When doing frequency calibration a spot tone at 1kHz as a reference, played back through EESDR3 while receiving WWV in SSB mode would make it very simple and easy to calibrate the frequency. Simply tune in SSB mode to 9.999.0 with the 1kHz tone playing and adjust until zero beat is achieved.
This video illustrates the feature well via the IC-7300
https://www.youtube.com/watch?v=Rt5NzyYaMiY
When doing frequency calibration a spot tone at 1kHz as a reference, played back through EESDR3 while receiving WWV in SSB mode would make it very simple and easy to calibrate the frequency. Simply tune in SSB mode to 9.999.0 with the 1kHz tone playing and adjust until zero beat is achieved.