I am using the Leo Bodnar Precision GPS Reference Clock as the external clock for my RSP2 and using the SDRPlay ExtIO interface with Spectrum Lab (no SDRuno). I measure a consistent +0.5 Hz offset of the measured WWV carrier frequency with respect to the expected value from 5 through 20 MHz (even with large FFTs and bin widths less than 0.1 Hz). I am not using any of the calibration coefficients that are stored in SDRuno (at least as far as I know). Are there any other places where a frequency offset could lurk, either in the RSP2 or in the ExtIO interface? If so, how can I adjust them? Any advice would be gratefully received, thanks.