Tuning & Testing the 80 Meter Vertical

It seems everything I do takes longer than expected. This is essentially a progress report on the construction of a 3-element, 4-direction 80 meter vertical yagi. When last I checked in the driven element (a tower with stinger at the top) was completed. Since only a few radials were installed and the antenna not tuned it was premature to talk about performance.

Before the 80 meter vertical yagi array can be built it is first necessary to get the driven element working as a simple vertical. I have slowly made progress to the point that I now have a very effective full-size vertical for 80 meters. This will also be its function after the array is built for the omni-directional mode. The character of the vertical changes markedly as radials are added.

It is important in a project of this complexity that it be broken into a sequence of steps with testing after each step is completed. Surprises can be investigated and dealt with before they can be obscured by further changes. I see this as an advantage rather than a burden since it is a tremendous opportunity to learn about antennas and propagation.

I'll step through the process as I go from the basic vertical with 4 radials and a monopole to a tuned 34 radial vertical for 80 meters, including what I learned along the way. Turning the antenna into a yagi will take more time. Reasons for the slow progress so far include: lack of 80 meter activity during the summer needed for on-air evaluation; connecting the antenna was inconvenient until I repaired the antenna switch; many other concurrent projects; and, non-radio summertime activities.

4 radials

Despite the stinger being fully retracted the resonant frequency with only 4 radials of 20 meter length the fell well below 3.5 MHz. The radial length dominates the short monopole (~18 m). This is expected since not only are the sparse radials resonant they are electrically much longer than 20 meters due to ground proximity lowering the velocity factor.

I didn't bother to precisely measure the resonant frequency since 4 radials was a transitory configuration. On air the vertical performed poorly when compared to the 32 meter high inverted vee. Both signals and noise were noticably attenuated. The match was good because the high ground loss raised the feed point impedance close to 50 Ω. Loss is in series with the radiation resistance.

With a perfect ground a full-size vertical ought to have feed point impedance of 37 Ω, and can be much lower as the monopole diameter increases, as it does when it is a lattice tower. The estimated ground loss with 4 radials was a minimum of -3 db, based on feed point impedance, but likely closer to -6 db. Measuring ground loss accurately isn't easy and I didn't try.

Some insights can be had even though the ground loss is high. By using perceived SNR (purely by listening) an inkling of how the antenna will perform with more radials can be ascertained. SNR on the vertical was better on the longest paths, such as to PY. The inverted vee SNR was always better before sunset when elevation angles on all paths is higher due to absorption at low angles.

8 radials

The addition of 4 more radials made a dramatic difference. Resonance made a big jump to ~3.8 MHz. This shows rapid progression towards non-resonant radials system as radial count increases from a low number. Efficiency improved so that it was more equatable to the inverted vee on reception tests. The inverted vee continued to outperform the vertical within eastern North America. On longer paths the received signals with the vertical were often equal or better than the inverted vee.

The impedance changed little, only dropping several ohms. Obviously there is more affecting the impedance than simply ground loss. I suspect the main reason is that with radials longer than an electrical λ/4 the current distribution on the radials places the current peak away from the feed point. Lower current at the feed point is associated with a higher impedance, thus partially masking the effect of the decreasing serial resistance due to ground loss. This has amply documented by N6LF in his extensive experimentation with verticals.

12 and 20 radials

I did not do on air tests for these radial count for the aforementioned reason of inaccessibility to the antenna from the shack. The only testing was measurement with my antenna analyzer.

The next 4 radials were not symmetrically interlaced with the existing 8. These radials went to the hubs of the 4 parasitic elements, elements which have yet to be installed. Collinear with these short 10.5 meter long radials is a 15 meter radial, bringing the total radial length to 25.5 meters. The parasitic element radials will all be 15 meters and these systems will overlap rather than employ boundary busses. These radials for the parasitic elements are the only ones bonded to the driven element's radial system.

Once these radials were buried the antenna's impedance was measured. The resonant frequency continued to increase though at the expected slower rate due to the monopole beginning to dominate as the radial system becomes increasingly non-resonant. The resonant frequency was ~3.9 MHz with an impedance in the low 40s.

The next 8 radials are symmetric with respect to the original 8. After adding them the resonant frequency increased to ~4.02 MHz.

Measurement precautions

The photo of the analyzer display shows a lower resonant frequency than what I quote above. This is due to the 1 meter length of transmission line between the analyzer and feed point. It adds several ohms of reactance which lowers the apparent resonant frequency by more than 50 kHz. That is ~1.5%, a not inconsiderable amount.

This is easily simulated using TLW to determine the impedance at the feed point. In this example notice the difference between the source and load ends of the transmission line. The amount may seem trivial, but it is enough to impact the performance of a yagi when tuning the parasitic elements, as I will be doing with this antenna. It is far less critical for single element antennas such as ordinary dipoles and verticals. Better analyzers include a feature to compensate for the transmission line so that you can directly read the feed point impedance.

When measured at the true resonant frequency -- with regard to the analyzer reading, which is limited to its inherent accuracy -- the resistance part of the impedance is ~40 Ω. This is more reasonable since the "ideal vertical" has a radiation resistance of ~37 Ω. Ground loss is certainly present. As we'll see below even this value is misleading since the ground loss is significantly greater than 3 Ω (40 - 37).

Another factor to keep in mind is the placement of the analyzer, the coax and your body during the measurement. Although all are small relative to the wavelength I have experienced up to ±30 kHz (±1%) variation with this antenna. Don't let the coax drape over the monopole or the radials, don't lean against the antenna or lie on the ground (on top of the radials). In some cases it can help to prop the analyzer on an insulating platform rather than hold it in your hand.

To bury or not to bury

I stopped burying radials after these first 20. It's a lot of work and I found that if I was careful to put little tension on a radial and walk along it to press it down that it was soon hidden under the vegetation in the hay field. Large dips in the field were levelled to help this along. I can mow over the entire radial field with ease. However I caution visitors to step carefully to avoid tripping and ripping them out. After a year even than warning may become unnecessary.

The other concern with leaving radials on the surface is when my neighbour harvests the hay. That equipment is not like a lawn mower and will tear up surface radials. When he did the harvesting this summer he was exceedingly cautious following my line of stakes and brick markers and would not have hit a radial had the parasitic elements used surface radials.

In light of this experience I have decided to stop burying radials. It's a lot of effort that I am happy to avoid.

The temporary run of RG-213 from the antenna was replaced with ~90' of LDF4-50A. It was laid in the trench along with the control cable and covered over. Heliax is rated for direct burial. From the tree line (see top photo) there is an overhead run of RG-213.

34 radials

This may seem an unusual number of radials until you consider the geometry of the radial system. My objective was to double the 16 radials. With the 4 additional ones that connect to the parasitic element base hubs there were 20. When I added the next set I should have only needed 12 more to reach 32. However two of the hubs were not in the required position for symmetric placement. Therefore I needed two more.

Should I eventually go for 64 radials on the driven element (1,280 meters of wire!) those hubs are aligned as required so I will only need to add 30 radials.

With the analyzer attached it is clear that we are approaching the limit with respect to the antenna's true resonance with so many radials creating a non-resonant ground plane. The additional radials increased the resonant frequency by only about 15 to 20 kHz. This is effectively nil since measurement repeatability at this level of accuracy is unlikely.

Of greater interest is the resistance value. Notice that it is 5 to 6 Ω lower than with 20 radials. That's a big improvement that is evident from on the air receive tests. On all DX paths during full dark the vertical now equals or exceeds the inverted vee with respect to absolute signal level and often SNR as well. This bodes well. I have worked several DX stations with the vertical and, while I did not do A-B comparisons, it does seem to get out well.

Notice that the resistance is well below that of the ideal vertical. That ideal is for a thin vertical (with respect to wavelength) such as a wire. For a fat monopole such as mine the radiation resistance is lower. Unfortunately NEC2 does not handle fat verticals very well and with experimentation I could not push a model lower than 35 Ω over perfect ground. Many hams report fat vertical radiation resistance below 30 Ω. Without a viable model I can only estimate based on the trend line that my vertical's radiation resistance is probably no lower than 25 Ω.

For the moment I will therefore assume that the ground loss is ~6 Ω. This approaches my initial goal of 5 Ω. With the high currents (low impedance) when the antennas becomes a yagi I should see a performance improvement by doubling the radials to 64, since I expect that this would lower ground loss to ~4 Ω and perhaps lower. But not this year.

After reaching this milestone I climbed the tower and raised the stinger to its full height. The resonant frequency moved ~200 kHz lower. This is ~75 kHz higher than the objective I set in the antenna design. I am not concerned since the low radiation resistance compels me to build a matching network for the antenna in its omni-directional mode to meet my SWR objective. Originally I planned a matching network to be switched in when the antenna is in directional (yagi) mode.

With the vertical working -- albeit using the rig's ATU -- the inverted vee will come down shortly for relocation to a different tower. It can have a lower apex and do well for short and medium distance contest QSOs and for select grey line DX conditions.

The ropes hanging from the stinger have been untangled and prepared to act as the upper catenaries for the 4 parasitic wire elements. In the coming weeks these elements will be built and installed and full radial systems laid for them. My objective is 16 radials for each parasite this year, possibly rising to 32 next year. Then I'll complete the matching networks and switching system. Unless I get sidelined by other projects this 3-element vertical yagi for 80 meter will be operational this year.

6 Meter Season Wrap-up: FT8 Conquers All!

It may seem premature to pen a write-up of the summer sporadic E season while the band continues to open periodically, helped along by the ability of FT8 to tease signals out of the noise. Despite this there is little doubt that it is ending. A few days make a big difference on the shoulder of the season, such as a noticable lack of signals when I returned from a family trip to FN30 last week. Now is a good time for reflection, before details slip from my mind.

For me these have been a very good few months on 6 meters. FT8 is obviously the big story due to its universal popularity and, more importantly, it delivered results. Big time. The difference is obvious by comparing this article with the one I wrote after last year's sporadic E season.

In two months using FT8 I made almost 500 contacts and worked 56 DXCC countries. On August 4 alone I put 40 European stations in my log. That was a phenomenal opening that lasted several hours. Many others on both sides of the Atlantic have been similar successful. I haven't seen DX activity like that since my last F-layer openings in 1990, and never via sporadic E.

Now I'll dive into the details. The past 2-½ months have been very educational to me and I've learned a lot about just how far one can push marginal propagation with the help of technology. These paths must have always been there but missed without the assistance of FT8.

Discovery

Some say CW can do as well as FT8 under weak signal conditions using good narrow filters. This may be true, give or take a few decibels. That means little when the opening to any particular station is fleeting because on CW you likely will not find the station since you must spin, spin, spin the dial hunting for them.

When they're spotted it gets easier since you can park on their frequency and wait, perhaps flipping among several spotted stations. It quickly becomes a tedious chore. Yet it can work and has worked for me in the past. FT8 is very different since you are in essence copying the entire band without lifting a finger. When a station is workable on FT8 you'll know immediately.

Discovery is perhaps the greatest advantage of FT8 on 6 meter sporadic E. You need no beacons, no spotting network and no arduous tuning around. When the station is workable you know it. Some DX stations -- CT1HZE in particular come to mind -- CQ continuously when conditions are favourable, essentially becoming beacons themselves, so you may not even need to check for actual beacons at the low end of the band.

Time is of the essence

Of course you must still work the station. This is a challenge since the typical FT8 QSO takes more than 1 minute. If your experience with FT8 is on HF this may seem inconsequential. On 6 meter sporadic E it is often critical since many of the longer DX paths last only this long if not shorter before rapidly fading out.

I have many partial QSOs, including perhaps another 10 DXCC countries, because signals faded, often never to return. I gave examples in my earlier FT8 article.

Despite this duration difficulty FT8 is still superior to CW since with FT8 you have more of a chance to make the contact because of the discovery challenge I described. In particular, you decode the desired station when the path opens so you can take advantage of its full length. Even so you'll need to get used to regular disappointment as you watch a signal gradually fade to nothing in 30 seconds, and there's nothing you can do about it. You can't speed up FT8 transmissions.

To ameliorate this difficulty more callers omit the grid square and jump straight to the signal report on the initial transmission, thereby reducing the time to complete a QSO. They are not being rude by omitting this information. Similarly they'll use RR73 rather than the slower RRR sequence, even if conditions are not truly good enough for RR73 to be a reliable concluding message.

WSJT-X supports these methods for shortening QSOs and they do come in handy when DX openings are breathtakingly short. Give it a try yourself.

Agony of the single decode

Often you never get a chance to attempt a QSO since there is only one decode of the DX signal. In these cases of marginal propagation a signal may peak above the noise for just one 15-second window. This behaviour is normal on the shoulders of an opening, while other times it really is just a single decode. Waiting for the opening to progress may be fruitless.

Examples of single decodes can be seen in the accompanying activity monitor from a few weeks back. There are two of them. Notice that the signal strength is very low. This is typical in the case of single decodes in these types of fleeting openings.

There are other peculiar single decodes that I've experienced. One was a CQ from a YO station with a SNR of -8 db. There were no other decodes and no other signals from Europe, although others in eastern North America were seeing a few marginally copied Europeans. I copied several stations from VE3 down to W4 reply to the YO. No one got through and there were no other decodes.

Unusual propagation must have been present for this to happen. Perhaps a bolide over the North Atlantic briefly provided a bridge between E-layer clouds. Intense meteor trails can support propagation on 6 meters long enough for a 15-second FT8 message. That's just speculation since I have no idea what happened. FT8 is providing us with new insights into propagation.

Signal reciprocity

When I first got on 6 meter FT8 I was surprised at the asymmetry of signal reports I sent and received; the reports I received were mostly worse than the ones I sent. I attributed it to the several decibels of loss in the 40 meters of ancient RG213 coax feeding the yagi. Now I'm not so sure.

As I said in my earlier article FT8 is no more a low power mode than any other. Many 6 meter operators have long used high power and they continue to do so on FT8 since it pays dividends in teasing QSOs out of marginal propagation, which is typical for long DX paths on sporadic E and other transitory propagation modes. I have become accustomed to signal report differences of 10 db or more, and often not being decoded by stations received well here.

There may be other reasons for the difference. For example, noise. Because WSJT-X signal reports are the calculated SNR (signal-to-noise ratio) each station's noise floor is a factor. Although external noise (QRN) is usually lower at VHF than HF there is still the receiver noise to be considered. I live in a low noise environment where I am able to turn up the receiver's pre-amp to improve SNR, a common requirement on VHF and higher where atmospheric and man-made noise is below the receiver's thermal noise level.

When is a QSO complete?

I was pleased to see this issue mentioned in the recently arrived September QST. There has been some confusion on the air, including those I try to work. For transitory 6 meter openings one's view of the matter becomes important.

The issue is exemplified by a QSO that proceeds as follows:

QQ8ABC VE3VN FN24
  VE3VN QQ8ABC -10
QQ8ABC VE3VN R-08
  VE3VN Q8ABC RR73
Q8ABC VE3VN 73
  VE3VN Q8ABC RR73
Q8ABC VE3VN 73

The other station insists on receiving a "73" message to complete the QSO. It isn't necessary since both stations have exchanged and confirmed call signs and signal reports. When conditions fade -- as they frequently do for marginal DX paths -- the "73" is never received. Should I log the QSO?

My concern is whether the other station logged the QSO, not whether the QSO is valid. It is valid. My choice then is to log the QSO or not. In almost every case I do. Whether he logged it may only be known when it is confirmed in LoTW or via some other system. In one instance the questionable QSO was a new country, which I logged but did not include in my DXCC worked list.

Quirks

In my previous FT8 article I mentioned a few quirks of the software and its users. Here are a few more.

I call CQ, someone answers on my transmit frequency and we complete the QSO. They then proceed to call CQ on frequency. This happens more often than you might imagine. I suspect carelessness rather than malice. Most likely they forgot to QSY back to their previous transmit frequency after we've worked. All I can do is QSY, which is a minor inconvenience on FT8 compared to CW or SSB.

WSJT-X occasionally decodes noise as a valid message. The frequency of these occurrences increases with how aggressive you set the decoding options. This is no surprise to FT8 operators. What does surprise me is that some of these messages are addressed to me! If it occurs while I'm CQing with "Call 1^st" selected the software will happily reply to the noise. I've seen numerous instances of others answering what are obviously nonsense call signs magicked into existence by WSJT-X. There is something in WSJT-X that causes it to try to preferentially interpret noise as your call sign.

WSJT-X occasionally loses track of its transmit state when a transmission is manually halted within the first second. You press the appropriate button and it goes on transmitting, while also receiving. With the rig's monitor feature enabled (which is usually the case here) the transmission is received and decoded. It is highlighted since my call sign appears in the message. It takes a couple of clicks of the "Tune" or "Enable TX" button to fix the problem.

In a good opening the full 3,000 Hz is densely occupied. Stations overlap since, due to the spotlight nature of sporadic E propagation, I can hear both stations but they can't hear each other. This is less of a problem that it might be because WSJT-X is astonishingly capable of decoding each of the overlapping signals, even when they differ in strength by 10 db. That's impressive, and useful. It's a skill even the best DXpedition operators would envy.

Contests

After observing FT8 activity on 6 meters during ARRL Field Day and the CQ WW VHF contest I've chosen to not contest with FT8. I like DXing and I'm happy to periodically work US and Canada on FT8 (especially west coast), but for contests it's just too slow for my taste.

There are other difficulties with FT8 use in contests that may be corrected when WSJT-X 2.0 arrives in several months. If you're already using FT8 on VHF the following should be familiar.

First, there is inconsistent use of NA VHF contest mode in WSJT-X. When selected the messages change such that stations decoding your transmissions will see messages that are seemingly incomprehensible. Unless both stations select (or deselect) this option QSOs aren't possible. Endless repeats between incompatible stations were often heard both weekends. Selecting the option midstream or between QSOs does not retroactively translate messages already received. I was puzzled by what I saw during Field Day since I hadn't yet learned about NA VHF contest mode. The manual enlightened me. Others remained confused.

Many NA stations incorrectly selected this option during the CQ WW contest. It is not intended for worldwide contests and none of the European and other DX used it. Once again confusion reigned. I avoided the option entirely while working DX during both contests.

After each contest many forgot to deselect the option. They had little luck working anybody! Eventually normalcy returned to the bands.

Unfortunately when I did try CW and SSB in the CQ WW contest I logged exactly zero contacts. I heard a few stations fading in and out, but failed to work the few that were present. Ten minutes of continuous CQing netted no replies at all. Yet FT8 activity was high. Perhaps I'll avoid VHF contests for a year or two until something changes to rekindle my interest.

50.323 MHz

Used a great deal for intercontinental openings early in the season its use recently has been almost nil. During the exceptional opening to Europe on August 4 the 50.313 MHz segment was packed with signals from 200 Hz to 3,000 Hz. During each of the several times I checked 50.323 MHz there were no signals found. Neither did my band scope show a blip +10 kHz the many times I glanced at it while active on 50.313 MHz.

Is the idea behind 50.323 MHz dead? We'll have to wait and see how this develops. My suspicion is that for the majority the importance of discovery (discussed earlier) is greater than reduced QRM from intracontinental activity. As matter stand I see no reason to monitor 50.323 MHz.

Signal quality

Monitor FT8 on any band and you'll soon discover poor signals. Perhaps because these digital modes are new, the software unfamiliar or the operator carries on with poor practices learned on other modes many seem unable to consistently transmit a clean FT8 signal. This not only hurts them but everyone using FT8.

Based on the WSJT-X spectrum display and other displayed data it is possible in many cases to make a good guess what they're doing wrong. Some that I'm aware of include:

• Misadjusted clock: WSJT-X will forgive small clock errors but can be intolerant of errors greater than 1 second. It is mystifying that many operators don't know they have a problem since WSJT-X displays the clock error on every message. You'd think they'd notice that every signal has substantial error. Either they don't notice, imagine everyone else is wrong or don't understand the importance. The most common consequence is that they can successfully monitor but their transmissions overlap with others resulting failed decoding when a QSO is attempted.
• Drift: In this era of rock solid digital oscillators we have grown used to frequency accuracy of 10 Hz or better. Imagine my surprise to see that a small fraction of signals drift. Sometimes the drift is only 1 to 2 Hz every 30 seconds, and in extreme cases I have seen drift of up to 10 Hz. Since WSJT-X highlights messages addressed to you (your call sign) you still see messages that drift outside your receive window, so it is usually not a serious problem.
• Compression: Speech compressors by their nature -- both AF and RF -- are non-linear devices. When properly adjusted on SSB they achieve a balance between distortion and comprehensibility while improving average talk power. On FT8 the compressor produces mixing products that create QRM and reduce the power of their fundamental audio signal.
• Transmitter ALC: When the ALC meter moves there are distortion products due to the introduction of non-linearity in the RF amplification chain. This may be tolerable at very slight ALC action but is always dangerous. When it kicks a lot you can be certain that you are generating spurious signals.
• Amplifier over-driven: In the quest for squeezing out those elusive DX QSOs many run a lot of power on 6 meter FT8, and it is no surprise that those amplifiers are sometimes over-driven. Since negative feedback to the transmitter ALC is frequently not used there may be no immediate indication to the operator that there is a problem. But as we've seen ALC is not the cure for a poor FT8 signal. Carefully adjust the transmitter power, and observe its ALC meter if it has one, to ensure the amplifier remains in its linear range.

Despite the presence of distortion products that pollute the spectrum for everyone else you can still be make QSOs since the fundamental signal is also present. IMD products can actually spread your power among 1 or 2 adjacent signals that are decoded. You may not notice these problems unless a friend (or one of the ubiquitous policemen) tells you. Pay attention. Everyone, including you, will benefit when your transmissions are clean.

WSJT-X decoding is so good at discarding distortion products that most of us can survive the onslaught of QRM. However that is no excuse for transmitting a poor signal.

CW and SSB

Well, what about CW and SSB? Once I made the move to FT8 in early June I have worked very little CW and SSB. Not only has FT8 been far more productive for my primary objective to work DX -- despite the painfully lengthy QSOs and sudden QSB -- when I switch to CW and SSB there is often no one there. Few signals other than beacons are heard and CQs go unanswered. Yet 50.313 MHz is bursting with activity.

I have no answer to this issue, and I can't even claim that it is an issue. There are many who shun FT8 and similar digital modes. To them it can be annoying to have fewer stations to work. I felt the same before June. As a practical matter, when I'm set up for FT8 it is not convenient to tune the CW and SSB segments. I would have to come up with a system whereby a second rig can share the antenna.

While I am not prepared to give up on the "legacy" modes there seem to be fewer reasons to use them as time progresses. In this I refer only to 6 meters, not HF. On HF my interest in FT8 is very low. The only band I may play with it is 160 meters, if only to see what it can do.

My plans

My move to FT8 on 6 meters was one of necessity. It was that or make far fewer QSOs. After one season on FT8 I've become a believer. FT8 delivers the goods: an astounding amount of DX, which is my primary operating objective on 6 meters.

This success motivates me to improve my performance on 6 meters in 2019. First up is to replace the poor coax with low loss Heliax. That will improve my signal by at least 3 db. When I shop for an amplifier I would now like one that includes 6 meters. In time I may add one or two more antennas, for stacking and elevation angle diversity.

Together these measures should improve my DX results on 6 meters. Despite my renewed enthusiasm for 6 meters this work remains lower priority than towers and antennas for HF contesting. We'll just have to see how far I get by next spring. I am also considering playing with other WSJT-X modes to try out other forms of VHF propagation such as meteor scatter.

Despite FT8 being less hands-on that traditional modes it has earned a place in my station. That is perhaps the biggest surprise to me this year. Who knows, 6 meter DXCC in another year or two could be mine thanks to FT8. That this is possible during a solar minimum is extraordinary.

Hamplus AS-82 2×8 Antenna Switch

Last year I purchased a used Hamplus AS82 2×8 antenna switch from a fellow contester. The specs are good and the brand seems to be in good regard. At first glance its construction appears sound and it is quite easy to wire up and use with a custom controller. That is, once I discovered how to drive the unit. Documentation is sparse and schematics do not appear to be published.

Pictures are from the Hamplus web page linked to above

From the start I had problems with it. I thought, perhaps, it was due to abuse, and I was unhappy that the seller did not disclose the problems. Due to the nature of the problems and his particular application it is possible he didn't know, therefore I will give him the benefit of the doubt. Regardless of this circumstance the problems are real and deserve an airing, since as I discovered the problems are inherent in the product.

As the winter season progressed the problems became increasingly manifest. Perhaps the intense cold played a part -- it is mounted outdoors with a precipitation cover. Making trips outdoors at night with a flashlight when the temperature is -20° C and the wind howling to effect repairs in the midst of a major contest is not acceptable! However, spring warmth did not bring relief.

As part of the re-cabling of the station this summer I had to repair the switch or replace it. It is critical to station operation. An antenna switch, even one designed for multi-op and SO2R antenna sharing, is not complex. The challenges are in reliability, electrical safety, fail safe to prevent one antenna being selected by both stations (lockout) and port-to-port isolation. I was not deterred by the lack of a schematic.

While not intended as a review that is in part what this article contains. I'll relate what I discovered about the product as I searched for and repaired the problems I experienced. The process was educational.

Problems

I'll start with a concise list of the problems I experienced with the switch:

• One antenna port (#8) could not be selected on one side since selecting that control line caused a power supply short. My power supply has electronic short circuit protection so nothing dreadful occurs.
• One side experienced intermittent disconnection or high resistance on most antenna ports.
• The other side had one non-functioning antenna port and one that was intermittent.

The lack of a schematic I already mentioned. Fortunately the circuit is simple enough and the parts large enough that signal tracing and testing isn't too taxing an effort. However removing the PCB proved to be quite a puzzle. That is, it could be removed with some difficulty but I could see no way to reassemble the unit. Yet the PCB had to be removed to diagnose and repair the unit.

Modifying the mechanical design

In the picture notice the narrow opening between PCB and enclosure and the blocking of access by the vertical flange. There are two sets of screws and nuts securing each of the 10 SO-239 UHF bulkhead connectors and the connectors are soldered to the PCB. The nuts are inaccessible except for one on each of the 6 outer connectors.

With some difficulty the nuts can be held in place while removing the screws. Holding them in place for reassembly is beyond difficult. I needed a better way, one decided before opening it up. After some thought I tentatively chose a technique that would work. I asked some friends if they had any better ideas but none was forthcoming. That convinced me to proceed on my chosen path.

Since the product is made in Brazil it is not surprising that metric fasteners are used on the SO-239 connectors. Despite the connectors being specified in English units -- the flange holes are ⅛" (~3.2 mm -- the 3 mm stainless machine screws and nuts are a comfortable fit. The screws have bevelled heads to seat within countersunk holes in the enclosure. The screws provide the electrical connection between the connector flanges and the enclosure to ensure a continuous ground plane.

A narrow steel tool was slipped between PCB and enclosure to jam the nuts against the connector bodies. Most screws had to be loosened this way. The quality of the stainless steel alloy is so soft that several screw heads (Phillips) stripped under moderate torque. These were drilled out on a drill press.

I elected to tap the connectors so that nuts are not required to secure the PCB. It is not an ideal solution because the metals used in SO-239 connectors are not designed for this usage it. But it does work. The base metal is typically brass with thin nickel plating. Tapping removes the nickel within the flange holes and so cuts threads into the base metal. Some care is required to avoid stripping the threads when tightening the new screws.  Lubricating the threads can help to avoid excess torque for future removal provided that the lubricant does not prevent a low impedance path from screw to flange. Dielectric grease may be a good choice.

Original 3 mm fastener (left) and new 4 mm screw

The smallest standard screw sizes that will do the job are either #8 or 4 mm. A #6 screw will dig into the nickel a small amount, even without tapping, but it is not enough. Tapping the flange holes for either #8 or 4 mm does not require drilling the holes to a larger diameter since the metal is soft enough for the tap to bite in.

As you can see in the picture I was not concerned with cosmetics since the flanges are not visible when the unit is assembled. Where you must be careful is to keep the tap at a right angle to the flange surface so that the threads are not cut at an angle. The flange is thin enough and the metal soft enough that this is an easy mistake to make.

I chose 4 mm screws for this project because of the local fastener emporium's wide selection of metric stainless steel machine screws. I could choose the perfect length to fully pierce the connector flange without getting near the PCB. Also, my metric taps get very little exercise!

I widened the enclosure holes for the larger screws using a large drill bit -- visually similar angle on the screw bevel -- to broaden the countersunk holes. When all was done it was easy to fit together the PCB and enclosure and use the new screws to hold it all together. Mission accomplished.

Connector attachment to the PCB

Did you notice that there's a connector missing in these pictures? When I removed all the fasteners and lifted the PCB from the enclosure that connector fell off. Both solder joints had failed. That certainly explains the observed intermittent behaviour of one side of the switch!

Each connector has two wires attached. A stranded wire is soldered to the centre pin and pierces the PCB, soldered to pads on both sides of the PCB. The hole is much larger than the wire so there are collars to bridge the gap. You can get an idea of the arrangement from the pictures shown above.

A solid wire is encased in a large blob of solder on the flange surface and pierces the PCB in the same manner as the centre pin but with a narrower hole. This wire is quite fragile and prone to fatigue and breakage as the connector wiggles on its wire supports. The wires are only protected when the connector is screwed to the enclosure. In a couple of case the solder blob did not hold the wire securely and broke off, and another broke during repair. The wires are not mechanically connected to the connector flange; solder alone does not make for a reliable connection.

This is good evidence of how the unit was most likely manufactured. However I cannot guarantee it was done this way, and I can imagine a couple of variations. But here goes:

1. Fasten the connectors to the enclosure with the screws and nuts.
2. Solder wires to the connector and position them in alignment with the PCB holes.
3. Place the PCB on top of the connectors and wires and solder them to them PCB.

Otherwise they must have special tools for slipping in and holding in position the nuts for the connector fasteners. Either way this is not a product intended for servicing by the owner, and perhaps not even for servicing by the dealer. It is therefore highly unlikely the previous owner had disassembled the unit. There is also no evidence of modification or post-manufacture soldering.

I replaced wires that had broken off from the pins and flanges. To ensure the affected connectors would sit flush on the enclosure I used the new screws to secure the connectors to the enclosure, sat the PCB over them (with the unmodified connectors slipping through their respective holes on the enclosure, then soldered the wires to the top of the PCB. With the wire lengths now assured to be the correct length I removed the PCB and completed soldering to the pads on both sides of the PCB.

Resolving the short

Finding the short on the port #8 actuator took a little detective work. First I examined the voltages and resistances on the working ports for comparison. This led me to conclude there was a short across the coil of the front relay in the chain. Since the relays are PCB mounted and the board is two-sided the fault had to be on the PCB traces under the relay body, in the relay itself or elsewhere. Lifting the relay is no simple feat.

I decided to focus on the third option since relays of this style rarely fail in this manner and the PCB layout and soldering is generally clean. Excess solder flux along the board traces were removed to ensure no solder bridges were hiding beneath. With nothing found I was left with a capacitor and a diode to examine. The capacitor shunts RF from the control lead to ground and the diode across the coil protects against back EMF when the control voltage is removed.

The capacitor checked okay so I lifted one end of the protection diode with a soldering iron. That solved the problem. The diode tested short. Look at the (fuzzy) picture for a close-up of the bank of back EMF protection diodes. From the package design and lettering it is evident these are 1N4148 switching diodes. They are not suitable for this application. The diode junction probably failed due to an unusually high voltage spike from the collapse of relay coil's magnetic field the diode is there to protect the circuit.

I replaced the failed diode with a 1N4007 from my ample stock and all was good. I really should replace the other 7 protection diodes at some point but chose not to do so at this time. With the changes documented earlier the PCB can be quickly removed to do it when I am ready.

Testing, reassembly and installation

With the unit reassembled I built a temporary wired connector (DE25) to apply power to the unit and a probe to ground the selector pins. With an ohmmeter I tested each port for continuity and equal low resistance value, then did the same for the other side of the switch. The PCB was then fully attached to the enclosure and again tested in the shack with real antennas and rigs. This test was for expected port isolation, SWR and receive and transmit performance.

Before I began repairs I was concerned that one or more relay contacts had worn due to poor quality or hot switching with high transmitter power. The previous owner, like me, used a custom control unit that may not have had protection against hot switching. A TX enabled signal is available from most current transceivers that control units can use to prevent antenna switching while the transmitter is active.

Luckily all the relays tested okay. Although these sealed DPDT PCB-mount relays have an industry standard form factor (2c) and are inexpensive it would be a lot of work to de-solder the 8 pins on each, and there are 24 of them. Plug compatible replacements that may be more available in North America include the Omron G2RL-24 with 12 VDC coils. I have not confirmed this so do your research before you replace one of the Tianbo relays.

When that test was passed the enclosure was fully boxed and reinstalled at its outdoor location. It now performs flawlessly. Hopefully this time it will continue to work as it should.

Last words

My purchase of the Hamplus AS-82 2×8 antenna switch was done on impulse to solve an immediate need. I did not want to buy new since it was the early days and I did not have a definitive plan for my antenna switching architecture, including physical layout, antenna/band hierarchy (flat or switching per band) and control system for SO2R or multi-op. I still need this switch as an interim solution for at least the coming winter contest season.

The design of the AS-82 seems sound and when it works it works well. The PCB quality is excellent. What is not so excellent is its construction and parts selection. I expect better for the price. I also expect a schematic and detailed interfacing specs. I can only hope their other products are better built. 

Many of the big guns design their own switching systems, eschewing commercial products entirely. Others buy from among several available high-end systems, including those that support more than two operating positions. The small number of dedicated multi-multi stations have simpler requirements since each operating position is only concerned with selecting from one of a small number of dedicated mono-band antennas.

As my station grows it is possible that the Hamplus switch or one very similar could form a core component of my switching system, supplemented with secondary switches for antennas on each band. The switching and control system design is ongoing. That is a subject that is very likely to appear in an article later this winter.

Skewed Wire Yagis

So you want to put up a wire yagi for the low bands. All you need is two sufficiently tall structures -- trees or towers -- tie a catenary rope between them, hang wire inverted vee elements from it and run coax along the catenary to the driven element. Simple and cheap high performance fixed yagis for 40 or 80 meters can be yours.

But what if those structures aren't positioned where you need them. If they are not on a line that is close to the direction (or directions if the yagi is made reversible) that is your objective it could kill the project or you'll have live with reduced performance due to the desired direction being off the centre of the main lobe or by reducing the number of elements to broaden the beam width.

For the case where the structures are towers (or just one of them is) and you plan well in advance you may be able to place the tower or towers to suit wire yagis. Otherwise you can only count on luck to have them where they're needed. I expect this is a dilemma that some readers have faced or will face since the all time most popular articles on this blog are designs for 2, 3, and 4 element 40 meter wire yagis.

The left diagram demonstrates the problem. The greater the angle between the catenary and the desired direction (two directions for an electrically reversible yagi) gain will suffer. The effect increases with the number of elements since the main lobe will be narrower. A 2-element yagi is therefore the least affected by direction error.

On the right is the hypothesized solution. The elements have been turned so that they are broadside to desired direction(s); they remain parallel to each other even. The questions to be answered include:

1. Is the main lobe (if it survives this abuse) along the catenary (a line through the element centres), broadside to the elements or somewhere in between?
2. How much are gain, F/B and SWR affected as the skew angle increases?
3. If the pattern does shift direction how great an angle can be achieved while maintaining a clean pattern an similar SWR band width?

In this article I will explore the problem with wire yagi models where the elements are askew from each other, as they would be when the catenary runs at an angle to the desired compass point. This computer model study should be enlightening and may give hope to those with unfortunately located support structures.

Model parameters

Since a 2-element wire yagi has a wide main lobe and wire yagis with 4 or more elements are uncommon and take more time to deal with in the model I will restrict myself to a 3-element reversible wire yagi for 40 meters with inverted vee elements. The antenna is one I've described in detail before, and indeed is the all-time most popular article on this blog according to web site statistics.

The diagrams above are based on my EZNEC model of the antenna. Refer to that earlier article for details on antenna design and performance since I will not repeat that data in this article. Apex height of the inverted vee elements will be fixed at 25 meters since I don't expect that height will significantly alter the effects of element skewing.

The yagi is reversible by switching a coil at the centre of the two parasitic elements, such that one becomes a director and the other a reflector. The driven element is at the centre of the array so that the performance metrics are identical in both directions (symmetric). Therefore we only need to examine the model in one direction.

Skewing the elements can be done in two ways:

• Rotate the elements in place. The greater the rotation angle the shorter the effective "boom" length. That is, the element spacing is reduced along a line broadside to the elements.
• Constant element spacing. The distance between element centres increases with rotation angle so that the element spacing remains constant.

A 2-element reversible yagi has transmission lines between the feed point and the elements. Therefore when you skew a 2-element yagi the electrical design must be adjusted for the latter method because the physical length of the transmission line must increase. Worse, the lines will be unbalanced due to the loss of left-right symmetry. In my opinion this is more trouble than it's worth. The 3-element yagi is far simpler since it has only DC control lines running to the parasitic elements. Common mode currents due to the asymmetry can be addressed without affecting antenna performance.

For the 3-element 40 meter wire yagi I will examine both skewing methods for angles up to 30° in steps of 5°. Patterns are only computed at 7.1 MHz, which is approximately the midpoint of the yagi's design range for best performance. Based on my modelling I don't expect any surprises in performance at other frequencies over the antenna's range of 7.0 to 7.2 MHz.

For the constant element spacing method I will not compute the increased "boom" length -- distance between element centres along the catenary. This is easily accomplished with elementary trigonometry if you are interested in building an antenna of this type.

Modelling results

As I increased the rotation angle (skew) in the models I was surprised by the yagi's resilience. Performance is sustained better than I expected. However the skewing is not entirely without cost. Scan the table of the calculated key performance metrics before you continue reading. The tables have been normalized to compensate for shortcuts and orientation oddities in my rotation methodology. None of this affects the results but did reduce the time I spent modelling.

There are several conclusions we can make based on the data:

• Gain, F/B and main lobe beam width are largely sustained for angles up to 30°. I didn't expect that I could push that far without negative consequences.
• The centre of the main lobe is between the catenary direction and broadside to the elements, and is the same for both skewing methods. The main lobe skew is ~60% of the physical skew in all cases.
• Although SWR bandwidth is unaffected the resonant frequency increases slightly at the largest skewing angles. Adjusting the matching network should be easy, or at least straight-forward.

Despite these promising results it was disappointing that the pattern skew fell short of the physical skew of the yagi. For a 30° physical skew the skew of the main lobe is 18° ±1°.

The azimuth patterns at a skew angle of 30° show a difference between the skew methods -- original in black and skewed antenna in blue. The rearward pattern is cleaner when the elements rotated in place. With constant element spacing the F/B and F/R are slightly worse. The F/B figures in table also clearly favour rotating the elements in place. [Note: The small skew in the left pattern plot is an artefact of my modelling shortcut discussed previously, not a true difference between the skewing methods.]

Application and items for further study

Hopefully this study can act as an incentive to a few readers with seemingly inconvenient supports for high performance wire antennas. It can pay dividends on the low bands as we survive the next 2 or 3 years the solar minimum will last.

To start, consider how far askew the line between supports is from what would be ideal for you operating objectives. Let's say the amount is 20°. Choose a skew angle of 30° and the pattern will be almost exactly where you want it. If the desired direction is 30° off the catenary you can get most of what you want by skewing 30°, since the pattern will be 18° closer to the ideal than it would otherwise be.

You can even do this with conventional yagis. The application I have in mind is side mounting a yagi flush to a tower face but have its pattern in a different direction when no tower face is suitably oriented. However this would require custom boom-to-element clamps and there may be awkward questions from visiting hams about your peculiar looking antenna. The skew of a wire yagi is less obvious to the casual observer.

If the desired skew is greater than 30° I strongly recommend developing a model rather than extrapolating from the models in this article. At some point I expect performance to rapidly degrade. I didn't attempt to find that point, but be assured that it exists. The same goes for wire yagis with more elements: do a model before jumping into construction.

Depending on my own interest I may extend the skewing concept to wire yagis with more elements, yagis with a coupled resonator and wire yagis with loop elements. It is reasonable to predict that all will benefit to a degree though it will require modelling to find how far each yagi design can be skewed before performance deteriorates.

The primary message of this study, I believe, is to use the supports you have and exploit skewing to make the best of your circumstances. Perfection is rarely necessary or even desirable. I would only caution against deployment of novel skewing arrangements without modelling beforehand to determine what you can expect and so avoid wasted effort.

Motivation

Skewing yagi elements may seem an odd idea and I admit it never occurred to me until about two weeks ago. I was walking back and forth in the hay field armed with a compass, wood stakes and a 200' tape measure looking for the ideal location to plant my second big tower. Tower siting is a compromise between safety, transmission line length, yagi side mounting, interactions and wire antennas. It is rare that all objectives can be fully satisfied.

This tower's placement in my original site plan for this QTH was based on these criteria. Details matter when one moves from a rough plan to literally pounding a stake into the ground, hence my recent surveying activity.

I expect to place the tower such that there will be some skewing required for wire yagis hanging off a catenary between the towers to make the project more tractable and to minimize interference from side mounted yagis pointing directly at antennas on the other tower (towards Europe). Shifting the tower site ~20 meters solves these and several other problems.

Thus was born my motivation to study skewing. A few hours later I sat down in front of the computer to study the implications and possibilities.

That tower project is now well into the planning stages with a tentative schedule. Wire yagis for the low bands may be in my future now that I have skewing data in hand. Stakes are in the ground.

WARC Bands Without WARC Antennas

For those who have followed this blog for the past two years may recall that my primary objective in building my station is contests. HF DXing is my secondary priority despite comprising the bulk of my daily operating. Contests are episodic which leaves a lot of time in between!

As a consequence my effort on towers and antennas favours the HF contest bands: 160, 80, 40, 20, 15 and 10 meters. However I also need antennas for the WARC bands -- 30, 17 and 12 meters -- for general and DX operation. I want effective DX antennas on those bands without requiring effort better spent on antennas for the contest bands, with respect to performance, time and money.

As an interim measure last year to get back on 17 and 30 meters I once again put up my tried and true multi-band fan inverted vee. Originally this antenna was a key part of my Ottawa station soon after I got back into ham radio several years ago. I was very happy to find that it delivered fantastic results with QRP and 100 watts on 15 through 40 meters. Of course that was during the solar cycle maximum when a little antenna (and power) goes a long way.

When I moved to this QTH in late 2016 I temporarily hung it off the house so that I could operate until my first tower was up. I moved it to that tower in late 2017 when I moved the 80 meter inverted vee to the big tower so that I would have resonant antennas on 17 and 30 meters, and for short distance contest QSOs on 40 meters.

The multi-band inverted vee is about to be retired once more, perhaps for good this time. The reason is that I no longer need it. I am able to operate very effectively on 17 and 30 meters with other non-resonant antennas. As we'll see, even non-optimal antennas can do very well under favourable circumstances.

17 meters on the XM240

Unlike a full size dipole or yagi driven element the Cushcraft XM240 does not resonate on the 3^rd harmonic, which would be 15 meters. Coil-loaded elements is the reason. Instead the antenna has a resonance at a lower frequency, almost but not quite on 17 meters.

This has long been known and many hams with this antenna have had some success using it on 17. The additional transmission line loss due to an SWR between 2 and 3 is modest since of the 350' (110 m) of coax ~90% is LDF5 Heliax.

When I purchased the antenna I built a model in EZNEC to learn, in part, how it might do on 17. Unfortunately an accurate model isn't possible with NEC2 due to the loaded elements, As of EZNEC 5 the stepped diameter correction (SDC) does not support loaded elements but this deficiency has been partly addressed in EZNEC 6. I don't know the reliability of the new feature.

Nevertheless it is possible to gain an insight into the antenna's pattern despite the resonant frequency being incorrect.

As you can see the azimuth pattern is bidirectional, just like a dipole. There is ~1.5 db gain due to the parasitic element (a very wide spaced yagi on 17 meters), making it slightly better than a dipole. Since the equality of the two lobes is frequency dependent the azimuth pattern above is not quite what you'll get at 18.1 MHz -- I evaluated the pattern at 19 MHz to approximately compensate for NEC2 inaccuracy. In practice I find that the pattern is slightly directional in the same orientation as it is on 40 meters, so it can help to point it at the DX rather than relying on it being bidirectional.

One big advantage this antenna has is height: 46 meters up. That makes up for its quirks. I am able to work DX very well, often breaking pile ups quickly with 200 watts. The XM240 is far superior to the multi-band inverted vee with its apex at 19 meters, and it's rotatable. With the XM240 a proper yagi for 17 meters is not currently in my plan.

30 meters on the 80 meter inverted vee

The WARC bands are not harmonically related to the others. Sometimes they come close enough to be tempting. This is the case of 80 and 30 meters, where the 3^rd harmonic of 3.5 MHz is 10.5 MHz and of 3.8 MHz is 11.4 MHz. When cut for the CW segment of 80 meters the 3^rd harmonic comes within 5% of the 30 meter band.

My inverted vee is cut for mid-band so the 30 meter resonance is around 10.7 MHz. Although the modelled SWR is quite high at 10.1 MHz in practice it is no higher than 4, after accounting for loss in the long run of FSJ4 and a shorter run of LMR400; that is, it is lower in the shack due to transmission line loss. I use the rig's ATU. As is usual with a harmonically fed dipole the feed point impedance is high even at resonance.

The pattern is oddly shaped but not too problematic. As is usual with an inverted vee the polarization is primarily horizontal broadside and vertical off the ends. At its apex height of 32 meters you might expect the radiation upward should be close to nil, but this is not so.

There are two current maxima on each leg of the inverted vee -- there is a single maximum at the antenna's centre when operated on its fundamental frequency. Thereforeon 30 meters the effective height is lower and there is a big lobe pointing straight up (pattern not shown)! This lowers gain in the main lobe at 30° elevation.

Despite these drawbacks the antenna works pretty well on 30 meters. Performance depends on the direction. If this antenna does poorly on a station I can always switch to another. Which brings us to the next antenna.

30 meters on the 80 meter vertical

From on high we go down low. The 80 meter yagi array construction is ongoing and is already giving an account of itself on the bands as an efficient ground mounted vertical with its (so far) 34 radials. I will have more to say on this antenna in future. In this article I'll restrict myself to its 30 meter performance.

Like the inverted vee the vertical's 3^rd harmonic falls in the vicinity of 30 meters and has two current maxima along the monopole. The 34 radials, each 20 meters long, form a non-resonant ground plane that extends much further than on 80 meters, with respect to wavelength. In comparison to the inverted vee the SWR bandwidth is very broad, a characteristic that appears at its 3^rd harmonic. I haven't carefully measured the SWR on 30 meters but it appears to fall between 2.4 and 3. Half the 250' (80 m) transmission line is LDF4 and the rest is RG213 and LMR400. The rig's ATU must be used.

In 30 meters it compares favourably to the multi-band inverted vee and the 80 meter inverted vee. Again, direction and elevation angle are factors. The vertical is omni-directional with a higher angle lobe common to verticals operated at its harmonics.

Sometimes the vertical does better and sometimes the inverted vee does better. In a minority of cases the multi-band inverted vee equals or slightly exceeds the 80 meter antennas.

The elevation pattern assumes 5 Ω ground loss. It is more difficult to estimate the radial system efficiency when the vertical is operated on its harmonics. I didn't try since its use on 30 meters is incidental rather than a design objective.

12 meters

I left this one last since 12 meters has two strikes against it. One is that it is rarely interesting at this point of the solar cycle. Two is that I have little interest in it. There is no rational reason for the latter.

The multi-band inverted vee doesn't work on 12 meters. In fact I've never had a resonant antenna for this band. That none of my panoply of antennas comes close to resonating is therefore no great loss. The few times I do venture onto 12 meters I pick one of tri-band yagis and use the ATU.

The high SWR is not extreme and the reduced system performance does not worry me, considering my attitude towards 12 meters. A poor antenna that is up high is usually enough to get the job done when I call a DX station.

Perhaps when the solar flux rises from the dead in a few years and most of the heavy lifting is done in my antenna farm I'll take the time to put up a resonant antenna for 12 meters, even a yagi if I get serious.

Summing up

With many antennas and a little bit of height it is often possible to recruit one of them to put you on a band for which you have no antenna. Obviously this strategy is less than optimal in most cases, yet as I've discovered not optimal can still do very well indeed. It is something to consider. However if your antennas are modest and not high it is entirely likely you will not achieve superior results. This is when a resonant antenna can be well worth pursuing.

The multi-band inverted vee is still up and occasionally put to use. In fact I'm using it more right now while summertime work on the station switching and cabling make other antennas temporarily unreachable. When that is done and the next stage of antenna and tower work begins it will be in the way. Retirement is tentatively slated for August.

The antenna won't be junked. If nothing else it make a handy portable antenna should I ever want to do that, or as a loaner to a friend. This may be optimistic since it doesn't wrap up neatly due to it peculiar construction. It ends up as a tangled mess every time I roll it up, no matter how careful I am.

IARU and WRTC

I did not make a substantial effort in the IARU contest this weekend. Not only do I not enjoy warm weather contesting -- too many opportunities to do things outside -- ongoing cabling and switching work meant I had just the TH7 at 21 meters and an inverted vee for 40 meters. The bigger antennas are not currently connected to the shack.

Despite all of this I did operate for several brief periods as CW LP. If not for this also being the WRTC contest-within-a-contest event I doubt I would have made any effort to be active. With some amusement I note that, apart from 80 meters, my station as currently configured is quite similar to what the WRTC competitors used. By accident I also used the same power -- 100 watts -- which I selected out of habit. IARU, being an ARRL sponsored contest, permits 150 watts in the low power category.

What I will do in this short article is provide my thoughts on how the competition may have played out. Of course I could be completely wrong. It is nevertheless interesting to test my understanding and make a few speculations. Eventually the full story and the facts will emerge. For background on competitor strategies and choices I recommend N3BB's excellent book, Contact Sport.

QSO totals

Compare the WRTC scoreboard and raw scores on 3830 and you'll immediately notice just how much higher the QSOs and scores are for the WRTC competitors. Their modest stations were no impediment. Like rare multipliers in any contest they attracted a lot of attention regardless of signal strength.

For this reason it is no surprise they spent the bulk of their time running. Indeed, despite spending half of my short time in the contest running I did not get called by any Y8. This continued to be true in the final 30 minutes of the contest when I'd expect their rates to be relatively low. Clearly they knew how to best utilize their time and energy.

Since there are 1,440 minutes in a 24-hour contest it is easy to calculate their overall QSO rates. The top placers were all above 4 QSOs per minute (240 per hour) averaged over the full contest period, with two stations and two operators. That's impressive! The high power multi-op stations could not match this level. I doubt the HQ stations (which are multipliers) fared any better.

Activity level and low power

In most contests those with low power and modest stations (especially QRP) usually must go high in the CW band segments to run. Big guns tend to congregate towards the low end of the band where it is difficult for smaller stations to run and be heard. Yet in this contest the low power Y8 competitor stations appeared to be evenly distributed across the band and could even be found hugging the bottom band edges.

Perhaps they could do this due to their starring role in the contest. On the other hand it is summer in the northern hemisphere when many contesters are loathe to spend time in the shack. I know I am. Despite midsummer conditions with its many attenuated propagation paths it seemed that the overall activity level was not high. That makes room available for smaller stations. Of course many of the big gun operators were congregated in Germany, not at their usual operating positions.

SSB

N3BB points out in his book that choosing the split between CW and SSB modes is a key strategic decision in WRTC. CW has the advantage of favouring low power and being picked up and spotted by the global skimmer network. SSB has the advantage of faster rate and a pool of operators who do not operate CW. In 2014 the competitive advantage appeared to favour those who emphasized CW.

From the scoreboard it appears that the CW advantage was suppressed in this year's competition. SSB totals are generally though not universally higher among the top scoring teams. If this is true why might it be so?

In 2014 the competitors were in W1 where the bulk of the valuable QSO points come from Europe. There remains a strong CW culture among Europe's contesters. From Germany looking west towards North America there may be proportionately fewer CW operators due to the now longstanding migration to SSB due to no-code licensing. Outside of the US, Canada and Europe the use of CW is even lower.

From central Europe I would expect that inter-continental QSOs favour SSB toward Central America, South America and east Asia. East Asia does not contribute many QSOs from W1 but it is a productive path from Europe. There are, for example, many non-CW operators in E2 and YB.

Could this have been a factor? I notice that North American teams are lacking among the top scorers. European operators may have better understood the need for SSB for racking up contacts on the available propagation paths beyond Europe and North America.

Low bands

Europe is a hotbed of amateur radio activity, including contesting. Pay close attention to the standings after any major contest and you'll notice that even the QRP participants in Europe work an enormous number of other European stations on the low bands, day and night. Did enough of the WRTC competitors from outside Europe understand the importance of the low bands? Intra-European contacts are worth less but there are so many more available.

In North America the low bands are mostly a wasteland during daylight hours, except in late afternoon and early morning during domestic contests, and then only in the eastern third of the continent. Europe is different.

Time will tell

Don't take my analysis too seriously. It is mostly speculation based on limited data. Time will tell whether I am right on any of my suspicions.

Being wrong does not worry me. In any competitive endeavour it is beneficial to study the competition to see what can be learned, whether to emulate or avoid the tactics they use. Answers may always remain elusive since the competitors themselves may be uncertain about what exactly they did right or wrong. Sometimes it is merely a matter of luck, be it good or bad luck.

For me contests are fun rather than a serious competition. I have no aspiration to compete in a WRTC. It is an opportunity to learn and to watch the masters in action. We should all always be learning.

Insurance Contact Dilemma

An insurance contact is when you work a DXpedition a second time on a band-mode. This is generally frowned upon since it takes time away from the DXpedition operators to work other stations, stations that may not have worked the DXpedition at all. Sometimes it's done by mistake.

Most often it is done to be extra certain that their call is in the log. Rare DX can cause anxiety! Before the internet became prevalent in the DX sport insurance contacts were more often due to anxiety about whether they got in the log the first time.The uncertainty may be due to QRN, QSB or QRM (deliberate or accidental) that obliterates part of the QSO. The DXpedition operator can contribute to the anxiety by not clearly repeating and confirming the received call before moving on to the next QSO.

There are also less than stellar individuals who do it to show off their big antennas and big power. With computer logging braggarts risk being called out by the DXpedition operator so this behaviour is no longer as common as it once was.

With near real time log uploads to services such as Club Log there is less cause for anxiety. It used to be that you might only learn one or two years later that you weren't logged! That happened to me a few times so I am appreciative of the benefits of modern technology. Since internet access may not be available or reliable from remote locales, resulting in upload delays from hours to days or until after the DXpedition is over, anxiety still occurs.

Which brings me to the recently completed Baker Island DXpedition: KH1/KH7Z. There were two QSOs that caused me some anxiety, and ultimately a pursuit for insurance contacts.

The first was 15 meter CW. Despite the poor solar flux there is a brief propagation peak in the late evening my local time. Signals are quite weak, putting us at a disadvantage to those further west on the continent. Nevertheless I managed to eke out a QSO around 04Z with my TH6 up 43 meters and with my usual 200 watts. Having a kilowatt would have helped get through but with a lesser antenna I may not have heard them.

The QSO was not without drama. It took a few overs until he copied my call correctly. Finally I heard it, sent my report and heard the confirmation. One more band slot in the log. Or so I thought.

The QSO was not in the online log after it had been updated up to and beyond the time of our QSO. This is not necessarily a problem since it often happens that logs from all operating positions are not uploaded at the same time. So I waited another day. Still nothing.

Perhaps I had been wrong when I heard him send my call that final over. I felt (and still feel) it was correct. I could wait and hope for the best or consider trying for an insurance contact. For many this would be simple to resolve: just get in there and do it. My reticence is due to my dislike of bothering the DXpedition operator again or, worse, hearing the dreaded "QSO B4".

Nevertheless I went ahead. Propagation peaked at the same time a few nights later and I made the QSO easily enough despite the weak signals. No incorrect call to correct this time. Lo and behold the QSO appeared online the next morning! It seems I had made the correct decision.

During the intervening time I got lucky one morning and worked them on 80 CW about 10 minutes after local sunrise when signals usually peak. I heard my call clearly above the noise after one extra over to communicate my call sign suffix. There was a smile on my face as the pile up crowded onto my transmit frequency for their attempt to make it.

The smile didn't last. As you can guess the very same thing happened. Again the QSO failed to appear. There was no happy ending this time since I was not able to catch them again on 80 at the right time and mode.

How does this happen? As the DXpedition wound down I happened to be chatting with a serious DXer friend of mine and we talked it over. We could think of several possibilities.

1. My mistake: Skill, experience and diligence can still fail us. Despite my certainty it is possible they copied my call incorrectly and I failed to hear the error and correct it. This happens quite a lot in contests, so I am accustomed to these irritating mistakes. However I tend to be especially careful when working a rare country.
2. Accidental erasure: Endurance operating takes its toll, whether in a contest or on a DXpedition. A wrong or forgotten keystroke and a QSO can vanish without a trace. Although this certainly happens I don't consider it highly probable in the case of my missing QSOs.
3. Typo: Operators have many different styles. Logging software can smoothly handle transmission of partial calls that are typed in and re-sending of updated call signs. Some operators are more comfortable sending the partial call by hand. Only after they believe they have the call correct do they type it in and log it. In this way I could hear my call being sent yet not be correctly logged. The likelihood this happening twice does not seem high to me. It's just a possibility.

Frankly the most probable explanation is that the mistakes were mine and mine alone, despite my confidence about what I heard. It is nevertheless a healthy exercise to explore the range of possibilities. Even if errors occurred at their end it does not absolve me: perhaps there are things I could have done to improve the outcome. That is, to make it easier for them to copy and log me. Insurance contacts are a poor substitute for accuracy.

All of this said there remains the faint possibility that my QSOs are correctly stored on the DXpedition PCs. There may be gaps in the records uploaded from the database, gaps that will be filled when they get home and process the logs. I am not very hopeful this will happen

Screen capture from Club Log

I did pretty well despite the lost 80 meter QSO. Unfortunately my 160 meter antenna is down for the summer since I did hear them on that band a couple of times. Baker Island on the low bands will have to wait for another 10 years, which is the earliest another DXpedition will be permitted on the island.

It give me one more thing to look forward to. I'd better get back to work on towers and antennas so that I'll be ready when that long awaited day arrives.

Making the Move to FT8 on 6 Meters

Six months ago over the Christmas holiday I downloaded WSJT-X to give FT8 a try. Since quite a lot of CW and SSB activity has moved to this new digital mode, in particular on VHF, it seems inevitable that I would take the plunge eventually. Also with a background in software and experience developing commercial applications using DSP and statistical analysis the technology alone was of great interest to me regardless of whether I would ever use it on the air.

On VHF/UHF, 160 meters and the new MF and LF bands the attractiveness of advanced digital communications is readily apparent. For a week I monitored the FT8 watering holes on most bands from 160 through 6 meters just to see what showed up that I might not otherwise notice courtesy of its low SNR capability. The software is easy to use and I was decoding traffic within minutes of installation. The only error I made was at first to connect the sound card input to the rig's microphone rather than the receiver audio. Without thinking I had stupidly connected like to like -- mic to mic -- a common enough mistake

The amount of activity was surprisingly high on every band that was open. On 160 meters there were numerous European stations on 160 meters when there was no CW signals present. Most of the calls were unfamiliar, indicating that FT8 either draws more hams to try top band or that FT8 allows smaller stations to be more successful. On 6 meters stations were copied when I had no particular reason to believe there was sporadic E present. On the HF bands the FT8 windows were crowded.

Based on the signal reports being exchanged the majority of signals would have been comfortably copied on CW. But since you can't predict signal strengths in advance this is not a slight against FT8 versus traditional modes.

Hibernation before a first QSO

First FT8 QSO

After a week of fooling around I pushed WSJT-X aside without having transmitted once or made any QSOs. It was peak DX and contest season and I was not willing to spend more time with it. Its time would come, I knew, when the peak sporadic E (Es) arrived in late spring. The migration to FT8 on VHF has been so profound that it would be that or miss a substantial amount of activity, especially DX, which is my particular interest on 6 meters.

In late May I became serious. After some experimentation I had the FTdx5000 working well with WSJT-X 1.9 and began making QSOs on June 5. I made my first QSO on 10 meters since propagation did not favour 6 meters when I was ready to go. As is my bent the first QSO of course had to be DX!

Now familiar with the software and certain I had everything hooked up correctly I exited HF entirely to focus on 6 meters. Indeed as I write these words that first FT8 QSO is my only one on HF. It may be a long time before there's another in my log.

Motivation and qualms

My sole motivation to try out FT8 is the wholesale migration of DXing activity on 6 meters from CW and SSB. Whether one likes it or not that is where the activity resides. This became very evident in 2017 and was certain to be even greater in 2018. While I had nothing against FT8 there seems something overly artificial about QSOs that fully rely on machine coding and decoding. This is a common sentiment among many hams.

It was therefore with only middling enthusiasm that I took the plunge. The technology itself is fascinating and delightful, and that pushed me along. My appreciation is in part because I have developed commercial DSP (digital signal processing) software. There is an undeniable urge to learn what far better minds than mine have been able to accomplish in developing FT8 and similar digital modes.

But would it work for me? Could I learn to enjoy FT8? Would DX fill my log? That is, would I work DX on FT8 only because that's where the activity is or because it delivers superior results? The only way to know for sure was to become active and stick with it through the sporadic E season. Before continuing I'll tell you now that my expectations were met. However it is not all roses.

What I've worked

No QSO, but how nice that he sent that last message

As I write these words I've been on 6 meters FT8 for 3 weeks. In that time I have primarily focussed on DX, but also North America west coast and Mexico as conditions dictated. A few times I ran shorter distance stations to improve my skill using WSJT-X. It's quite easy, just click, click and click some more, and watch the log fill with QSOs.

Although it can be boring I usually fill the time by browsing the internet, eating or skipping away for a few seconds at a time to do small chores. It's a very different kind of amateur radio than I'm accustomed to!

In these past 3 weeks I've worked close to 170 stations (no dupes), with 40% of those outside of the US and Canada. I haven't counted countries but there are quite a few, many of which are new for me on 6 meters. Stations I've copied or almost worked range from JA to OA to OH to 4X and TY.

For the longest of paths the opening might last no more than one 15-second transmission, never to be heard again. FT8 is a bit of a tease that way. Despite the frustration it is fascinating to watch what is getting through. I often leave the station monitoring 50.313 or 50.323 MHz when I am busy elsewhere and see what the propagation delivered while I was away.

Usually there little to see while other times I am appalled at the opening I've missed. For example, the JA opening seen in the adjacent screen capture. It lasted 7 minutes with over two dozen Japanese stations copied. But I wasn't there to work any of them. Oh well, there's always next time (or next year).

The briefness of so many openings -- shorter than it takes to conduct an FT8 QSO -- may seem unreasonable yet this is not really true. Although it is true that a CW or SSB QSO can easily be completed far faster than FT8 and thus benefit from ultra brief openings you have to be in the right place at the right time to do it. This is quite difficult though I've done it numerous times. It makes me wonder whether one of the fast modes would be more suited to DXing on 6 meters. Perhaps MSK144 that is used for communication via meteor scatter pings.

With FT8 you monitor the entire "band" at once and can see and respond to one of these micro openings in seconds. In a typical east European opening there can be dozens of these in quick succession. Of course one to two minute QSO may be too long to fit into the opening but at least you have a chance. Most often on CW and SSB you would never even notice the openings and so work nothing at all. On balance FT8 wins this contest, in my opinion.

Switching to 50.323 MHz

Birds flocking together in the fall are a good analogy to 6 meter FT8 DXers. After days of false starts somehow consensus is reached and the flock takes off together to begin the migration south. In the same fashion everyone congregates on 50.313 MHz until the unspoken signal is given and we all make the move to the intercontinental DX window.

What is that signal? One that motivates me is exemplified by the above spectrum view. In good openings the standard FT8 window fills with many signals or a few very loud ones. When this happens our receiver's AGC gets busy protecting us against excess IF amplification and distortion. This effectively desenses the front end and can render weaker signals undecodable.

In a pinch you can use a narrow filter. Most of the time that is a poor solution since you may not know the DX station's frequency or you'll miss new ones. When copy of weak transitory signals becomes difficult or uncertain that may be the time to QSY. Like those birds they'll individually rise up and look around and if they like what they find they'll keep flying. Eventually a tipping point is reached and the entire flock of DXers moves.

In my short experience the whole process takes only a few minutes, including most stations on both ends of the intercontinental path. It's a fascinating study in human psychology.

Who's active

One fact that jumped out at me immediately is that few of the call signs I've heard on HF and VHF were familiar. Often one hears many of the same stations every day on CW and SSB. I was intrigued by the presence of many hams I would not otherwise hear. I like that. It gives a DXer like me a whole new set of stations to work.

There are of course also many recognizable calls, hams who are active on CW and contesting. It makes for quite a mix. Obviously this latter group remains active on both digital and traditional modes. Perhaps they are experimenting with FT8, like me, or have made it a regular part of their activity on HF.

Despite criticisms of FT8 as being machine to machine (partly true) if it gets more hams active that's a good thing. Whatever I may think of FT8 from a philosophical perspective it is now necessary to pursue DX on 6 meters. Being stubborn or a curmudgeon about it does not put DX in my log. It is yet too early to tell how this in combination with the aging out of the older generations will change amateur radio.

Quirks, tips and common mistakes

During my short time on FT8 I have learned quite a lot. Some of it is covered by others, such as in ZL2IFB's excellent guide, though oriented more towards HF where propagation lasts longer than mere seconds. Others I have learned on my own, though all are probably documented by others, somewhere, if you know where to look. I find WSJT-X documentation silent on many questions I needed answers to.

The following are a few of the things I've learned. These points are oriented to 6 meters, especially DXing, and so may not be useful to everyone. Perhaps some will be of use to you.

Decode errors: Although FT8 uses FEC (forward error correction) its algorithms are so aggressive that it is not uncommon to see messages such as the one at right. The more aggressive you dial up the algorithms the more of this you are likely to see. The phantom signal usually has a very low SNR though not always. My first experience of decoded noise was RTTY in the 1970s. The random sequences could be hauntingly close to plain English. The resemblance to real messages is especially true with FT8 since the they are in essence just numbers that map to character sequences.

Power: For optimal decoding of your signal at the other end your signal should have the minimum distortion. What is annoying but passable on CW and SSB does not work at all with FT8. From what I see on the WSJT-X spectrum display many haven't figured this out yet. I leave the rig power at 100% (200 watts on my FTdx5000) in SSB mode and use the WSJT-X power control to set the power output to no more than 50% (100 watts). There is no ALC action and the transmitter isn't stressed. Setting the rig power to 50% requires heavy ALC action and some distortion getting through. Since I use audio equalization the power varies with the transmitter offset, which may require fine tuning.

Mode switching: I use SSB for simplicity in setup and tear down of cabling. Using the rig's digital modes and associated attachments can mean less fiddling with transmit controls when switching modes. For example I have to turn on VOX and disable the compressor for FT8 and reverse the process when returning to SSB. Happily I have fixed level jacks on the rig back panel for audio in and out for computer interconnection rather than having to swap cables when switching modes. The mic must be disconnected since it always mixes with the audio input from the back panel jack.

Simplex vs Duplex: Many calling me transmit on the same frequency while I almost always call others on different frequencies. There is no simple rule. When you are confident there you are likely to be the only caller it can be helpful to go with simplex since the other station presumably chose a clear frequency. Otherwise duplex is the better bet.

Respect directed CQs: When, for example, a station called CQ EU do not reply if you are not in Europe. That seems simple enough yet many call anyway. In the intercontinental segment at 50.323 MHz all calls are presumed to be for DX. Because some persist in calling anyway I turn off the Call 1st feature when I make a directed CQ and manually select a station to answer. I learned to do this when calling CQ DX on 50.323 MHz and my station automatically responded to a domestic caller. This brought out an over-enthusiastic policeman who DQRM'd the QSO. Disrespecting the band plan is unethical but DQRM is illegal. Avoid doing both, and especially the latter!

Policemen: Speaking of policemen there are quite a few of those on 6 meter FT8. Who would have guessed. They hound non-DX QSOs in the DX window, harangue splatterers and those in the wrong time sequence, or simply broadcast what they believe are helpful messages. In their enthusiasm they forget to include their call signs. The policemen, too, have migrated to FT8 from other modes.

Timing: There is no consistent use of even and odd slots on domestic QSOs though there are conventions. When DXing respecting time slots becomes important. The simple guideline proposed by the UKSMG (UK Six Meter Group) is largely adhered to and works well. Don't expect to work much DX if you transmit in the same time slots they use! When everyone respects the time convention you'll notice that spectrum display is empty on even slots except for those weak European signals. When they all mix together on 50.313 MHz the QRM often renders weak DX signals unable to be decoded.

Multiple callers: By not using Call 1st the CQing station can choose who to respond to, at the price of having to be nimble with the mouse. If the desired station is using Call 1st, which is most common, it can take multiple attempts to get through, if the propagation holds for many minutes. This can be gamed to get through sooner by noting that Call 1st is with respect to WSJT-X decoding order. From observation the decoding order is determined by frequency and number of required decoding passes. If you signal is reasonably strong you should transmit well below the desired station because you'll be decoded first! When it takes a second pass due to QRM or propagation phase distortion you'll lose out to someone else. Although not a guarantee the tactic does work.

Calling etiquette: When the CQing station responds to another station some keep calling throughout the QSO while others tail end (after 73 or RR73), while still others are silent until a subsequent CQ is sent. Continuous calling seems impolite to me even though it really doesn't cause harm other than to fill the other station's screen with a few extra messages. Consensus on this point seems elusive.

RR73: Many CQing stations use RR73 rather than RRR to complete the QSO to, presumably, speed the QSO. Unfortunately that doesn't necessarily work. RR73 ought to be used only when signals are strong otherwise WSJT-X will resend it if the expected 73 is not received. But after the caller sends 73 and another RR73 is received the 73 message is not automatically sent since the transmitter is disabled. It must be sent manually, which wastes at least another 30 seconds if you are not very quick with your hands. For the present I avoid using RR73 when I respond to callers to my CQ. Another speed technique is to send a signal report as the first message rather than one's grid. It seems to work well for brief DX openings although it may irritate those who collect grid squares.

NA contest mode: There is one, much to my surprise. During the ARRL VHF contest some used it and some didn't, resulting in mass confusion. I hadn't even heard of it at the time and could not understand the peculiar exchanges (I still don't) which I could not find in the WSJT-X manual. So I avoided FT8 during the contest. Some operators forget to turn the feature off after the contest.

Aurora: Forget it. The auroral curtain causes rapid frequency (Doppler) and phase shifts that defeat all attempts to decode FT8 of reflected signals. The decoding algorithms in WSJT-X are impressive but even they cannot "put Humpty Dumpy back together again." Switch to CW.

FT8 and me

After a month of FT8 activity I am prepared to decide whether it's for me. On HF, no. At best I like it as a type of beacon network to tell me if there's propagation. On 160 meters I can see that it could be interesting, so come this fall I will likely give it a try. But DX only. For 6 meters I find it useful, interesting and I almost but not quite have enthusiasm for it. With it I am near certain I am able to work far more DX and capitalize on marginal openings.

Sure, being able to monitor all activity simultaneously is a bit of a cheat. However it is not all that much worse in that sense than using the spotting network. It's like having my own CW skimmer. For a long time ham it only requires some getting used to the difference in operating style. It's hard to argue with a log containing dozens of DX contacts over the past few weeks. I have no doubt they are real QSOs, no worse than what is typical on all bands and modes.

The worst thing about FT8 to my mind is the boredom. Sitting in front of a screen watching the green bar advance one slow second after another is very tedious. Yet you must have quick reactions to respond to a station in the 2 or 3 seconds after decode to hit next 15 slot. Miss it and you lose 30 seconds (or much more if someone else works the station you want), and that can easily mean missing the contact entirely due to the short openings for the longer DX paths.

I liken it to baseball where most of the time you stand around doing nothing and a small amount of time moving like lightning. Your vigilance must not waver. When the time comes you must react very quickly and do everything properly despite the need for speed. You often don't get a second chance.

At least the 6 meter sporadic E season is short. I think I can put up with the negative aspects of FT8 for a month or two in order to work the DX. Time will tell. It may not even matter what I think if the mass migration to FT8 on 6 meters holds. One night during a great opening I moved to CW to relieve the tedium. The one QSO per minute I sustained for 20 minutes was a welcome change. Compared to FT8 that's a fast rate.

After the CW run I switched to SSB and worked a few more before settling into a rag chew with an old friend. Difficult to do that on FT8. Each mode has its quirks and benefits. FT8 fits well into the 6 meter operator's repertoire.

Plans for improvement on 6 meters

My 6 meter station is the same as it was last year and changes will not happen until next year. Although the sporadic E season is only a little more than half over I am too busy with other projects to improve my equipment. My antenna is big, high and working well, I've made the move to FT8 and the DX is rolling in. That's sufficiently satisfying for this year.

There are two deficiencies I would like to deal with. The first is the transmission line. It's an ancient 40 meter run of RG213 that is very lossy at 50 MHz. The matched loss for pristine RG213 would be -2 db and perhaps another -0.3 db due to the low SWR. It measures almost twice that loss due to its age-related deterioration. That's a lot!

Ancient RG213 may seem a strange choice since I have ample amounts of LDF5 and AVA7 Heliax. However the Heliax is slated for long runs to and up big towers for HF antennas. I will not allocate a precious 40 meters of it until I have more in hand. HF contests and DX are higher priority.

The second deficiency is power. It is sometimes (and falsely) claimed that FT8 is best suited to low power, even QRP. Of course low power is often all that's needed, but that's equally true for other modes. For the majority of CW and SSB QSOs you could turn your power down to 5 watts and still be solid copy. Of course almost no one does that. When it comes to brief and marginal DX openings on 6 meters power comes in very handy, whatever the mode. Many FT8 DXers on 6 meters run high power and it delivers results.

When I do purchase an amplifier it would be nice if it covers 6 meters. This isn't mandatory. I am willing to delay or forgo high power on 6 meters if the amplifier I want is available at the right price and only covers HF. As an interim measure improving the coax next spring will give me the equivalent of several hundred watts. An amplifier is not my foremost need.