^? This is this is why, when possible, I like to have the second receiver on AM and listening to WWV on both radios. That way, I'm actually comparing their approximately 800 cycle (?) tone with my received audio on the uBitx. That way, and with the uB near carrier zero-beat, there's still a working audio note well within human hearing so I can listen for the difference between the two in terms of only a couple cycles per second. If you can pick that out, meaning if you have a musical ear, it's just one other option to try.

Ted