JT4A mode on 500kHz

The next (operational) project is emerging from the mists..... Several people have started to experiment with JT4A WSJT mode on 500kHz. This allows basic EME/MS style QSO exchanges so should allow me some 2-way contacts on the band with my low ERP. Still to work out how to run the software though: when I tried the other night I could see strong traces but no decodes. Getting this sorted will be half the fun. Then I might try to mode on VHF too. JT4A uses a bandwidth of 17.5Hz with tone spacings of 4.375Hz and can decode down to -23dB S/N. This is somewhat less sensitive than WSPR but would still allow QSOs with quite a large number of the stations who've heard me on WSPR.