ARI EME Contest - Autumn part - 19-20th September 2020
Within a week of last weekend's ARRL EME MW, I was starting my second shift until late at night on the construction of a parabolic antenna, or rather an EME antenna station designed for microwaves. I was able to set up the antenna, measure whether it was geometrically correct, put everything in a "watermark" and, most importantly, get the control system working. I use the F1EHN system, which allows you to track the antenna position to an accuracy of 0.01°. I added only power control of engine speeds, which is essential for such position differentiation. Everything was in place by Thursday night, so I kept the antennas with Sun noise to calibrate the Friday before the ARI contest. I watched it all day so I could store corrections in my F1EHN memory. In the end, the system turned out to be so stable and solid that all you had to do was store the error correction that always comes from connecting the sensors, because no matter what you do, tightening the screw on the flexible coupling so that it doesn't run off by at least 0.5°is a miracle. But all it took was one correction for the whole period. I was very surprised that I could use the same correction error for the 24 GHz band as well.
Friday evening, I still had time to make three test QSOs. It was with Mirek OK2AQ, Hark PA0HRK #64 and IK6CAK. The antenna RX perform brilliantly, and the measured parameters of Sun noise 14.6dB and Moon 2dB are exactly as calculated from the VK3UM calculator. It's the first system where I've met a tenth of a decibel with a calculation. So on Saturday morning, after the moon raise, I started working in the 10 GHz band. I managed to do everything on the band, so I decided to devote Sunday morning to the 24 GHz band test. Calibration of the antenna was not necessary, it all matched the parameters of the 10 GHz band. So I measured the noise of the sun, 12.5dB, that's 2.5dB better than the previous Prodelin antenna. In the coming days, I'll still be working on optimizing the feed's position in the focus of the dish. I wrote about the reasons last time, this new antenna is calibrated to 38 GHz and so it had to show up somewhere. Unfortunately, the moon is now very low on the horizon, with a maximum of 26 degrees on Sunday, and the parameter about measuring its noise is degraded by atmospheric attenuation and other influence. Still, I measured 1.8dB. No one was on the band, however, but thanks to the new EME DL0SHF beacon at 24 GHz, I was able to test the reception as well. Everything was functioning normally. A beacon of awesome power, although the spread on the signal was 360 Hz !!! Then came Manfred DL7YC, who is QRV of JO62, so the moon is even lower on the horizon these days. We waited until about 1 p.m. UT, when he was supposed to have the horizon clear and see the moon. We tried the QSO and it came through with tremendous signal, perfect decoding despite the 345 Hz spread. Exchanged reports -10/-17DB. So 24 GHz works too. With the new 24GHz feed horn Mirek OK2AQ designed for me, I can hear my own echo. I look forward to the trials when there's a really microwave EME window. In October, there will hopefully be a chance to do the measurements again in the 47 GHz band and try some QSOs at 24 GHz.
Used new dish 2,6m
DL0SHF CW 24 GHz - 559 easy copy
QSO QRA64D with Manfred DL7YC left print screen and waterfall with visible spread on ton 364 Hz
|18/09/2020||14:40||PA0HRK||JO22DC||-11||-14||10 GHz||QRA64||#64 JT||755|
|19/09/2020||09:24||UA4AAV||LO21||-08||-10||10 GHz||QRA64||#65 JT||2138|
|JO62PK||-10||-17||24 GHz||QRA64||#12 JT||291|