FYI, I've posted a few pictures of the inside of this oscillator. Noteworthy is the tiny Dewar flask. http://s701.photobucket.com/user/edpalmer42/library/Isotemp%20OCXO107-10%20Oscillator If you click on the magnifying glass at the bottom of the picture and then do it again, you'll get the full size picture. After about a week of operation, aging was < 5e-10/day (spec is < 2e-10/day). An impressive result for such a short run time. Adev with drift removed at Tau > 100 sec. is stuck at ~1e-11 as measured against a Tbolt. I can't find a spec for it. The Tbolt and measurement system are capable of much better performance than that so the Isotemp appears to be the limiting factor. Maybe longer run time would bring it down. Ed