[time-nuts] Old Crystal.

[Magnus Danielson]

Hi,

On 2021-03-01 01:23, Attila Kinali wrote:
> On Sun, 28 Feb 2021 18:35:57 -0500
> Dan Kemppainen <dan at irtelemetrics.com> wrote:
>
>> If any of you have any suggestions on where to find information on how 
>> to get something like this to oscillate properly, guess at correct 
>> parameters, or even measure any of the parameters I would really 
>> appreciate it.
> The best way would be to use a network analyzer and measure
> the crystals LCR parameters. Using that you can use the
> standard harmonic oscillator literature (Parzen, Frerking,...)
> to design the circuit.
>
> I seem to have misplaced my literature on how to measure
> crystal oscillators. But if you search for "Neubig" and
> "crystal measurement", you should be able to find some of
> the nice documents that Bernd Neubig has written on the topic.

The same Neubig made a comment that your normal network analyzer isn't
such a good tool, even a very good one. The reason being you need both a
wide and narrow sweep to make the model values accurate enough. Most
network analyzers achieve the wide sweep, few do the narrow sweep and
then having that combined to fill in the LCR parameters of a suitable
model, not so much. Things you learn by eating breakfast with him. Turns
out that my network analyzer is good for the measurement, but not for
model fitting.

Neubig have been very much involved in standardizing measurements, and
doing those well to characterize accurate enough those high-Q resonators
have it's challenges that leads many efforts into incorrect values.

Cheers,
Magnus