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SP/OK1DFC
10 GHz - 24 GHz 17th of August - 19th of August 2023
last update on 26.08.2023 |
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Micro EME dispatch to SP in 10 & 24 GHz bands During the EME and MW meeting in Zielenci, I made a small EME expedition, this time only in 10 and 24 GHz bands. How it all turned out in the sequel. Micro EME expedition SP/OK1DFC in JO80EI - QTH Zieleniec When I got an invitation to Zieleniec for an EME and MW meeting, I thought to dust off my portable EME setup and try to make some contacts. I was asked to do some lecture on 24 GHz, so I chose 24 GHz as the band to demonstrate as well, and brought 10 GHz as a supplement. The plan was to arrive on Thursday, set up and test the equipment and main operation on Friday and Saturday. But the weather was against it, so everything was different. I had no idea that this micro expedition would give me so much new knowledge to operate in the 24 GHz band. So, first of all, about the weather. On Thursday, August 17, I arrived at the site and started to build the workstation. The tripod, rotator and dish were ready in an hour. I still set up the dish control in AZ and EL in the sunshine on the table outside the tent. Just as I started to set up the tent, the first storm rolled in. I somehow hid everything and waited for it to pass. The heavy rain soaked the landscape and in about an hour I was able to continue. I anchored the tripod with the dish and finished the workplace in the tent. I managed to rectify the dish and then the sun set behind Sherlich. I cleaned up what I could and went to have dinner and sleep. On the morning of Friday, August 18, I had anoncited activity in the 3 cm band. After an early breakfast I got everything ready for 10 GHz operation. Measured the Sun noise, 13 dB, and then the Moon noise, 1.5 dB. So everything looked great, and I announced on HB9Q that I was QRV. It was easy to make several contacts on 10 GHz. Then I changed to 24 GHz. At low elevation, the Sun was only 9 dB and the Moon 0.9dB. A hint that the high humidity would be against any major activity on this band. OK1KIR were on HB9Q, so I immediately asked for a test. I decoded them easily, -15DB, but nothing for them. I was still monitoring the Moon noise, which was 0.4 to 0.5dB less against normal than I should have. Meanwhile, it started raining again and another storm came. The humidity was 92%, a killer value for the 24 GHz band. Since the spread was also over 550 Hz, we agreed to do another test when the rain passed for the afternoon. So in the evening we tried the contact and the first attempt I decoded OK1KIR again - 19DB, they did not decode me. Then I notice that instead of decoding at 700 Hz at Q65-60E, I decode OK1KIR at 1000 Hz. Clearly, the broad spectrum of the Q65-60E does not pass the entire USB filter, and so they don't decode me. I don't understand the 300 Hz difference at the moment, but Vlad OK1DAK at OK1KIR has tuned 300 Hz down and bam, I decode them easily -17 and they get me -32 in the AVG window. So the first connection is home. The moon is setting behind Sherlich again, so I'm packing up and getting ready for the morning when I'll sked with JA1WQF. The morning of Saturday, August 19, I am back in my tent early. The temperature rises quickly in the morning and with it the humidity in the air increases. I measure the noise of the sun and moon. Again misery with distress. The path attenuation is enormous due to the passage of the signal through the atmosphere. At 08:40 I start calling JA1WQF. Unfortunately, I can't hear, can't see, can't decode. JA1WQF is the same, and the moon is still setting among the trees, so they are the only ones on the band OK1KIR, with whom we try a contact at 09:24. Since we already know about the 300 Hz deviation, the contact is a matter of moments. The sun is rising higher and higher and the temperature is climbing towards 30°C. I open the tent, which is impossible to stand in the heat. Mirek OK2AQ arrives and we discuss for a while the possible problem of 300 Hz deviation. Mirek suggests to turn off the 10 MHz GPS normal and turn on the internal OCXO Morion in TRV. At 10:43 we try the OK1KIR contact again and everything is clear. I'm on the right frequency, and decoding is also easier. -17/-22 DB. Experimenting has stimulated a lot of interest among the hams present, and so it's busy around the tent. Questions about all sorts of EME traffic are being discussed in circles. Just before moonset, it is getting slightly cooler and the humidity seems to be dropping. Around 17:00 it's only 64%. Geert PA0BAT wants to try a contact. After previous experiences I am not very hopeful, he has only 11 W but a 3 m dish. The moon noise slowly climbs up as the humidity drops. Soon it is already 1.1dB. At 17:27 I start to call PA0BAT. Geert is excited, decoding all my transmission periods. Soon I decode his as well and the -15/R-17 link is home. Great joy on both sides. Then the moon sets and the game is over. I have to pack up and get everything ready for Sunday's trip home. In conclusion, I must say that despite the small number of contacts I have gained a huge amount of information and data. It clearly shows that there is no summer with high temperature and humidity on 24 GHz EME. I also verified that pointing into rain clouds against a cold sky will raise my receive noise by 1.5 to 1.8dB depending on cloud density. All of these findings have quite a profound effect on the ability to make EME contacts when signal levels are at the very limit of reception capabilities. If we had power on the order of 100W and not just 20-23W, things would certainly be different, but that's for another story.
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180cm dish and 10 GHz TRV in feed point
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Setup of work place in the tant
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