Hi Gary, you are probably getting a big signal from around the natural resonance of the loop. There are quite a lot of strong FSK signals in the region around 400 to 600kHz you may be seeing a Navtex
Dear Gary, I read with interest that you are still looking to DI2AG. Did you see it last days? Due to technical reasons it had only 0.5W ERP last week and will still transmit QRP until sunday evening