[time-nuts] questions about oscilloquartz 10MHz module

[Attila Kinali]

On Sat, 1 Feb 2020 21:08:42 -0500
Bob kb8tq <kb8tq at n1k.org> wrote:

> are representative, the 8663’s don’t quite get to that level. The typical 
> spec unit is at 1 to 4 ppb over 0 to 70.  That’s
> reasonable performance for a modern single oven. I very much doubt they 
> built a true double oven simply to hit
> a single oven spec.


I don't know what your definition of a "true double oven" is, but
the 8663 definitely uses two ovens. You can find its construction in [1].
The basic design is that the crystal is mounted on a copper plate, which
becomes the inner oven, that is placed in a hermetically sealed package
that doubles as outer oven. All together is than mounted in the outer
package. 

I guess the "low" performance of the double oven comes from the low
thermal mass of the innver oven. That said, Mark did some measurements
with the Star4 GPSDO (uses an 8663) and attested it superp holdover
performance.

			Attila Kinali

[1] "A new kind of view for a Double oven Crystal Oscillator"
by Lefebvre, Weber, Aubry, 2007
https://doi.org/10.1109/FREQ.2007.4319182
(can be also found in the EFTF 2007 proceedings)


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