The path between JP90JC, Grisslehamn and JP90SF on Ecker/land is 44km with only some low rocky islands in the LOS (Line Of Sight).
SM0RPT is preparing the 24GHz equipment. The picture show the path from Ecker, land JP90SF toward JP90JC.
The first attempt on Friday on 24G was easy with very high signal strength.
47GHz part of the test.
Pertti had made a 47GHz station that is capable to deliver 50mW, which is QRO on 47GHz. He has mounted both 10GHz and 47GHz antennas on the same boom. This make the antenna alignment easy, as 10G is used for optimizing the antenna the other station.
OH2AXH is setting up his portable station in JP90SF
SM0DFP fixed station has also all microwave antenna arrangement on one boom. Antennas are 24m agl and 40m asl.
SM0DFP fixed antennas for microwave.1.8m dish for 1296, 2320 and 3400MHz, from left 24G, 5G7, 10G, 47G parabolic dishes.
The fixed 47G rig has only 0,25mW output, so Pertti need to be >23dB above the noise at my end before he can expect to hear my sigs. As a back up, we can use the SK0CT Rover and go portable to the water front. SK0CT 47G beacon is able to switch from automatic CW ID to manual key CW, and deliver 20 mW. It is used as part of the Rover.We started with my fixed station doing 10G alignment, it looked very promising with strong signals, so strong that it caused overload on my SDR-IQ. We had to go QRP to be able to have usable S-meter indications. When QSY to 47G, nothing was heard. After some discussions over the phone, we decided that the OH boys joined Johan with the ferry back to Grisslehamn. Here we could make a check of the equipment in a controllable environment.
We started the SK0CT 47G beacon, turning the antenna to the sky to limit the signal strength. And yes, we could receive the beacon, but Pertti's rig only produced a 559 signal whereas my rig received a 599+40 signal. After some fault finding, we quickly found the culprit, a newly installed 47GHz BP filter that was not tuned. The tuning screws were lose, indicating that the filer was never tuned. In spite of several attempts to tune the filter, using the beacon as a signal source, we gave up and decided to simply remove the filter. This was easier said than done, it took two hours to remove the filter as the rig had to be taken apart in order to reach all little screws that hold the wave guide plumbing in place. After re-assembly of the rig, it worked much better, both on RX ant TX. The unwanted mirror frequency was a minor problem at this stage.
OH2AXH assamble his 47GHz rig after repair.
Pertti and Jukka stayed overnight at SM0DFPs place. After a quick cup of coffee in the morning they returned to Åland with the morning ferry on Saturday.
Breakfast in Grisslehamn, from left, OH6DD Jukka, OH2AXH Pertti, and SM0DFP Per.
When in Åland, they set up the station and I used my fixed station and we aligned antennas on 10G, then QSY to 47G, and now I heard some weak sigs. We never got the sigs up above 5dB over noise. As we must have at least 20dB signal in my end before any sigs were expected in the OH0 end, so we decided to go for plan B. i.e. using the SK0CT's rover and go to the water front, about 800 meters away.
About 40 minutes later we got usable signals both ways on 47G and could complete a QSO with 559/559. The distance is 44km, breaking the old SM record of 27km. We were quite surprised that there was such an improvement in signal strength when at sea level with antennas.
After the QSO we decided to make an attempt to extend the distance. Pertti and Jukka had found a good place in JP90VC at a distance of 55km from JP90JC. We decided that the best time to try was in the early morning on Sunday. As I had quite strong wind, nearly making the antenna tripods fall over, I wanted to go to another place, a bit more sheltered from wind in the Sunday test.
On Sunday morning all looked ok when again aligning antennas, and we moved from 10G to 47G, we were very surprised that the signals were nearly equal in strength. The ERP difference between the bands is about 30dB. We quickly exchanged 599/599 reports on 47G.
Setup in the SM end, produced peak 599+40dB signal strength.
The signals were about 599+40dB when peaking, indicating there is good margin to allow for a much longer path. We also saw that the antenna direction was uncritical, same observation in both ends.
Some things worth noting.
1. Antenna is not necessary producing best signals when placed high. In our case, the signal strength increased in the order +20dB when lowered from 40m to 5m asl.2. Once the antennas were in the duct at sea level, the antenna direction was uncritical. +/- 10 degrees gave no noticeable difference in signal strength.
3. The signal strength was proportionally better on 47G compared to 10G when antennas were in the duct.
Extract from the log book:
2011-Aug-05-1252 UTC OH0/OH2AXH
JP90SF - SM0DFP JP90JC 24GHz 59/59 44km
2011-Aug-06 -1314 UTC OH0/OH2AXH JP90SF - SM0DFP JP90JC 47GHz 559/559
44km
Second
attempt to extend the distance on 47GHz
2011-Aug-07-0514
UTC< OH0/OH2AXH JP90VC
- SM0DFP JP90JC 47GHz
599/599 55km
Metrological data
2011-Aug-05-1252 1005hPa,
Humidity 81%, Temp 23C, Wind 5 m/s
2011-Aug-06-1314 1002hPa, Humidity 69%, Temp 24C, Wind 7m/s
2011-Aug-07-0514 1098hPa, Humidity 61%, Temp 19C, Wind 2 m/s
No vertical profile is available.
Video recordings (a bit shaky)
First SM - OH0 24GHz QSO
First 47GHz signals heard from OH0 in
SM, but no 2-way QSO yet
SK0CT Rover setup 1
SK0CT Rover setup 2
First SM - OH0 47GHz QSO 44km
Second SM - OH0 47GHz QSO 55km
(c) SK0CT