Hi Most of the British Racal standards are 5MHz. It may well have been down to what was the best performance of the nationally avilable crystals. Everthing is a compromise. It is easy to double a 5MHz output to 10MHz. One way is to pass it through a bridge rectifier (high speed diodes of course) and then filter it. old 10Mbs "thin" ethernet filters from network cards work well. Check the archives and do a websearch. Robert G8RPI. ________________________________ From: Bob Camp <lists@rtty.us> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Friday, 2 August 2013, 20:12 Subject: Re: [time-nuts] 5MHz x 10MHz Hi It may well have been teamed up with a piece of Russian designed equipment. Bob On Aug 2, 2013, at 2:40 PM, Euclides Chuma <euclides@w2c.com.br> wrote: > Hi, > > I thank all for your responses. > > My question arose because I bought a TFL Rubidium Standard and the signal output is 5 MHz. It is a great rubidium standard so I dont understand the reason of the 5 MHZ signal output since the 10 MHz is the common standard. > > Best regards > _______________________________________________ > 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.

Hi You might want to check the equipment you are going to use with it. A lot of early gear that is marked "10 MHz" really has a range of frequencies it will accept. They often will accept anything that is a sub-multiple of 10 MHz (5, 2.5, 3.33333, 1.25 etc). They used a simple phase detector to lock up a local 50 or 100 MHz oscillator in the equipment. Bob On Aug 2, 2013, at 2:40 PM, Euclides Chuma <euclides@w2c.com.br> wrote: > Hi, > > I thank all for your responses. > > My question arose because I bought a TFL Rubidium Standard and the signal output is 5 MHz. It is a great rubidium standard so I dont understand the reason of the 5 MHZ signal output since the 10 MHz is the common standard. > > Best regards > _______________________________________________ > 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.

Hi Even today you will get better ADEV off of a large package (HC-40) 5 MHz crystal than off of a 10 MHz device. Of course very few people make such an oscillator any more. Buyers are after other things. Bob On Aug 2, 2013, at 3:51 PM, Robert Atkinson <robert8rpi@yahoo.co.uk> wrote: > Hi > Most of the British Racal standards are 5MHz. It may well have been down to what was the best performance of the nationally avilable crystals. Everthing is a compromise. > It is easy to double a 5MHz output to 10MHz. One way is to pass it through a bridge rectifier (high speed diodes of course) and then filter it. old 10Mbs "thin" ethernet filters from network cards work well. Check the archives and do a websearch. > > > Robert G8RPI. > > > > ________________________________ > From: Bob Camp <lists@rtty.us> > To: Discussion of precise time and frequency measurement <time-nuts@febo.com> > Sent: Friday, 2 August 2013, 20:12 > Subject: Re: [time-nuts] 5MHz x 10MHz > > > Hi > > It may well have been teamed up with a piece of Russian designed equipment. > > Bob > > On Aug 2, 2013, at 2:40 PM, Euclides Chuma <euclides@w2c.com.br> wrote: > >> Hi, >> >> I thank all for your responses. >> >> My question arose because I bought a TFL Rubidium Standard and the signal output is 5 MHz. It is a great rubidium standard so I dont understand the reason of the 5 MHZ signal output since the 10 MHz is the common standard. >> >> Best regards >> _______________________________________________ >> 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.

Hi Except for HP, everything from the US would have been 5 MHz as well. Bob On Aug 2, 2013, at 3:51 PM, Robert Atkinson <robert8rpi@yahoo.co.uk> wrote: > Hi > Most of the British Racal standards are 5MHz. It may well have been down to what was the best performance of the nationally avilable crystals. Everthing is a compromise. > It is easy to double a 5MHz output to 10MHz. One way is to pass it through a bridge rectifier (high speed diodes of course) and then filter it. old 10Mbs "thin" ethernet filters from network cards work well. Check the archives and do a websearch. > > > Robert G8RPI. > > > > ________________________________ > From: Bob Camp <lists@rtty.us> > To: Discussion of precise time and frequency measurement <time-nuts@febo.com> > Sent: Friday, 2 August 2013, 20:12 > Subject: Re: [time-nuts] 5MHz x 10MHz > > > Hi > > It may well have been teamed up with a piece of Russian designed equipment. > > Bob > > On Aug 2, 2013, at 2:40 PM, Euclides Chuma <euclides@w2c.com.br> wrote: > >> Hi, >> >> I thank all for your responses. >> >> My question arose because I bought a TFL Rubidium Standard and the signal output is 5 MHz. It is a great rubidium standard so I dont understand the reason of the 5 MHZ signal output since the 10 MHz is the common standard. >> >> Best regards >> _______________________________________________ >> 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.

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: lists@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 <mfeher@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-bounces@febo.com [mailto:time-nuts-bounces@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: magnus@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.

Even HP used 5MHz when it counted (no pun intended!) - the 5245L used a 1MHz timebase while the higher spec timebase in the 5245M used 5MHz. DaveB, NZ ----- Original Message ----- From: "Bob Camp" <lists@rtty.us> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Saturday, August 03, 2013 8:47 AM Subject: Re: [time-nuts] 5MHz x 10MHz > Hi > > Except for HP, everything from the US would have been 5 MHz as well. > > Bob > > On Aug 2, 2013, at 3:51 PM, Robert Atkinson <robert8rpi@yahoo.co.uk> > wrote: > >> Hi >> Most of the British Racal standards are 5MHz. It may well have been down >> to what was the best performance of the nationally avilable crystals. >> Everthing is a compromise. >> It is easy to double a 5MHz output to 10MHz. One way is to pass it >> through a bridge rectifier (high speed diodes of course) and then filter >> it. old 10Mbs "thin" ethernet filters from network cards work well. Check >> the archives and do a websearch. >> >> >> Robert G8RPI. >> >> >> >> ________________________________ >> From: Bob Camp <lists@rtty.us> >> To: Discussion of precise time and frequency measurement >> <time-nuts@febo.com> >> Sent: Friday, 2 August 2013, 20:12 >> Subject: Re: [time-nuts] 5MHz x 10MHz >> >> >> Hi >> >> It may well have been teamed up with a piece of Russian designed >> equipment. >> >> Bob >> >> On Aug 2, 2013, at 2:40 PM, Euclides Chuma <euclides@w2c.com.br> wrote: >> >>> Hi, >>> >>> I thank all for your responses. >>> >>> My question arose because I bought a TFL Rubidium Standard and the >>> signal output is 5 MHz. It is a great rubidium standard so I dont >>> understand the reason of the 5 MHZ signal output since the 10 MHz is the >>> common standard. >>> >>> Best regards >>> _______________________________________________ >>> 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.

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 <actast@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: lists@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 <mfeher@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-bounces@febo.com [mailto:time-nuts-bounces@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: magnus@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.

Some instruments (Tek 494 for instance) use a 100 MHz VCXO phase locked to 10 MHz for lower phase noise when multiplied into the microwave bands, demonstrating that there is more than one way to skin a cat. Didier KO4BB Bob Camp <lists@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 <actast@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: lists@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 <mfeher@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-bounces@febo.com >[mailto:time-nuts-bounces@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: magnus@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. -- Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things.

Hi The whole drop frequency / better Q thing really only applies if you are looking for ADEV with tau's > = 0.1 second. If you are after phase noise, then there are other things to worry about. Bob On Aug 3, 2013, at 7:52 AM, Didier Juges <shalimr9@gmail.com> wrote: > Some instruments (Tek 494 for instance) use a 100 MHz VCXO phase locked to 10 MHz for lower phase noise when multiplied into the microwave bands, demonstrating that there is more than one way to skin a cat. > > Didier KO4BB > > Bob Camp <lists@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 <actast@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: lists@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 <mfeher@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-bounces@febo.com >> [mailto:time-nuts-bounces@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: magnus@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. > > -- > Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other things. > _______________________________________________ > 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.

On 08/03/2013 02:28 PM, Bob Camp wrote: > Hi > > The whole drop frequency / better Q thing really only applies if you are looking for ADEV with tau's > = 0.1 second. If you are after phase noise, then there are other things to worry about. White noise and flicker noise of oscillator and buffer amps comes to mind. Naturally noise in the crystal itself. Cheers, Magnus