Thanks Guys, you have instilled a great deal of confidence in these "smartclocks" for me.
Anyone know where I can buy a month's supply of patience then? ;) On a more serious note, I have rack mounted both clocks with UPS power and they shall not be disturbed. http://www.vk2hmc.net/blog/?p=86 Many thanks, mark -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles P. Steinmetz Sent: Wednesday, 17 April 2013 4:03 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Z3805A high value PU Mark wrote: >For the first 6 hours PU stayed at 432us, then it dropped sharply to >5.6us and then slowly climbed to 18us. >Doesn't seem right to me. Nothing it does in the first 6 hours has anything to do with anything. (1) The oscillator will be swinging around wildly (comparatively speaking, relative to its stability after it has been running unmolested for months). (2) Further, 6 hours is almost certainly a shorter period than it normally uses to forecast PU, so a forecast after ANY six-hour period of data collection (even when fully warm and stable) will not be its best estimate. I do not know HP's algorithm, but it sounds like it didn't seriously try to compute PU until after 6 hours, then it started trying with (1) too little data and (2) data from an unstable oscillator, so it's no surprise it is wandering around. I'll be very surprised if it settles down near its long-term stability in less than a month of continuous, undisturbed running (continuous meaning don't turn it off, undisturbed meaning don't move it or bump it very hard -- if you do either of these, start counting from zero again). Be patient. OCXOs need time to reach stability when re-started in a new environment (particularly if they have been off for more than a few days and/or bumped around, both of which are probably true of yours). Some are better about this than others, but what I've said is pretty typical of the 10811-and-better class of OCXOs, IME. Best regards, Charles _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
