage's RG6 span. Coax loss reduces signal level but does not affect the antenna pattern.

Signal level seems comparable to the 170 meter long northeast Beverage. A direct comparison isn't possible yet since there is no Beverage switching system. Theoretically the gain should be perhaps 1 db worse for north and 2 db worse for south. There is no need for amplification.

The biggest obstacle to listening tests was finding enough stations! Despite the pandemic confining hams to their homes the springtime decrease of low band activity is striking. North is always a problem since it is really only Asia in that direction and that is a difficult path at the best of times. To the south there is little activity in the Caribbean and South America and US station location cannot be determined from their call signs.

Despite that difficulty I cound enough stations to determine that the antenna does work, and it works well. To the north on 160 meters the main lobe is wide enough to show improved SNR on European signals and high rejection when pointed south. I found more Caribbean and South American activity on 80 and 40 meters, where the main lobe narrows, to give the antenna a good workout. However the very narrowness of the main lobe and the many minor lobes on 40 meter made comparisons a challenge.

All the South American activity I've monitored on 160 meters is FT8 so that's what I tested with. The evaluation was qualitative since signal strength readings in WSJT-X can be deceptive. Good signals from PY, LU and VP8 in the south direction disappeared or became too weak to decode in the north direction.

Comparisons on 80 and 40 to my yagis -- both of which have only modest F/B -- was very promising. The Beverage greatly improved SNR for stations to the south. Due to the narrow main lobe I wasn't able to find suitable stations to the north on those bands for make a definitive conclusion. I didn't get up early enough to look for east Asia activity (north direction).

Summing up

The antenna works to my expectations so I will continue with the rest of the Beverage plan. I will try to build the east-west reversible Beverage and the remote switch this month before the bush if full of ticks. It is possible to take protective measures but it is not worth the effort and risk. If I still have enough time the northeast Beverage will be "twinned" to make it reversible. What doesn't get done now I can continue in the fall.

The north-south Beverage has been disconnected and the feed line moved back to the northeast Beverage. Since I can only have one of the Beverages connected for the time being this is the one that is most useful. Soon the primary 160 meter transmit antenna will come down for the summer and my low band activity will slow considerably.

Next winter I will have a higher performance low band antenna system, both receive and transmit. I expect it to be well worth the time and effort invested.