[time-nuts] 10MHz Rubidium reference source for frequency counter

[John Miles]

> I know what your next question will be, "I see that these rubidium
> oscillators all can be adjusted over a range that falls on both sides of
> 10MHz.  What should I use as a calibration source to adjust my rubidium
> oscillator?"   Then you think "If I have this 10MHz calibration source, why
> not just run the frequency counter off that and not bother with the rubidium?"
> 
> 
> OK there is good reason to use Rb.  It warms up fast, it remains stable for
> a long time.  It is self contained and compact and does not rely on any
> external signals.

You really have to tweak the heck out of a GPSDO to achieve medium-term stability comparable to that of a cheap rubidium (see attached comparison against typical and exceptional GPSDOs.)  Of course, at taus greater than several hours the GPSDO will eventually win.

-- john, KE5FX
Miles Design LLC

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