I think it's more in who had them and tried to calibrate them, as some of these are actually programmed for the desired frequency. I forget which pin that is, but I think it may show it in one of the pdfs. There's another pdf available out there from a ham who did a lot with these, and it did show how to program/calibrate them.
I know a few of the guy's over in Asia like to play with these before they sell them, so I think a lot of it's all in whom you get them from. Best, Will *********** REPLY SEPARATOR *********** On 7/13/2011 at 4:56 PM WB6BNQ wrote: >David, > >The answer to your question is quite complex. A number of factors control the >operation of a passive atomic resonator acting as a filter. Temperature, pressure, >buffer gas mixtures, external magnetic forces, coupled light excitation, the length >of the cavity, the interrogating external RF energy level are but some of those >factors. > >The "Atomic" nature of the filter is based upon the extremely narrow resonance of >electron absorption of energy which occurs at a specific frequency and is influenced >by the previously mentioned factors. That specific RF excitation frequency is >different for each element in the Periodic Table. For example the Hydrogen Maser is >around 1.45 GHz; the Rubidium is in the 6 Ghz range and the Cesium is in the 9 Ghz >range. > >None of the specification sheets even approach trying to answer such a question >directly. However, with certain qualifying assumptions, it could be inferred from >"certain" specs, if available, as a general idea, BUT, by no means the complete >answer. > >For example, looking at Symmetricom's XPRO Rubidium spec sheet, they give a 10 year >spec of ?+/-1x10e-9. The assumption is the unit was built correctly, was adjusted >to be precisely on frequency at its intended installation site and was left powered >on, in a stable atmosphere, without failures of any kind for the entire 10 years. >If the product truly met those assumptions and specs, then I would say, with some >confidence, that if you picked up a used one working properly that it would be >reasonable to assume after powering up and allowing it to come to a stable >temperature (24 hours) and it indicated a locked condition that it would be within >1x10e-9 of the correct frequency. Unfortunately, FEI is not so forth coming with >their product literature, but I suspect their units are similar. > >Also, be aware that at least one member on this list has reported buying two 5680A's >from China and they were both significantly off frequency by many hertz. Inspection >and determination of the problem is a project in motion. This same member has >further stated other reports exist on the WEB of other units exhibiting the same >problem, although I have not seen those reports. > >It may prove out that the two 5680A's have a problem. It is equally possible that >they are deliberately offset for some specified yet unknown reason. Time will tell. > >While a Cesium frequency standard is by definition and without question accurate, >that only applies under a narrow set of circumstances. It is possible to miss >adjust such a beast and that is why multiple standards labs constantly cross check >themselves. > >Remember, to error is human and machines do what we tell them ! > >Bill....WB6BNQ > > >"Dr. David Kirkby" wrote: > >> If an old random 10 MHz Rubidium oscillator is working (i.e. powers up, and >> eventually locks), what is the maximum possible frequency error it could have? >> >> Could it remained locked with an error of 1 part in 10^7, 10^8, 10^9, 10^10 etc? >> >> I assume there are physical limits which would simply stop it functioning too >> far from the correct frequency, but don't have much clue what they are. >> >> -- >> A: Because it messes up the order in which people normally read text. >> Q: Why is top-posting such a bad thing? >> A: Top-posting. >> Q: What is the most annoying thing in e-mail? >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. > >__________ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __________ > >The message was checked by ESET Smart Security. > >http://www.eset.com _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
