Monday, February 27, 2017

New Antenna: How They Play

When I completed the Trylon tower and antenna construction and put it on the air I promised to report about how the station performs in regards to my technical assessment of what to expect. With close to two months of experience, one major contest and several DXpeditions I am now ready to come to some conclusions.

I've done this before from my previous station in Ottawa. I believe that this kind of analysis is something any ham should do. However it must be done honestly. The task is not easy when there is no possibility of a direct A-B comparison due to the previous antenna, tower or complete station being removed. Yet this is quite typical, and the source of much uncertainty or outright error. While I am not immune to misleading myself I try to keep my skepticism intact when I undertake such a comparison. Whether or not I succeed you will have to judge for yourself.

Perhaps the greatest tests of my current station were the ARRL DX CW contest and working the A5A and XX9D DXpeditions. Early indications from the contest are that I placed highly among the W/VE entrants in the SOAB LP category.

20, 15 and 10 meters with the Explorer 14 up 23 meters

Modelling showed a modest though far from insignificant improvement of 3.5 to 4 db compared to its 14 meter height in my previous station in Ottawa. In practice I definitely notice it, and so do those I call.

Running 100 watts I can enter any pile up with confidence. Sure I don't get though immediately when the big guns are in there. But I do get through sooner than I did before. In contests I can establish runs on 20 and 15 meters without any real trouble as long as the propagation cooperates. There is little on the high bands the big guns work that I now cannot at least hear. That was often not the case beforehand.

Another 3 db with 200 watts and my results have only gotten better. A higher antenna will be needed to capture those marginal openings that only the big guns can take advantage of. That is of course in my plans. For now I am cruising the bands with more confidence and success than I have in a long time. QRP and little antennas are challenging and fun, and so is this. It is just that the nature of the challenges changes.

40 meters with the XM240 up 21 meters

This antenna full meets my expectations. The modelled 10 db of gain over the inverted vees I used back in Ottawa is certainly present. Without high power I am now competitive in the pile-ups. If I hear a station I can work it. Long path openings to VK and Asia in the early evening yield many QSOs, including VK6 and XX9D.

In contests I can get a run going without much difficulty. Any evening if I call CQ there are Europeans who answer. After signing with another station who had called CQ I frequently get called by others (but of course I QSY). This is a level of performance I have not had before on 40 meters.

Front-to-back (F/B) on any 2-element yagi is poor, and this antenna is no exception. I can often work stations off the back without any difficulty. When I point to Europe during contests I can continue to work the US. Off the back it is much like what I previously had with an inverted vee. Not great, but good enough for contests when I do not have the option of a second antenna for diversity.

Because of the high SWR at the bottom of the band I operate with rig's internal ATU. The SWR is not so high that the transmission line losses are a worry. The XM240 will make for a good secondary antenna once I have a bigger antenna installed on the 150' tower.

Structurally I can see that I need to make changes to the antenna. The galvanized muffler clamps that secure the elements to the boom and the boom to the mast do not have the best gripping strength. They get their grip in part by the edges of the formed sheet steel saddles dimpling the boom and mast. Worse, in the case of the boom-to-mast clamp the saddles bend under the axial force. Solid saddles are a must for at least the boom-to-mast clamp.

80 meters with an inverted vee up 19 meters

An inverted vee with the apex up only λ/4 is not a good DX antenna. Even so it works. Sometimes it's because the elevation angle is at times higher than expected on the low bands and other times because verticals are deployed in a way that the ground loss is high: inadequate radial system or high-density suburban environment.

My country count on 80 meters has surpassed 100, starting from my DXCC "reset" in 2013 when I returned to the air after a 20 year absence. In reality my country count is ~200, if I were to bother with the paperwork. I won't because I don't care: I like working DX, not QSLing or award chasing.

The latest additions were TX5T and VP6EU during this morning sunrise opening. In ARRL DX CW I worked 65 countries, which is quite good for 150 watts and an inverted vee. I would say that the inverted vee has surpassed my expectations despite being merely a convenient and easy temporary antenna until I can put up something more substantial later this year.

With a better antenna or more power I will be pushed over the threshold where I will often not be able to hear many stations that can copy me. Directive receiving antennas are a must. As I write this my first Beverage antenna is nearing completion. I will say more about it in a future article.

160 meters with the 80 meter inverted vee

This should not have worked at all, yet it did. Modelling estimates an impedance of 6.5 - j1000 Ω. With 40 meters of RG213 the calculated loss is -22 db. Measurement with an analyzer tells a different story, perhaps only -6db of loss. This measurement is misleading since the 1:1 balun at the feed point will behave unpredictably under such a severe mismatch -- this is typical of baluns and RF transformers. From on the air experience the loss is substantial.

In the January NAQP CW contest I used an external tuner and unscrewed the outer ring of the connector. That seemed to work pretty well. In ARRL DX CW I did not bother. The FTdx5000 ATU found a match (to my surprise) which made me lazy. With the help of excellent conditions I worked an unbelievable 20 countries on top band with this ridiculous antenna system. Running 150 watts out my effective power was no better than QRP.

While interesting it is unacceptable, with or without the connector half unscrewed. I will have something better when fall arrives. But for those running QRP it shows what can be done with low effective power on top band, assuming a decent antenna is used.

6, 12, 17 and 30 meters

I have no antenna for any of these bands. On 12 meters I use the rig ATU with the Explorer 14, on 17 meters I use the XM240 the same way, and on 30 meters I use the third harmonic of the 80 meter inverted vee, but also with the ATU in line. At least 6 meters hasn't been a worry since sporadic E season is still a couple of months in the future.

Despite this improvisation I have had little trouble working many DXpeditions on 12, 17 and 30 meters. It is just a little more work than would otherwise be the case. I don't mind that. After all if I can reach DXCC on 17 and 30 meters with QRP and simple wire antennas my present situation is not so bad!

I briefly contemplated putting up my old multi-band inverted vee back up just so that I would have a resonant antenna on 17 and 30 meters. After considering how much trouble that would be I decided against it. While not ideal the use of the ATU with judicious selection of a non-resonant antenna is adequate to my needs for the next several months.


The new rig is a delight to use. The receiver is top notch and I am exploring its features as I tune the bands through contest congestion, DX pile ups and QRN. I can narrow the DSP down to 50 Hz to copy the weakest signals and not experience any objectionable ringing. This has proved invaluable numerous times in contests, certainly improving my score with QSOs that would otherwise not make it into the log.

The noise blanker seems to create fewer artifacts than others I've used. The notch filter attenuates interference without unduly affecting fidelity of the desired signal. Split operation is smooth, and since it functions identically to that of other Yaesu rigs there was no learning curve. Dual receivers works just as it did in the FT1000 MP I previously owned. Except now I have far better filtering on the sub-receiver. I have yet to try SO2V operation in contests.

Since I have only 3 antennas at the moment the ability to connect 4 antennas to the rig makes band changes a breeze during contests. I do not need or use an external mechanical switch and I can defer a sophisticated system such as 2xN switches and band decoders until later. I connect a dummy load to the fourth antenna position.

The monitor scope (SM-5000) is, as many report, mostly a toy. It did come in handy once. During the ARRL DX CW contest openings on 10 meters were elusive. Since I operated unassisted I would briefly change bands, look at the band scope to take in activity across the entire CW segment at a glance. Any blobs present were tuned in and copied to see if it was something I wanted to work. If there were no blobs the bands was either dead or the signals were very weak. I could always check again later.

The extra 3 db from the 200 watt output is noticable and welcome. I am definitely no longer QRP! However I was disappointed to learn that the power can only be turned down to 10 watts. This is not a rig I can easily use to enter the QRP category in contests, which I likely will still do from time to time. Perhaps that'll be the time I return to using the KX3.

Of course the biggest problem with this rig is the weight. At 42 pounds (19 kg) it is difficult to carry and move. It isn't portable, and unlike many other rigs does not have a handle. For my purposes it is not really a problem. If you need portability in a high performance rig buy a K3S.


Putting up a tower and antennas mid-winter is not without its difficulties. When I'm fighting with connections, bolts and heavy and unwieldy antennas while the north wind is blowing is not really a lot of fun. Shortcuts were taken. That has caused problems, some of which I've had to fix and others I have decided to let be until the spring. I'll run through these quickly.
  • My ancient rotator cable sprung a leak. Due to an injudicious placement of a splice when I routed the cables into the new house entry conduit a large snowfall followed by a thaw appears to have caused a conductance path between wires inside the splice. That is, water infiltration. That it happened during the ARRL DX CW contest added to the misery. I had to run into an adjacent room to see where the yagis pointed. At night I needed a flashlight. The next day it settled down. I redid the splice and moved it out of harm's way.
  • If that wasn't enough, a day after fixing the splice the rotator suddenly turned slowly or not at all. Within minutes it wouldn't turn at all. With DXpeditions on the band this was unwelcome news. With an ohmmeter I quickly discovered one of the motor winding wire showing over 2 kΩ resistance. I retested the splice, which was fine. So up the tower I went. Two trip later it was fixed. The connector off the wire tail from the rotator, while nicely sealed was not fully seated. I looked it over, twisted it closed and the rotator resumed full function.
  • My ancient Vista laptop kept crashing early in the ARRL DX CW contest. It is a known network hardware fault that rears up occasionally. Since I was operating unassisted I turned off the WiFi card and pulled the Ethernet cable, and it didn't crash again. This computer is on my priority list for replacement.
  • Intermittent power line noise has appeared, affecting the high bands only. The noise is impulse, slow or rapid depending on the weather, and can be silenced with a noise blanker on 6 and 10 meters but not on 15 and 20 where the impulses are poorly defined. After a heavy rain the noise vanished and has yet to return. I was able to pin down the direction which narrows my suspicion to two pole transformer and several other poles. I can do this since this rural area has few power lines. I'll be watching this one.
  • I purchased a large quantity of cylindrical ferrite RFI chokes to place on Ethernet cables between equipment and on the cable coming down from the terrestrial wireless internet access antenna. In some places it helps while in others it does little more than more the noise around as the resonance of the cable between chokes and terminations changes. There are other options I will explore.
  • I purchased a new headset to replace my old Heil headset on which the mic cable is intermittent. It's old and needed replacement anyway. The new one has an electret element which I had planned to build an interface to the rig, which only supports dynamic mics. But used as headphones they either need better adjustment or they simply won't work out. First, they are uncomfortable after several hours, and so are bad for contests. In the middle of the ARRL DX CW contest I tore them off and went back to the Heil. It was then I noticed the audio quality on the Heil headphones was better.
Looking ahead

There are few easily determined quantitative results that can validate my subjective observations. Propagation, activity levels (mine and others) and even mood can dominate objective measurements. I can only point to what I have to show, and in this case it is contests and DX chasing. The indications are good.

Spring is rapidly arriving and with it a new season of tower and antenna work. I have much planned for this year. As I plan and anticipate the list of project ahead I can also sit in the shack and work the world with a better station than I have had in a very long time.

After a busy fall and winter with the move, tower and antenna work, and house renovations I can finally sit down in the shack and profit from that hard effort.  And I am. Look for me on the bands.

No comments:

Post a Comment

All comments are moderated, and should appear within one day of submission.