[time-nuts] Good clean-up oscillators

[Magnus Danielson]

Fellow time-nuts,

While we often look at long-term stability, ADEV etc. we consider 
oscillators in their free-running properties. This is all fine and dany, 
but when we want to use an oscillator as a clean-up oscillator, the 
servo-loop with surpress much of the low-frequency/high-tau properties 
and replace that with that of the reference.

Consider for instance that we have a LPRO rubidium and we want to use a 
clean-up oscillator to provide better phase-noise, what would be a good 
selection?

While there is plenty of choices, it is a bit different from that which 
is relevant when considering it as a free-running oscillator. The white 
noise which dominated far-out would dominate, and only some of the 
flicker phase becomes relevant.

I could easily get a OCXO of good quality, but really, what would be 
interesting choices? Have someone measured this enough to get a kind of 
rough idea at least?

Cheers,
Magnus