[AMRadio] National Calibrator

[Jim]

Has anyone ever worked on a National XCU 50 crystal calibrator? 
Specifically I am curious about the Valpey crystal in it.  The one 
meg side is not working and I believe the quartz slab may be cleaned 
to restore operation.  The caveat is I am a bit hesitant to open the 
case without knowing what to expect.

Has anyone here ever taken one apart that can tell me how they are 
constructed?

73

Jim/W5JO