Taking apart an old NDK 48MHz ovenized crystal oscillator from the 80s, making some measurements; and taking macro shots of the quartz. I make some initial frequency measurements before taking it apart, and then after ripping out the crystal I run it through a tracking generator to look for resonance peaks. Interestingly the crystal seems to operate at a slightly different frequency to what's written on the OCXO packaging, and the 'big' crystal package actually has a small one buried inside!