A73A in CQWW SSB 2011

A73A QSL CardThis year I had to honor to be invited by the Qatar Amateur Radio Society (QARS) to operate the CQ WW SSB contest with them. The station set up in a fieldday style on the northern tip of Qatar, about 100km way from the capital Doha. We are directly located at the beach and used almost exclusively vertical antennas. A73A entered in the category Multi Operator / Multi Transmittors, running 6 Stations in parallel. Keep on reading for some pictures and lessons learned.

The location

The location was selected very carefully. The station was located in bay on the northern tip of Quatar surround by almost 260º of salt water. Due to the nature of this bay, the water was very shallow and even with stronger winds, there were no waves on the water. From the Gulf region, Europe and the US are the same heading direction which favors a simpler antenna setup.

Antenna setup on the Highbands (10m…40m)

On all highbands (10m…40m) we used a phased array of 2x 2el N6BT Bravo verticals.  These parasitic two element vertical arrays consist of a driven element and another element which can be alternated with a coil & relay to act as a reflector / director. The big advantage of these antennas are their physical dimensions. They can be easily installed by one person. With their two resonant radials no additional radials have to be installed.
The driving element was fed through a W2DU current balun. Driving the antennas with 1,5kW heated up these baluns excessively. After 39 seconds keydown you couldn’t touch them any more. A few seconds later they went into saturation and significantly and worsened the SWR of the antenna.
I’m not sure if these high amount of common mode current is a design problem of the antenna (feeding the antenna not on Lambda/4)  or selecting the wrong kind of ferrite material for the W2DU balun.

Anyhow, the antennas worked great. Supplemented with a W0XB Stackmatch II Plus (enabeling InPhase / Out of Phase) we were able to cover 3 direction with each double pair of verticals.

  1. Endfire (Reflector + Driver) towards EU / NA
  2. Endfire (Director + Driver) towards VK
  3. Broadside (The two vertical arrays out of phase) towards LU/PY and UA

Unfortunately, one of the stack matches was wired wrong and we transmitted the first day on 40m always broadside. The deep null in the antenna pattern towards EU/NA resulted in very little QSOs. Fortunately we found the problem the second day so that we could at least recover a bit.

The only Yagi we had was a A4S connected to the 10m station. Within the same beam direction, the verticals were always louder than the Yagi. However the Yagi became useful in working multipliers which were off the main beam directions of the vertical array.

4 vertical antennas we used at A73A during CQWW SSB 2011

two N6BT parasitic vertical arrays phased with 0º or 180º with halfwave spacing

A73A N6BT Verticals

15m and 20m N6BT vertical arrays with 80m 4-Square in the background

Setup 2011

Sunset: Vertical arrays for 10m, 15m, 20m and 4-Square for 80m

10m Antenna A73A

An A4S was used on a crankup tower as the secondary antenna on 10m; located next to the shack

stackmatcch plus at A73A

A plastic chairs ensures that the Stackmatch does not get in contact with the water during high tide

Antenna setup on the Lowbands (80m & 160m)

On 80m we set up a classical 4 Square with two elevated radials for each vertical. The antennas were standard aluminium tubes sold be DX Engineering. The 20m tall verticals were phased with a Comtek Coupler enforcing the right current at the feedpoint with a Quaterwave 75 Ohm Transformation line.

160m had another 20m tall aluminium vertical with an L-extension making the antenna resonant on 160m. Two elevated radials were added.

All antennas performed amazingly good. Especially the front/back and front/side of the 80m 4-Square was very impressive.

160m L-Antenna with two elevated radials during sunrise

Receiving antennas

Unfortunately, both – our beverage towards EU and the K9AY loop didn’t work. While having some kind of ground loop noises on the Beverage (unfortunately we couldn’t find the root of the problem in time) the K9AY worked equally in all directions. I’m personally somehow fed up with this antenna now. I´ve already tried severals in different parts of the world with kits of different manufactures and non of them worked properly.

Team building up the K9AY. Shack & 80m 4-Square in the background

The Shack & Infrastructure

The whole operation was splitted into four temporary housings of different sizes. Two were used as shacks, one for sleeping and one as bathroom and kitchen. All of them had were airconditioned which is in Qatar a necessity rather than  luxury. Within the Shacks we used almost on all bands the same setup:

1x FT2000 or FT1000MP MK-V

1x Microham MK2

1x ACOM2000A

A73A Campsite

The A73A campsite during the CQWW SSB preparations

A73A shack

Main Shack @ A73A with 20m, 40m, 80m and 160m operating positions

A73A powerplant

A rented power generator provided more than sufficient power

A73A - DH1TW operating 10m

A73A - DH1TW operating 10m in the secondary shack (15m station is in the background)

The operators

A73A Team CQWW SSB 2011

A73A Team CQWW SSB 2011 with some German visitors from the A71DLH operation

A73A consisted of a multi national mainly of the GCC states. Here is the list of operators:

  1. A71BX, Ali
  2. A71CV, Abdulla
  3. A71Co, Khalid
  4. A71AM, Saif
  5. A71AD, Rashid
  6. A71EL, Mohammad
  7. A41MX, Farid
  8. A61ZX, Ibrahim
  9. HZ1DG, Abdulrahman
  10. 9K2RR, Faisal
  11. 9K2HN, Hamad
  12. K5GN, Dave
  13. DH1TW, Toby

The Contest

In general the conditions were amazing all over the whole weekend. I had the pleasure to work most of the time on 10m (during the day) and 160m during the night. 10m was by far the best band. We finished with almost 4000 QSOs and I hardly remember another contest having so much fun in working the pileups.
However if you are more or less the only station from a country, the pileups can easily get too big. This means that there are so many stations calling that you can’t identify the complete callsigns without asking. This slows down the rate.
Here is our claimed score:
Station:  A73A

Class: M/M HP
QTH: Qatar
Operating Time (hrs): 48

 Band  QSOs   Zones  Countries
  160:   340    13       62
   80:  1134    27       92
   40:  1081    27      101
   20:  2280    40      145
   15:  2815    40      147
   10:  3978    40      161
Total: 11628   187      708  Total Score = 29,229,805

Lessons Learnt

- Always have proper Antenna Measuring Equipment with you. Good options are DG8SAQ VNWA or the Funkamateur Antenna-Analyzer. An MFJ-259 is the last alternative.
- There is a small high-tide and a big high-tide. Make sure all the material is high enough above the water and prepared for the big high-tide.
-  CAT5 is not ideal for wiring your antenna switches. The wires are ridged, so be very careful, they break easily.
- Always plan 30% more time for setting up the stations than planned. Something always doesn’t work.
- Proper Tools are indispensible. For the first time I used the DX-Engineering coax cable prep tools. It can be so easy to make Rg213 cables with properly connected PL-259s!


During the 7 days which I stayed in Qatar I closed a lot of new friendships. I was impressed by the hospitality of my hosts. I had an awesome time and I’m very thankful to the Qatar Amateur Radio Society for inviting me to this amazing event.

A part of the A73A team

New friends taking the last picture after the disassembly of the station

Pictures have been taken by A71BX, HZ1DG and A41MX

About Tobias (DH1TW)

Self-confessed Starbucks addict. Loves to travel around the globe. Enjoys the technical preparations of Amateur-Radio contests as much as the contests themselves. Engineer by nature. Entrepreneur. For more, follow him @DH1TW


  1. Fantastic article Tobi, see you on the air friend.
    73 de Jesus EC1KR (aka ED1R)

  2. Congratulations Tobi and all the team.

    73, Javi

  3. Nice article, I think the team had great time and enjoyed this amazing activity.
    I look forward to meet you soon my friend Tobi
    73 de Ali

  4. Peter 1LX says:

    Great – and the antenna farm is very very nice.
    I did not know about the N6BT antenna and maybe it will be one of my favorite athome.

    73 Peter DF1LX

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