[time-nuts] Sapphire instead of Quartz for much better Phase Noisespecs

Richard (Rick) Karlquist (N6RK) richard at karlquist.com
Sun Nov 28 23:26:53 EST 2004

One of these oscillators costs as much as a cesium standard.
They in no way replace quartz as a cesium "flywheel", but
are used to generate low phase noise microwave frequencies.

Rick Karlquist

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Brooke Clarke
> Sent: Friday, November 26, 2004 10:37 AM
> Cc: time-nuts at febo.com
> Subject: [time-nuts] Sapphire instead of Quartz for much better Phase
> Noisespecs
> Hi:
> There's a company in Australia making oscillators with fantastic 
> phase noise specs which are based on Sapphire instead of quartz, see:
> http://www.psi.com.au/tech.htm
> Research work on these is being done by the University of Western 
> Australia and others, see:
> http://www.fsm.physics.uwa.edu.au/
> Some of what I have read indicates that the phase noise in these 
> oscillators is limited by quantum mechanics and that they are 
> used in some of the fountain type Cesium standards.
> But it appears that they are used as phase locked microwave 
> frequency sources rather than free running oscillators.  But 
> phase noise should translate into good Allan variance and so they 
> should also be good when free running.
> Does anyone on this list have information and or experience with 
> Sapphire based oscillators?  For example how does the aging rate 
> compare to quartz?
> Have Fun,
> Brooke Clarke, N6GCE
> -- 
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