BASIC Tech Group - MyNews 7 - Harmonics from Si5351 DDS?

Using a Si5351 module from Adafruit (Kanga) as a VFO for my Direct conversion RX and for my WSPR TX.

The WSPR TX is transmitting on 7040.1kHz with the "M6KWH IO92 20" message..



I have the RX connected to my Macbook via a Startech A/D convertor running at 48kHz sample rate. The on the Macbook I ran two programs, Argo.exe a Windows program running un Wine emulator, and WSPR program native to the Mac.

These are what the two prgrams show when the RX is tuned to 7038.6kHz.



and



What you can see here is that a lot of harmonics or side lobes are being received. I don't know if these are being transmitted by the WSPR TX or if they are spurious reception by the RX. What I get on the WSPR readout is two IDs, one at the nominal 7040.1 frequency (at 100 on the scale) and another which is 100Hz above. These two and others can be seen on the Argo screen.

I have tried all sorts of software changes but not found the cause...