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:

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 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:

Finally, you can watch my ADS-B feed at


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

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.

70 cm FT8 Activity

70 cm FT8 activity is scheduled every 2nd Wednesday evening of the month. I participated the first time on 13th April. Since I did not use FT8 on 70 cm in the past a lot, I could log a lot of first contacts, in total 25 QSO. ODX was the QSO with John G3XDY almost 700 km. Not bad with  75W and single 16 element Yagi antenna and rather poor propagation conditions. Sure, I will check the 3rd Wednesday of the month when 23 cm activity in scheduled.

HRD Logbook upload to

HamRadioDeluxe is a great ham radio software suite with a lot of dedicated tools and features. Its HRD Logbook has also capabilities to sync  with other databases including LOTW, eQSL but also I had some problems with which was caused by blacklisting of one of their servers. It took me some time to debug but finally Mike VK4EIE provided the important info that data is uploaded to (instead of just It is not any email protocol used but just port 80 (html) for that purpose. For some reason was blacklisted and therefore caused upload fails. After was whitelisted the software worked perfect for the purpose.

Lessons learnt: In the good old days, hams were busy to fix problems with their transceivers or antennas. Today, we spend more time to fix software or Internet issues.

Nice Tropo ConDX on 13/14 January

Good tropo condx to UK on January 13th and 14th. Completed QSO >500km listed.

13.01.2022 08:07 IV3BLQ JN65 -9 1 FT8 613km
13.01.2022 15:34 G3YDY JO01 -18 -16 FT8 711km
13.01.2022 16:41 SP9EYX JO90 -11 3 FT8 553km
13.01.2022 17:24 OZ5TG JO45 -9 9 FT8 534km
14.01.2022 08:18 G4DKB JO01 -24 -5 FT8 711km
14.01.2022 08:22 ON5ZZ JO11 -24 -14 FT8 573km
14.01.2022 08:26 G4DCV IO91 -17 -20 FT8 850km
14.01.2022 08:30 G0VUH IO93 -16 -22 FT8 878km
14.01.2022 08:39 G7IGC IO92 -19 -17 FT8 857km
14.01.2022 08:43 G3TCG JO00 -18 -20 FT8 717km
14.01.2022 08:44 M0MIZ IO91 -24 -8 FT8 850km
14.01.2022 08:47 G4YTM IO93 -16 -7 FT8 878km
14.01.2022 08:54 M0AAX JO01 -5 -9 FT8 711km
14.01.2022 08:54 GW7SMV IO81 -3 -9 FT8 988km
14.01.2022 09:05 M0PNN IO82 -14 -14 FT8 992km
14.01.2022 10:38 G3TKF IO81 -22 -3 FT8 988km
14.01.2022 10:40 M0CFV IO91 -18 -7 FT8 850km
14.01.2022 10:57 G6WRW IO82 -9 -7 FT8 992km
14.01.2022 11:15 MX1SWL/AIO91 -14 -14 FT8 792km
14.01.2022 11:27 G4ZZL JO01 -23 -9 FT8 711km
14.01.2022 11:30 M0JVN IO91 -22 -3 FT8 850km
14.01.2022 11:32 G4CKS IO91 -22 -20 FT8 850km
14.01.2022 11:35 G0JCC IO82 10 14 FT8 992km
14.01.2022 11:38 ON4ASV JO11 -17 -19 FT8 573km
14.01.2022 11:43 M0GGO JO01 0 0 FT8 711km
14.01.2022 11:45 M0FXX IO91 -3 -11 FT8 850km
14.01.2022 11:49 G6CPX IO92 -7 -6 FT8 857km
14.01.2022 11:55 G3ZSS IO90 -18 -8 FT8 857km
14.01.2022 16:27 G3TCG JO00 2 5 FT8 717km


It was a great pleasure to participate the Marconi Memorial Contest on 2m in CW from home QTH in JO50NV. Operatung about 10 hours only, I was quite satisfied with 185 QSO. Conditions were not really great.

IARU Region 1 UHF/SHF/Microwave Contest

DL0GTH focused on 70cm during the contest which took place October 2-3. Unfortunately, some OP were not able to join the team resulting in no activity at DL0GTH on 23cm, 13cm, 9cm and 6cm bands. Nevertheless, our small team had a lot of fun in the contest. Congratulations to DR9A who have likely won the contest.

IARU Region 1 VHF Contest

DL0GTH participated the contest from Schneekopf in JO50JP on 4th/5th September with much smaller than usual equipment. Nevertheless, the results achieved were much better than anticipated with such reduced equipment: 1086 QSO and >410000 points. Looking forward now to the October UHF/SHF/Microwave Contest.

July VHF/UHF/SHF Contest

Even, I participated a few hours only, I am quite satisfied with the results. No skeds, no airplane scatter software use.
144 MHz: 101 QSO, ODX IQ5NN 823 km
432 MHz: 20 QSO, ODX OM6A 583 km
1296 MHz: 10 QSO, ODX DG2GR 192 km
Now, I am looking forward to September IARU-Region 1 VHF Contest. DL0GTH will be QRV again from JO50JP in multi OP mode.

Returning to normal life

Fortunately, new Covid-19 infections went down significantly, shops and restaurants are open again and I am looking forward for some ham radio events. I also got my second shot of vaccine and feel much more safe now. Likely, I will participate July VHF/UHF contest in Single OP category still. But I am confident that DL0GTH will operate as Multi OP station in IARU-Region-1-VHF contest. CU on the air.