Frog sounds - How far can you hear a frog croak?

Currently I've done 6 QSOs with the Frog and my dipole antenna.

 

Call

QTH

Distance (km)

DM5* Leipzig 369
DL1* Korntal 24
DJ0* Salzgitter 398
DJ3* Wedemark 433
OK1* Pisek 427
F4* QUEBRIAC 810
IK5* Gallicano 712
DJ7* Hannover 430

The W/km is currently at 490μW/km - not bad I think :-)