May 2013: Murphy in the Rain

Last year Mr. Murphy was a frequent guest at DR9A. Not only did he make us climb the mast twice during the July contest. He made sure Henning DF9IC would suffer from a bad lumbago in time, so we had to cancel our participation in the October contest.

Thus we all looked forward to the May contest this year. As the new 13 cm dish was prepared already for the October contest but never tried so far, we all were keen to try out a new band.

Unfortunately Mr. Murphy was again paying us a visit during contest preparation. He made sure, that during the final test of the 13 cm PA on Wednesday the sequencer broke and had to be replaced. And that the only available TLC393 died in time and out of the ten unused, brand new relays available in the box the one picked was broken. So Henning DF9IC had a hard time already. Both Helmuts (DK8SG and DB1TP) did not do much better packing the van for 144MHz, the small 2C39 driver PA that worked flawlessly over the years did not like the van at all - in the lab it was ok though. But all this of course could not stop us, the van was driven up the hill already Thursday evening and the 144MHz antennas installed to give us some head time on Friday.

More or less in time Helmut DK8SG, "tall" Helmut DB1TP, Henning DF9IC, Alexander DL8AAU and Ralf DG3IAM started to build up the rest of the antennas on Friday morning. Thomas DF8IJ, Suad DK6XZ and our guests Martin DL5NAH and Oliver DL1SFK joined in the afternoon. The next task after the 144MHz antennas is our 5GHz WIFI link - again to Ronny DK3UO, who had already provided our internet uplink in September last year - but in the meantime, he has moved to a new place. Another test from the lookout tower on Monday had proven the link to be working, after Ronny had installed his bridge on his 20 m mast in spite of the bad weather. But the link already gave us the first headache: Mr. Murphy decided to become a permanent member of our crew. We had to install and tear down the dish and rotator three times to get it working... - The following installation of the 432MHz antennas went smooth, so that we could start the challenge to get the 13cm dish and equipment in place in the early afternoon. With many helping hands it proved to be easier than expected. The azimuth indicator behaved a bit strange, but we could hear the DB0SHF beacon through the trees and the power meter in the shack went all the way to the right... - everything looked good. Too good probably. To get us back to reality, it started raining. Not too heavy at the beginning, but steadily, so we slowly got soaked while installing the 23 cm antennas. Especially the quados proved to be unpleasant to install, as you have to look up into the pouring rain all the time. Not to mention the RCD that blew twice resulting in a 300m walk for Helmut to reset it.

Paying more attention to the non-working dish rotator azimuth display we found a strange problem: the potentiometer resistance was measured 500 Ohm with a meter - but when connected to the indicator box the applied 5V dropped to few 100 mV through the series protection resistor. A lab power supply also sensed more or less a solid short circuit. How could that happen? A quick "visit" to the dish in about 15 m above ground could prove that whatever it is, it is inside the rotator. If you disconnect the cable, no short circuit anymore... We decided that the Ohm meter will do it as direction indicator for the contest.

Rain did not stop over night, and by Saturday morning the whole place was more like a swamp. We erected the mast to full height and realized that we could not copy GB3MHL on 23 cm. After some analysis we concluded that the relay in the pre-amp box that switched between the two yagi groups was not activated for whatever reason. Fortunately the rain stopped, so Alexander DL8AAU could climb the mast again and tried to figure out the cause for the issue. One of the cables was not attached well enough to the box, the issue was gone after replugging. Not well understood, but it was good for the whole contest - maybe Murphy was distracted? - Probably not, the 13 cm transmitter did not want to output any power anymore. Not even the not so quiet cooling fan did turn on - should all the hard work of preparing the outdoor PA and power supply be for nothing? It seemed to be the case - RX fine, lots of beacons could be heard, but no power on the meter. So again a three band contest - as usual. 15 minutes before the contest all three remaining stations 144 MHz, 432 MHz and 1296 MHz had been installed and were operational.

We started the contest in time and 2 m and 23 cm worked pretty well, 70 cm had no RX the first 10 minutes, but was ok after playing with the cables at the transceiver. After a few hours we were reminded of Murphys presence when a station mentioned cuts on the 23 cm modulation. 30 min later, the IC7400 completely stopped to output any power. Luckily the 13 cm station used the same kind of transceiver - and as 13 cm could not transmit anyway, swapping the devices solved the problem for some time. Until one hour later the third IC7400 transceiver in the shack used for 70 cm seized to receive anything again - this time for good. As we ran out of working IC7400, we tried a K3, but could not find a good microphone. So Henning had to drove home - a one hour drive one way - to fetch his last remaining IC7400 instead of taking the late shift on 23 cm... Not to mention the 144 MHz PA that broke and had to be replaced. When the shit hits the fan... Only positive aspect: the RX of 13 cm seems to work fine, G3XDY could be heard well - and the internet link worked flawlessly this time.

The next day finally started with lots of sun and a blue sky. One last highlight was a test on 47GHz from the lookout on the Hohloh with Andreas DL2FZN on the Lemberg tower JN48id - the highest point of the Swabian Jura ("Schwäbische Alb"). Murphy slept a bit longer that day, but did not miss the opportunity to make us forget the power supply cable of the IC202. So climbing the 28 m high Kaiser-Wilhelm tower twice for the test... Unfortunately we underestimated the height of the trees south of the Hohloh; unfortunately we could not make the QSO.

The final result was just ok, we did 867 QSO on 144 MHz (332k, ODX 959 km YT1S), which is worse than 2011. On 432 MHz we reached 135k and on 1296 MHz about 62k.

Tearing down the whole station and packing the equipment was rather slow this time, we left the place around 9 pm. Overall a bit disappointed as the competition again was better than us and the 13 cm equipment failed despite all the work spent to build it.

It can only get better in July...

During installation the dish is accessible from the roof of the van.

Then it is swiveled to North East, lifted up, and the lower support is added.

Quados in the rain, waiting for their application.

Sunshine on Sunday, after 36 h of rain.

Secret camouflage antennas on the left arm - but they didn't help.

47 GHz test from the nearby tower.