[time-nuts] Re: Sapphire instead of Quartz for much better PhaseNoisespecs

Tom Van Baak tvb at leapsecond.com
Mon Nov 29 01:03:37 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

> 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.
> Brooke Clarke, N6GCE

I've seen the cesium fountains at NIST and USNO
and as I recall the local oscillator was a combination
of Oscilloquartz 8607-08 BVA quartz oscillator and
a Sigma Tau H-maser. The stability of these special
BVA's is down in the -14's at a second. See one at:


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