Our 6m WSPR beacon design works fine now. The key is to use a 25 MHz high-quality TCXO, like the 25 MHz HCI 0.5ppm TCXO!

6m WSPR Demo 1 6m WSPR Demo 2 6m WSPR Demo 3 6m WSPR Demo 4 6m WSPR Demo 5

2m WSPR is still out of reach for this VFO design - see the following drifty screenshots:

2m Drift 1 2m Drift 2 2m Drift 3

While WSPR is no good, 2m FT8 works pretty fine!

2m FT8 Demo 1 2m FT8 Demo 2

Of course, the next challenge is to get 2m WSPR beacons working at a low cost.

References