HI > On Apr 11, 2018, at 5:38 PM, Richard (Rick) Karlquist <[email protected]> > wrote: > > The aging spec on the 10811 is 5 parts in 10^10 per day. > After 60 days, it could be off 30 ppb. So what we > have here is a non-ovenized AT cut that is better > than an ovenized SC cut. I'm sure.
As a practical point - they didn’t leave the factory until they hit that spec, Manufacturing being what it is, having OCXO’s hang around was not a popular thing. The 5x10^-10 per day at 5 or 10 days might well drop by quite a bit a month or two later. Back in the day, this was a “who knows / who cares / meets spec” sort of thing. I’m not sure that everybody buys the “log rule” for aging. I think there are a lot of reasonable objections to it. That aside, if there *is* a rule that applies to 80% of your crystals …. that’s doing very well. By watch standards that is “perfection”. Measure something over a 10 day period and plug that into the firmware. Yes, the watch sits in test for 10 days … .and you charge for that. > > I am reminded of the old Accutron ads. The headlines > guaranteed so many seconds a day or whatever it was. > The fine print says they don't actually guarantee that. > The only remedy under that guarantee is that they > agree to adjust the watch to be in spec at the > watch repair shop and hand it back to you. Thus, > they didn't have to worry about aging. Just come > into the shop as often as necessary :-) I wonder how many watch shops are set up to re-shoot the memory in a watch CPU? Most of them seem to have a hard time swapping a battery and keeping things dry enough that the watch doesn’t fog up in the cold …. Bob > > Rick N6RK > > On 4/11/2018 9:26 AM, [email protected] wrote: >> That comes out to about 30ppb, and this is a pocket watch so they dont seem >> to depend on the temp stabilization of being attached to a human wrist. >> https://www.ablogtowatch.com/wp-content/uploads/2018/03/Citizen-Cal-0100-Eco >> -Drive-Movement-04.jpg >> Ive been reading about the new watch that contains this crystal for about a >> month, but just saw some more detail today > >> --- >> AT-CUT QUARTZ CRYSTAL OSCILLATOR >> While AT-cut quartz crystals have indeed been in production and use since as >> early as 1934, the technology is more common in larger applications and not >> necessarily wristwatches. To address the needs of individuals seeking only >> the most accurate performance in a wristwatch, Citizen sought to apply and >> optimize this available technology in a way that could serve watch consumers >> on a more direct and personal level. When working to reach the accuracy of >> the Cal.0100, Citizen opted for an AT-cut quartz oscillator instead of a >> more traditional tuning fork shape (XY cut). Perhaps most notably, AT-cut >> variations allow for greater temperature tolerances, specifically in the >> range of -40°C to +125°C. Additionally, this configuration allows for >> reduced deviations caused by wearer orientation, which can cause significant >> changes in accuracy that aren't negligible when attempting this kind of >> performance. As a result, wearers will not have to worry about errors caused >> by spatial orientation and positioning becomes less of a concern. The same >> can be said about durability, which Citizen also improved upon in >> conjunction with the AT-cut oscillator. After all, shock experienced in >> day-to-day situations could easily prove detrimental even for quartz >> movements. And when the goal is an annual accuracy of ±1 second, that just >> isn't acceptable. >> https://www.ablogtowatch.com/citizen-cal-0100-eco-drive-watch-movement/ >> --- >> Is this possible with an MXCO running across this wide temp range? How are >> they compensating for aging at this level of precision? >> Thanks! >> _______________________________________________ >> 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. _______________________________________________ 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.
