[time-nuts] Old Crystal.

[Tim Shoppa]

G3UUR and K8IQY have simple test circuits for measuring crystal motional
parameters.

G3UUR is great for comparing or matching a batch of similar-cut AT crystals.

The K8IQY method is a bit more comprehensive for "unknown" crystals and
involves very tiny step sweeping around the resonance you're interested in.

K8IQY detailed writeup here:
https://www.k8iqy.com/testequipment/pvxo/Atlanticon2002V1R5.pdf

Tim N3QE


On Mon, Mar 1, 2021 at 3:36 AM Magnus Danielson <magnus at rubidium.se> wrote:

> 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
>
>
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