Last 24hrs on 472kHz with earth-electrodes and 5mW ERP

In total, 11 different stations have received my 5mW ERP WSPR signals from my earth-electrode "antenna" in the last 24 hours with the best report being from F1AFJ (607km) at 2202z last night at -29dB S/N. In the same period I received 12 unique stations.

472kHz - unique spots in last 24 hours

If I can match the earth-electrode "antenna" I shall be trying 160m for a change this evening and overnight. G8LCO has suggested this. If the earth-electrode "antenna" acts as a loop in the ground, I'd predict poorer results at 160m as the loop would be smaller. On the other hand, the FT817 would be better on RX (greater sensitivity) and my ERP higher (I think). Not sure of the noise floor here on 160m, but it could be poorer on 160m than 630m. Proof will be in the results - that is the fun.