[time-nuts] Quartz crystall and beyond

[Alex Pummer]

  IMPROVING THE FREQUENCY STABILITY OF MICROWAVE OSCILLATORS BY
  UTILIZING THE TEMPERATURE COMPENSATED DIFFERENCE FREQUENCY OF A
  DUAL-MODE SAPPHIRE LOADED CAVITY RESONATOR



https://images.search.yahoo.com/yhs/search;_ylt=AwrUiqr58Fpe2kYAigIPxQt.;_ylu=X3oDMTByNWU4cGh1BGNvbG8DZ3ExBHBvcwMxBHZ0aWQDBHNlYwNzYw--?p=poseidon+scientific+whispering+gallery+oscillators&fr=yhs-dcola-001&hspart=dcola&hsimp=yhs-001#id=0&iurl=https%3A%2F%2Fwww.researchgate.net%2Fprofile%2FMichael_Tobar%2Fpublication%2F242255140%2Ffigure%2Ffig1%2FAS%3A669508037509121%401536634563175%2FThe-frequency-of-the-WGE-11-0-0-mode-and-the-difference-between-the-WGE-11-0-0-and-WGH_Q320.jpg&action=click

73
KJ6UHN
Alex

On 2/29/2020 2:57 PM, Richard (Rick) Karlquist wrote:
>
>
> On 2/29/2020 1:58 PM, Attila Kinali wrote:
>
>> Different concept. Quartz oscillators are mechanical resonators.
>> Cryogenic sapphire oscillators are electro-magnetic resonators.
>> The problem with those is, that they are large and need liquid He
>> for cooling. Not only is He expensive, but it also needs a cryostat
>> that will mechanically shake the CSO. But they get down to a few parts
>> in 10^-15 between 1s and ~1000s, I've even seen papers with a few parts
>> in 10^-16 in the same range(e.g. [1]) . There have been attempts to get
>> them to liquid nitrogen temperatures [2]. But they only got down to 
>> 1e-13
>> (i.e. where good crystal oscillators are). And not much happend since,
>> beside an attempt to get them working at room temperature [3]
>>
>
> Agilent (now Keysight) attempted for years to put a whispering
> gallery oscillator in an instrument.  It wasn't cyrogenic.
> They actually heated/cooled it to lock it to a 10811.  The real thing 
> that stymied them was microphonics.  I retired in 2014 and don't know 
> whatever became of this effort.  The two biggest experts on WGO's went 
> with Agilent during the Keysight spinoff, which might have finally 
> killed it completely.  A cryogenic WGO would face the same microphonic
> issues.
>
> Rick N6RK
>
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