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.
Bernd -----Ursprüngliche Nachricht----- Von: [email protected] [mailto:[email protected]] 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: [email protected] [mailto:[email protected]] 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: [email protected] [mailto:[email protected]] 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 <[email protected]> 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 -- [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. _______________________________________________ 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.
