Lars,
I see that you have an attempt.
What is your output power and what antenna are you using?
I have an output of 15 watts at 7 MHz in ft8 mode and I use a vertical inclined Delta Loop, which I feed from above.
The antenna consists of 43.8 meters of wire. The device is an sBitx v2, which is cooled by the heatsink and the RPi.
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Gyula HA3HZ
HA3HZ