[time-nuts] Double-Oven Thunderbolt on Ebay

Rick Karlquist richard at karlquist.com
Fri Aug 8 23:02:19 UTC 2008


John Ackermann N8UR wrote:
>
> One thing to note -- good phase noise and good ADEV don't necessarily go
> together.  Case in point is the -60158s are spec'd at 1x10e-12 at 1
> second, which is better than most of the 10811A variants, but the phase
> noise isn't as good as other versions (like the -60258 you have).
>
> John

Yes, in fact, they have almost nothing to do with each other.
Short term stability at 1 second is determined entirely by
the crystal and phase noise at 1 kHz is determined almost entirely by
the circuit.  This is in the 10811 or any decent oscillator.
Of course it is possible to use a poorly designed circuit that
degrades the 1 s stability (or a really bad oven).  And a crystal
of much lower Q or higher intrinisic phase noise might affect
phase noise.  But in practice in the 10811, absent pathological
corner cases, what I originally said is accuracy AFAIK.

Rick Karlquist N6RK





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