[time-nuts] quartz thermometers
Tom Van Baak
tvb at LeapSecond.com
Sat Mar 12 11:03:15 UTC 2016
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" <namichie at gmail.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
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 <ken at hartmans.org> 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 <bill.iaxs at pobox.com> 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
>>>
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