Neville, Apparently it's not vacuum mounted, but helium filled. Lots of good info here:
http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1965-03.pdf /tvb ----- Original Message ----- From: "Neville Michie" <[email protected]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Saturday, March 12, 2016 2:19 AM Subject: Re: [time-nuts] quartz thermometers > It always puzzled me that quartz crystals would be considered prime > temperature sensors. > I can see that an instrument could be built that reliably showed many decimal > places of reading, > but I could never accept that a vacuum mounted quartz crystal would be > closely enough > thermally coupled to whatever was having its temperature measured. > Sensors like thermistors, thermocouples and platinum resistors can be made of > the right shape and size to > thermally couple to solids and liquids and so can make successful measurement > systems. > Many important measurements rely on having no disturbance of the physical > system by the > use of the thermometer. > > cheers, > Neville Michie > > >> On 12 Mar 2016, at 8:21 pm, ken hartman <[email protected]> wrote: >> >> Interestingly, the use of AC-cut crystals (high linear tempco of frequency) >> is found in the development of OCXOs. Using a reference AC-cut resonator - >> in place of the final AT/SC resonator - one can learn much about the >> thermal characteristics of the oven loop performance. While not a precise >> temp sensor, it is a high sensitivity indicator of temperature variations >> of the resonator. >> >> On Fri, Mar 11, 2016 at 11:44 PM, Bill Hawkins <[email protected]> wrote: >> >>> It may be that the need for that kind of resolution died out. >>> >>> The next step up from quartz thermometry is resistance thermometry. >>> The linearization equation for platinum has enough terms to make it >>> uncertain around .01 C. >>> Temperature calibration baths usually use platinum resistance sensors. >>> >>> It may be that the triple point of water does not have the certainty to >>> reach '0.0001C' >>> >>> Disclaimer: I only worked with industrial sensors from Rosemount, Inc. >>> as an employee. >>> >>> Bill Hawkins >>> >>> >>> -----Original Message----- >>> From: Alan Ambrose >>> Sent: Friday, March 11, 2016 11:42 AM >>> >>> Hi, >>> >>> I hope this is still relevant and not too off-topic...but since it >>> involves crystals and tempco... >>> >>> Quartz thermometers (e.g. the HP 2804A) with their 'linear cut' crystals >>> and '0.0001C resolution' seem to have been a thing from the mid-60's to >>> the mid-80's: >>> >>> http://www.hparchive.com/Journals/HPJ-1965-03.pdf >>> >>> There still appear to be some manufacturers making the crystals: >>> >>> http://www.statek.com/products/pdf/Temp%20Sensor%2010162%20Rev%20B.pdf >>> >>> Anyone know why they died out? Did a better technology replace them? >>> >>> TIA, Alan >>> >>> _______________________________________________ >>> 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.
