Tuesday, July 18, 2017

Tower Prep -- Almost (but not quite) Vertical

The big tower is still not up even though there has been a lot of activity. Consider this list of tasks I have been up to recently and you'll see why:
  • Repairing tower sections
  • Cleaning, scraping and repainting tower sections
  • Making the first set of lower guys
  • Gin pole design, construction and testing
  • Acquisition or refurbishment of a multitude of hardware: splice bolts; thimbles; turnbuckles; shackles; tower guy yokes; etc.
  • Transportation of tower sections to the site
There are also the environmental challenges such as a continuing very wet year, delay in my neighbour harvesting the hay crop and ticks. Of course tower work has to fit around the other items that fill my days. It is all taking longer than I'd like. Big stations involve big work.

Consider this a progress report. You'll get an idea of what's involved in working with big towers if you've never done this before. Most hams never do, and for good reason! None of this is a surprise to me and went into my plans from the start.

Bending jig

Used tower will usually have flaws. Commercial tower when taken down is often not treated with tender loving care since its resale value is rarely more than as scrap metal. Ham towers may be mistreated or carelessly handled. Expect to do some repairs.

In my case several sections had bent metal at the splices and a number of dented diagonals and girts. All were reparable without too much trouble. A few questionable damage areas were discussed with an engineer who knows this tower very well.

For example, several of the sections had old welds at the splices where they were tack welded for continuity assurance in an AM broadcast antenna. I removed those with a hand grinder so that the sections would smoothly slide together.

Simple bends were repaired with a block of wood and a small sledgehammer or with a pair of large adjustable wrenches. For the few cases where these were not effective I constructed a bending jig to hold the tower section while I applied some extreme force with improvised tools and snipes.

The jig is quite simple as can be seen above. Two short 1' screw anchors hold the ends of a heavy chain that is adjusted to fit snugly over a tower section adjacent to where the damage is located. This allows a force far greater than the section weight (120 lb) to be applied to the area to be bent with a long pipe acting as a snipe. When some of the force is axial to the tower I pressed lengths of rebar into the ground to prevent the section from sliding.

The jig also serves to hold the section in place while another is slid into the splice area. I did this to confirm proper alignment of the sections and holes for the splice bolts. Doing this on the grass helped since I was working alone and the heavy sections could be dragged into position.

Cleaning and painting

When I had 7 good sections (base section included) to reach the second guy station at 70' I set up an assembly line to clean and paint them.

This is a tedious process although not difficult. I stood them on the ground where the sun would be blocked from mid-afternoon onward -- never paint in direct sunlight. With a hose I washed off the dirt and debris that collected from years of outdoor storage. Stubborn stains were scrubbed off.

I then removed loose paint and rust spots with a set of steel wire brushes. There was little rush despite the tower's age. The sections are hot-dip galvanized and then had the standard aircraft red and white paint baked on at the factory. But they're old and needed to be refreshed. Frankly I could have skipped all of this since the tower will certainly outlive me. I expect the tower will be demolished if it's still standing when I move on.

Unfortunately galvanizing requires a special primer before the metal rust protective paint can be applied. I used the primer to cover the bare spots and then painted over the damaged and primed areas with the finish coat. To avoid an overly odd appearance I painted the exterior of all sections. Now all the sections are white except for two sections that were never painted (bare galvanized steel). I was free to use any colour since at 150' the tower is too short to require aircraft hazard colour banding.

Transportation

From the house yard the travel distance to the tower site is ~150 meters (500'). I cannot carry these sections on my own at all and it is very arduous for two strong men. Since I had no intention of conning a friend (or friends) into doing this I had to devise something to allow me to transport the tower sections on my own without undue effort.

Indeed I prepared for this two years ago. After I transported the sections to my home in Ottawa and paid several teenagers to load and unload them and stack them in the back of my yard I knew that I'd need a wheeled device if I was to be able to move them on my own. So I designed and built a very simple device with a couple of scrap lawnmower wheels, a short length of 2x4 lumber a threaded rod and a few fasteners. Simple it is but it works and has been heavily employed recently.


The device can be seen in this photo taken after the 7 repaired and painted sections were moved to the tower site. It is still attached to the second section from the left. Two bolts secure the lumber platform to the splice bolt holes in the section. The 120 lb sections are moved rickshaw style but with the driver facing backward to avoid being poked by the unforgiving tower legs. Attaching and detaching the device takes no more than a minute and usually can be bolted and unbolted with fingers alone.

Although the wheels are small it has had no trouble dealing with the countless rocks, holes and vegetation along the route and more than a few tight turns. The design isn't perfect and I've had to occasionally adjust the wheel nuts and threaded rods when one of the wheels locked up. If I'd built two of them transport would have been easier though at the expense of doubling attachment and detachment time and more cumbersome towing and steering. Feet are nimbler than wheels.

Where it fell short was with the base section. The device can only attach to the top of the section so the other end, the heavy end, had to be carried. That was fine while working with it in the yard but not for the long route out to the site. Although it looks smaller the base section is heavier than the others. So I improvised.


I admit it looks ridiculous yet it worked. The heavy base plate fit nicely inside the front end of the wheelbarrow frame without interfering with the wheel. Since the plate is rectangular and not suitably oriented with any of the section legs it has a habit of trying to twist the section and whatever (or whoever) is holding it. This includes the wheelbarrow, as you can see.

A little bit of muscle is needed to keep the wheelbarrow level during the tow out to the site. What I couldn't do was make turns of small radius. In several places I had to turn the section by hand and then remount it on the wheelbarrow. Despite these inconveniences the trip was done in less than 10 minutes. You can see that I used the system to carry scrap lumber and other material out to the tower site.

But wait, there's more!

The 7 completed sections are less than half the total of 15 sections I am raising. There are 8 more of them to be cleaned and painted.

When I took the adjacent picture the metal was repaired and I had done a first pass with a wire brush. There is more scraping and painting ahead of me even while I go about the task of getting the first set of sections up in the air.

Coming up

All going well tower raising will begin shortly. I will follow up with articles on my gin pole design, guy design, temporary support for the lower sections (until the first guy station is reached) and other topics that may be of interest.

In the meantime I have other station work to perform on the Trylon tower. My T2X rotator is acting up again, coax will be upgraded and I need to adjust the yagi positions to better accommodate rotation loops. I have even been doing a little bit of operating and contesting though nothing serious during the warm summer months.

I'll leave you for now with the following pretty picture. This is looking east from the house toward the field where the tower is going up in the aftermath of a storm that moved through as I was wrapping up this article. Imagine if you will a 150' tower rising from behind the trees in the centre of the picture and piercing the rainbow. It will easily rise that high.


Thursday, July 6, 2017

Computer Contest Logging in 1977

As this year's IARU Radiosport contest approaches my thoughts turn back to the very first one. It was in 1977, 40 years ago. As I recall how it came to be the ARRL had such great success with the one time running of the Bicentennial contest in July 1976 that they saw an appetite for a summertime international contest. They must have been right since it's still going strong.

Back in 1977 I was in university working on my B.Sc. in Computer Science and on the cusp of exiting my teen years. I was an enthusiastic contester with a small home station and I was a member of club station VE4UM at the University of Manitoba. Since 1977 was the university's centennial we got a most unusual special call sign: VC9UM. At the time there was no 9th call district in Canada; it is now assigned to New Brunswick.

Dupe sheet from my 1970s files: contest unknown; the other side has US 6 to 0 and VE; one sheet per band
Every contester who predates K1EA's CT has painful memories of paper logging and dupe sheets. It was easily the worst aspect of contesting. There were a talented few who could simultaneously operate a keyer and write the log and use a dupe sheet. The rest of us cursed as the rate picked up and we scrambled to manually check the dupe sheet, fill it in (or chase away the caller) and log the QSO. Big gun multi-ops often had one person on the radio while another managed the log and dupe sheets. Unlike today dupes typically involved a penalty, and you didn't want that.

Imsai 8080: Not good enough, unfortunately (photo credit)
Personal computers at the time were wholly unsuited to the task of contest logging and dupe checking. Hams were experimenting with the simple home computers then available, such as the IMSAI 8080, using teletype machines as terminals and paper tape for storage. Soon enough the PC (including an updated IMSAI) would have the capability but in 1977 it was still a few short years in the future. The major impediments included:
  • No operating system: All I/O and other core tasks had to be manually coded.
  • No high level programming languages: It was all machine code or symbolic (assembly) machine language, or cross-compilers that ran on mainframes and minicomputers and downloaded to microcomputers.
  • No direct access to mass storage: Even floppy disks were not yet available, let alone anything larger. Programs were typically stored on and loaded from paper tape, either on the teletype terminal or the recently available electronic paper tape readers.
  • Insufficient RAM: Directly accessible semiconductor was typically no more than 4 KB. Try to fit a contest log and the logging software into that!
  • It cost money and we didn't have any. We were poor students barely scraping by.
Nevertheless computer logging was being done by a few. The early baby boomer contesters were by that time in their late 20s and working in industry. Many were engineers or an early generation of computer programmers and worked in large companies or other organizations with mainframes and minicomputers. An enterprising few were able to negotiate personal use of those machines over contest weekends.

This was no small accomplishment since those computers filled machine rooms and were expensive to power and required salaried operators to keep them running smoothly. It was typical for these computers to only be run during regular business hours except when dedicated to supporting clients with longer hours.

An idea is born

A friend and I talked it over. He -- Derrick VE4VV (SK) -- was also a fervent contester and a fellow student one year behind. We were too young and lacked influence to convince anyone with any power to grant us use of the university IBM S/370 mainframe or one of the several departmental PDP-11 minicomputers scattered across campus. I did try. The furthest I got was polite interest. The needs of graduate students and faculty would not be adjusted to suit my requirements.

From my personal library -- I enjoy hanging on to a few mementos
Since it was summer break I was working for a government agency as a systems and application programmer. I regularly used the a government owned S/370 and we had our own PDP-11/45 minicomputer. My attention focussed on that minicomputer. Like any machine that size it was turned off at the end of every workday. Could I get it left on for the weekend? That was my challenge. Software development was the least of my worries.

I shared my desire with my supervisor. Although he had no power to grant my request he became a strong ally. He was not a ham but had an interest in it. He also liked the idea of getting management to do something unconventional, to kick them out of their comfort zone so to speak. He talked it over with his boss. It took some persuasion to at least turn him neutral on the project. But it was his boss who would have to make the decision and he was a stereotypical senior government bureaucrat. He was not a mean person but one with a very narrow and well-defined comfort zone.

Of course he refused. Not only would it involve an expense for no sensible reason he could fathom it was a valuable government resource he was in effect turning over to a couple of teenagers. He saw it as risking unwelcome public exposure for him and his political masters should something go wrong. It was pointed out to him that I was in position every hour of every day to do anything at all with that computer, including access to confidential data and an ability to severely disrupt operations.

It took a few days when to my surprise and delight I received grudging approval. I never found out what was said to finally clinch the deal and at the time I didn't much care. What I did care about was that in fact we had no plan, no software and no idea how it was all supposed to happen in the few days we had until the contest started.

Putting a plan together

We had access to a minicomputer, but that was it. Every other problem was entirely up to us to deal with by dint of hard work. We needed remote access to the PDP-11/45 since downtown Winnipeg and the university are 10 km apart. The only possibility was 300 bps dial-up telephone modems of which we had two on the minicomputer for staff use.

Acoustic modems I've used (Columbia University)
If you've never heard of these contraptions they involved dialing the computer modem on a telephone then inserting the handset into the "ears" of the modem when you heard the carrier tone. If all went well the modem would detect the carrier and establish the data link. They were terribly unreliable and often dropped calls or failed to connect on the first attempt. At least we were only calling across town. Long distance calls and especially overseas calls often experienced phase shifting (it was almost all analogue transmission at the time) which was not tolerated well by the modems.

The terminal itself was a challenge. After exploring a couple of alternatives we borrowed a VT52 from my office and transported it to the club station. This wasn't easy since these "dumb" terminals were large, heavy and fragile. I didn't want to think what would happen to me if I dropped it or bumped into a wall as my friend raced ahead opening doors for me and guiding me around obstacles on the downtown streets towards his car.

VT52 from Wikipedia
It was remarkable that we got the terminal and communications link working at all. For the duration of the contest Derrick only experienced two line drops.

Software constraints and features

As already mentioned, when I got approval I had not yet written a single line of code. There was only a little over a week to develop a contest logging application from scratch. I didn't even have a clear idea of how to do it, what the user interface would look like and how I would deal with bugs and other disasters. All of this needed to be fleshed out, and quickly.

People are often surprised that many poets do not feel constrained by the need to fit their thoughts and emotions into a strict meter and rhyme template. Although a challenge it limits the range of possibilities to a solution space that is more tractable. My dilemma was much the same. I was limited by an interface that could paint no more than 30 characters per second on the screen, a couple of bulky hard disk drives and 32 KB of address space (the computer had 80 KB of magnetic core RAM, but each process was more limited by the system architecture). It simplified the problem by limiting me to what would fit these constraints.

The first thing to recall is that there was no such thing as computer control of rigs. Back then all transceivers were dumb. Neither were there integrated keyers. Well, that's not entirely true but very uncommon for contest software at the time since PCs were still terribly inadequate. There was no way a simple 300 bps ASCII connection to a dumb terminal in the shack was going to do anything like that. So the rig, keyer and microphone were manually operated.

All we were going to do was log and dupe. That's it. But that's a lot. If you're too young to remember those days it may not register just how difficult that was to do manually while operating, especially for a single op.

The software we decided would do the following, and nothing more:
  • Manually set the band and mode; Radiosport is a multi-mode contest.
  • Check for a dupe when a call is entered, and report log details for the earlier contact.
  • Enter an exchange and log the contact. The computer fills the time.
  • Check the band and mode, just in case.
  • Simple real time reports of contacts and zones logged.
  • Ability to back fill QSOs in case of temporary computer or communications outage.
  • Print log and dupe sheets and calculate score.
That's it. But as already said that's a lot.

The programming language was FORTRAN. Only that and assembly code were available. The DEC compiler for the RSX-11D operating system on the PDP-11/45 had libraries to support use of the data management services on the various storage devices. For our purpose these were two disk drives of 20 MB storage that were the size and weight of large washing machines. I forget the model number but they were roughly equivalent to the IBM 3330. Access time was not fast; that was a critical consideration if we were to achieve acceptable performance.

The VT52 has a graphics mode whereby the 24x80 character matrix could be directly manipulated. I eschewed that option since it added complexity and didn't seem to add much value for our limited feature set. I stuck with a scrolling text screen to keep it simple. It worked surprisingly well for the operator.

Development phase 1

With the clock running down I soon realized not all the planned features could be developed in time. Yet I was able to get the core functionality working within a few days, designing and coding in my spare time and, to be honest, during work hours. My supervisor knew what I was up to but chose to say nothing since my work assignments were progressing on schedule. More days were consumed in tweaking the software and data management to boost performance.

My design choices were greatly limited by the technology available to me. That a program could only be 32 KB, including code and dynamic data storage forced my hand. Think about the length of a call sign. Let's assume 16 bytes per log entry for a call sign, exchange data and time stamp. A log with 1,000 QSOs requires 16 KB, or half the address space. I had to support more than twice that number of QSOs and still have room for the program and the library routines that the compiler would include.

I investigate a variety of data compression algorithms. Unfortunately all involved substantial complexity. Then I discovered the program was consuming more space than I'd hoped for. I thus opted to put the log on the hard disk and optimize access with extensive hash tables and other techniques.

Happily it worked quite well during testing. Derrick came in one evening and I had him log random QSOs for a couple of hours to test the data base process. Afterward I analyzed the tables and adjusted the hash algorithm. Performance depended heavily on the QSOs being reasonably evenly distributed by a randomized hash key derived from the call sign.

For disasters in which the log data base was lost due to system or program failure I stored a plain text journal file on the second disk drive, writing to it after a QSO was logged. Although we never needed it there was comfort in knowing it was available. The journal file could only be used for post-contest log recovery since I had not yet developed code to recreate the log from the journal file.

User interface

The user interface was extremely simple, and surprisingly effective despite the simplicity. After connecting to the minicomputer the user signs in and executes the logging program. There was no setup to be done since only the one contest was supported. In case of a crash you run it again and carry on logging.

Whether running or S & P the UI was the same: enter a call sign and hit return. If it isn't a dupe nothing happens except for another prompt. You then enter the exchange, signal report optional. A dupe was flagged with log details and the sound of the terminal buzzer. It might look something like this (I forget the details so this is not precisely as it was). Plain text (not bold) is user input:
>=b20
>=c
>k3lr
>k3fr

>8
0334
>g3aa
>57927
0336
>f6abc
DUPE: *** F6ABC *** 1/2315 20 CW
>=s
>ve1xx
>9
0341
The first two commands (user input with the "=" prefix) set the band to 20 meters and mode to CW. Then a call sign is entered. The operator either made a mistake or didn't work the station and enters a new call sign. This action automatically erases the earlier entry.

The subsequent entry of an exchange (zone number) causes the call to be logged. Since no report was entered it defaults to 599 in the log. The time of the QSO is the only feedback given. Recall that we're working at 300 bps and brevity is important.

For the next call entered -- G3AA -- a signal report other than 599 is received. It is entered before the zone, just as it is sent by the the other station. The software parses the line to extract both items. The software assumes that 59 (or 599) is always sent so there is no way to log a different sent report.

The next call entered is a dupe. The log details are presented. The "1/" in front of the time indicates the day of the contest -- could be 1 or 2 since the first Radiosport was a 48 hour contest. The other data is parroted since the operator could have quite easily forgotten to change band or mode or typed the call incorrectly. Either way the operator proceeds to the next QSO. If it was a typo the correct call is entered followed by an exchange in the usual sequence.

Next, the operator changed mode to SSB and successfully logs an SSB contact.

The software did not fully validate call signs since the variety was too great and I didn't want to cause problems for the operator should the program improperly flag a valid call sign. Only simple errors such as a call beginning with a "0", no numeral present, trailing numeral and a few others were flagged. It was up to the operator to retype the call or ignore the warning and proceed to enter an exchange and log it. Although simple it worked well enough that we only found one badly formed call signed in the log after the contest.

There were a few other commands available. There was "=q" to report the number of QSOs in the log and "=z" to report the list of zones worked on the current band. Before entering an exchange a QSO time could be entered with something like "/20404" to override the computer clock and log the time as 0404Z on day 2 of the contest. This was needed in case of system outage so that manually written log entries could be put into the computer log during a break or after the contest.

I had a couple of debugging commands in there as well. These were of no use to the operator so I didn't even both to tell Derrick about them. If needed I could have walked him through their use over the phone.

The contest weekend

Late Friday afternoon Derrick drove over to my office to pick up me and the VT52. We had already acquired a modem from a helpful professor at the university -- it was summer and there was unused equipment available. I was given a key to the building front door and computer room by my boss. As the office closed for the weekend the operator shut down the computer per his procedures.

I restarted the minicomputer and ensured that it and the telephone ports were operational. I created a user account for Derrick to use. Then I shut the lights, locked the door and crossed my fingers. Off we went to the university to get him set up for the contest. I took a bus across town to my own home and station. Derrick was doing a single op, as was I from my own station. But I was on call in case disaster struck and I had to get downtown in a hurry to fix things. My attention was split between the contest and worrying that the phone would ring.

The phone never rang. That is, not until a few minutes after the contest ended. Derrick gave a enthusiastic report of the logging software. He couldn't stop laughing because it was the easiest and most relaxing contest he'd ever done. Apart from typing all he had to do was talk into the mic or press buttons on the memory keyer. Duping was a suddenly a relic of the past.

Since we were both tired from the contest we wrapped up and met the next day. In 1977 computer contest logging was a rarity. No one I personally knew had done it so I had no direct knowledge of how big a difference it would make. The difference was big, very big. We both realized right then that contesting would never be the same after the introduction of computers in the shack.

We got down to a serious post mortem discussion. Since he'd already practiced with it there was no learning curve to deal with during the contest. The limited feature set was itself a feature. He made a crib sheet with the commands written on it and found he didn't need it. We began talking of new features we could add.

A few problems did occur during the weekend though nothing too inconvenient. One was the expected line drops. Bell 103 modems with those bunny ears were not exceptionally reliable. We were lucky the problem only occurred twice. Each time he was able to redial and get back to business in a couple of minutes. He never had to resort to paper logging.

A bigger problem was that dupe checking became noticably slower with more than 1,000 QSOs in the log. Although the delay never got to be much more than 1 second in the heat of the contest it can seem an eternity. A few minutes of forensic analysis after the contest uncovered the problem. It had an easy solution. I counted myself lucky that nothing worse happened. The problem wouldn't have appeared if used at my small low power station since I made only 625 contacts in that first Radiosport (I actually found a copy of my old log).

The most delightful experience Derrick reported was the amazement from other hams, particularly when operating SSB, when he could not only tell stations they were dupes but the exact time of the QSO. Time and again they'd be suspicious and then astounded that the QSO was in their logs right where he said it was. Some even called back minutes later just to tell him he was right.

What they imagined was going on they likely never figured out and Derrick never told anyone on the air. Recall that this was 1977 and even technically savvy hams typically had zero experience and knowledge of computers. This was great fun!

Development phase 2

At the end of the contest we had a log and nothing more. I made backup tapes of the data base and software to protect our investment. Our next task was to print and score the log so that the VC9UM entry could be submitted. Those were features that I had deferred since they were not needed during the contest.

The log sheets were easy enough to format to look similar to the official ARRL/IARU log sheets. The one significant task was to parse the call signs in the log to determine the country and combine that with the zone (continent?) to calculate points for each QSO. At least that's the way I remember it. My memory of the scoring in that first Radiosport contest is hazy.

Dupe sheets were a problem. Of course there were no dupes since the software had already taken care of that. I went ahead and developed the features to score and print the log while Derrick made a few calls to the folks in Newington CT. There was an unanticipated difficulty.

Bureaucracy and the computer

The ARRL contest desk of 1977 refused to accept computer generated logs. They also demanded handwritten dupe sheets. This is despite the fact that the printed log sheets were nearly identical to the official sheets and there were no dupes. Both demands were nonsensical. Nevertheless they were unmoved by his protestations.

When it was pointed out to them that neither added any value, they would only point to the rules that declared entries must use the official log sheets (or copies of same) and that logs of over 200(?) QSOs must include dupe sheets. Flexibility was not in their vocabulary. That rigid compliance with the rules involved a substantial amount of work to manually transcribe the log and generate dupe sheets moved them not at all.

Derrick gave up the fight and spent a summer weekend doing what they demanded. It would be many years yet until the ARRL looked upon computer logs as helpful and even desirable. We were ahead of our time.

Aftermath

With a great success in our pockets we wanted to do it again. CQ WW was coming up in the fall and we set that as our goal. We had many ideas for improvements and new features that I was eager to build. This time it would be a multi-op effort so that I would not be left out of the fun.

It was not to be. Once I was back in school and no longer employed by the government the same senior bureaucrat was adamant that access to the PDP-11/45 was absolutely and categorically out of the question. My friends on the inside tried their best to no avail.

I made another play for the university department's PDP-11. It was even more impossible than before because the fall semester was in full swing. While there was still interest in what I was doing, and nothing sells better than proven success, they told me that, unfortunately, academic priorities would not and could not be set aside for even that one weekend.

That was the end of my foray into computer contest logging. I never did it again although I thought of it often.

Not long after that initial experiment I was working towards a post-graduate degree, and after that I moved across the country to start my professional career. PCs were by then very capable of contest logging and that's what many were doing. In my files I located notes from early 1980s of a far more sophisticated computer logging system. Those plans predated CT by a year. But I had no time for it and not even a station of my own to use it with.

When CT came out I was intrigued and thought of what might have been had I stayed with it. But by then my contesting activities were entering a lull as I put what little radio time I had into DXing and fooling around with antennas and modelling software. I did use CT a couple of times but that was for me and contest software for many years to come.

I missed a few generations of contest software and the computerization of radio equipment while I was absent from hobby between 1992 and 2013. When I made a serious return to contesting in 2014 I adopted N1MM Logger as my contest software from among the many excellent alternatives available. Three years on it remains my software of choice.

There is no reason at all for me to think about developing my own contesting software. I am more than happy to use the superb software that others have developed. I am content to be a user and put my energies into station building and operating.

Tuesday, July 4, 2017

The Price of Safety

I've been thinking lately about personal safety when it comes to hams and towers. It's come up on this blog from time to time. Too many hams are injured or killed pursuing the hobby we love. Many more come close to harm without really appreciating the precipice they were teetering on. They were just lucky someone else saw the danger and either warned them or did something about it.

When I say I've been thinking about safety I mean thinking about it more than I usually think about it. One reason is that I am about to put up a very tall tower. I've worked on big towers though never one of my own. This means I'll be at a great height more often than ever before. The other is that I recently did several tower jobs for others, involving both hams and non-hams who are not experienced with towers or tower safety.

How much is safety worth? Is it worth a friendship? This is not idle speculation. When you're up the tower and you see a friend step into the jaws of danger you have a choice to make: say something or don't say something. If the situation is urgent you may end up shouting words that are far from polite. Words that we never want to pass between friends.

When I was young I paid little attention to danger. Teenagers are immortal of course. Many times I climbed towers without any safety equipment to perform a routine maintenance task. Teenagers live in the moment where a one or two day delay to borrow even as little as a leather lineman's belt from a friend is too much. As I grew older I became more sensible as I hope most of us do.

When you've been on towers as much as I have over the decades you get to see far too many things that speak of mortal danger. I've been lucky not to have ever been seriously injured or had it happen to others I've worked with. Mostly that's due to good planning and a sensible crew. Other times it's just good luck. Face it, hams take stupid risks far too often.

When I was younger and most of the other hams were older I was reluctant to speak out when stupidity sprouted up around me. I am now far less likely to hold back. It is not a spontaneous eruption but rather a calculated urgent and forceful tone, a technique I learned from many years in corporate management. I want to incite an immediate response to mitigate a present danger.

What are these dangers? There are too many to list! Let me give a few examples:
  • Children allowed to play in the work area, including the tower base directly below me.
  • Refusal to wear a hard hat, or taking it off to be more comfortable.
  • Undoing a safety harness because it's "in the way".
  • Insisting on standing in exactly the wrong place when pulling on a rope and thus putting everyone at serious risk due to imminent mechanical breakage.
  • Acting with zero regard for the safety of the rest of the crew and risk to property.
  • Putting their hands or other body part where a sudden change in rope tension could result in severe injury.
  • Unsafe use of power equipment.
  • Chatting when they should be paying close attention.
  • Disappearing for a personal break without telling anyone.
  • Making mistakes out of no fault of their own other than a lack of experience. This is a management fault, often with me being the guilty party.
  • Not asking for a break when they need one or they aren't strong enough to accomplish a task. We all have our limits.
  • When a mistake is made the person loudly casts blame elsewhere. Ill will is bad enough but more worrisome is that failure to own up is a signal that more and worse mistakes will follow.
It's the innocent errors that most concern me. The others can be managed by not inviting or uninviting those who are unwilling or incapable of learning and correcting behaviour. Sometimes it can be accomplished diplomatically by finding a suitable task that puts them out of danger to themselves and others. The person may take offense so be prepared.

It can't always be done diplomatically and the need to act may be urgent. That's when I raise my voice. That's the moment when a friendship can be put in jeopardy. Afterwards or sooner if possible I make a point of apologizing to those I shouted at. I go on to explain that I was compelled to do so because I was concerned for their immediate safety or that of others. Usually they understand and all ends well. But not always.

July is the midpoint of antenna season in these northern latitudes and therefore marks a good time to revisit safety. Pardon the preaching but this is a message that cannot be repeated often enough. Sacrifice a friendship if you must. It is better to have a living ex-friend than a dead friend.

I am not immune. There are times when I am the target of a warning or unexpectedly stern advice. I've learned not to take it personally. I listen and usually discover that the warning or advice is warranted. To err is human and I am human. Welcome the intervention of your friends. They care about you.  I swallow my pride and gracefully adapt to the situation. And I learn.

When it's done right everyone gets to go home with a smile on their face, happy with a tower job done well, and still be friends.

Sunday, June 25, 2017

Planting the LR20 150' Guyed Tower

As I write this the foundation work for the LR20 150' tower is complete. Really complete. It has been a long road, one that began in November. At the time I planned and expected to have the tower ready to be raised before Christmas. As I mentioned at the end of the article about planting the Trylon Titan tower we got socked with an early winter storm that forced many woes. Suffice to say the tower did not go up this past winter.

Yet we went ahead. It didn't work out well. In this article I'll let you in to the full story, warts and all. Aside from the many problems encountered, and overcome, much went right. Regardless it is a story worth telling. I haven't seen many articles on the internet that described the full procedure of planting a large guyed tower in amateur stations. Just small snapshots.

Yet it's a major project that can provide many lessons to those who want to do the same. I hope you enjoy it, and perhaps learn a few things. That includes the things you should not do.

Hiring out

A local tower construction and service company, Ontower. They are happy to offer their services and expertise to local hams who have turned to them for assistance. This has become common as the ham population ages and fewer are able to help out their friends as they have in the past. In any case it is only a minority of hams with big tower experience. I have put up high guyed towers but I do not consider myself an expert.

I got to know them over several months. They were free with their advice and sensitive to the needs of non-commercial projects. It also helped that they have the equipment and parts on hand to put up towers far bigger than my own. So we came to an understanding.

Act 1 - Clearing a path

The day before the big day the weather unexpectedly turned. The ground was covered in snow. They were unable to drive their truck and backhoe float across the hay fields to reach the tower site. The backhoe operator used its small blade to plow a 250 meter path to the tower base, and then to each of the anchors. Wherever there was a turn a clearing was made to allow for the large turning radius of the truck and trailer, and also for the arrival concrete truck.

Tower work in Canada, eh?

By the time all was done the fields were crisscrossed with paths made by the backhoe and by people walking from point to point. So far so good. It wasn't to remain that way. The day warmed and the snow began to melt.

Excavation

I surveyed and staked the field in advance. The crew of two brought a small backhoe. I could have hired a large backhoe but there is an advantage when the equipment operator and crew don't just have experience digging holes but digging holes for towers. Their backhoe had just enough reach to excavate the 6' depth of the anchor holes.

Other than exchanging a few ideas at key points they knew exactly what to look out for and what to do. There were no mysteries to be explained. Our only serious concern was whether we'd hit bedrock since their machine could not cope with that. My luck held and other than some large rocks the excavation for the base and three anchors proceeding without drama.

We did have contingencies in mind in the case we did hit bedrock. For the base it is possible to anchor the pier to the bedrock, at some trouble and expense. Or if the level was sufficiently below the frost line to modify the base to suit. For the anchors they and another expert I consulted suggested sitting the anchor on the bedrock and adding overburden on top and ahead of the anchor (building a mound) to compensate. An anchor's tension limit is not set by its depth but by the mass and solidity of the soil it is pushing up against when the guys are under load.

The excavations were greater than the specification for this size of LR20 tower since the anchors they supplied and the squares and hoops for the rebar cages were for a 350' tower. This requires more concrete, which is an acceptable trade off.

Rebar cages and concrete forms

While one person operated the backhoe the other built the rebar cages. I did the cutting and bending, leaning on my experience and tools from building the Trylon base.

They supplied the square wooden case for the base and round tube for the pillar. For the anchors we dispensed with cases; what they call "mud holes". The downside of the latter is that the holes are inevitably larger than required and require more concrete to fill. It's a trade off: more concrete or more time and expense to build and work with casing. It doesn't have to look pretty.

Left: anchor and rebar in mud hole; Centre: anchor cage almost ready to go; Right: forms and rebar for base

Notice that the anchor has two large buttressed vertical plates. When under tension the load is distributed over the reinforced concrete, preserving its rigidity. The reinforced base platform distributes the load over a wide area of undisturbed soil. Numerous J-rods bound with circular ties run the height of the pillar to preserve pier integrity under vertical load.

But are these reinforced concrete foundations up to spec? There is no clear answer to this question. Tower manufacturers have become increasingly coy on this point. No one prescription or set of options is sufficient for all soil conditions. And that's what counts. Commercial towers require soil tests and the services of an engineer to specify the foundations for the prevailing soil and environmental conditions, including seismic activity and ground water.

What I have done instead is to oversize and overbuild the base and anchor foundations. I also know that the soil in this area is very stable and the water table is deep. There is an extended period of saturation in heavy rains and spring thaw. The top soil is less than 2' (60 cm) deep, below which is a dense mix of clays and rock. It is so hard that shovels barely dent it, even when soaked in water.

Aligning the anchors

Overnight most of the snow melted, turning the fields into a muddy mess. Half a day was spent finishing the forms, setting the anchors, levelling everything and aligning the anchors to the base. The alignment was done by sight to ensure the anchor rods pointed directly at the base. An inclinometer was used to set the vertical angle of the rods according to the tower spec.

They recommended against using the anchor plate as an equalizer plate since it adds a potential point of failure. Instead the plates were welded square to the rods. With the vertical angle correctly set the pre-load tension on the guys will net to zero vertical force on the anchor rod.

Of course with maximum antenna wind load at the top of the tower there will be an upward force when the wind blows. However that is true whether or not the plate pivots. As they explained, with a round bar for the anchor this is well within the load spec for the material. Alternatives that some use, such as angle iron for the rods, overbuilding is required to maintain anchor integrity.

Concrete - Uh oh!

Early afternoon of the second day we were ready for concrete delivery. Or so we thought. The plan was to have the concrete trucks -- we needed two in sequence -- drive across the hay field and pour directly into each hole in turn. Two time-separated pours were planned for the base, a point which I'll return to later in the article.

Unfortunately by the time the first truck arrived the surface was softened by melting snow and stayed wet due to the heavy overcast. The driver was dubious but trusted the crew since the companies regularly worked together on tower sites. But the final decision was mine. Hoping for the best I gave the go ahead signal. That was a mistake. As I've said before, hope is a 4-letter word that it is best to avoid.


The truck didn't get far. No matter how many tires the load is spread over or how many axles are driven (they have this option) 60,000 lb needs a strong surface for support. I found myself in a difficult spot since I was responsible for getting the truck out of there.

Happily I was dealing with professionals. Ontower got a local construction firm to send out a front end loader. It had two tasks: quickly unload the concrete and pull the unloaded truck out of the mire. While we waited for it the concrete truck driver told me dark stories about the cost of freeing a stuck concrete truck or a ruined truck due to the concrete setting. I reciprocated with how stories of how technology would enable driverless trucks and put him out of a job.

A little laughter goes a long way when you are in a tight spot waiting for rescue to arrive. Every so often he'd interrupt the conversation to add water to the concrete to keep it from setting.

Eventually the front end loader arrived. I have to say I was very impressed at how well it all went from that point. That scoop you see holds a lot of concrete and had no problem going over 200 meters of muck to dump the concrete into the excavations. It took fewer than 20 trips to transfer over 7 cubic yards of concrete. An hour later the concrete truck was empty and towed back to the road. Two anchors were complete. But it was late in the day and we had already cancelled the second truck. The remainder of the concrete work would have to be rescheduled.

There was the unanticipated effect on the anchors of pouring tons of concrete from a height. Front end loaders are not gentle machines. The anchors shifted slightly and were no longer directly pointed at the base. The error was approximately 2°. None of us caught the mistake until it was too late. We discussed it the next day and decided that it would not be a serious problem. The anchor was oversize and round and the deflection would be modest when the guys were tensioned. I still worried about it, but nothing could be done. At least not yet.

Intermission - Winter doldrums & spring floods

We tried to reschedule the concrete work several times, included the depths of winter. The weather did not cooperate. Not only was this job delayed so was the concrete work for my garage. The early end to the season inconvenienced many in the construction trade.

Concrete work can be done in frigid weather if you are willing to pay up. After several weeks we decided it would be best to put the work off until the spring. Although a sensible decision there were a couple of factors not taken into account. First, the excavations and forms were stable when the ground was frozen and ice filled the holes. Spring thaw changed that. Several cubic yards of topsoil slumped into the holes, covering the forms and rebar and allowing the water level to rise higher. Second, we had a record breaking wet spring.


So the delay continued. It continued so long that the work had to be fit into their summer high season. I did what I could by periodically pumping the water and removing some of the slumped material. Saturated topsoil is a gummy soup that is pretty much impossible to shovel. There was also the danger of additional slumping while working below ground. I had to give it up and wait. Besides which I was getting tired of removing ticks that leapt onto me with glee from the head high hay. Protective clothing was little help.

Act 2 - Getting it done

Finally the great day arrived. A new crew arrived and so did a large backhoe with front end loader the same size as the one we used in the fall. Although this machine was a significant expense it meant we could clean the holes, deliver the concrete and back fill all four holes in one day. This time everything went according to plan. It was also an opportunity to renew my respect for heavy machine operators. He demonstrated a care for the work and fields and an artistry in how he went about the job.


The first job was to clean the holes. This involved carefully scraping off the overburden to expose enough of the forms and rebar that they could be lifted without breakage. Mission accomplished. But it was tense and dirty work. The bucket you see is ~3' (1 meter) wide and required gentle manoeuvering. Those machines pack a big punch.

I took on the job of cleaning the rebar so that the crew could do more important work. I ended the day covered in muck, as was the crew. Something died inside the base hole rebar cage which added to the unpleasantness. As if that wasn't enough didn't I already mention the ticks? What I go through to boost my contest scores!

While marking the lines to the two misaligned anchors the senior crew member noticed that if the base was moved 2' (60 cm) he could get all three anchors pointed at the base. That's why the base excavation seen above was extended. Many problems can be solved when you have the right tool at hand.

The backhoe bucket is so large that the anchor hole had to be widened even more than before. A form was prepared in advance with scrap lumber they had on hand. This saved some money on concrete, but require a lot of shovelling to back fill around the form. Without it the form would burst or float on top of the concrete.


The base is done differently. First the forms were rebuilt. Concrete blocks are used as rebar chairs. They must be concrete to ensure a good seal that will repel water infiltration. We used 20" tube for the pillar which is the minimum to sufficient concrete around the rebar. Previously we used 24". It is higher than required so the vertical rebar isn't visible. It'll be dealt with later.

The second frame shows concrete delivery using the "small" scoop. Once the concrete for the platform is poured it is enclosed with plywood. The hole is then back filled halfway and the concrete for the pillar is poured with a shovel. Only a few feet of unsupported tube is exposed so that the concrete does not burst the form.

Afterwards the hole was fully back filled, then compressed and levelled. Extra soil for all excavations (displaced by the concrete) was dumped off the edge of the hay field. Under the crew's direction the areas near the anchor plates were untouched. This will be filled by shovel to avoid damage by the backhoe.


Finale

The vertical rebar in the pillar is not centred while the concrete is poured. That's difficult to do. Instead the rebar is manually centred when the pillar is almost full. The concrete holds the rebar in position as it sets. The same procedure was use for my garage pad. That crew lifted the mesh as the concrete was poured to, again, avoid the problems of using chairs.


The final act was to push in the tower 1" round pier pin into the centre of the pillar and level it. It is a myth that concrete is self levelling. That only works when the concrete has a lot of added water, which slows curing. One of crew dribbled some water over it and used a trowel and a small level.

Three days later I drove out on the tractor, mowing tick-bearing hay along the way. I cut the form from the pillar and inspected the result. It looks good! You can see the top 4' of the 10' ground rod that the backhoe operator helpfully pushed in with the bucket until it hit an obstacle. Later I'll try to pound it in further with a sledgehammer.

Looking back, or, to err is human

Many things went right and many things went wrong. My first mistake was being overly ambitious about getting this tower in before winter. It cost me some money and a bit of grief but did not in the end cost me any time. If I'd moved more cautiously it would not have been done sooner.

Another thing I'd do is start with the big backhoe rather than try it with the less expensive small one. I was tentative in the beginning since I wanted to reduce the expense if a smaller machine could do the job and also limit the loss if we hit bedrock and had to resort to an excavator with a rock breaker. Should there ever be a second big tower on this property I now know what to do.

Relying entirely on the judgment of professionals is not always recommended. An important lesson I've learned is that although they are good at their jobs and give good advice they are perhaps too sensitive to the customer's costs and wishes. That is, they have learned in their careers that they must work quickly and get approval for anything that entails extra money or time. Risk doesn't always get the attention it deserves.

I had a few "Gimli Glider" moments with the concrete. Although Canada is a metric country there is a lot of building material that is measured the old way. Thus I am used to ordering concrete in cubic yards. But the concrete company works in cubic meters. They will do the conversion but you must be careful that they in fact do so. For the final stage I needed 4 yards, and I added a half yard margin. The order was relayed through the crew to the operations manager to the concrete company. They assumed and delivered 4.5 meters. The unused concrete was delivered elsewhere. We're working on getting a refund.

The ground in this region becomes saturated quickly in late fall and doesn't percolate downward until late spring. For all the pumping I did to get the work going again the holes completely dried on their own by the time the work recommenced. Fighting with water is a losing game. There are more powerful pumps around than the sump pump I used, but they're expensive even if only rented for a day. I spent an hour or more yesterday disassembling and cleaning the sump pump so that it will again be ready for emergency backup use in the house.

Looking forward - plans to raise the tower

I have not yet finalized how I will raise the tower. I could call in the professionals, which would be quick if more costly (and less fun) than calling in friends. Going the professional route would also require having everything prepared in advance, including all the guys, hardware, tower section repairs, prop pitch motor assembly and more.

Alternatively I can call in a small crane to lift the first 40' so that the bottom guys can be attached. I would then continue upward by gin pole. The method that involves the least equipment is to drop the base section on the pin and temporarily guy it until the tower is high enough that the first permanent set of guys can be installed.

I have decisions to make. Since the concrete will cure faster than I make my choices I can proceed whenever I'm ready. It would be nice to wait until the ticks are gone or the hay is harvested.

Tuesday, June 20, 2017

Antenna Swap: How They Play

I write this article with a light heart since at long last there is significant progress on my 150' tower. That story I will leave for another time since it is an interesting and lengthy tale. With that progress note I will return to my most recent antenna project. It has now been close to a week with the new antennas on the Trylon tower, enough time to speak about how they are performing and my immediate plans.

6 meters with the redesigned A50-6

On the very first DX opening I worked 9 new countries, and another the next day. This brings my total to 30 DXCC countries on 6 meters. This does not include the many more countries I worked back in the 1980s. I chose to reset my DX counters to zero when I returned to the hobby in 2013 after a 20+ year hiatus.

From my experience in the pile ups and marginal openings that the A50-6 up almost 24 meters is competitive with respect to big guns in this area of the continent. While there are better equipped stations and sporadic E propagation is fickle enough to confound easy comparisons I feel confident in stating that I have a very good signal on 6 meters.

Looking north from the top of the tower
The pattern is sharp, the F/B excellent and the SWR is not perfect but reasonable. Compared to testing on the ground the frequency of minimum SWR moved upward from 50.3 MHz to 50.9 MHz. Either the gamma match was disturbed while lifting it or there is interaction with the TH7 antenna lying 2.5 meters below it. I may yet push the A50-6 a little higher on the mast.

This success is despite using 40 meters of ancient RG213 that has more loss than new coax. Compared to the AVA7 Heliax I intend to use on VHF I estimate at least -2.5 db loss. That hurts a little, especially on transmit. In addition to the main run there is ~6 meters of LMR400 equivalent Ultraflex for the rotation loop and run up the mast and down the boom.

The old RG213 is contributing to the impedance problem since it measures ~47 Ω. For now I am using the rig's ATU to allow full power at the low end of the band by taming the ~1.7 SWR.

To alleviate common mode I used two snap-on ferrite cylinders at the feed point plus a 1-turn coax loop. It isn't perfect but the best I could do with what I had on hand. The clean pattern I am experiencing is a good sign.

I am eagerly anticipating the remainder of the sporadic E season. Unfortunately it is unlikely I'll have the AVA7 installed before band fades away. That requires a trench, burying it and other cables that are not yet in hand, and figuring out how I will terminate the ground end of the Heliax. I am not sure I want to bring this 1-⅝" coax through the wall and into the house! I would like to do all coax terminations and switching outside the house.

TH7 performance

This long boom tri-band yagi is performing about as well as expected. The difference between it and the short boom Explorer 14 it replaced is not something that is evident without a carefully done A-B test. This is impossible since I cannot have them both up at once. Suffice it to say that it certainly seems to perform at least as well. That's good.

What isn't good is that the match on 15 and 10 meters is not as it ought to be. On 15 meters the SWR minimum is at 21.375 MHz and on 10 meters it is 28.550 MHz. Both are too high and are not what they should be based on the measurements from the manual. On the other hand 20 meters resonates exactly as it should.

It is possible that there is a trap problem or I have somehow made an assembly error. Another area of concern is the rotation loops for both it and the 6 meter antenna since both run near the phasing lines between the two driven elements. This may be creating some imbalance and thus mismatch, and it would tend to be more noticable at higher frequencies. But I really don't know.

What I will do is raise the TH7 several inches to provide more clearance from the tower top. This will allow routing of the rotation loops in a way that would reduce interaction with the phasing harness. It will also reduce the likelihood of the rotation loops snagging the tower legs.


It is conceivable though unlikely that the balun I installed at the feed point is part of the problem. I replaced the Hy-Gain BN86 voltage balun with the more appropriate current balun from Balun Designs. It is wider than the BN86 so the arms of the feed point had to be spread a little.

Aside from that it fits surprisingly well and is a superior solution to common mode than a scramble wound coax choke. Although I do notice less computer and other local noise on receive compared to the scramble wound coax I had on the Explorer 14 there are likely too many variables to confidently say that the balun has significantly improved common mode rejection.

Loss of 40 meters for the summer

Taking down the XM240 certainly reduces my capability on 40 meters. This is acceptable for the remainder of the summer months when low band activity is lower than other times of the year. The only significant impact that I see is during next month's IARU Radiosport contest. Since I haven't decided whether to enter that contest I am not too worried. In a pinch I can put up an inverted vee.

The yagi has been disassembled and will remain in storage until I decide what to do with it. For expediency I may put it up at the top of the 150' tower. There is also the possibility that I will convert it to a W6NL Moxon. I'll wait and let circumstances dictate what I'll do when the time to act arrives.

An antenna for 40 meters at the height it was on the Trylon -- 21 meters, or λ/2 -- is needed for contests since it is a good height for short haul paths such as the US, Caribbean and even Europe. I intend to address that lack with a side mount antenna (to be determined) on the big tower.

Mast and tower load

With the swap of antennas on the Trylon I am now more comfortably set for storm force winds. The high wind load of the TH7 (approximately 12 ft²) is right at the top of the tower, which is far better than the 10 ft² of the Explorer 14 that had been 2 meters up the mast.

The wind load of the A50-6 is 3 ft² and it is only slightly higher than the Explorer 14 former height. Better yet, the maximum projected areas of the antennas are orthogonal to each other: on the elements for the TH7 and on the boom for the A50-6. Therefore they are never both present at one time.

In advance of doing a detailed calculation it appears to the best to turn the antennas orthogonal to high winds so that the booms face the wind. Back in the 1980s I had a similar arrangement with a TH6 at the top of the tower and the A50-6 10' (3 meters) above the tower, on the very same mast. That tower was lighter duty than the Trylon yet survived some fierce wind and ice conditions.

However that is no guarantee of future success. All is takes is one strong gust of wind to take it all done. If you wait long enough there will always arrive weather conditions that will take down any tower and antenna combination. The more conservative your approach the longer you will wait. All anyone can do is make that wait longer than your lifetime, and do regular maintenance.

One point about the current arrangement bothers me: the TH7 boom. The XM240 it replaced has a larger diameter boom that has also been strengthened per W6NL's prescription. Although thick walled the TH7 boom flexes quite a lot in the wind. When combined with the brake play of the Tailtwister rotator there is a substantial movement of the antennas and mast when the wind rises. Although not an immediate concern this sets up the possibility of oscillatory load adding to ordinary wind load. I plan to watch this closely.

Part of the larger plan

With the completion of the change from temporary yagis to a more permanent arrangement I am one more step along the road to realizing my antenna farm plans. For the summer my attention will be focussed on the big tower.

Sunday, June 18, 2017

Tractor Pull

Putting up modest towers and antennas can be done with a little muscle. Gather some friends, set up a pulley or gin pole, and haul away. Some food and drink afterward completes a fantastic day of learning, fun and a bit of work for you and other local hams. I highly recommend it. Just be sure there's at least one person there with the expertise and standing to successfully direct many hands.

As the towers and antennas grow in size and weight there comes a point where human muscle is not enough, or there is insufficient safety margin. There are too many hams unwilling to use safety equipment (even if only a hard hat and gloves) or too willing follow their own whimsy rather than the team leader. It's a disaster waiting to happen. Don't be afraid to handpick your crew from among those you trust to do the job right.

When I raised the Trylon I dispensed with a crew entirely until it came time to top the tower and put up the 40 meter yagi. This suited me since it was winter, my new property is a long drive for my friends and I wanted to do the work during weekdays when most people are at work. I overcame the challenge by designing and building a winch driven system for lifting heavy tower sections and antennas.

It worked well but was slow going. By relying on muscle to operate the system a 4:1 mechanical advantage in the winch was mandatory. It took a lot of cranking. It was safe and effective though slow. There are better ways. Those involve engines or motors, whether used in a crane, winch or...a vehicle. Thus we come to tractors.

I've used small garden and lawn tractors and far larger farm tractors to raise towers and antennas. All can work well if you use them appropriately. Power is both a blessing and a curse. Countless people have been injured or killed by machinery improperly employed or maintained.


Over the winter I purchased a garden tractor for mowing the large country property I own. I made sure when I shopped that it also would be up to the task of plowing snow and doing tower work. Luckily the parents of a business colleague were retiring from a hobby farm to the city and had a lightly used garden tractor to sell.

A deal was quickly made and I arranged transportation. The tractor sat unused for the remainder of the winter. Amazingly it promptly started in the spring despite being out in the weather with no more protection than a tarp and without recharging the battery. It has since been used for its primary job: mowing the grass. I have also driven it into the hay field to create (hopefully) tick free paths to my tower excavations.

Ropes and pulleys

Using a tractor or any powered vehicle for hauling objects up and down a tower requires a few simple techniques. However they are very important for a safe and successful procedure. In the following picture the key aspects are visible.

Ground crew: Brian VE3CRG on the tractor and his wife Mollie who handled the tag lines

This is the Cushcraft XM240 immediately after it has been lowered by the tractor. The tractor held it above ground while the fragile capacity hats were removed. Notice the pulley attached to the bottom of the tower. The pulley two things. First, the forces at the top of the tower and mast (where there is another pulley) are kept vertical. Otherwise the bending moment on the tower could cause structural damage. I discussed this topic some time ago with regard to gin poles.

Second, a garden tractor is not so massive that it will maintain contact with the ground were the rope to angle upward. The pulley translated the vertical force to horizontal so that the tractor has maximum traction.

The pulley is attached to the tower since it is a convenient and strong place to take the large forces involved. The pulley pivots upward approximately 45°, so keep that in mind when choosing an anchor point. Since the antenna is only 75 lb (35 kg) I went with the simplest attachment option: ¼" aircraft cable with a couple of cable clips. A better choice is a chain to reduce chafing and stress for heavier loads. The only suitable chain on hand was used to couple the rope to the tractor frame.

Some go further and fabricate a heavy gauge steel bar across the tower base which eliminates pulley motion upward. Although the cable could be made shorter to limit upward motion its length reduces chafing of the rope against the side of the tower. This method has a limit since if the pulley moves up too high the tractor can lose traction.

Measure the work area

Before using a tractor in this fashion you must clear a path for it that is reasonably flat and long enough radially outward from the tower base. If you run out of room you're stuck with an antenna dangling midair and no where to go but back where you started.

The XM240 was mounted 21 meters (71') above ground. I measured 30 meters (100') out from the tower as the starting point for the tractor to lower the antenna. This is not only to ensure that the tractor does not run into the tower before the antenna reaches the ground but also to keep the tractor out from under the antenna when it drops to the ground. In the picture above the tractor started its journey at the line of trees in the background. You can see the tire tracks in the grass.

The rope is 200' (60 meters) of ⅜" nylon. This is the minimum recommended for this operation. With the pulley mounted 75' up there is 150' required to go up and down the tower and 30' on the ground for the tractor to stay clear of the antenna. Another 5' to 10' is used for harnesses to the antenna and tractor. Very little is left unused.

To lift the TH7, which is about the same weight and breadth as the XM240 the process is reversed. The tractor pull starts at the edge of the antenna and backs away to lift the antenna. Whether lifting or lowering the tractor operator is facing the tower and rest of the crew.

Power is dangerous

As I tell the ground crew: you can't argue with 22 horsepower. When something goes wrong and you put up a fight the tractor always wins. When antenna hardware snags in the tower the tractor keeps moving. When a crew member gets tangled in a rope the tractor keeps moving. When the antenna or tower section strikes the pulley atop the tower or gin pole the tractor keeps moving.

Modern small tractors for residential use are surprisingly forgiving machines. Say you brush against a building, tree or large rock. Often the tractor will "see" the resistance and let the clutch spin. While this helps keep the crew safe it should not be relied upon to avert a disaster.

Older tractors are less forgiving: they'll just keep going. That's when someone can be seriously hurt. For large farm machinery or a truck there are fewer if any safety features, and the power is far greater. You are better off employing the smallest machine that will get the job done.

I've used garden tractors to successfully lift 200 lb tower sections. Only use more powerful machines when the operator is sensible and experienced.

Tag lines

Use tag lines to direct load around obstacles and to prevent snagging hardware on the tower, guys and side-mounted antennas. Tower sections require only one tag line while yagis should have two. For tower sections tie the tag line near where the lifting rope or cable is tied but on the opposite side. For yagis place one on either side of the boom cradle. The two 100' tag lines are visible in the picture above.

It is generally better for only one crew member to handle the tag lines. Little force is required so this is not a problem. When there is a person on each tag line I can almost guarantee they will find it difficult to coordinate their attempts to steer the yagi..

The crew handling the tag lines will be the first to know when the load snags on something or is about to do so. Give them the authority to stop the operation immediately when they detect a problem. The tractor operator must be prepared to quickly react.

Crew taking a well earned rest
Traction

Tractor power is of no use if the wheels spin on the ground. Excess power only makes the problem worse. Garden tractor engines are designed to use the power for mowing, not so much for hauling.

On wet grass or snowy ground a small tractor can easily lose traction under load.  This occurs more often when lifting rather than lowering.

On uneven ground if one drive wheel has poor ground contact the differential will spin the lifted wheel and apply no torque to the other one. A tractor with a more sophisticated drive train is desirable if it is available. Otherwise plan the route for the tractor will extra care.

When traction is lost determine the cause. Many problems can be solved with more weight over the wheels. Some tractors provide an area where weights (stones, bricks, etc.) can be placed. In a pinch have one or two crew member jump onto the back of the tractor.

If you can't solve the problem you'll likely have to lower the load back onto the ground and try something different. Larger tractors are unlikely to lose traction with the weight of loads hams typically lift, however there is greater risk of injury and damage from all that power.

Communication

I cannot overly emphasize the importance of communication between the tower crew, ground crew and tractor operator. Agree on hand signals or voice commands beforehand, and practice if you can. Handheld radios can be very helpful. They don't have to be ham band devices. However you do it remember that tractors are loud and so you cannot always rely on shouting to get the message across. We want the tractor operator facing forward at all times so that they can see and respond to directions from other crew members.

Although we are all friends there must be a command hierarchy. In this hierarchy the tractor operator is at the bottom. That is, when anyone else tells them to stop or go they do so. Make sure he or she understands this. Don't assume they'll obey. No one, no matter how responsible, should be allowed free reign over the power they are handling.

As with all tower work the highest authority goes to those on the tower. Next in line is the ground crew. As already mentioned, last in line is the tractor operator. This arrangement strikes a balance between vulnerability and the potential to cause harm.

Don't hesitate to call a temporary halt to the operation if anyone is having difficulty coping or there is a point of confusion. Everyone should have this authority and not be timid about using it. The tractor operator should know how to lock the wheels when necessary.

We did have a few instances of miscommunication even though we all understood what needed to be done. Corrections to our procedures were made as we went along. No harm was done.

Finished

In the picture the TH7 dangles atop the tower under tractor power, and a properly set brake. After taking this picture I climbed the tower (wearing a hard hat) and bolted the antenna in place. We used the tractor to adjust the antenna height by a few inches to put it exactly astride the mast bracket.

The A50-6 was hand lifted since it is light and relatively fragile. It is best to avoid tractor power in this and similar cases. Always use the right tool for the job. It went up first since it goes highest on the mast. The TH7 must be carefully handled so that it does not tilt upward and strike the smaller VHF antenna.

It was getting late so we quit once the antennas were in place and the tractor and ropes put away. The next day I went up on my own to finish the job. This involved pushing the 6 meter yagi higher up the mast, removing the pulleys, pointing the antennas, attaching the rotation loops and testing that everything worked. Back on the ground I disassembled the XM240 and stored it and the Explorer 14 out of the way until they are again needed.

Both antennas use the RG213 runs I already had on the tower. This was not my intention. I ran into some difficulty preparing Heliax runs in time. I'll deal with that later.

In my next article I'll report on how the antennas play. For now I will only say that I am generally pleased with their performance. For the foreseeable future these are the only yagis going on this tower. Other than perhaps a 2 meter yagi for VHF DXing. This is part of my broader plan for the station.

Next tractor job

I will next use the tractor with a gin pole to construct the 150' tower. Each tower section weighs 120 lb and there is additional hardware that is similar weight. With an experienced crew the tower should go up quickly, with the tractor providing most of the muscle.

I may use the tractor to tram yagis to the top and sides of the tower. Muscle power will be used to raise Heliax and other fragile station components. Sometimes 22 HP is too much power.

I love a crew that tidies up the job site without being asked