Hello Time-Nuts, thanks to Mark´s breakout board I was able to fire up my X72 rubidium. It seems to work fine. FW is 5.19. As far as I understand from the (rather crappy) manual, I should be able to discipline it to 1pps, but I wasn´t lucky using the commands from the manual. I switched to Lady Heather. It looks like I get TIC results from the X72 - The mode is reported as "Free running", so I guess this is the difference between the incoming PPS and the local one. So far so good, but if I try to enable HW disciplining, nothing happens. Also strange, "PPS IN" is reported as "OFF"... Did anyone on this list sucessfully discipline the X72 to external PPS? Or has a manual that fits better to the 5.19 FW? Or can shine some light on how the X72 1PPS feature is supposed to work? Any hints are highly appreciated. Thanks & regards, Matthias