Hi HP was as much into 1 and 5 MHz as the rest of the world in the 1950's. It took them quite a while to really decide that everything was going to be 10 MHz. I'm sure there were some "interesting" discussions in various labs during the late 60's and well into the 70's.
Bob On Aug 3, 2013, at 8:43 PM, Pete Lancashire <p...@petelancashire.com> wrote: > Another 5 MHz HP was the 5360A > > > On Fri, Aug 2, 2013 at 6:14 PM, Bob Camp <li...@rtty.us> wrote: > >> Hi >> >> The math is pretty simple: >> >> The Q of quartz goes up as the frequency goes down. >> >> A crystal resonator's performance (Q) is limited by it's thickness to >> diameter ratio. >> >> At some point the resonator design impacts the Q of the resonator more >> than the Q of the raw quartz. >> >> Holders are available that will rationally hold a maximum diameter blank. >> >> It's the intersection of all of the above that implies a best solution. >> The "sweet spot" is not just quartz, it's the combination of all of the >> above. >> >> Change any of the above (like the holder) and you get another "sweet spot" >> >> ------------------------- >> >> Is that simple? Of corse not. Many things need to change to let you make a >> high performance blank that's much bigger. Many things need to change to >> keep the Q of the quartz the limiting factor. >> >> ------------------------- >> >> Why has it not been done? The drive in the marketplace is to smaller / >> cheaper. This is totally the opposite direction from that. The investment >> to make larger blanks goes at least back to the design of the gear that >> grows quartz. What we have is "good enough", but it's far from the best we >> could do. Quartz is not the limiting factor. >> >> Bob >> >> >> >> On Aug 2, 2013, at 7:52 PM, Tom Knox <act...@hotmail.com> wrote: >> >>> >>> Interesting, I have heard for years from the senior Time and Freq >> researchers I work with that 5MHz was a sweet spot. I will ask if there is >> a reason and proven physics behind it but these are individuals that are >> well grounded in science. They almost always multiply 5MHz if they needed >> 10MHz etc. >>> Perhaps I missed something. It wouldn't be the first time I was schooled >> by the TimeNuts. >>> Best Wishes; >>> Thomas Knox >>> >>> >>> >>>> From: li...@rtty.us >>>> Date: Fri, 2 Aug 2013 14:39:21 -0400 >>>> To: time-nuts@febo.com >>>> Subject: Re: [time-nuts] 5MHz x 10MHz >>>> >>>> Hi >>>> >>>> Quartz it's self has no "sweet spot". The only issue is how low you can >> go in a specific sized crystal holder before you start to run into trouble. >> A TO-5 crystal will have a different minimum frequency than an HC-40. >>>> >>>> Bob >>>> >>>> On Aug 2, 2013, at 2:30 PM, Mike Feher <mfe...@eozinc.com> wrote: >>>> >>>>> It was my understanding that this "sweet spot" was optimum a little >> above 3 >>>>> MHz, so, 3rd overtone crystals are used to generate a stable, low phase >>>>> noise 10 MHz. Prior to that, 5 MHz was used and before that 1 MHz >> Regards >>>>> - Mike >>>>> >>>>> Mike B. Feher, EOZ Inc. >>>>> 89 Arnold Blvd. >>>>> Howell, NJ, 07731 >>>>> 732-886-5960 office >>>>> 908-902-3831 cell >>>>> >>>>> -----Original Message----- >>>>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] >> On >>>>> Behalf Of Tom Knox >>>>> Sent: Friday, August 02, 2013 2:02 PM >>>>> To: Time-Nuts >>>>> Subject: Re: [time-nuts] 5MHz x 10MHz >>>>> >>>>> It is my understanding that Quartz has a sweet spot at 5MHz that makes >> it >>>>> ideal if the lowest possible phase noise and highest stability are >> needed. >>>>> >>>>> Thomas Knox >>>>> >>>>> >>>>>> Date: Fri, 2 Aug 2013 19:57:16 +0200 >>>>>> From: mag...@rubidium.dyndns.org >>>>>> To: time-nuts@febo.com >>>>>> Subject: Re: [time-nuts] 5MHz x 10MHz >>>>>> >>>>>> Hi Euclides, >>>>>> >>>>>> On 02/08/13 18:31, Euclides Chuma wrote: >>>>>>> Hi, >>>>>>> >>>>>>> Why any equipments use 5 MHz and others use 10 MHz reference >> standard? >>>>>> >>>>>> There are some benefits (traditionally) in using 5 MHz over 10 MHz, >>>>>> but >>>>>> 10 MHz have become a common standard. The actual frequency isn't >>>>>> really magic, but 5 MHz and multiples became somewhat standard in the >>>>>> old MIL STD 188 for time-keeping, and it fit fairly well with what was >>>>>> already in use. There are folks here that can correct me on massive >>>>> details. >>>>>> >>>>>> Today 10 MHz is more common because, well, engineers then to be >>>>>> following habits, and 10 MHz "sounds nice". I use 10 MHz mainly >>>>>> because the application requires it, otherwise I use whatever >>>>>> frequency fits my other needs, or what becomes easy to source. >>>>>> >>>>>> PS. Have not seen you post before, so welcome to time-nuts! >>>>>> >>>>>> 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. _______________________________________________ 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.
