Well, Corby may have started something. I had the pieces to a Frequency Electronics FE-5650A lying around in a bag, so figured I would share as well. There are two photos. The first is an exploded view with the lamp (not dis-assembled) at the left. In the center is the microwave cavity with the filter and resonance cell (heat shrunk together) and the magnetic shield that goes over the whole assembly. At the right is the cover that goes over the cavity with the C-field coil inside. The second photo is the end view of the lamp assembly and the Rb cells turned on end. They are miniature (about 1/2" diameter) compared to the HP 5065A. Skip Withrow