EME from Mali
Results of the TZ6NS EME Operation in Mali, November 2006.
By Ned Stearns AA7A.
Mike Fulcher, KC7V/TZ6MF, and Ned Stearns, AA7A/TZ6NS, planned and executed a small EME DXpedition to Mali, West Africa in November 2006. This effort was tightly integrated into a larger project, the CQWW DX CW Contest DXpedition, TZ5A which was pulled off by the VooDoo Contest Group. The VooDoo Contest Group consists of US and UK hams that have been meeting in West Africa for over a dozen years and have put together a string of highly successful contest operations that have placed high in the world-wide rankings in the CQWW DX CW Contest. Mike and Ned, members of the VooDoo Contest Group, have recently become infatuated with some of the new digital communication technology that has been evolving in the EME community and decided in 2006 to try their hand at putting together a portable 2 meter EME station that would exploit this new technology that permits even modest-sized stations to participate in EME. And, once the equipment for this year’s effort was moved into Africa, it could be used in conjunction with the 2006 VooDoo Contest effort and possibly for many years to come as this roving contest group moves their act to other West African nations in the years to come.
EME Antenna Setup
The antenna selected for this trip was a single M2 2MXP28, which is a cross-polarized yagi with 14 elements on horizontal and 14 elements on vertical polarization. This antenna was selected to minimize the effects of polarity rotation. Without dual polarization, our small station would be rendered ineffective for long periods of time while the effects of Faraday rotation.
The antenna boom segments and each of the elements were marked with an engraving tool to reduce the likelihood of being mis-assembled. One of the element keeper clips was retained in each element in order to save time in centering the element in the boom during re-assembly. The entire 2MXP28 antenna, its mast, the AZ/EL mechanism and all coax and control cable was packed into a single Snow Board carrying bag that barely met the 50 pound (20 Kg) baggage weight limit to bring on the airline. Bringing large antenna systems on DXpeditions is now a huge challenge. Weight will become a driving parameter for all DXpeditions that move hardware into and out of DXCC entities. The VooDoo Contest station approach is to keep all hardware in Africa and move it between countries from year to year in a bus or other form of ground transportation. Only small amounts of new hardware is needed to be brought in every year to keep the stations going. Mike and I will add to this EME station over the next few years to see if we can improve its performance over time.
The mast for the EME array was a 20 foot long, 2 inch O.D pipe that was in the VooDoo Contest station spare parts pile. The mast will be guyed using four guy poly ropes. The guys are attached at about the 16 foot level on the mast. In this way, the yagi will only come in contact with the guy ropes only in extremely high elevation angles.
The bus and the cover for the bus in the right side of the picture to the right was not anticipated. Since the VooDoo Contest Group operated from this same hotel in 2005, we thought we knew exactly where to put the antenna and what constraints we would run into when installing the antenna in this position. However, when we arrived this year, there was this new structure that was of some concern in that it might provide some blockage in the path to the moon at moonrise or produce some impact to the antenna pattern. As it turns out, our antenna was taller than this metal structure and probably was affected little by its presence. Mike and Ned’s hotel room were selected to be as close as possible to the antenna position to keep the coax runs short. And, it was hoped that it would take less time and energy to run out to the antenna using the south end doors and re-aim the antenna often to keep the pointing errors to an absolute minimum. Little did we know that the hotel management would keep the fire doors at the south end of the hotel locked 24 hours a day. This was not only unnerving in that we were subject to elevate risk due to a potential fire, but we had to run a very long distance to the antenna every time we re-aimed it. We calculated once how far we ran to do this antenna aiming. It came to almost two miles over the course of the operation. So, if you were wondering whether we went the extra mile on this operation, we claim we did.
The VooDoo Contest Group erected 10 full size HF antennas for the CQWW DX CW contest effort. The VooDoo Contest Group erected its first EME antenna in 2006. The single 2MXP28 was walked up and easily guyed on the first attempt. Due to the simplicity of the antenna, the receive preamp, polarity switching relay, and transmit/receive relay were all mounted out at the feedpoint of the antenna, towards the rear of the antenna. In order to keep the antenna balanced, the boom-to-mast clamp was positioned about 5 feet toward the rear of the antenna’s natural balance point. This kept the final antenna assembly fairly well balanced when all of the preamp, relays and cables were attached to the boom of the antenna.
It took less than two pounds of force to lower the antenna using a rope attached to the forward end of the antenna boom. To aim the antenna at the moon, we simply moved a weighty object to a point in the direction of the desired azimuth and adjusted the length of the rope from the forward end of the antenna boom to the weight to set the elevation. This approach may seem crude but required no additional baggage weight to implement. The antenna is mounted with the cross-polarized elements in a +45 and -45 degree offset from vertical. We did not use the traditional method of mounting the element in the normal horizontal or vertical sense. This was done consciously in order to minimize the interaction between either antenna plane and the metal mast. Use of a non-conducting mast is not practical.
While preparing for this trip back home in Arizona, Ned used a bucket of rocks for the Elevation Weight. Rocks are plentiful in Arizona and so were buckets. In Mali, rocks are also plentiful but buckets with handles were not. So, we needed to create a handle for our EME Azimuth weight in Mali in order to attach the ropes to set the elevation.
Mike and Ned probably tied and untied the knots to this bucket a thousand times over the course of two weeks. We also used a rope attached to the back of the 2MXP28 in order to keep the antenna from drifting during times of high wind. It was necessary to use the back rope only a little while every day.
The antenna certainly looked impressive. Many times throughout the day, other visitors to the hotel or many of the hotel workers would stop by and point at this thing. Since neither Mike or I speak French, the formal language of Mali, we resorted to a lot of hand waving and gesturing in order to try to explain what this thing was for. The fact that our gesturing was directed often to the moon probably provided a clue to the observers that the users of this thing had some affliction that was somehow related to the moon.
Our EME operation started right after new moon in late November 2006. Finding the moon in the sky around new moon is a challenge. We resorted to using Mike’s Boy Scout compass for setting the azimuth of the antenna. We had no clue of the magnetic declination angle but were probably not far enough off to be of consequence given the fairly wide beam width of a single yagi antenna system. Setting the elevation was done by using a manual protractor approach. The way we did this was to form your hands into fists and then use your fists held at arm’s length from your eyes as a measure of an angle. We found that, in general, your fist subtends an arc of around 6 degrees when held at arm’s length. So if the antenna needed to be at an elevation of 42 degrees, we would stack our fists, one over the other, for 7 times and be fairly certain that after the 7th time we were looking up into the sky at around 42 degrees. Of course, one had to be sure to be looking down the bore site of the boom to make sure to measuring the elevation angel of the boom. We performed this act throughout the first week of the operation until the sun set, and then we simply aimed the antenna at the moon. In the second week of the operation, the moon was visible from moon-rise to moon-set and we did not have to rely on the compass or manual protractor.
The EME station concept is shown above. It is centered about the use of the Elecraft K2 radio as the IF. The reason for the use of this radio is primarily due to its selection by the VooDoo Contest Group as the principle radio for our HF contest station design. We use seven K2 radios in the CQWW DX CW contest station (one each for 160, 80, 40, 20, 15 and 10 meters and one for a multiplier station). We always bring a spare to keep Murphy at bay. So, the spare is used in the EME station and available for a hot swap if needed in the contest. The station control box contains all opti-coupled discrete control interfaces between the computer and the radios as well as transformer isolated audio interfaces between the laptop sound ports and the radio’s mike and speaker ports. Every attempt to avoid ground loops (e.g. opti-coupled and transformer-coupled interfaces) and mitigate EMI effects (e.g. I/O lines wound on ferrite cores and extensive use of shielded cable) were thrown into this box since the ability to troubleshoot in a remote site is a problem. We transport laptops and K2’s into the target country every year, but every other piece of this EME system is now stored in Africa and ready for use in coming years.
Operating the Station
The EME station fit nicely on the desk into one of our hotel rooms. Using the K2 radio and the small MFJ 4125 power supply kept the footprint very small at the operating position.
A Daiwa CN-801 wattmeter was used to provide transmitter power level and antenna SWR measurements. Mike and Ned operated in a tag-team mode for the entire operating period. One operator would work the station while the other would routinely adjust the antenna and rest whenever possible. We operated in roughly three hour shifts which kept the operator fairly alert at all times.
We went long stretches at times where no signals were observed on the screen. And then, there would be times when there was a flurry of activity where the screen filled with stations and we frantically tried to work everyone we saw. We kept in touch with the EME community, at first, by checking into the N0UK JT65 site at the start of daily operations and prior to frequency changes using an Internet Cafe in the hotel. Internet access was problematic at this hotel. It was not until the last day of EME operation that we finally got Internet access in the operating position. We were happy to see that many stations were looking for us every day. We kept to our schedule religiously in order to work as many of the deserving as possible.
We completed operating after 7 days on the air with 72 unique call-signs in our log. A total of 76 QSOs were complete with 75 on the JT65B mode and one on CW (thank you W5UN!). The list of completed contacts completed by day is provided below:
These contacts are in their order in our log. Since this is the first time ever 2m EME operation from Mali, this list can be used to determine “first’s” to work TZ from their respective country. Congratulation from Mike and Ned to all who got into the TZ6NS log. We only wish that everyone’s call-sign could be in our log (AA7A and KC7V, too). Good luck and hope to see everyone next year from ???
Our portable EME operation probably tested the capability of many EME stations and the patience of many EME operators. Our power was a little low (around 550 watts output in the shack) and our antenna was not as big as what we are used to at home. However, what we lacked in size and power, we tried to make up in effort. Mike and Ned are seasoned EME operators and derived immense joy from each and every contact. We have plans for a bigger effort next year but we also hope to show to others that a simple EME setup can obtain significant results with an appropriate amount of planning and preparation. We were disappointed in the noise situation in Mali. We struggled with noise at the direction of moonrise and never heard a signal from VK/ZL or JA despite dedicated effort in those directions. Hopefully, future site selection will be better in that regard or possible improvements in the antenna will tighten up the pattern and help to reduce the effects of noise. It is hard to know what you are walking into at a remote site such as this and possibly a little more testing of this issue will be done next year. Without reliable Internet access, it was difficult to run any schedules. We will try to get that ironed out better next year. CW operating was just not possible. The line noise at this site was horrible and drove us crazy when listening for any length of time at all on the headphones. We saw no CW signals (besides W5UN) in the piles and might have tried if some were discernible during quiet times when no JT65B were being seen.
We are already starting to plan for next year even before all of our credit card charges have shown up. We have scouted the next DXCC site for the VooDoo Contest Group for 2007 and all we can say right now is that we intend to be able to see the ocean from the next operating location.
73 from Mike (KC7V) and Ned (AA7A) and we hope to see you all again soon.