SAQ transmission of May 1st, 2018

by Alberto I2PHD                                  

This time SAQ was received using the Airspy HF+ SDR receiver.

The audio of the transmission can be heard here

The Airspy HF+ was fed from an untuned loop preamplifier, with maybe too much amplification.
This made almost mandatory to use a low pass filter to clean the band, as shown in this photo.

This is the schematic of the low pass filter :

And this is its Bode plot :

A visual excerpt of the audio signal as received by the DUO :

73  Alberto  I2PHD