Well Dick, Assuming it is setup and properly adjusted, it is absolute as a frequency reference by "definition." It does have a given resolution as stated in the manufacturer's manual for the instrument. This resolution [or noise floor as I see it] is due to a number of factors, not least of which is the condition of the physics package (the actual Cesium tube). They do ware out !
Time is another matter all together. the 5061A has a rated accuracy of 1 x 10^-11 and reproducibility of 5 x 10^-12. Thus it can be considered that the unit drifts by 1 part in 10^-11 and that means the time is drifting by that much. As time is relative you always have to compare against another clock to determine where you are relative to the other. You could own the very latest, top of the line Cesium (absolute to parts in 10^-13) and still have the time problem. So it becomes a matter of what your needs are and your applications for which it is used as a reference. The manual for the hp 5061A is available via the Internet and if you can't find it let me know and I can send a copy. It would do you well to read it and gain an understanding of its fundamentals. There are other publications that would be worth studying; if you want or need those let me know as well. 73....Bill....WB6BNQ "Richard W. Solomon" wrote: OK, dumb question time. I have a few GPSDO's (Trimble T-Bolt, Z3801A, TrueTime & HB units). How much better can the Cesium be than any of those ?? 73, Dick, W1KSZ -----Original Message----- >From: ewkeh...@aol.com >Sent: May 8, 2009 12:53 PM >To: time-nuts@febo.com >Subject: Re: [time-nuts] fleabay cesium > >The cesium is from the same source as the two HP 5062. A friend of mine is selling them for me. I am in the process of cleaning house and that is also where the FTS1200 came from. More things are to come. I think this one is a later model because it has the newer power supply board and the DC cesium oven controller. I think it is the one unit. It should say in the description. I know I tested it, also measured beam current with the LF test. It des not have the two lights but during test they where installed and the pictures are of the actual unit. If you want to know any thing else please let me know.? Bert Kehren Miami > > >-----Original Message----- >From: Brian Kirby <kilodelta4foxm...@gmail.com> >To: precise time and frequency measurement <time-nuts@febo.com> >Sent: Fri, 8 May 2009 12:06 am >Subject: [time-nuts] fleabay cesium > > >seems to be a decent price cesium for sale ($600 starting HP5061A)? >? >[1]http://cgi.ebay.com/HP-5061A-Cesium-Beam-Frequency-Standard-WORK ING_W0QQitemZ250415440530QQcmdZViewItemQQptZLH_DefaultDomain_0?hash= item3a4dec6292&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A4|65%3A 12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A200? >? >nobody has bid and 21 hours left...? >? >just a heads up - I know nothing about the unit or the dealer...? >? >Brian KD4FM? >? >_______________________________________________? >time-nuts mailing list -- time-n...@febo.com? >To unsubscribe, go to [2]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 [3]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 [4]https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. References 1. http://cgi.ebay.com/HP-5061A-Cesium-Beam-Frequency-Standard-WORKING_W0QQitemZ250415440530QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3a4dec6292&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A4|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A200 2. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts 3. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts 4. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ 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.