Sunday, January 21, 2018

Sound of Silence: QRN Eliminated

Back in December I mentioned (and showed a picture) of power line noise I have been experiencing at times throughout 2017. Now it's gone. To refresh our memories here is the noise on 6 meters with the yagi pointed directly at the noise source.


That's bad, real bad. As the frequency is decreased the noise gradually declines in signal strength with increasing loss of pulse definition. On 6 meters through 15 meters the noise could be mostly removed with the noise blanker, at the expense of inter-modulation distortion (IMD) products. This gets particularly ugly when faced with contest and pile up conditions.

Interestingly there was no impact on 80 or 160 meters. On 40 meters the yagi saw the noise as an deterioration of the noise floor, but not whten using the inverted vee.

Now the noise is gone. From the discussion I had with the utility crew I suspect it will not be back.


This is an exceedingly uninteresting picture, and it's just how I like it.

I have to say that the local electrical utility, Hydro One, was very responsive and helpful. This is welcome since we have among the highest electricity prices in the country. On top of that we face high distribution fees in our "rural, low density" township.

As a general rule utilities like to find and fix problems like this one. What they don't like is wasted labour costs spent searching for and not finding the source of the problem. This is why it is helpful to first localize the problem before calling them out. The intermittent nature of so many power line equipment problems can then be eliminated as a time waster. The crew lead told me that there is quite a lot of old and problematic equipment out here that they would in any case like to replace. My call had the effect of giving them a reason to do so.

I did not localize the problem since I am not equipped to easily go out with portable equipment that can find problems like this one. What I could do was accurately determine the direction from my house. In our low density neighbourhood this was enough since there is very little distribution equipment compared to towns and cities. In fact I could point them directly at the most likely culprit.

Although the noise was not present when the crew arrived with their bucket truck they went right to work. They found and replaced two cracked insulators, isolated the lines from rotting wood posts and replaced old switches just in case they were contributing to the problem. As they worked the noise appeared, disappeared, came back in spurts and then disappeared for good. I could listen as they worked since the power wasn't disconnected on my segment of the distribution network.

Then they switched off my power and went north to replace suspect switches at two other transformers. I have had weak power line QRN in that direction a few times so perhaps that will also disappear. Time will tell. Is there still some power line QRN? Yes, but just weak source or sources that are not serious problems. At least not at present. As equipment ages and deteriorates the future appearance is more a matter of when not if.

Rural distribution is typically 14,400 VAC, twice that in urban areas. It can run as high as 28,800 VAC. The higher voltage is more prone to causing arcs when equipment deteriorates. I don't know the distribution voltage on my road. I ought to have asked.

Now I have one less worry when I switch on the rig. The only serious noise remaining is from the Ethernet cable drop from my terrestrial wireless ISP antenna. I may deal with that later this year. It is now a minor problem since I mostly use the antennas on the new tower which are quite a lot farther from the house. All the LED lighting I have been installing has been clean, as is the new heat pump. A year ago I replaced a dimmer switch that created a lot of QRN on the low bands.

I am getting closer to having a QRN free QTH. Listening here in the relatively empty farm and bush country is wonderfully quiet. You can't work them if you can't hear them. Now I can hear them. They don't always hear me, but that's to be expected.

Thursday, January 18, 2018

2018: Unfinished Business and More

2017 was a big year at VE3VN, though one with even bigger objectives. In January of last year I had just topped the Trylon with a small tri-bander and a 40 meter yagi and then was left spinning my wheels after the aborted first attempt to plant the foundation for the 150' tower. Ongoing delays in putting up the big tower pretty well defined the entire year. My ambitious objectives for 2017 were only partially fulfilled.

As the so-called polar vortex descended upon us before Christmas, bringing my late year antenna projects to an abrupt halt, I could do nothing but wait it out. Over the holidays I could have done quite a lot indoors to progress matters while waiting for the weather to improve but the reality is that I did very little. I needed a rest.

Now that the weather has improved and my enthusiasm is perking up it is time for my annual look back and plan forward, something that has become a regular feature of this blog. Writing it down may do more for me than you, by forcing me to face certain truths about what I can do and what I should or should not attempt.

Hopefully readers will gain something from it as well, in particular those who have ambitions to improve their antenna farms. If this sort of article bores you I won't be offended if you choose to skip it. Perhaps I'm the only beneficiary is me. Putting plans in writing forces me to carefully think and decide whether the plan is doable and encompasses my interests and capabilities.

With that introduction let's plow onward.

What went wrong

Without question the most vexing item to plague me in 2017 was the necessary time to raise the big tower. There were a few things that caused the delay:
  • Our wet spring was a record breaker. Excavation and below surface work could not be resumed until June. It was originally slated for late 2016 when an early winter storm interrupted the work. If that had been done the tower would have been raised months earlier.
  • Let's face it, we're all getting older. There are fewer hams willing and able to help out than in the past. The situation is not getting better. I nearly succumbed to hiring the work out professionally even though I am fully capable of working on the tower. The friends who did come out to help were a real blessing. Even so they are limited in how much time they can spend here. Excellent weather was wasted when they could not make it.
  • I care about doing a proper job. That entailed quite a lot of research, backtracking when I was unsatisfied with a tool or procedure, and long hours. On the plus side I am have no fears that the tower will come down in the first serious storm to come along. Since maintenance is the bugaboo of large antenna farms it pays to get it right the first time so that you don't have to redo it again and again.
  • The active flora and fauna in a hay field create their own hazards. Wading through the high hay inevitably means dealing with ticks until early July at least. After that the black flies, mosquitoes and their larger cousins were so fierce as to frequently drive me indoors. Even if I cleared the field it would only reduce the tick population and help not at all with the rest. That would also annoy my neighbours who rely on the hay to feed their livestock.
During the quiet times between bouts of tower work I did quite a lot of antenna modelling and exploration of physical design alternatives.

Unfinished business

Although much of my 2017 plan was not completed there are a few projects that were started and then rudely interrupted. Weather was the main culprit. Cold, windy, snowy conditions hit fast and hard in December and did not let up. Apart from a few warm days recently the bitter conditions have resumed. The following items must wait for spring to arrive.


I had hoped be far enough along with construction of the 80 meter array that it could be used as a simple vertical over the winter. I succeeded with putting in the screw anchors for the guys just in time. When the weather warmed I stood up the first two tower sections and used rope as temporary guys. When I returned the next day to finish insulating the legs from ground I discovered that two of the screw anchors had moved. After further testing I decided that the anchors are inadequate for the prevailing soil conditions; the sub-surface soil turned into a slurry that demands deeper anchors with more bearing surface. That job is not practical in the extreme cold.

Cable burial had to be deferred when the frost penetrated the ground and didn't relent. Until April I can only hope that the deer don't abuse the Heliax buried under the snow and ice. All of the cables are suitably rated to survive the winter.

Terminations of the many runs of Cat5 control cable are open air rather than sealed in boxes at the towers. The few connections needed right now are manually spliced and roughly weatherproofed. Fine work of this type is too difficult in cold weather since much of it must be done with bare hands. The gel-filled cable can handle a moderate amount of moisture exposure without damage.

80 m array

The 80/40 meter fan inverted vee is temporary and will come down later this spring. I want it for long enough to compare it to the 80 meter vertical array that I am building, or at least in its preliminary omni-directional (single element) configuration. This is necessary intelligence to predict the array's performance and determine whether I still need a horizontal 80 meter antenna for short path and select DXing conditions.

The design of the 80 meter vertical yagi array has refined and compared, on the computer, to the 4-square array for a range of ground types and radial systems. I plan to devote an article to the revised antenna within the next month.

Design of the switching system has lagged. It's simple enough but it has to be fully specified and then built. The feed line and control cable to feed the array is ready to be installed once the weather improves. These, too, require trenching and burial.

I expect to have a horizontal antenna for short path work to complement the vertical array. I haven't yet decided exactly what and where. There is a dependency on high band yagis for which I want to avoid destruction interactions when they are on the same tower.

New tower

As I reread my plan for 2017 in preparation for this article there was one item that had me laughing: putting up a second big tower. In retrospect my optimism was, to put it mildly, misplaced. Yet for 2018 this is back on the table. Indeed without a decision my antenna plans cannot be finalized. That is, what do I put where?

There are considerations of stacking and interaction to be thought through. Otherwise I'll find myself putting antennas up then taking them down again within the year. That amount of churn may be acceptable for this winter on the existing big tower but it should not become a habit!

If it does go up it will be placed approximately south of the house in the spot reserved for it in my original site plan. This location has its good and bad points with respect to antenna interactions between towers. The main negative is that yagis on the towers will in certain cases point at each other when working Europe or the US. On the positive side this is an ideal orientation for low band wire yagis by running a rope between the towers.

Should the tower go up I already have one in reserve at an attractive price. I haven't bought it yet and the seller will give me first refusal in the unlikely case another buyer appears. The tower is identical to what I already have -- Leblanc & Royale LR20 surplus broadcast tower. I can use the same tooling to raise it and custom attachments will fit both.

It will not be as high. My aim is between 120' and 140' to allow stacking on 20 meters and 15 meters. The existing tower can then be dedicated to 40 meter antennas and then either tri-band yagis or 10 meter antennas. Wires antennas for the low bands will fit in somewhere. It is common practice for those with two towers to put 40 and 10 on one and 20 and 15 on the others to minimize interactions. In addition the 20 and 15 meter antennas tend to point in the same direction for much of the time, and this arrangement is helpful in that regard.

My decision on the tower is pending. There is more to think through before committing to it this year.

Yagis for the high bands

I had big plans for yagis on the big tower last year. Instead all I could do was put up the tri-band yagis I had on hand in the rush before the winter closed in for good. What I have is effective though limited in capability and flexibility. High band yagis are now a priority.

For the next 3 years I can get away with nothing more than what I have on 10 meters. All the openings are marginal and fleeting, and therefore addressable with a tri-band yagi up high and another down low. Indeed it is likely that I will still have a tri-band yagi on top of the big tower rather than a mono band yagi (or yagis). If I get another tower up then I can alter this plan. But if I do that I suspect I'll have little time (again) to build and raise antennas.

This brings us to 20 and 15 meters. Yes, there are other bands up there -- 17 and 12 meters -- which are not contest bands and therefore lower priority. Assuming I have no more towers this year I want to get at least one long boom 20 meter yagi and two on 15 meters fixed on Europe, and if I can I will make one or two of them rotatable. Alternatively I can pick up a cheap TH6 on the used market and stack it with the top TH6, substituting it for the Explorer 14 up ~115' (34 m).

The 5-element 15 meter yagi I designed for the boom tubing I have on hand is still a possibility. So are other options. This is a decision I must defer for a while longer. What I will most likely have to choose between is mono-band or tri-band yagis but not both since having both near each other cause unwanted interactions.

The bottom line is that I must remain flexible for the next several months until other plans solidify. Rather than overreach as I did in 2017 I will be pragmatic and seize opportunities as they appear.

40 meter challenge

I am shelving plans for a full size 3-element yagi on the big tower. I may do so eventually but not until I am truly ready to tackle a project that large. Instead what I'd like to do this year is to build a full size fixed 3-element yagi at ~80' (25 m) switchable between northeast and southwest. This will give me excellent coverage of both Europe and the US under most conditions.

A fixed yagi simplifies design, construction and installation. If all goes well I can put a similar antenna up top next year or later. Stacking the two is a possibility if they are sufficiently similar or identical. I expect the XM240 to remain on top for at least this year. It could be moved elsewhere, possibly converted to a W6NL Moxon for increased agility on 40 meters.

My preference for the fixed yagi is to use dipole tubing elements on a boom of at least 40' (12 m). A wire fixed yagi is less desirable due to the decreased average height and clutter in the hay field. Of course the first problem can be remedied by raising the apex, though at the expense of interactions with planned side mount yagis for the high bands above it.

I have most of the aluminum on hand for the boom and element centres, but not the smaller sizes. There are numerous other construction details that I need to work through. I don't mind spending some money on an experiment provided it doesn't get out of hand.

I will rework earlier models of wire yagis, shortened element yagis and full size yagis for now, and leave the final decision to the summer with construction slated for late summer or early fall.

Receive antennas

The Beverage I put up last winter continues to perform exceedingly well. Unfortunately it is only useful for working Europe and other regions in that direction. For contesting that's still a lot since it is a very productive path. Now my problem is all the other directions. There are several options that are compatible with my situation.

I have ruled out a vertical circle array. They are expensive, complex, can only be optimized for one band and require pre-amps that (according to others) often overload in the presence of a kilowatt on another band. This is unfortunate since they are reported to work better than Beverages.

Although simple and cheap, high performing Beverages have their challenges. For one, installing and maintaining them in the bush where I most want to put them is difficult, trees fall on the wire (this has already happened though without serious damage) and having enough of them to fully cover the compass without encountering siting problems and common mode risks due to the coax running from each to a control box. I will need to design and build a control box and remote switch.

I am currently investigating reversible Beverages to reduce the magnitude of the problem. Since running parallel wires through the bush is really difficult I am tentatively planning to experiment with a reversible Beverage made out of coax. It will either be east/west or north/south. Achieving good balance in the transformers seems to be the key requirement to ensure good directivity. I can do this while the weather is frigid, only risking frostbite!

If it works well I'll do more of them, though possibly not until the fall.

Station automation

Remote antenna switching, automatic antenna selection when changing bands, rotator control, filter selection, SO2R and more fall under this topic. That's a lot to do. I've begun some of it with a remote 8x2 antenna switch, although with a manual selector in the shack. Automation is not only convenient but also necessary for effective contesting when SO2R and multi-op.

I don't expect to get very far this winter. Since I plan to mostly build rather than buy the control systems I have purchased an Arduino and accessories to prototype simple items such as band decoders, antenna selection and control of the prop pitch rotator. Design of the systems and integration with the station are the major challenges. Writing the software is straightforward since I have done quite a lot of commercial software development and the academics to back it up. It should be fun.

I am as yet undecided whether to build or buy, or have a mix of both. It's a question of time versus money and customization to my own needs and wants.

As a consequence of automation I will to consider the impact on amplifiers and antennas. I will have to decide to spend more on a broadband solid state amplifier (or two) or have to fiddle with their tuning if I opt for cheaper and more robust tube amps. Antennas should have low SWR across the band for automation to be simplest. Otherwise broadband amps will complain and both transceivers and tube amps will need to be adjusted when changing bands, changing frequency and switching among antennas for the same band.

For the winter I will mostly stick to experimentation and prototyping, aiming for implementation in the autumn.

Amplifiers

This is the year I intend to return to QRO with at least one amplifier. There is no definite schedule. I will react to opportunities as they arise. Two amplifiers will eventually be needed for SO2R and multi-op contests. Two 240 volt circuits will have to be installed.

Choosing those amplifiers will be challenging. Ideally they will be solid state, no tune amplifiers capable of full power at an SWR of 2. They can be expensive. Amplifiers that require tuning, including economical tube amplifiers on the used market, are more flexible.

The latter would require extensive station automation so that band and antenna switching only requires setting the dials on the amps, otherwise time is wasted and costly mistakes are more likely.

VHF

If time allows I'd like to put up a 2 meter yagi on the Trylon just below the 6 meter yagi. That will serve me well for playing in VHF contests and occasional DXing. The original plan to use my roll of AVA7 (1-⅝" Heliax) for these antennas has changed. I will instead reserve that coax for the new tower to reduce loss on the high HF bands. It's a matter of my personal priorities.

The VHF yagis will most likely share a single run of LDF5 Heliax with a switch on the tower. I have no compelling reason to operate on 2 and 6 meters at the same time.

Last but not least: self improvement

Building a world class antenna farm with equipment and station automation to match is not enough. If you were to put a typical competent contester at the controls of such a station they would lose. Every single time. Too many imagine that if they had a big station that soon the walls would be covered in plaques. Not so.

Contesting is a skill that requires talent and constant practice. In that respect it is no different from an elite athlete or a highly performing tradesman or professional. It only seems easy in our imaginations. Skill improvement and operating techniques are beneficial for the little guys as much as for the big guns. Do not excuse yourself from making the effort.

That is a roundabout way to say that I am becoming a major impediment to better contest results. Although I have extensive contest experience and would even class myself a good operator there just is no comparison between myself and the upper ranks of the contesting world. I will have to improve. That became particularly clear to me this past weekend in the NAQP CW when I found myself in a team with a few of the country's foremost contesters and competitors in the forthcoming WRTC 2018. It was a humbling experience.

Operating a big station is very different from doing a contest with low power (including QRP) or modest antennas. The required intensity is unrelenting. As one big gun told me: you always have to be running. You have to be there CQing or the casual operators won't have an opportunity to call you. With a big signal your log will fill with QSOs and multipliers without scouring the bands.

They do of course also hunt for QSOs and multipliers, but they do so concurrently on a second rig. SO2R is mandatory. Liking SO2R and running is optional, but you must do it. I do not yet have the equipment or skills to do SO2R. That is in my 2018 plan. First I will start with simulations then advance to smaller contests. Even if I never equal the best at the craft (likely) my score potential will greatly improve. Station automation will support what's needed.

Old dogs can learn new tricks. Never stop learning.

Tuesday, January 9, 2018

Antennas on the Big Tower: How They Play

I now have sufficient experience with my new tower and antennas that I can begin to see how they perform. This is important in forming my plans for the future. None of the antennas on the tower is intended to continue for the long term. As a recap these are the currently deployed antennas:
  • XM240 2-element short 40 meter yagi, rotatable at 47 meters
  • TH6 tri-bander, rotatable at 44 meters
  • Explorer 14 tri-bander, fixed northeast (Europe) at 34 meters
  • 40/80 meter fan inverted vee, broadside to NE/SW at 32 meters
  • 160 meter t-top wire vertical with 8 x 30 meter radials, 20 meters from the tower
Heights are correct to ~1 meter. All main runs are Heliax (3 x LDF5, 1 x FSJ4) plus LMR400 to the lower antennas and RG213 to the 160 meter antenna. Coax from the outdoor 8 x 2 switch are LMR400 Transmission line loss is very low and not a significant factor for any of the antennas.

Power has been 200 watts (FTdx5000) in daily use, and 5 (KX3), 100 or 150 watts depending on the contest and entry category. My first take on performance was after CQ WW CW, before the TH6 and XM240 were connected. I expand upon that here with more on-the-air experience and with all antennas in operation.

Note on S-units

Do not interpret S-unit differences in the discussion below in decibels. The S meter on almost every amateur receiver is not linear with respect to decibels per S-unit and even nominal decibels per S-unit are not the same among receivers. The "standard" 6 db/S-unit is mostly a fiction. Even the more typical quote of 4 db/S-unit is not reliable.

I therefore do not attempt to estimate decibels from S-units when comparing antennas. In any case signal strength over time on any ionospheric path is too variable for the purposes of good precision.

So don't look for quantitative measurements here. My observations are informal indicators of relative performance. This is nevertheless useful. Exact antenna measurements on sky wave signals are hard to do. Really hard.

160 meters

The wire t-top vertical performs exceptionally well for such a simple antenna. It shows what can be done when you have a 43 meter tall support to work with! It's been used in 3 contests so far -- CQ WW CW, ARRL 160 and Stew Perry -- and casual DXing. I am pleased its performance. But how good is it?

The best test so far was the Stew Perry Top Band Challenge. Many stations with good antennas operate with QRP since there are significant bonuses to both parties in the QSO and the points multiplier is especially rewarding on long DX paths. Looking at the results so far I did well in the category despite being on for only 5 hours. I worked as far as eastern Europe, a similar distance to other QRP stations with good antennas.

In daily use I find that I can crack small pile ups even though many or most stations are running high power. Most hams have difficulty putting up an effective antenna on 160 meters and it shows. With just 8 radials a simple near full size vertical is very competitive. I now have 62 DXCC countries worked on top band from casual and contest activity.

This antenna is especially useful as a base line. It allows me to calibrate performance against others with better antennas and therefore make an informed plan for a permanent antenna. More receive antennas are needed before I increase power to a kilowatt since I can see that I will only attract callers that I would otherwise not hear. That's a good problem to have.

80 meters

This band is where I believe I have seen the smallest performance improvement. It's the same inverted vee I had at lower height, now combined with a 40 meter inverted vee for dual band use. The previous apex was 19 meters compared to the current 32 meters. It certainly works better although the improvement is incremental.

Horizontal antennas on 80 meters need to be higher than where I have it. Consider that λ/2 is 40 meters, and at its apex height of 32 meters the inverted vee's effective height is likely no better than 25 meters, or only a little more than λ/4.

A proper comparison cannot be made until I at least have the driven element of the 80 meter array operational as an omni-directional antenna. For now I have to be satisfied with good, not great results. It has been good enough to work VU and other difficult to reach DX with just 200 watts.

40 meters

This is a band where height makes a substantial difference. Right now I have three antennas on 40 meters, the two on the big tower and the multi-band inverted vee at 19 meters on the smaller tower. It is only on a small number of nearby paths that the lowest antenna is better so I will restrict the discussion to the high inverted vee and rotatable XM240 on top of the big tower.

Before sunset the inverted vee is often stronger towards Europe though not always. It's important to switch between the two to find what works best. Once it is dark there is no question that the yagi is always the best choice. Since the F/B is poor it can also be used most of the time to work Europe and North America without bothering to switch to the inverted vee, even though domestic signals may be stronger on it. Short paths are already strong enough except for the smaller stations.

On intermediate length paths such as to Europe and the Caribbean the yagi is at least 2 S-units better. Where it really shines is on the longer paths. For example, long path to east Asia in the early evening can be better than 5 S-units better on the yagi. This is no surprise. With 100 to 200 watts I have had little difficulty putting countries such as BY, JA, 9V, YB, UA0, HL and others in the log. Working 6O6O was more difficult but it's in the log. South America and the Pacific, and the Antarctic, are typically 3 to 4 S-units better on the yagi.

Perhaps the biggest problem with the yagi is that the prop pitch rotator turns slowly: ~0.6 rpm. You really have to think whether it's worth the time to catch one multiplier. Most of the time it's faster to use the inverted vee and have to call several times to get through.

30 meters

While I did not put up a new 30 meter antenna I have one nevertheless. Just as the 80 meter inverted vee worked well on 30 meters, the third harmonic with a tuner, it still works the same at its new height and form as a 40/80 inverted vee.

Unsurprisingly at 32 meters height it compares favourably to the multi-band inverted vee up 19 meters on the shorter tower. The difference ranges from 1 to 3 S-units depending on path and distance. Noise pickup is lower since it is much further from the house. I now rarely use the lower antenna on this band.

20 meters

Of all bands 20 meters is the most enigmatic when it comes to my current selection of antennas. I have in effect 4 antennas on this band, from the multi-band inverted vee up 19 meters to the TH6 up 44 meters. Path length, direction, time of day and overall conditions determine which antenna works best.

As I've discussed before the Explorer 14 fixed on Europe still does pretty well for working the US since the F/B is not great on 20 meters. Three elements on such a short boom is far from ideal. Even so it can be very useful by limiting the necessity of switching antennas, and of having a second antenna pointed at the US much of the time. The situation will change when I redo the antenna later this year.

Despite the lower height the Explorer 14 almost always delivers the best signals from Europe. On marginal opening the higher antenna does better. The performance difference is 1 to 2 S-units most of the time, but is occasionally greater.

On other short to medium length paths the rotatable TH7 works quite well despite being much lower at 21 meters height. Even to the current 6O6O DXpedition the Explorer 14 and TH6 are about equivalent. In this case I favour the TH6 because the better F/B is better at hearing through the pile up.

This selection of antennas, and nodes in the elevation patterns, make plain that the ionosphere determines the path, not the antenna! On 20 meters 44 meters (2λ) can be too high much of the time.

As for 40 meters it is on the longer paths that the high antenna shines. Whether it's Asia, the Pacific or South America the TH6 is better than the TH7 by no less than 2 S-units and can be another 2 to 3 S-units better than that. On long path to VK and the Pacific the difference is remarkable. Signals pop out of the noise on the TH7 to almost S9 on the TH6.

Of course there is no need to always use the best antenna. Other than for the longest paths I will more often simply use the one closest to the correct direction, turn it and use it. Making the QSO is what matters, not burying the other fellow's S-meter.

Height clearly brings a new level of performance to my station on 20 meters. This bodes well for upcoming DX contests when I expect to increase QSOs and multipliers.

17 meters

There are two unintentional antennas for 17 meters on the big tower: XM240 and 40/80 inverted vee. Both are efficient and present good feed point impedance, although the rig's ATU is required for full power operation. That the XM240 resonates is no surprise since it is widely known that the antenna has a harmonic resonance near 18 MHz. Unlike full size 40 meter antennas the third harmonic resonance (3λ/2) is lower due to the effect of the loading coils.

There is good and bad performance on 17 meters with these antennas. The good is that they're much higher than the multi-band inverted vee up 19 meters. The bad is that the azimuth patterns are complex with multiple nodes and lobes typical of antennas operated well above their fundamental frequency.

As a result it requires switching among the three antennas to find the best signal, and then adjusting the tuner. This is inconvenient though acceptable for a non-contest band. For now I can live with what I have. A resonant gain antenna (yagi) on 17 meters is low priority.

15 meters

Most of the time the TH6 outperforms both lower yagis. It is rarely worse. This may in part be due to the low MUF and therefore low elevation angles on all paths at this time of year and solar cycle. It seems that every 15 meter opening is fleeting.

When the band is open to Europe I will swing the TH6 towards more distant shores and the TH7 towards the west or southwest, using the Explorer 14 for Europe. While not ideal for all openings to Europe it gives me the flexibility to roam all the high bands for multipliers with the TH6 up high and for shorter paths with the TH7 down low. This approach works well in contests.

On longer paths such as South America, the Pacific, the Indian Ocean and east/south Africa the high antenna is superior to the TH7 by 3 to 4 S-units. Compared to the Explorer 14 to the Indian Ocean and east Africa (about the same bearing from here as southern Europe) the difference is smaller, usually less than 2 S-units.

10 meters

My experience on 10 meters with the new antennas is limited due to conditions. When the band has opened to South America, ZS and ZL the high TH6 is the clear winner by 2 to 4 S-units or more over the TH7 at 21 meters height. With no European opening on 10 meters this winter I cannot yet compare the TH7 to the side mounted (fixed) yagi lower down by a full 1λ on 10 meters.

Indications are generally favourable for when conditions do improve, and they will do so as the winter progresses despite the low solar flux. Back scatter signals from US stations appear to be stronger as well on the high yagi. Again, this is as expected.

Where I go from here

The tower is high but the antennas are not the best. It is enough to show the promise but not deliver it, at least not yet. Three more things have to happen in order to put out a dominating signal.

The first is to replace tri-band yagis with mono-band yagis. Depending on the band and boom length an improvement of from 1 db to 4 db can be expected. The price to be paid is clutter on the tower, expense and management of interaction between antennas and with the guys. This is not a job you want to get right the first time.

The second is to stack those mono-band yagis. Depending on height, boom length and spacing the gain improvement typically ranges from 2 db to 4 db for two identical yagi and more by adding more yagis. The problems of expense, clutter and interactions are obviously worse. If one or more of the yagis in a stack can be separated and rotated the challenge is even more acute.

The last is to increase power. Running 100 watts in a contest with this antenna farm is competitive against others with similar power, but not with those using more modest antennas and a kilowatt. There is no easier and cheaper way to gain 10 db than to plug in a box and turn it on. Of course this is no help with receiving well or competing against those with high power and big antennas.

You might also wonder whether one or two S-units matters at all. For casual operating perhaps not. Where it makes a big difference is in contests, putting many more QSOs with smaller stations within reach and cutting through the QRM at the other end, especially within Europe. Your individual interests determine whether the improvement is worthwhile.

These are topics I will come back to later. I have decisions to make before I can proceed with my plans for 2018 and beyond. I intend to be modest in my ambitions. But for now I am on the bands and having fun with what I've built so far.

Saturday, January 6, 2018

Disappointing Pile Up Behaviour

The pile ups on the ongoing 6O6O (Somalia) DXpedition have been fierce. This is especially true in this region of North America since we have had fewer opportunities than many others. I expect to eventually work them though I have not yet done so. Unfortunately there is behaviour going on that particularly troubles me.

It's not the DQRM. Yes, there is DQRM as there seems to be whenever a rare station appears on the bands. It's ugly and I don't like it, but I can deal with it. It isn't the wayward who transmit on the DX's transmit frequency. We all make mistakes, and that includes me from time to time. It's embarrassing but you move on. Everyone discovers their mistake and corrects their transmit frequency, some later rather than sooner. The hurled obscenities are also regrettably routine and I don't let it bother me even though it reflects badly on all amateur radio operators.

No, this time it's something else. Every DXer knows there are those who will continue to call on top of the station the DX is attempting to copy. I don't mean those who do so unintentionally. It is easy in a pile up to not clearly hear the DX at all times or to double with them.

This egregious behaviour not only slows down the pile up it also delays the acquisition of a QSO by those creating the QRM for the DX operator. This should be so evident that any operator with an ounce of intelligence would understand that this is a bad idea. Many continue the practice despite zero evidence that the DX will reward them for their bad behaviour.

Again, this is routine in pile ups, regrettable as it is to see. Hams are people and bring all their human faults to the hobby. So we deal with it. What has me upset right now is a small subset of these persistent QRMers, the ones who ought to exemplify proper operating ethics.

I'm talking about contesters. Not just any contesters but those who regularly feature at or near the top of the results in all the major contests. They are well known. Too many call signs I recognize are repeatedly dumped on top of the station the 6O6O operator is trying to copy.

The guilty have excellent DXing technical skills, quickly finding the station the DX is responding to. That they then QRM the frequency with their high power and massive antenna farms is poor sportsmanship. That they do this persistently from on QSO to the next is outrageous. It is also embarrassing to have to say that some of these are hams I have met in person and there are one or two in my own contest club.

These are contesters I greatly respected and admired only 24 hours ago. Now I don't. I expect better from contesters, the members of my own tribe, so to speak. Superior operating ability and technical excellence in station design for some is seemingly not matched by their ethics and their treatment of others. That makes me sad and angry.

I am not going to name them. Even if I did I doubt it would help since humans are great at rationalizing and outright denial when caught in the act. It isn't even necessary since those chasing the DX can hear their call signs for themselves in the pile up. They persist despite knowing that everyone knows who they are and can hear what they are doing.

I don't have a solution. I can only hope I am overreacting and that the problem among elite contesters is less than I fear.

Tuesday, January 2, 2018

Closing 2017 With QRP

In advance of the new year celebration there were two contests I decided to enter: RAC Winter Contest and Stew Perry Top Band Challenge. The first was partly obligatory to contribute to the Canadian presence for the event, but also to exercise the new antennas. This was the first contest I've operated with the full complement of antennas I put up during the year.

For Stew Perry my interest was different. As an experiment I entered as QRP to see just how well my 160 meter antenna would perform against others under similar conditions. Although designed and built as a temporary solution it does do pretty well, putting me well on the way to top band DXCC and contributing nicely to contest totals.

So I resurrected my KX3 and plopped it front and centre on the operating desk. It looks a little out of place next to the FTdx5000 and other equipment! The KX3 has been boxed up since before the move in 2016 and this seemed a good opportunity to get use out of it. Power on the FTdx5000 only dials down to 10 watts, which makes it unsuitable for QRP.


I set it up the day before the RAC contest to get it integrated with the PC, keyer and antenna switch. Memory is a tricky thing so I had to take 15 minutes to familiarize myself with the controls once again. I had to think for a few moments to recall which buttons to press to turn it on. I took the opportunity to update the firmware which has gone through several releases since 2016. In comparison to some other transceivers Elecraft makes the process absolutely painless.

My activity in Stew Perry was limited, by intent. This was an experiment rather than a serious contest entry. After the RAC contest ended and the evening meal I moved a few cables and fired up the KX3 on 160. Operating time as ~5 hours total, 4+ during the evening and then a little more in the hour before dawn.

I wrote a lengthy soapbox comment for 3830 score submission, if you want to read it. For the blog I'll keep it brief.

The antenna worked very well with only 5 watts. I didn't work a lot of DX, yet that I did work DX put a smile on my face. My furthest contacts were PJ2T, S5, HG and SP. I got a partial copy from a Russian station that would have been a real coup had we been able to make the contact.

Looking at the incoming reports I can see that my performance was on a par with the best results of QRP entrants from this part of North America. That's useful feedback. Now that I know what this simple wire antenna can do, it becomes a baseline from which to plan a permanent antenna for 160 meters.

What I also learned (or relearned) is that the KX3 is not up to the challenge of a band full of exceptionally strong signals. Operating was frustrating at times. Receive filtering is terribly inferior to any competitive base station transceiver. The critical issues were filter skirts at the narrowest settings and opposite side band bleed through (single signal reception). On the plus side the audio coming out of the headphones was an absolute pleasure to hear.

Despite the negative notes the KX3 is a fantastic little rig. It is perhaps unfair to compare it to its bigger cousins. On the hand I firmly believe that every comparison should be against the very best available, no matter the price or size. I still like and I am keeping it. Should my interest in occasional QRP operating wane I will revisit this. Elecraft sells companion products to increase power to 100 watts and make it more of a base station rig. I don't see the point; better to buy a high performance base station rig if that's what you want.

With these contests 2017 is in the rear view mirror and my thoughts turn to 2018. Ideas and plans are slated for articles later this month.

Wednesday, December 27, 2017

XM240 Update

Although I purchased my Cushcraft XM240 in 2015 it was only in use for the first half of 2016 when it was at a height of 21 meters. The antenna had been strengthened per (most of) the recommendations by Dave Leeson W6NL. It did well on 40 meters but with several negatives:
  • The cheap muffler clamps used on the aluminum channel element-to-boom clamp in lieu of the stock Cushcraft clamps did not work out. They could not prevent rotation of the elements on the boom in high winds. The thin steel saddles had little grip and if tightened further would only damage the boom.
  • The same was true of the muffler clamps used for the boom-to-mast clamp. At least boom rotation could be corrected by climbing the tower, which cannot be done for the element clamps.
  • Although tuned per the instructions (interpolated between the two lower settings) for the lower part of the band the antenna resonated ~7.125 MHz rather than the estimated 7.075 MHz. At 7 MHz the SWR rose to 3 requiring the use of a tuner, the risk of loss over long coax runs and undesirable extra steps for band changes and frequency excursions in the heat of a contest.
I set myself the goal of correcting these problems before raising it onto the new 150' tower. I was partly successful. With more time I could have done better, but in the larger plan this antenna's quirks were not highest priority. It was enough to get it working reasonably well even if not to the utmost possible for a small and compromised yagi such as this.

Boom-to-mast clamp

Please refer to the adjacent picture for the this and the next sections. This is a larger version of one published in an earlier article.

The previous owner's muffler clamps -- 2 for the boom and 4 for the mast -- were replaced. For the boom I substituted the two Cushcraft stock saddle clamps, originally intended to attach the stock boom clamp to a mast of up to 2.5" diameter.

They are snug on the 2.5" O.D. boom, but required reaming the holes on the custom ⅜" plate to make them fit. Ordinary muffler clamps do not follow any dimension standard, varying between suppliers despite being stamped with the same size, in this case 2.5". The Cushcraft clamps are truly 2.5" I.D.

Rather than 4 muffler clamps for attaching to the mast I used two DX Engineering saddle clamps. Twice the number of muffler clamps does not compensate for their poor strength under axial load. I carefully selected spots on the plate to drill the 4 holes for the mast clamps to minimize the risk of weakening the plate due to the multiplicity of holes already there.

Integrated truss support

In coordination with the new mast clamp holes mentioned above I utilized two existing holes on the large plate to bolt the aluminum angle stock for the integrated truss. This innovation is required since the truss extends above the tower mast.

The truss is set up and adjusted on the ground. Once up the tower I eyeballed the alignment and declared it good. I was wrong. Only later did I notice that the boom wasn't exactly horizontal. The error of ~2° downward is small enough that the performance impact is not significant. But it does look a bit odd from afar since the booms of the XM240 and TH6 are not quite parallel.

I suspect I made the error because at first the mast clamps were not fully tightened so that I could manoeuver the yagi. I snugged the clamps tight at the very end when my ground helpers had to leave, delaying lifting it up the mast. Apart from looking less than perfect I am not concerned about it. Very likely the antenna will come down next year and I can fix it then if necessary; when it goes back up it may not need the integrated truss support.

Element-to-boom clamps

To avoid weakening the aluminum channel used to support the elements with more holes I decided to revert to the stock Cushcraft boom clamps rather than use better quality saddle clamps. Installing them according to the manual was interesting in that it required a specific tightening sequence for the bottom, middle and top fasteners. Nevertheless I did it as prescribed.

The only omission was the boom truss which is supposed to attach to these clamps. I don't like the idea of a ¼" stainless steel bolt threads radially loaded so I continued with the custom boom clamps for the truss.

The Cushcraft clamps were a bit of an enigma. Despite following the manual and no matter how I fiddled with the alignment of bolt holes in the clamp and the element channel it was impossible to make the elements perfectly square with the boom. Although I did the best I could the elements are not as parallel to each other as they ought to be. The error is small enough to be of little importance to performance, yet it is aggravating. Whether the error is mine -- I don't see how this can be true -- or that of Cushcraft/MFJ quality control is difficult to say.

Another quirk, though not one attributable to Cushcraft, is that with the stock boom clamps for the elements the elements are not in the same plane. When one element is horizontal the other is not. This is due to the machining of the custom boom insert. This is not an issue for muffler clamps securing the elements to the boom since the elements can be rotated to make the elements co-planar. Again, the error is small and not a hindrance to performance.

Tuning adjustment

The tuning challenge is this: decrease the SWR in the CW segment of 40 meters without changing the gain and F/B curves. From experience using the XM240 the positioning of the F/B and gain curves are where I want to keep them, providing acceptable performance between 7.0 MHz and 7.2 MHz. Two element yagis, especially those with shortened elements have narrow optimum bandwidths for gain and F/B so you don't want to mess with those metrics if they are already correct.

Why the feed point impedance differs from what the manual promises is not clear to me. One other contester I've spoken to noticed the same behaviour. He deals with it in the shack by adjusting the match on his tube amplifiers. Modelling isn't an option to fully investigate the antenna's performance since NEC2 is inadequate and NEC4 is not an investment I am willing to make.

All is not doom and gloom since there is another way to get what I want without extreme effort. The method relies on understanding how yagis do what they do. In particular that the gain and pattern, and their associated electrical parameters are unaffected by modest changes to the driven element. By modest I mean with respect to the element's physical dimensions and matching network, if any, at the feed point. Changes to parasitic elements are another matter entirely, and must not be touched for the following procedure to work.

Since this antenna has no matching network -- only a common mode choke -- and I want to keep this simple I am constrained to making changes to the length of the driven element, in particular the tubes serving as the elements tips.

Although NEC2 cannot be accurate for this antenna I created a proxy model a couple of years ago to investigate aspects of the antenna that interested me. The model uses constant diameter elements and therefore makes no allowance for reactance errors due to the tubing taper schedule -- Leeson's stepped diameter correction in EZNEC does not support loads (coils in this case) or capacity hats. The resulting model is frequency shifted downward and likely alters the pattern and impedance a small amount. Even so it is good enough for what I had in mind.


In the second of the two proxy model SWR curves each half of the driven element has been extended 5 cm (2"). This moved resonance down 50 kHz without changing the frequency range of the pattern. Ignoring the inaccurate frequencies calculated by NEC2 it is the amount of downward shift that is of interest since the actual antenna will do the same. Just imagine, if you will, that the lowest SWR shifted from 7.125 MHz to 7.075 MHz.

You might guess that we could push the matter further if CW is of utmost importance. That would be wrong. While a subtle difference notice the reduction of 2:1 SWR bandwidth below resonance from ~105 kHz to ~85 kHz. The reason is that radiation resistance drops sharply near maximum gain, which for a 2-element yagi with a reflector is below resonance. Further lengthening of the driven element reduces the SWR bandwidth and increases the minimum SWR.

Out of some concern with the reliability of my proxy model I extended the halves of the driven element 1.5" (3.7 cm) a little less than the modelled 2" (5 cm). Once up the tower I measured the SWR with my analyzer and saw that the minimum SWR was 1.1 at 7.085 MHz and the SWR at 7.0 MHz was 2.0. With some relief I declared the mission accomplished.

Back in the shack the frequency of minimum SWR shifted upward to 7.1 MHz while the SWR at 7.0 MHz stayed at 2.0. This is not surprising since used 50 Ω coax is rarely 50 Ω, and such is the case for the 330' (100 m) of LDF5-50A tested and used to feed the XM240. The effect of impedance variation is more noticable at low SWR than at higher SWR. If you think about it for a few moments I think you'll see why.

Tram experience

The XM240 is the heaviest antenna I've trammed up a tower, coming in at ~75 lb, or 10 lb heavier than the stock antenna due to the W6NL designed mechanical improvements. It looks pretty nice in the picture I posted earlier. The reality was not quite so wonderful.

My lawn tractor was not entirely up to the task of tensioning the tram line with the heavier antenna. Some sag is normal on the line even with high tension since the weight of the antenna is concentrated at a single point by the pulley. The lack of adequate tension became noticable as the antenna approached the tower.

Sag at the upper end of the tram line meant that the angle of the antenna's motion gradually shifted towards the vertical. My friends on the haul rope experienced this as an increased effort to move the antenna due to loss of mechanical advantage.

That was a minor problem compared to the changed orientation of the yagi. With the haul rope angle becoming increasingly vertical the element tips rotated upward. That made my job on the tower more difficult as I struggled to rotate the boom so that the mast clamps could be installed.

Next time I'll consider using a fixed anchor for the tram line and a winch so that tension will not be limited by the small tractor's traction and weight. I nixed the offer from one of my friends to use his car since the valuable vehicle is at risk of body damage should the antenna swing just a small amount as it lifts off the ground. The elements of a 40 meter yagi are long!

LCA performance update

Soon after acquiring the antenna I began looking into the performance of the element loading coils. There was a story going around that the coil Q was ridiculously low, coming in at under 100. If true the loss would be excessive. I wondered if it would be worthwhile to replace the Cushcraft LCA (4 of them) with a high Q home brew replacement.

Based on my own inspection of the coils I determined that the low Q assessment could not be true. This is because the fibreglass form is hollow not solid as assumed in the one ham's calculation. I estimated the Q to be closer to 200, and therefore with a loss less than -1 db. Earlier this year I received an email from Bernard F6BKD describing his measurement of the LCA with an HP Q meter and got a value of ~200. Now I have the data to believe the coil loss is no worse than in my model.

This is still not ideal. I can live with it until I replace the XM240 with a higher performance yagi (or two) for 40 meters or upgrade it to a W6NL Moxon, thus eliminating the LCA entirely. For now it continues with its stock electrical design. However I did was wrap the coil anchor screws with cable ties since the self-tapping screws are reported to loosen over the years.

Isolated reflector element is still isolated

Both elements of the XM240 are electrically isolated from the boom. Many owners of the XM240 short the reflector element to the boom claiming that it reduces noise -- by draining static buildup on the element -- and adds to the top loading when shunt feeding the tower on 160 meters.

I didn't do this because, quite frankly, I forgot. I have since had instances of static QRN on 40 meters with the XM240 and not on the inverted vee during rain and snow showers. This may indicate that I should have shorted the reflector. The matter is more complicated than that and there are other possible explanations for the observed static. Next time the antenna comes down I'll rectify the problem, just in case.

The future

I haven't yet said how the antenna performs at its new height of 47 meters above ground. That will come in a later article on how all the antennas play. For now I'll only say that it does very well.

Over the winter I will rethink my long term plans for 40 meter high performance antennas. Due to the mechanical challenge I am not yet ready to tackle a full size 3-element yagi on 40 meters. The tower and rotator are up to challenge so it is not out of the question that I'll follow that route. What I can say is that I remain unsatisfied with the performance of 2-element yagis since the gain, F/B and SWR bandwidths are narrow.

The W6NL Moxon conversion of the XM240, or the alternative built from scratch solves the F/B and SWR problems but not the gain. That will require another element. Despite this I remain impressed at what Dave Leeson has accomplished with the XM240 conversion and the performance objectives he met in the design. Many hams have done the conversion and are very pleased with the result

There will be more to report on this subject in the coming months. In the meantime there are many other antenna projects of higher priority. I am well set on 40 meters for the next months with the XM240 as it is and complemented with the inverted vee lower down the tower.

Friday, December 22, 2017

Winter Closes In

Antennas and feed lines on the 150' tower were finished just in time. Since then the weather has turned very cold and snowy. Several winter projects have had to be delayed, and some are likely to be cancelled. Temperatures have plummetted far below normal for even this climate, with frost penetrating the ground sooner than expected. The weather forecast shows no relief until at least the beginning of January. Work in this weather is uncomfortable and unsafe.

One important job that I had to put off was to rent a trench digging machine. It is now very likely that feed lines and cables to the big tower and in other areas will have to stay above ground until spring. The machine does not handle snow very well and there is a potential for mishaps due to freezing in the top level of soil.

This is not so bad were it not for the deer. I worry that they'll step on the Heliax. So far the few I've seen have stayed on the other side of the tower. I am fortunate that they haven't tangled their hooves in the 160 meter antenna radials.

Winter antenna projects

80 meter array base
I have begun work on the 80 meter vertical array. Now progress is stalled due to the weather. Working fast when the temperature happened to rise above freezing I planted the base for the driven element (tower) and the three screw-in guy anchors. When (if) the weather moderates I'll get back to work on it. My minimum objective this winter is to have it working as a simple omni-directional vertical.

The array has been redesigned from what I originally intended for a variety of practical reasons. Once the model has stabilized I'll write an article on it, following by another on the actual construction. Indications are that I can achieve improved performance, and better assess how it compares against the more commonly-used 4-square array.

Additional Beverage antennas for the low bands have been roughly surveyed. There are numerous practical considerations on their placement, topology and switching which I am gradually working through, along with research on how others have addressed similar issues. I hope to make progress on all of these over the winter, though that is difficult to plan at this point. Weather determines the pace of outwork work for the next few months.

Moving indoors

There are many projects I have planned and can do indoors over the winter. Building a competitive station is more than towers and antennas. Here are a few I have on my plan.
  • Fully integrate the FTdx5000 with the PC. With the ancient laptop gone I expect few difficulties connecting the SCU17 interface to get audio, spectrum and CAT from a single USB connection. With this in hand there is more I can do with contest software and to experiment with digital modes.
  • Arduino kit to prototype station control hardware and software. My first project will be a direction indicator for the prop pitch rotator, followed by much more. Some of this will be purely experimental, with only the most useful devices promoted to actual equipment. I want more automation and software control in my contest station. The choice of prototyping technology does not dictate that the final version will be Arduino.
  • SO2R and multi-op contesting requires a variety of audio, switching and rig control systems. Most I do not yet have. Winter is an excellent time to review options and experiment.
  • Ergonomics at my operating position leave much to be desired. I am experimenting with different arrangements of rigs, computer, chair, desk and accessories to make operating more pleasurable and contests more endurable.
Articles on these will follow as and when they significantly progress. I also intend to experiment with other things such as digital modes, if only to play around and see what others are getting excited about. Although I don't expect to become a digital modes enthusiast the technology intrigues me. Perhaps this is because I have experience developing DSP software and coming up with tactics for dealing with poor SNR.

Garage workshop
LR20 jig and some of the stored cable

With more of my store of tower, cable and related hardware installed out in the field there is more room in my garage workshop. Amazingly I still have well over 1,000' of Heliax and perhaps 200' of large diameter aluminum tubing and pipe in there!

The unheated garage is not terribly comfortable for winter work. The thermometer on the back wall reads -10° C, and it's only 2° colder outside. On the other hand there's no wind chill. Despite the conditions in there I am arranging the space to permit a few construction projects to proceed over the winter.

One example is a section of LR20 tower that I picked up this fall. It will serve as a jig for construction of side mount hardware and other attachments for the 150' tower. This is far more convenient and safer than working on the actual tower. Unlike self-supporting tapered towers every LR20 section is essentially identical.

Immediate concerns

Ever since I moved in I have been tracking down noise sources to ensure the best possible receive conditions. The problem is not acute for the present but could be once I return to QRO operating and have to deal with many more weak replies during contests.

Despite being far from neighbours I am not free from noise. Some of it comes from within my own house. One persistent problem is noise from the many computers, interconnect cables and unshielded Cat5e cable to the terrestrial wireless antenna that is my sole source of internet access. The noise is greatly reduced for the antennas on the big tower since they're farther from the house.

Then there's this:


Depending on the weather power line noise in the southwest direction can be S9 on the high bands through 6 meters. The noise blanker can mostly deal with it though not without distortion when signals are present, and inter-modulation under contest conditions. There are a couple of power line noise sources in a couple of other directions that are not problems since they appear to be quite far away.

The local utility has come by to discuss the issue and plans to return in January to track it down. They have been very responsive and appear interested in getting it fixed. As is often the case it can be difficult to resolve since the noise appearance is not sufficiently predictable and the utility works to a schedule. If all else fails I'll rig up a portable sniffer so that I can help locate the source. It helps being in a sparsely populated rural area where the number of potential sources is small.

Aside from noise I am beginning to fret about what antennas to put up next year. This will require careful planning before I can begin design and construction. My ongoing experience with the antennas I have is proving very helpful to determining where the need is greatest. I plan an article to report on how the current complement of antennas is playing.

2018 planning

Come January I will make an attempt to finalize my station construction plans for 2018. Many yagis are certain to be in my construction plan, and one more big tower is possible. I'll try to be more realistic in my objectives than I was for 2017. It's the dependencies on weather and assistance that most imperil any plans I can come up with since those are often outside my control.

Expect an article later in January as I do my traditional of the year that was and look forward to the coming year. In this climate winter serves as a bookend to both seasons.

Enjoy the holidays wherever you are. From today onward the days get longer in the northern hemisphere so spring can't be too far off. As time permits expect at least one more article before year end.

Saturday, December 16, 2017

Concise Reviews of Parts and Accessories I've Used

With all the construction work I've done on my station this year I have gained some wanted, and unwanted experience with a variety of products. Rather than keep it all to myself I will give a concise review of several of these. Almost all are brand specific, with a couple of exceptions.

Since my experience with these and competing products is limited don't solely rely on what I have to say. Look around and you'll find other, perhaps better products and other opinions. Be sure that the reviews you listen to are informed by actual use, preferably over the long term.

Cable ties

Let's get one stinker out of the way. Over the years cable tie quality has improved quite a lot, especially those most common in the retail market. Countless cable ties litter my antenna farm to hold thousands of feet of all types of cable, near the ground and on the tower. Many work well, but there are exceptions.

One to avoid
Strolling down the electrical aisle of a well known big box store I noticed the rack of cable ties. Since I go through so many I grabbed a couple of packages of an unfamiliar brand, though reasonably confident by the description and the store's generally favourable reputation. It didn't work out.

Out of a package of 100 I used 80 of them on a recent climb to attach cables to my big tower. The failure rate was ~20%. Yes, really. The ones that survived installation are still there (I hope) and will require periodic inspection to determine whether they must be replaced. Here are the ways they failed on a cloudy day with a temperature of -1° C:
  • Break at a right angle bend around steel tower legs. Other brands never did this under the moderate tension applied while tightening the cable tie.
  • Torn strap during handling or when pulling on the free end to tighten it.
  • Failed tooth in the ratchet box.
Despite one bad brand be careful not to dismiss unknown brands. I have had good success with black cable ties manufactured close to home or in Asia, and even house brands of reputable stores. Since this is a new station the cable ties have at most survived one full cycle of seasons. I am not yet confident enough to recommend a specific product. But as you can see there is one I can warn against.

DX Engineering U-clamps

Earlier this fall I ordered a variety of DXE saddle clamps and Cycle 24 galvanized muffler-style clamps from DX Engineering. I used 3" saddle clamps (both 5/16" and ⅜" bolts sizes) in the modified boom-to-mast clamps for the TH6 and XM240 to attach to the 2.875" mast turned by the prop pitch motor. The Cycle 24 clamps I've used everywhere from boom trusses to mast steps and as mechanical aids for tram lines anchors and to hang pulleys for heavy lifts.


Aside from one incidence of user error (that's me) that galled one of the stainless steel u-bolts I am very satisfied with both products. They're easy to use, quality appears excellent and they have excellent holding strength in comparison to common galvanized muffler clamps. The winds have been blowing hard on top of the big tower, the temperatures have plummetted and neither yagi has budged.

The only complaint I have is that the stainless flat washers that come with the saddle clamps are thin and weak. They distort easily, and especially if the clamp surface isn't perfectly flat. I had this occur on the TH6 boom splice and mast clamp where there is a narrow flat surface on the inner side. The difficulty was resolved by removing the flat washers. The lock washer now sits directly on the aluminum surface.

The Cycle 24 clamps that I used and reused several times have not distorted due to asymmetrical loads and the galvanizing remains intact. Bolt threads have withstood heavy leaning on the nuts with a big wrench. They're inexpensive and I keep a few in my toolbox for odd jobs.

Hamplus AS82N

Shown with weatherproofing incomplete
A 2x8 antenna switch walked up to me at a gathering of contesters and asked me to buy it. I did. Well, that's almost true except the walking and talking was done by the device's owner. Hamplus has a good reputation and the price was right so I bought it, thus advancing one part of my station automation plans for SO2R and multi-op.

It's designed for outdoor and indoor use. I wanted it outdoors so that's where it went. With a few lengths of pressure treated lumber and a handful of hardware I affixed it to the side of the Trylon tower under a simple weather cover. It is now working just fine along with the manual control unit I built for it. Putting it outdoors reduces the mess of coax coming into the house, yet is readily accessible for maintenance.

So far it is working well. It has one flaw that prevents selection of one of the antennas from one of the two sides. I don't know if the short of adjacent lines from the connector is that way from the factory or due to abuse. Unfortunately the fault is on the underside of the board which can only be accessed by removing a multitude of almost inaccessible fasteners securing the 10 SO239 jacks to the chassis. This is very annoying. I haven't made the attempt as yet and perhaps I never will. So for now it's a 1x8 + 1x7 switch.

Also annoying is the skimpy and inadequate documentation at their web site. There one can find the pin out for the DE25 connectors but not how the switching is to be accomplished. That is, to select an antenna is the pin grounded or powered? Of course if you use their controllers you don't have to know, but that is not what many contesters do, opting for custom hardware or software control. A conversation with the seller (who also didn't use a Hamplus controller) eventually resolved the issue: ground the pin to select that antenna.

Nice switch, unpardonably poor documentation. Worse, the AS82N isn't documented at all so I had to rely on a similar product and compare that with what I found under the hood.

Splicing tape

The more expensive your cable and equipment the more important it is to protect them against the elements. Don't skimp! This is not the place to save a few dollars when it comes to protecting low loss, expensive coax and outdoor electronics for switching and control. Do it right. Cheap vinyl tape has its place in the great outdoors but not to seal a connection that must not leak or allow incursion of damp air (condensation and corrosion).

I have nothing unique to offer in this regard since many have already said it. Yet too many hams don't listen. You decide.

Left to right: inexpensive Scotch; no-name self-vulcanizing; Temflex rubber splicing; good Scotch outer layer
Use a sealing tape around every joint, whether fixed (e.g. coax entry at back of connector) or movable (e.g. male coax connector head). Don't rely, for example, on the rubber gaskets found in N and Heliax connectors to protect you. Assume that every inadequately protected joint will fill with water, moist air or pollutants. Over months and years it will certainly happen.

In larger gaps I use an underlayer of Coax-Seal (not shown). I protected the back of every Heliax connector with this additional layer. I avoid Coax-Seal on the connector ends since it can become gooey and difficult to remove when disassembled years later.

Temflex rubber tape (third from left) can be difficult to wrap but appears to work well. I bought this roll from DX Engineering but it or similar products are available where electrical supplies are sold. It sticks together by self-adhesive rather than an adhesive coating. I have a similar product from another major brand that I have not yet used and so cannot yet compare to Temflex.

The self-vulcanizing tape (second from left) is thin and stretchable, and is easier to handle than the Temflex. I have yet to have a seal fail with this type of tape. Be careful not to overstretch or tear it. I've used both this and the Temflex in freezing temperatures without problems.

On the left is a good quality name brand inexpensive vinyl tape. If you do use it try to avoid using this or (often lower quality) no name or house brand tapes as the outer layer. Few can withstand years of exposure. The worst have such poor adhesive or flexibility that it will soon unwrap on its own. The Scotch 33+ or Scotch 88 makes an excellent outer layer.

The better tapes are available in wider widths from commercial suppliers. This makes wrapping and protection much easier. Old Heliax connectors I've scrounged that are covered with wide tape are clean and dry after years of exposure.

Rotator grease

When I refurbished a heavily corroded Hy-Gain Tailtwister rotator (T2X) last year I switched to synthetic grease. Unlike any petroleum based grease I've used the rotator turns as easily at -20° C as it does at +20° C. I'm sold. We'll have to see how it performs over longer periods.

I have no particular brand or type to recommend. Look around in any auto parts store and you'll find many varieties. Although synthetic grease can be expensive you don't need a lot and it comes in small packages.

Heliax connectors

When it comes to expensive Heliax connectors sometimes beggars can't be choosers. If you do have a choice I recommend the modern single-piece connectors over the two-piece connectors. Below you see a selection of both types.


On the left are used two-piece connectors for LDF5 and LDF4. Particularly annoying are the centre pins of the LDF4 two-piece connectors which are soldered onto the solid centre conductor. It's difficult, hot and messy work that is also hard on the foam dielectric. I've done many of these years past and I hated every moment. LDF5 two-piece connectors are much easier to put on since the centre conductor screws into the hollow centre conductor.

One-piece connectors are much easier once you get the hang of the technique. New ones come pre-greased and the best require you to simply trim the jacket, cut the outer conductor and foam at a right angle on a corrugation ridge and cut the centre conductor to a precise length. That done the connector slips straight on and you tighten with two wrenches. It's the same procedure on all the connectors shown: LDF4 N-male, LDF5 DIN-female and LDF7 DIN-female.

Windows 10

Avoid if at all possible. If you cannot avoid it on your shack PC you will soon curse the jackasses in Redmond. Here are some of problems you should expect to deal with:
  • Peppering you with advertising and installation of unwanted software applications.
  • Automatic restarts (surprise!) in the middle of a contest (or rag chew) to apply urgent (?) updates.
  • Gives software update downloads highest priority, making your other uses of the internet (e.g. spots and RBN) slow to a crawl.
  • Occasionally replace proper device drivers with the wrong ones after updates.
  • Shuffle the COM port numbers after some major updates.
  • Intrusive windows that pop up and demand your attention and action when you're running Europe at 5 QSOs per minute.
There are cures available for most or possibly all the problems, but what a hassle. I think I've got my new shack PC suitably configured, for now at least. For example, while I was typing this article I heard a click and turned around to notice that the shack PC had shut down all my applications (including my logging program and Telnet connection to monitor 160 meter activity), started applying updates (of unknown type) and then did a restart.

I think I now have that problem solved. At least I hope so.

Unless you are willing to do go through some aggravation to research and apply fixes, including some that are quite arcane, I recommend sticking with Windows 7. Apple and Linux are not viable alternatives for many of us since most ham software is Windows only.

Tuesday, December 12, 2017

Topping the 150' Tower

At long last the big tower project is substantially complete. By "substantially" I mean that a few small tasks remain although all the antennas are in use and rotating as they should. This project has taken quite a bit longer than I anticipated or planned for so not everything planned has been accomplished. Even so I am pleased (and relieved) to have achieved this milestone.

In an earlier article I described getting to the point of having the tower complete. Now I'll talk about the process to make it operational; that is, with working antennas. One disappointment is that I was unable to light up the top yagis in time for the CQ WW CW contest.

Time pressure

As the saying goes: time waits for no man. Back in August I was feeling pressured by the approaching winter when major tower and antenna work is out of the question. Even with this foreknowledge I failed to do all that I wanted.

My primary constraint was people. A lot of manpower goes into this size of project. You can either hire people or rely on friends. As the ham population ages the ability to solicit help declines, and many who are enthusiastic and willing are not physically able to do so. Hiring professionals is no panacea since everything must be prepared in advance and any mistakes or gaps will result in substantial additional costs.

Ultimately I ended up relying on myself and on friends. You can never have too many friends! Cherish them and return the favour of their assistance.

Antenna complement

With the calendar inexorably advancing I shelved plans for yagi construction and went with what I had on hand. Those yagis and a couple of wire antennas to give me the required coverage for effective contesting and DXing are what I have for this winter season.
  • Cushcraft XM240 at 47 meters: I made a few changes to the antenna since it was on the Trylon tower earlier this year. I'll cover this in a separate article.
  • Hy-Gain TH6 at 44 meters: With no time to spare I put this ancient antenna up top for low angle, longer path DX on the high bands. The antenna was refurbished, including trap repair, new trap covers and replacement of the Hy-Gain balun with one from Balun Designs.
  • Hy-Gain Explorer 14 at 34 meters: The antenna is fixed on Europe. It works well enough for a short boom tri-band yagi, though it is not what I had in mind. Next year it will be replaced by a more suitable set of yagis for the important European path.
  • Fan inverted vee for 40 and 80 meters with apex at 32 meters: The 80 meter vertical array is a winter project and there was no time to build a wire or tubing yagi for 40 midway up the tower. This is my solution for the winter, after which I plan to remove it to make room for a more permanent high performance solution for 40 and 80 meters.
  • T-top vertical for 160 meters: The antenna is simple and surprisingly effective with only 8 radials. If I'd known how well it worked I would have planned a more serious effort in the ARRL 160 meter contest. Now I am looking forward more cheerfully to upcoming contests. This is a winter antenna that will be taken down in the spring. I don't yet know if I'll put it up again next autumn.

XM240 in flight, with integrated boom truss I've been so busy and the bands less than stellar that I have not yet had opportunity to thoroughly test the antennas, especially on bands where I now have two or three choices. There are some expected behaviours and some that were unexpected. This is a subject for a future article.

The prop pitch motor is working well so far. I attached the direction indicator potentiometer on my final tower climb and it will be wired up to the shack controller shortly.

Tram line, again

Raising the TH6 and XM240 with a tram line was similar to how the Explorer 14 was raised. The important differences were the greater weights of the yagis, larger size and top attachment to the mast rather than the tower. These all require changes to the procedure.

First, the ground anchor must be moved further out from the tower so that the tram line angle is similar or even lower to maintain or improve, respectively, the mechanical advantage. I had 300' feet of steel cable on the reel and I used it all. I was close enough to a small forest area that I considered using a tree for an anchor rather than my lawn tractor. That would have required a winch to set the tension, which in the time available was an undesirable complication. As it was we were challenged by the autumn dampness which reduced the tractor's traction in the hay field. It needed manual assistance to set the tram line tension.

Hauling yagis up the tram line
Rigging the antennas for balance and centering required more care due to the greater sizes of the yagis. This was the most time consuming part of the procedure. The XM240 has the added complication of attaching the fragile capacity hats after the antenna is off the ground. Since the yagis were substantially heavier there were two people on the haul rope.

The XM240 was lifted low on the mast and raised afterwards to the top. There is a substantial bending moment on the mast which would require a back stay to make the tram line mechanically sound. I chose to keep it simple and not use a back stay. Once the XM240 was on the mast and tested with an antenna analyzer I climbed the mast to install a pulley at the top and thread another rope through it.

When my crew returned the following week I tied the haul rope to the mast rope and with their muscle I lifted the yagi to the top of the mast. In comparison lifting the TH6 immediately afterwards was straight forward.

Fixing problems

As you might expect not everything went according to plan. One of the stainless steel saddle clamps was damaged while fighting the TH6 into horizontal orientation. The threads were greased and (although I know better) I compensated for incorrect position with extra torque on the wrench. The threads galled. A few days later I went up with another clamp and a tap to either replace or repair the u-bolt threads. I was able to save the clamp quite easily by chasing the threads.

The TH6 boom truss turnbuckles were threaded a few turns and taped to the boom. A turnbuckle and one of its screws unwound itself and fell off. They somehow survived the 150' fall without any visible damage and with the threads intact. After cleaning the boom truss was completed a few days later. The less on to secure turnbuckles and their screws better for the lift.

After the yagis were up for about a week I went up to do some work and got a surprise. One of the shims between the lower and upper masts worked itself loose, moving upward and falling to the bearing plate.

I put it back and found that it fit loosely. The next time up the tower I brought along a muffler clamp to hold down the shims so this wouldn't recur. This is a good reminder that the lateral force on the mast due to wind on the yagis is substantial. I was not surprised that the shims would gradually deform under the force to match the mast curvature, but the way that shim got pushed out of the splice was a surprise. Perhaps next year I'll revisit the shims.

Lifting coax and cable

Coax and wire cables are surprisingly heavy when measuring 130' (40 m). They are not so heavy that lifting is difficult, the concern is that the cable will be damaged when hanging by its own weight. Even LMR400 must be treated with care. LDF5-50A Heliax (⅞") requires special measures.

I cleared one of the tower faces of obstacles to clear the way for the lift and ensure the Heliax would not encounter any sharp bends. Due to the position of the side mount brackets and the need to avoid the climbing face this left exactly one choice. Unfortunately that side held the large drive unit for the prop pitch motor at the 140' level.

I mounted the pulley immediately below the drive unit. The Heliax would pass through one strut and terminate just below the top of the tower's north side, and there attach to the rotation loops. To accomplish this Heliax was lifted from a point 10' to 12 ' below the top. The rope is taped at intervals above that to protect the cable from interference and damage. The N-connector is covered with a cap designed for this purpose.

Andrew sells cable hoists that wrap around the Heliax and distribute the load equally around the circumference over several inches of cable length. I don't have one. Rope can be used to achieve the same requirement with a coil of many turns, wrapping the end so that the rope can't unwind and ensuring that all knots and bends are on the outside of the coil. After each lift I inspected the cable to ensure there was no damage, not even scuff marks or scrapes on the jacket.

The cable threads between the Explorer 14 boom and tower. This was accomplished without duress. When the cable approached the pulley I climbed the tower. There I removed the tape wraps one at a time from the top as my helper on the ground lifted the cable in short steps. Once in position I spliced it to rotation loops and worked my way down the tower securing the cable at every tower diagonal. If you use the Andrew mounts (expensive) you can get away with intervals up to 5' or 6' depending on wind and ice loading.

For major installations such as this I strongly recommend mechanical and electrical tests of every section of feed line once the connectors are attached. At the very least use an antenna analyzer and a dummy load to check that the impedance or return loss is as it ought to be across the widest possible frequency range. Once it's installed and a problem is discovered it is very difficult to isolate and deal with. Don't take shortcuts. I also recommend using the best quality products to protect connectors and splices from the weather.

Cable on the ground

Temporary overground cable runs
Each run of feed line is in two sections: Heliax from the switch box near the house to the tower; LMR400 or Heliax up the tower to the antenna. I acquired numerous 100'+ lengths of LMR400 as reel ends from a local supplier at a discount for this purpose.

Since the side mount antennas (Explorer 14 to Europe and 40/80 inverted vee) are temporary I used the full lengths of LMR400 and coiled up the extra. I preferred this to cutting the cable to length to "future proof" to avoid the risk of waste when it is redeployed.

As I type this the cables cross the open hay field above ground. Digging a trench and burying them had to be deferred, on advice of the renter, because the trencher would cause clumping of the half-frozen soil, freeze when exposed and then not settle properly when the soil is pushed back in. I may yet get this done before Christmas once the weather rises above freezing. In the yard I expect to have an aerial run for the cable since burial would encounter too many obstacles.

Not yet tidied up
Switching

The 2x8 antenna switch is installed at the base of the Trylon (70' tower). This proved to be a convenient termination point for the many coax runs, including those on the Trylon itself. This unit has all the connectors on the bottom, making it easy to build a weather cover. The tower provides support for the housing and cable terminations. Heliax cables are terminated with jumpers to the switch box to avoid having to contort the Heliax and to make it easy to transition from N to UHF.

There are two runs of LMR400 to the shack, plus existing runs for non-contesting antennas. Managing cables this way is much easier than terminating everything indoors and grounds inactive antennas well away from the house. I believe this is a good trade off with having to install and maintain switching boxes outdoors. It will only grow more complex as I add more antennas to my antenna farm.

I'll have more to say about switching in a future article. It can get complicated.

Finishing and clean up

As I descended the tower the final time after installing the last Heliax run and attaching the direction indicator for the prop pitch motor I stripped off the tower what was left of the rigging. This was little more than a pulley and the 100 meter long haul rope.

Short path to east Asia on 40 through 10 meters
While I finished attaching the Heliax to the tower my helper coiled the rope and cleaned up the area around the tower. We left everything tidy. All the cables were given one final test, final splices sealed and all tools and material carted off and stored. I even swept the garage clean.

With that and some on air testing of the antennas the tower project was declared complete. Of course there will be much more to come next year, but this is nevertheless a major milestone. I am very happy with how far I've come and the obstacles overcome.

Aftermath

Winter projects have already begun. The base is in for the 80 meter vertical array and the new PC is configured for contests. Yet there is much more in my plan.

How far I go this winter will depend on the weather and my inclination. Some rest and relaxation is planned, or at least turning to non-ham projects and activities long put off.

I committed to give a February talk to local contesters and DXers on the subject of building my new station. That should be fun.

Right now the snow if falling and the north wind blowing. This is a good time to switch on the radio to use and enjoy what I've built. That's what this is all about.