DC6GF on Air


My QSL Card

Since winter 2022, I started to bring DC6GF on air again from my new QTH. After a long pause from amateur radio activity, I decided to become QRV on shortwave for the fist time.


USB sound card and PTT adapter.

The TRX I use is a IC-706MK2G that I used exclusively on 144MHz until now. The tuner matches the capabilities of the TRX regarding power and the digital interface was improvised from existing components, packaged in a 3D-printed housing. It contains the sound card and the RS-232 interface for PTT control, both attached to one USB port using a small hub. The antenna I use currently is a GPM-1500 but a better one is already available. However, as some adaptions are required, it will be installed after some other projects are done. The cable between the tuner and the antenna is a 7mm type from Messi & Paoloni.

Achievements until now

Since my first QSO mid of march 2022, the QSO count in FT8 and FT4 is nearly 1000 and I reached 106 DXCC countries including New Zealand which is about as far as it can get from my QTH. 89 of them are confirmed via LoTW. I also set-up an E-QSL account, however, I did not manage to upload my log.

Lessons Learned

For most experienced operators, these findings may be obvious but from my short time of activity, I learned the following:

  • Propagation predictions are about as accurate as the weather forecast. You have to be on the band to see how the propagation actually is.
  • Especially on weekends, QRM is the most important limiting factor to reach the DX station. Although the band may seem empty, there are tons of other stations near you you do not hear (or see in the waterfall).
  • As a result from the previous point, FT4 sometimes is the better choice for low power stations compared to FT8 just because the FT4 frequencies are not as crowded as the FT8 ones.
  • Split operation is an important capability for successful FTx operation. If you answer on the same frequency, chances are very high you are not alone and neither of you is heard. If you answer on a different frequency, the chances of being copied are much higher.
  • The (my?) IC-706MK2G changes its output power significantly over the NF frequency band. Highest output power can be achieved between 1500Hz and 2500Hz.

Things to do…

The following things are on my short term agenda:

  • QSL cards are ordered. As soon as they arrive, I will try to have the last 11 missing countries confirmed to apply for the Digital DXCC.
  • Find out how to configure E-QSL to accept my log from CQRLOG.
  • Learn CW. A paddle by CT1ILT is already on its way.
  • Set-up my alternative vertical antenna.

DB0SIG wieder auf Sendung

Nach einem etwas längeren Serviceaufenthalt, ist DB0SIG seit dem 12. Juni 2022 wieder auf Sendung. An der Hardware selbst wurden keine Änderungen vorgenommen. Alleine der Aufbau wurde etwas stabiler gestaltet (der 3D-Drucker muss ja schließlich genutzt werden) und nach dem Einsatz von roher Gewalt lässt sich der Deckel des Gehäuses nun auch tatsächlich ordnungsgemäß schließen. Auf der Softwareseite wurde der etwas betagte, aber noch einwandfrei funktionierende, Raspberry Pi der ersten Generation mit der neuesten stabilen Software versorgt.

So sieht DB0SIG von innen aus.
Der Digi mit geschlossenem Gehäuse.
Die Antenne von DB0SIG bei strahlendem Sommerwetter.

DB0SIG Refurbished

The Setting

DB0SIG has been running for some years on the same hardware setup. This setup consisted of an old Alinco mobile radio and a TNC with APRS-Digi firmware. In the beginning the TNC had occasional bit flips what did not strengthen my confidence in the system. So, as time allowed, I ordered some new parts to assemble a new and hopefully more reliable and flexible APRS digipeater.

The new Setup

The new setup consists of the following parts:

…and this is how it looks all glued together. Obviously I forgot to buy a box.


Setting up the TNC-Pi

I ordered the TNC-Pi as a kit which apparently gave the guys at the German customs a little headache. After tracking said the packet arrived at the customs, nothing happened for almost two weeks. When I had almost given up on the project, the post woman unexpectedly delivered the packet after all. Building the kit by the manual worked very well. The only deviation I had was the voltage at the PIC being only 3V, not the stated 3.3V. After powering up the TNC-Pi on the Raspberry Pi, one has to disable the serial console that supplies debug output on the device /dev/ttyAMA0. This is the port where the TNC-Pi connects. For this I removed all references to the device from the boot command line in /boot/cmdline.txt and added enable_uart=1 to /boot/config.txt. After that and configuring kiss as stated in the manual, kissattach still failed. Some research brought me to the solution that you have to remove the line

T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100

from the file /etc/inittab. One reboot later, everything worked as expected.

Setting up the RS-UV3

The RS-UV3 required some minor modifications to run with the power amplifier. The more interesting part was powering up the device to see if it is really working. As I had no USB-to-serial adapter at hand, I used an Arduino with the soft serial example as a simple interface and Minicom as the terminal.

The Software

On the Raspberry Pi, Raspbian was already installed. On the APRS side, I use APRX which can be downloaded here. OH2MQK provides .deb packages ready for the Pi. These can be identified by the armhf (instead of the i386) in the filename. When the file has been downloaded onto the Pi, the installation reduces to a simple dpkg -i aprx_2.08.593-1_armhf.deb. The final task was to adapt the configuration in /etc/aprx.conf to my needs. As the file is very well commented, it is easy to come to a working setup. In the long run some parameters may need some fine tuning. For example, I activated the telemetry but it generates a lot of traffic so I will probably deactivate it once the setup has been running stable for some weeks.