Autodyne receiver for WWV

While scanning QRP-L today, I found an interesting link to a project which gave some details about a little WWV receiver that can serve as a frequency standard.   I haven’t had the time to work out how it all works, but it looks reasonably straightforward:

Here’s the original schematic from Chuck Adams, K7QO:

Picture 1

Nick, WA5BDU has some variations and additional comments which are interesting:

autodynereceiver kennnick.