Mike I think we must be talking to the same smart people. I think 5MHz was adopted over 3MHz simply because 5MHz multiplies to other commonly used frequencies with greater ease. I think the top frequency standards have evolved to 5MHz Third Overtone SC cut crystals for a reason. The evolution has gone on from the days of Tesla and improved greatly during the glory days of Quartz in the years leading up to atomic standards with countless hours of experimentation and research. Those lessons learned are constantly examined through the lens of the latest science. I may be wrong, but I have not heard of any extreme design prototype quartz oscillator with superior Phase Noise and Stability. Our house standard F1 a cesium fountain is used roughly one month every few months to characterize roughly 12 5071A cesium standards steering about 5 MHM 2010 cleaned up with a number of 8607 option 08 oscillator. (The equipment choices are not a recommendation or endorsement, and there are possibly m any product that could meet or exceed the performance of these fine products.) But the oscillators selected are 5MHz third Overtone SC cut.
Thomas Knox > From: [email protected] > To: [email protected]; [email protected] > Date: Sat, 2 Nov 2013 09:50:50 -0400 > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > Exactly - I mentioned this on here about 3 years ago and all of the > self-proclaimed geniuses poo-pooded it. I was told early in my engineering > career in the early 70's, by a very smart man, when I thought I had all of > the answers, that considering all of the trade-offs regarding performance, > around 3 MHz for a crystal is best, operating in the 3rd overtone mode, > hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now, > getting close to 70, I just see what I can learn from all the "smart" people > on here, and keep quiet most of the time. Regards - Mike > > Mike B. Feher, EOZ Inc. > 89 Arnold Blvd. > Howell, NJ, 07731 > 732-886-5960 office > 908-902-3831 cell > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of David McGaw > Sent: Saturday, November 02, 2013 1:30 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] The 5MHz Sweet Spot > > This all seems to be forgetting that the crystals are usually operated at > 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A > high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a > large piece of quartz. Running at a harmonic greatly reduces the influence > of the package. > > David > > > _______________________________________________ > 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.
