Hallo Dale and jdow, thanks for the suggestions. I did not feel like putting my (clumsy) hands on other dll's, so I tried what Dale suggested. Unfortunately it did not work. I then contented myself to explore the HF with DX Patrol with HDSDR and indeed it works - but I found strong broadcasting signals on 21 MHz, in the 15 mtr. amateur band. This was already strange, but my heart sank when I tuned the same frequencies with my faithful Yaesu FT-897 and found nothing like that. It has to be some sort of artifact (on a conventional superhet I would think of image frequencies).  I think I'll skip HF listening with the little gizmo for a while...

Best regards,
                                  Francesco - PE1F