OX2K - 2m, 70cm and 23cm EME DX-pedition

During the period from 29th May to 4th June the OX2K DX-pedition activated Greenland on HF, 50MHz, 144MHz, 432MHz & 1296MHz. On the last 3 bands we had to revert to EME to make contacts from this remote location.

Sondre Stromfjord, or Kangerlussuaq in Greenlandic, is located at the end of a 140 km long fjord just north of the polar circle. The favourable weather conditions have made it the main hub for both internal and external air traffic to Greenland with regular direct connections to Denmark, Iceland, and Canada. The airstrip was build by the US during World War II and served as a refuelling stop for planes going between North America and Europe.

During the cold war Sondre Stromfjord hosted a military base, submarine communications site and a relay station for the US missile radar surveillance. The surrounding mountains were thus filled with radio installations, most of which were abandoned in 1991/92, meaning that masts, cables, power generators and huts were available with only minor modifications.

With the help of Holger, OX3HI, we gained access to a site a few kilometres south of the community on Black Ridge. It took Holger, together with Per, OX3DU, and Michael, OX3LG, nearly all winter to remove the old equipment, clean the radio hut and make new 208VAC installations. From this location we worked HF, 50MHz, 144MHz and 432MHz, and the hut now serves as the club station for Sondre Stromfjord.

Today Sondre Stromfjord has a population of 400 most of who work at the airport and the associated facilities. The entire community is literally build along both sides of the airstrip and the town centre is within 100m of the terminal building. There is only ONE shop in Sondre Stromfjord which while we were there was running low on stock and awaited the first supply ship which was due in a few weeks. The ice in the fjord makes it possible to access the harbour for only approximately 3 months between June to September.

To the east there is a 25 km gravel road leading to the inland ice. There is a currently a lot of activity here as Volkswagen are building a car test track for over 100km in on the ice. This road is also the entry/exit point for expeditions crossing the inland ice to the east coast. On the way to the ice you can see remains of an old US fighter jet plane which crashed in the 1950's and is well preserved due to the very dry continental climate.

To the west, a 13 km road from Sondre Stromfjord to the harbour is the longest paved road in Greenland! A further 3 km by gravel road takes you to Kellyville, a tiny community with a population of 9 people.

2 km further on is the abandoned site of the submarine communications installation and all that is left is the generator/transmitter hut. From this location you have a clear view to the inland ice more than 40 km away. It is almost impossible to determine how far away things are because there are no known references such as houses, cars, buildings etc. You can also see the mountains surrounding Sisimiut on the coast an amazing 140 km away, demonstrating the dryness of the air and lack of modern pollution.

1296MHz - Kellyville

Kellyville is maintained and run by Stanford Research Institute. The 32m dish which is normally used for incoherent scatter radar studies of the ionosphere, has an estimated gain of 49dBi, equal to a beamwidth of approximately 0.5 degrees. All transmitter equipment is made for low duty cycle pulse transmission and not suited for amateur radio service.

On the evening of our arrival we went to Kellyville to look at the installation and talked to the site manager, John, to get an overview of how we should hook up to the system.

We wanted to use the system with as few changes as possible to quickly get on the air. Due to limited pre-information on the system and a note from Gudmund, SM2BYA, regarding the polarisation, we were very concerned about how it would work out.

The transmitter for the ionosphere scientific studies is a 3MW 1291MHz pulse klystron amplifier connected to a waveguide which runs some 100m to the feedpoint/polariser. We gained access to the waveguide at the klystron output and inserted a coax-waveguide transition for our TX-signal.

From a distance the 32m dish looks nothing special but standing on the 18m high pedestal where the dish is mounted suddenly gives a whole new perspective of the actual physical size, 32m is BIG.

The RX-port of the polariser ends in an insulated cylindrical 'chamber' between the 2 elevation gears (the chamber is big enough for 4 people!). The RX-port is a waveguide-coax transition, so all we had to do was mount our pre-amp and optionally use a relay to provide additional isolation to protect our pre-amp when transmitting. We measured the isolation between TX and RX-port on the polariser to approximately 30dB so we needed the isolation relay.

For RX we used the existing 1290MHz-28MHz down converter at the feed point. The LO frequency is controlled from a signal generator inside the building and is set to the LO frequency divided by 3. In normal operation the system is using overlying LO so the signal is inverted. We programmed the LO for listening down from 28MHz @ 1296MHz.

Using a FT-1000MP we could benefit from the dual receiver allowing us to monitor for others while simultaneously working calling stations. The 28MHz IF signal were carried to the building by the existing RG-214 cable.

The following morning we returned with all our equipment, including 2 complete setups in case something failed or had become damaged or lost.

The connection to the TX-port was only a few meters from our operation position in the transmitter/workshop building and a short length of 1/2" LDF was used. The pre-amp and isolation relay was mounted and the relay was controlled from our sequencer via the existing control cables.

After a final check to ensure that the relay and pre-amp was working it was finally time to test the TX-line and listen for our own echoes.

The tracking of the moon was done by computer controlled motors and we were thankfully not required to turn the dish manually.

We performed a TX and SWR check then aimed the dish at the moon. All of us were anxious to see if our system was working. We transmitted some dashes, switched to receive and instantly heard our own echoes with S5-7, YES it worked.

It was just in time for the EU moonset and we immediately called CQ and soon the first stations were in the log.

We were very relieved and happy to confirm that the dish polarisation was in accordance with the amateur convention!

There were some minor oscillations in the auto-tracking system, which made the dish scan the moon with +/- a few tenths of a degree, enough to cause some QSB. Normally the dish is used to track fixed objects/positions in the sky. Tracking the moon meant that the computer had to do some extra calculations, which took more time, causing the system to become a little unstable.

This problem was fixed by John the next day. We’d always had good strong echoes but in a QSO with Stig, OZ4MM, he told us that our signal had changed dramatically from the time at our moonrise and some 5 hours later. We now realised that there was an offset problem, which John confirmed and he told us that they had an earlier suspicion to an offset error.

We could easily enter offset corrections into the tracking computer, but it was an educated guess as to where to start and the dish would frustratingly return to the park position (Az=0°, El=90°) to begin a new event every time we changed something. After some time (days!) we had the offset routine optimised. The best way was to turn the dish to a point where the echoes would just disappear on either side of the moon for both azimuth and elevation and then simply aim for the centre point in both axes. We could hear our own echoes with 1W, but could not easily reduce the power further to find the limit. The moon-noise was quite evident which is uncommon on 23cm.

In our preparation we had calculated to be able to work stations having 20dBi antenna gain and 100W so we were especially alert during EU moon set and US moon rise. I don't think we actually worked any non-EME stations but the best effort in real weak signal stuff was our "QRZ PA3..." to PA3DZL calling and 'testing' us with only 10W and a 2.5m dish.

To keep track of common moon windows we used VK3UM EME planner.

Our common windows with JA and VK were limited because the dish could not operate/track below 10° elevation. The limitation was implemented to avoid any inadvertent hazardous radiation when operating at 3MW level.

144MHz and 432MHz, Sondre Stromfjord

Our plan was to use 4 yagi systems on 2m and 70cm which would give us reasonable antenna gain allowing us to work a fair number of stations while keeping the mechanical effort to a minimum.

The antennas were placed approximately 30m apart on opposite sides of the radio shack. The 70cm antennas were mounted on the "scaffold" and the 2m antennas on a wooden post. Both systems were connected by 1 5/8" LDF for the major part of the TX-line, which limited the loss considerably.

Both systems were mounted in a H-frame with an azimuth/elevation rotator, G-5600. It had been our original plan to pre-assemble the H-frames and antennas and to test them thoroughly before everything was shipped to Greenland, however due to lack of time this was not accomplished. Unfortunately, as feared, we encountered problems when mounting the antennas. The G-5600 azimuth/elevation rotator was simply to small for an EME antenna and could not elevate the system without the antennas being fully balanced.

On 70cm we managed to mount all 4 yagis, and with the help of small counter weights consisting of small bags filled with gravel, the system was able to elevate.

After several tries on 2m we had to settle for only 2 yagis, but it was still better to be QRV with 2 yagis than to go QRT with a broken rotor.

Our amplifiers were a 4CX1500 on 2m and 2 x 3CX800 on 70cm both build by Michael, OZ2ELA/OX3LG.

By Tuesday evening everything was ready, with all the equipment installed and the antennas beam heading calibrated. Sun noise was quite strong and we could even hear thermal noise from the ground so we were keen to get started, but of course had to wait for moonrise on Wednesday morning.

Finally we had moon rise, but for the first 20 mins the surrounding mountains and inland ice were obstructing the path. Only once 5 degrees elevation was reached were the first signals heard. On 70cm we soon heard our own echoes but on 2m it was harder with the smaller system. The first QSO on 70cm with DL9KR was run by Michael, OX3LG, with Bo, OX3LX, eagerly watching. Bo then took over while Michael recovered from being the first ever to work a 70cm QSO outside of Greenland. On 2m PE1LCH was the first in the log and soon followed the next stations.

To avoid any interference between 2m and 70cm, we had to synchronise the transmit and receive periods. We chose to use 2 min periods normally used on 2m. All skeds were 30 min where OX2K would transmit in the first period. It was quickly clear that this was not a good solution however, when instead of 2 min periods, suddenly a 4 min period was present at every full and half-hour! This produced great confusion.

We used split frequency operation transmitting on 144.085/432.085, in sked listing on 090 and random 080-085. The majority of people calling us on random used 085, which caused a lot of QRM, especially when the timing sequence went wrong.

It took some time before the systems were running correctly and on Wednesday we finely adjusted the beam heading to make sure we hit the moon. The poor readout on the control units for the azimuth/elevations rotators did not make things any easier.

Unfortunately one of the control cables for the 2m system was damaged and we lost a couple of skeds on Wednesday before the fault was corrected.

On Thursday the input circuit in the 2m PA suddenly failed. This unit was finished literally hours before it was due to be shipped and had been tested for only a limited time with a dummy load. However Michael "the wizard" fixed the input circuit and we were quickly back on the air, without having to setup the spare PA. Unfortunately some innocent HAM's suffered from this incident and they could not understand what had happened.

Despite the limited system on 2m we succeeded with many of the skeds and also some random QSO's.

The best signals were every morning, when the moon rose over the inland ice with 5-15 degrees elevation. Ground gain must have been a factor with the gently sloping ground for the first few kilometres to the east. One of the strongest was W5UN who was 559-579 with or without ground gain as long as the moon was visible!

A good tool to find stations and aim antennas was a DSP FFT program (FFTDSP 4.2) where we could "see" even very weak signals in the LF bandpass. It was the first time any of us had seriously used such a program and it will definitely not be the last!

When all the OX2K stations were up and running we activated 2 HF setups, a 50MHz setup, a 2m setup, a 70cm setup and 23cm at Kellyville. Consequently due to lack of operators it was difficult to keep all the stations running which meant that some EME-operators had to do 20 hours shifts. This was far from ideal, especially for the operators, but the result was reasonably good. Sometimes the 2m EME operator was assisted by a non-CW/EME operator to press a button on the memory-keyer or to "look" for signals using the FFTDSP program.

In retrospect it is fair to say that the expedition was a huge success. Given the remote location, the limited amount of equipment and the fact that we managed to work EME on 3 bands simultaneously, the result is VERY good.

In the near future the 2m antennas from Force 12 will be mounted permanently. We also intend to install a 2m PA to make future DX-peditions more simple.

Besides working EME we were also active on 1.8-50 MHz and for all of us it was probably the greatest experience we’ve ever had as radio amateurs, and most of us are already thinking where we should go next.

73 de OX2K

The results for 2m, 70cm and 23cm EME:

144 MHz: 36 QSO (primarily skeds), 36 initials, 15 DXCC, 12 first time and 3 continents

432 MHz: 39 QSO (primarily skeds), 35 initials, 15 DXCC, 15 first time and 4 continents

1296MHz: 113 QSOs (22 in SSB), 76 initials, 20 DXCC, 20 first time, 5 continents.

We succeeded in working HB9Q, SM2CEW and WA4NJP on both 2m ,70cm and 23cm!

Technical data:


OX2K-Kellyville, GP46MX.

TX: Icom IC-1275, PA: SSB-electronic, TLA 1270-100 B 100W.

RX: Yaesu FT-1000MP, SSB-electronic LNA, SLN-series nf < 0.3dB.

Antenna: 32m dish, 49dBi.

Software: VK3UM EME planner, Nova for Windows, Spectran DSP display.

OX2K-Sondre Stromfjord, GP47TA.


TX: Yaesu FT-847, PA: 4CX1500A
RX: LNA: SSB-electronic LNA-145 nf < 0.4dB
Antenna: 2 x 20 el. Force 12


TX: Yaesu FT-847, PA: 2x3CX800A7
LNA: SSB-electronic LNA-435 nf < 0.4dB
Antenna: 4 x 28 el. model 432-9WL

Software: Nova for Windows, FFTDSP 4.2 by AF9Y.

Our sincere thanks to

- the site maintenance crew at Kellyville and especially John Jorgensen for all his help

- Dansk Mikrobølge Teknik for the SSB-electronic Low Noise Amplifiers

- Northern Lights Software Associates, NLSA, for Nova for Windows

- AF9Y, FFTDSP 4.2

- Force 12 for 4 x 20 el. 144MHz yagis


OX2K homepage Download OX2K echoes

SRI homepage

Dansk Mikrobølge Teknik

Force 12

Northern Lights Software Associates


For more general infomation about Greenland