This evening I am trying a different approach to the 500kHz antenna. My 15m longwire is strapped to my ground wire and now is acting as a radial. My main antenna is now the vertical coax feeder up to my 28MHz wire halo antenna. The coax has inner and outer strapped together so it is acting as just a thickish wire. The 28MHz halo will act as a top capacity hat.
The WSPR beacon will run overnight, so I will see whether the changes make my signal any different. Measured antenna current is quite a bit higher, so I am moderately hopeful a few more stations might receive my WSPR beacon if the ERP has increased a few dB. It will still be <1mW though.
After the first hour, I think my reports from M0BMU seem slightly better than before, maybe 2-3dB stronger? This is a hopeful sign, although it may just be conditions and QRN levels at the far end.