Hi all, I am playing around which an HP 55400 system, using an HP Z3801A as PRS, conditioning a rubidium holdover card. The system has 8 2048kHz outputs (the 1/5/10MHz output cards are supposed to exist, but never seen one in 20 years). Using the rubidium (FE-5680A, checked inside) and HP "Smartclock" this system should generate a "better" clock with superior phase stability which is what telco folks care about (I think this means that frequency stability is ok too but not 100% sure). What is interesting (at least for me) is that this system reports a lot of statistics on it's PRS input and one can apply these measurements to other inputs even if they are not used in the smart calculations, these are just measured against this generated supposedly perfect clock. Indeed when I measure TDEV of the Z3801A versus a Thunderbolt using the 5370 TI (the best I can do) this seems close to the measurements on the PRS using the above (reports at 1 4 16 256 and 1024s TDEV). Does this mean I should do the effort of diving in and extracting this perfect clock and turn it into my reference 1 PPS? Or am I better of investing in a 10811-60159. Don t want to spend more than a few 100. I did measure the 2048kHz out (in frequency) and these are not so good but of course these are the result of another PLL locked to this clock. br / tnx Xtof on4iy