[time-nuts] Sapphire oscillators

[Richard (Rick) Karlquist]

A lot of hype has been coming out of the left coast down
under for many years, with this being the latest example.
This technology tends to produce the world's most sensitive
microphone.  It's also a fairly sensitive thermometer, too,
which the helium bath tends to mask.  The prices asked
have tended to be fairly high.  Agilent (now Keysight) has made sapphire
resonators like this for use at room temperature on an
experimental basis.  They have a considerably better
design; I just happened to be talking to the designer
today, who is no longer with Keysight.  Last I heard
(2014) they were struggling with microphonics.  There
was also the well known problem of insufficient management
support for the technology.

Another issue is identifying the electronics that can
utilize this signal without degrading it.  And how to
measure this electronics to prove it isn't degrading
the signal.

Before the sapphire craze, HP/Agilent developed a
1 GHz dielectric resonator cavity (not a coaxial
resonator) that was huge.  The "puck" rivaled a
hockey puck.  I don't believe this ever got productized.
It was another big microphone of course.

Another HP experimental oscillator was a VCO that
covered an octave using around 100 varactor diodes.
It was called the "wagon wheel oscillator".  Again,
it was a hero experiment.  The total RF power was
enormous.

Just putting all this into perspective.

Rick


On 11/9/2016 4:20 PM, Jim Palfreyman wrote:
> Anyone got any comments on this?
>
> http://www.theleadsouthaustralia.com.au/industries/technology/worlds-most-precise-clock-set-for-commercial-countdown/
>
>
> Jim Palfreyman
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