DARC µWave Contest

The DKØNA team enjoyed sunny warm weather during last week’s contest which was dedicated to >1 GHz amateur radio bands. First time, we used 3 antenna systems on 23cm which worked very well, especially the new quados antenna created a new contest feeling on 23cm. The results were almost perfect. Based on claimed scores, the team achieved 2nd place on 10 GHz but 1st place in Europe on all other bands. Please find the claimed scores: slovhf.net/claimed/

New 144 Antenna

After 25 years of operations w/o any problem, the 144 MHz 9 element Yagi antenna had very poor SWR. Either the antenna feed system or the coax cable was defective. So, I decided to replace both, the antenna and the feed cable. The bigger problem was to rent a car with lifting platform. With the help of my brother DL3AKA, the replacement was successfully done and I returned on 2m band again. Now I hope that it will run another 25 years…

2nd VHF/UHF/µWave Contest @ DK0NA

Contest operating is always fun, especially with good friends in multi operator section. We used the new 23 cm quados antenna (made by DB6NT) as 2nd antenna first time. Exciting. Sure, we were also satisfied with the results on other bands.

Good start into the V/U/SHF contest season

After a very successful 2022 contest season with DLØGTH, I joined the DKØNA contest team for the 2023 season. The location in JO5ØTI usually is not the best in Europe but in winter conditions it was an advantage to operate 700m a.s.l. Even there, we had problems with ice on 70cm antennas forcing us to install a backup antenna which worked well. The tropo conds were poor with a rather slow start into the contest. Even with some small technical problems we were more than satisfied at the end of the March subregional contest.

UKW Europa Diplom

Applications for most of amateur radio awards can be done online meanwhile.  Good for lazy OMs like me who always disliked manual handling of QSL cards and paper based application processes. Therefore I was happy that the DARC  UKW Europa Diplom application is now also possible via DCL and I used the opportunity for an Trophy class application which was immediately approved.

FM Hotspot

The activities on VHF/UHF FM repeaters have been decreasing for some years, even with increasing number of repeaters. However, I realized that this  changed in past two years. And I was wondering that quite distant stations were working via local repeaters. The reason for that are linked repeaters. Linking FM repeaters was not really new but limited to a few ones. Then a team of enthusiasts began to build a larger network using SM0VCX svxlink software. It moved from Thueringen-Link to FM-Funknetz with >200 stations online, including many stations using hotspots. Even, I can work about 50 repeaters from my location, it just triggered my interest to experiment. So, I bought a DJSPOT device (designed by Gabriel BV5DJ)  running on Raspberry Pi Zero. Features well known in digital modes (DMR, DSTAR, YFS) are no available in FM too. And the device can be also run as Echolink node.

Airplane Scatter with plane data from Hams

Thanks to Thomas’ (OV3T) initiative to setup  ADS-B data servers fed by hams, DL2ALF made these servers available in his great Airscout software.  All Europe is already well covered and we all can benefit from this independent data source in 2023 contest season and other DX. I am happy to help with my ADSB RX data from JO50.

2022 Weather Review

The year 2022 closed with new records. Mean temperature at my home location was 10.8°C which is 2.4K above reference, the warmest year ever.  April was the only month with relatively lower temperatures.

Even worse than temperature deviation was the precipitation of just 378mm which is 34% below the reference level. I could see the impact every day in my garden.

Still, some people doubt global warming. Unbelievable.

Good Tropo ConDX on 144 MHz

There has been some good tropo conDX around for some days. Howewer, better for stations north of my QTH. Today it was good to north-east. Unfortunately, I have poor takeoff in that direction with a hill 100m higher in just 1km distance. Nevertheless, I managed to get some Belarus stations in my log.

IARU-VHF-CW-Contest (Marconi Memorial)

The Marconi Memorial Contest is the last major VHF contest of the year. And it is the only one CW only. This was the only contest I participated from home while I operated the other VHF/UHF/SHF/Microwave contests as member of the DLØGTH contest team. Unfortunately, another OM decided to operate just one 1 km distant to my location causing some QRM of S9+ across the whole band 😒

This resulted in some limitations for me. I was simply not able to operate when the other station called CQ. So, I looked for some time slots when QRM was not there or sufficiently reduced. Nevertheless, I managed to work 177 stations in about 10 hours effective time resulting in a (claimed) score of 56.000 points.

The conditions were below normal. Most activity from eastern Europe:


ADS-B RX Upgrade

My ADS-B RX has been running for two months and I am still looking for some improvements to increase the range, number of airplane messages decoded. The first big step was a LNA and 1090 MHz filter between the antenna and RTL-SDR receiver. On the software side, I added an automatic gain control.

Today, I replaced the RTL-SDR stick by an Airspy R2. This SDR RX has much better performance. On the downside however, it also requires much more computing power. It pushes the Raspberry Pi 3B with 1GB RAM to its limits.

Some graphs with situation before change (RTL-SDR before 8am) and after (Airspy R2 after 8:15am) can be seen in this PDF: graphs1090_ Performance Graphs

Links to my ADS-B life data can be found here: https://dl2akt.de/links/

IARU UHF/SHF/µWave Contest

This was a contest I would call ‘not as planned’. DLØGTH planned to operate from our home contest QTH on Schneekopf in JO5ØJP. Because of very bad weather forecasts with a lot of rain and wind >100km/h, we decided for the safe option and went to JO5ØTI again. Thanks to DKØNA team! This was really the right decision because even at lower altitudes, the weather was really bad. So, we decided to operate with the antennas available, i.e. we did not use any additional antennas. E.g. just one antenna for each band.

With such a limited setup, our goal was to end the season with a good result sufficient to win the German contest trophy. We never thought that we could achieve any good results on European level.

At the end, it worked much better than expected and Sunday afternoon the conditions became a bit better which enabled some very nice QSO in the last two hours of the contest.

IARU VHF Contest on 3rd and 4th September

DL0GTH returned to its home contest QTH at Schneekopf mountain in JO50JP for the most important 2m contest of the year. We are still limited in terms of operators and therefore, we used a rather lean equipment with just three antenna systems on top of small masts. Still, we had a lot of fun. The contest started rather disappointing with very poor conditions with rain. But it significantly improved at night and at the end we were very satisfied with the results achieved. 1080 QSO and ~400k points.

Now, we are looking forward to the last big contest event in 2022, the UHF/SHF/Microwave contest on 1st and 2nd October.


LNA+SAW filter added to ADS-B RX

I added 1090 MHz LNA and SAW filter made by Nvarcher to my ADS-B RX equipment. It is directly connected to the 5.5 dBi antenna and power supplied by USB-C. The device remarkable improved the RX, adding >10dB dynamic range resulting in about 50% more airplanes ‘seen’ and stable DX >400 km. You can find the situation befor (w/o LNA/SAW filter) and after (/w LNA/SAW filter) in the embedded PDF  document: graphs1090_ Performance Graphs

Now I am considering to replace the RTL-SDR.com USB stick by Airspy R2 SDR RX and more antenna gain with a collinear antenna which may provide another ~10 dB dynamic range.

ADS-B SDR RX up and running

Because of some issues with airplane feeds into Airscout, I decided to set up my own ADS-B RX and feed data to several feed servers including Opensky, adsbexchange and Adshub. There is a nice receiver kit promoted by Opensky but sold by Jetvision (owned by DL4MEA) which I bought and installed in less then an hour.  The kit description and easy installation guide provided by Opensky: https://github.com/openskynetwork/receiver-kit

Finally, you can watch my ADS-B feed at https://opensky-network.org/receiver-profile?s=-1408231534


DARC Microwave Contest

The DLØGTH/p team had great fun on 5th and 6th June in the DARC Microwave Contest. We operated from DKØNA location in JO50TI again. We enjoyed very good rain scatter condx. Since we always try to improve our equipment DL2ALF designed a new switch box (see picture below) which enable to switch all transverters and antennas directly with Wintest band change key. Less chance for operators mistakes. Finally, we are also satisfied with the results achieved.

Station setup with the new remote switch box (middle of the picture)



Almost final results


The Radio Society of Great Britain honers DL2ALF.

‘1962 Committee Cup – awarded for outstanding amateur development at VHF/UHF. Awarded this year to Frank Schmähling, DL2ALF for the outstanding development of AirScout software for aircraft scatter.’ See facebook.com

Congratulation to Frank for the great achievement.

Thuringia Ham Meeting

Radio amateurs of Thuringia met in Mühlhausen on 14th May. It was the first of its kind Ham radio meeting for more than two years. Unfortunately, the participation was rather poor. Maybe, some Hams were still concerned of COVID19 or just because the location was a bit remote for most regions. However, I enjoyed to meet some old friends as well as watching very interesting presentations.