The most comprehensive teardown and analysis of this unusual type of equipment . . . ever!
Links:
Description of cavity wavemeter operation:
http://www.rfcafe.com/references/electrical/NEETS-Modules/NEETS-Module-21-3-31-3-39.htm
Teardown of Sony NAS-CZ1 Clock Radio CD Player:
http://www.youtube.com/watch?v=Yz6IGuR7xpU
Toshiba Satellite P75-A7100 and Numitron Clock:
http://www.youtube.com/watch?v=dIB0KoxcWyk
