Our WSPR beacon design works fine even on the 4m band (~70 MHz) . The key is to use a 25 MHz high-quality TCXO, like the 25 MHz HCI 0.5ppm TCXO!
2m WSPR is still out of reach for now - see the following sporadic decodes.
Of course, the next challenge is to get 2m WSPR beacons working 100% reliably at a low cost.
Initially, we will be driving Si5351 with a 10 MHz clock output from a GPSDO to achieve this task.
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