Hi Another variable - can you be *sure* the oven starts at 25C? Some of these cuts are running > 1 ppm / C in the vicinity of room temperature.
Bob On Jan 28, 2013, at 5:06 PM, Magnus Danielson <mag...@rubidium.dyndns.org> wrote: > Hi Bob and Bernd, > > I don't know *why* I had you in mind for this question? :) > > On 01/28/2013 10:54 PM, Bernd Neubig wrote: >> Hi Bob, >> >> you are right. Sorry for my mistake. >> FC (and some) IT cut crystals are used in OCXO, because the curvature around >> the upper turn point is "flatter" than for an AT- cut with the same >> turn-over temperature. >> IT-cut crystals are sometimes used, when the oven temperature must be in the >> range 95 to 100°C, because the operating temp of the OCXO must cover the >> whole "industrial" temperature range up to 85°C. >> The yield is higher than using SC-cut crystals for such applications. > > OK. It would be handy to have a list giving the 25°C frequency vs. the > nominal for the AT, BT, SC, FC and IT cuts, just as a handy short-hand. > > The previous postings where not very clear, so I had to ask the stupid > question again. > > Cheers, > Magnus > >> >> Bernd >> >> -----Ursprüngliche Nachricht----- >> Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im >> Auftrag von Bob Camp >> Gesendet: Montag, 28. Januar 2013 18:40 >> An: 'Discussion of precise time and frequency measurement' >> Betreff: Re: [time-nuts] What cut do I have? >> >> Hi >> >> The only time I've seen them used in OCXO's both the FC and IT were run on >> the upper turn (just like an AT). Thus the frequency goes down as it warms >> up. >> >> Bob >> >> >> >> >> -----Original Message----- >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On >> Behalf Of Bernd Neubig >> Sent: Monday, January 28, 2013 11:48 AM >> To: 'Discussion of precise time and frequency measurement' >> Subject: Re: [time-nuts] What cut do I have? >> >> Hi, >> IT and FC cut crystals are not very often used in OCXO. But if, then the >> lower turn point is used (below the inflection temperature), which means >> that the cold oven starts at a lower frequency, which increases with warm-up >> - same direction as for SC-cut crystals. >> >> Regards >> >> Bernd >> DK1AG >> >> -----Ursprüngliche Nachricht----- >> Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im >> Auftrag von Bob Camp >> Gesendet: Montag, 28. Januar 2013 03:39 >> An: Discussion of precise time and frequency measurement >> Betreff: Re: [time-nuts] What cut do I have? >> >> Hi >> >> It could also be an AT, IT or FC cut. A lot depends on just how hot the oven >> is running. Best bet is indeed AT. >> >> Bob >> >> On Jan 27, 2013, at 7:40 PM, Magnus Danielson<mag...@rubidium.dyndns.org> >> wrote: >> >>> On 01/28/2013 01:01 AM, Ed Breya wrote: >>>> If you meant to say the frequency starts out too high when the oven >>>> is cold, then I think it's AT cut. >>> >>> OK. I looked at the previous posts and it was not very clear from >>> them, >> and I was too lazy/busy to heat up an idel AT OCXO. I just felt the +41.4 >> ppm deviation was a little low for an AT cut. >>> >>> Meanwhile, out of 22 LPROs tested, only 3 has BITE error, so 19 locks up. >> Out of 4 cesiums tested, 3 locks up and one fails. Trimming needed on all. >>> >>> Cheers, >>> Magnus >>> _______________________________________________ >>> 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. >> >> _______________________________________________ >> 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. >> >> _______________________________________________ >> 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. _______________________________________________ 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.