This radio is capable of very low-frequency RX-audio response. And this allows one to get very accurate results when zero-beating.
It is best to use the highest frequency WWV signal you can hear (usually 15MHz).
Frequency calibration is a user adjustment on the rear panel. (See page 94 of the manual.)
Here’s an accurate way to do it:
Tune-in to 15MHz WWV (15.000.000).
Switch to either USB or LSB.
Make sure PBT and all noise reduction is turned off.
Set the bandwidth to 3.6KHz, with “sharp” filtering.
Set the “RX bass” to maximum (in the menu).
You should hear the audio cut in and out. This is normal.
Now adjust “CAL” (on the rear panel) until the audio cuts out at the slowest rate possible.
After calibration, be sure to change “RX bass” back to it’s normal setting.
Here is a demo video I made :
April 28, 2014