BillyTampa: Did you ever get to the bottom of this? I also observe an offset of about +0.5 Hz on all WWV frequencies that I can hear (using my Bodnar GPSDO). SDRPlay tech support thinks this might be due to the accuracy of the fractional-N synthesizer in the receiver chip (something like it can’t get closer than 0.5 Hz to a required frequency). This seems like a reasonable suggestion, but then, how can it be tested, and more importantly, how does it change with other settings of the receiver? Presumably one could find a combination of LO and other settings that would cause the synthesizer to use an “integer” frequency that would not have this problem, but I have not yet been able to figure out how to do that. So, I wonder if you made any progress on this issue. Thanks!