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[rn3aus]

I hope that I will be able to leave a trace one day.

Hello Markus! Welcome!
You are right, the grabber uses a direct conversion receiver with a tuning frequency of 136968.3 Hz (20 MHz / 146).
As expected, due to the doubled reception bandwidth of a simple direct conversion receiver, the FST4W reports are degraded by 3 dB ((
Perhaps in the future the receiver will be replaced by SSB superheterodyne.

[df6nm]

Thank you Alex for the explanation! You might consider adding a second mixer for the quadrature signal (e.g. a Tayloe switching mixer). The 90° phase shift for the LO can be derived digitally in the last divider stage. SpecLab can process IQ input directly, so you don't have  to make an analog audio phase-network, but you will need a soundcard with stereo input.

73, Markus

[rk2y]

I hope that I will be able to leave a trace one day.

Hello Markus! Welcome

I hope that I will be able to leave a trace one day.

Hello Markus! Welcome!
You are right, the grabber uses a direct conversion receiver with a tuning frequency of 136968.3 Hz (20 MHz / 146).

Почему не 20/160?