I recognize that unusual start upcharacteristic. I will guess with a rather high confidence that thatoscillator is made by C-mac / Rakon. I have some C-Mac CFP04-A1oscillators, and they all exhibit that characteristic. These are newin the box, actually I wish there was a way to remove the packingtape, so I could find out who originally bought them. Likewise I alsohave a few C-mac STP2145, that all exhibit the same issue. I do havesome much newer Rakon ocxo's, but those are still attached to theirgpsdo boards. I'm not sure if testing those this way will fry the onboard DC/DC converter. I did some testing an posted about thesame issue here, and on the eevblog(more in depth) as well. https://www.febo.com/pipermail/time-nuts/2016-June/098521.html http://www.eevblog.com/forum/beginners/help-me-understand-allan-deviation-measurements/ Thanks, I'm not alone Brendan.