[time-nuts] quartz thermometers

Magnus Danielson magnus at rubidium.se
Sat Mar 12 13:03:52 EST 2016


Well, the B-mode is at 10,9 MHz so you need to detune the mode 
suppression such that the C-mode at 10 MHz is suppressed.
This becomes clear from their 1981 HP Journal article.

Oh, and in a side-note, it states that the 10544 is a BT-cut, so they 
even spilled that in public 35 years ago.

Cheers,
Magnus

On 03/12/2016 05:24 PM, Richard (Rick) Karlquist wrote:
> Does anyone have a documented way to do this?
>
> I asked the original designers of the 10811
> (Burgoon and Wilson) about this a few years
> ago and they couldn't remember what the circuit
> mods were.  I got hold of their lab notebooks
> and it wasn't in there either.  What I remember
> them telling me 35 years ago was that you
> remove the complicated mode suppressor between
> the base and the emitter and replace it with
> the equivalent capacitor.  I tried this, and
> guess what:  it still oscillated in mode C!
> All these years no one knew the mode suppressor
> wasn't necessary.  I tried to redesign the
> mode suppressor to suppress mode C.  There
> wasn't any good way to make this work.  I
> finally had to finagle the tuned circuit
> in the collector to force it to mode B.
>
> My E1938A circuit does not use a mode suppressor
> as such.  The natural selectivity of the
> tank circuit is sufficient.
>
> Can anyone add anything?
>
> Rick
>
> On 3/12/2016 5:33 AM, Magnus Danielson wrote:
>> Hi,
>>
>> For the 10811 you can modify it to change mode and then use that mode to
>> measure and trim the temperature oven.
>>
>> There exists crystal oscillators where the 10 MHz is a traditional
>> SC-cut mode and then a 30 MHz mode is exercised which measures the
>> crystal temperature. In the Microprocessor Controlled Crystal Oscillator
>> (MCXO) one then measure the difference in frequency and uses this to
>> re-synthesize a correction on the 10 MHz. The benefit is that it is the
>> temperature of the oscillating crystal that is being measured.
>> Naturally, it could be used for oven control and/or EFC control too.
>>
>> The MCXOs exists in manufacturing, but whenever you ask about them they
>> just wonder what military project are you working on.
>>
>> I'd love to experiment with this form of temperature sensing one day,
>> when I have time... if that ever happens...
>>
>> Cheers,
>> Magnus
>>
>> On 03/12/2016 10:21 AM, ken hartman 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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