From top to bottom:
- Varactor for fine tuning, my guess it is used as part of a temperature compensation loop here. Lightly coupled to the DRO.
- The DRO puck inside it's glass prison.
- Coupling loop for the oscillator and the oscillator transistor.
- Output isolator, made from a circulator with one port terminated.
- Output port on the left side.
-20dB dB sample of the oscillator output signal.