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

[Brooke Clarke]

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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