[time-nuts] Old Crystal.

[Azelio Boriani]

This (see jpeg picture) crystal from Morion seems to have a Q of
1147576, as measured on a Saunders 150B.

Youtube video of the 150B in action:
<https://youtu.be/y-rCgumTn4Q>

Parameters from the 150B:
Holder, Cs (pF), Ct (pF), Fs (MHz), Fp (MHz), Rm,  C0 (pF),Cm (pF),
Lm (uH),       Qu
Glass,  25,      31.05,   5.127993, 5.128964, 2.3, 6.05,   0.011759,
81917.1860871, 1147576

On Mon, Mar 1, 2021 at 3:46 PM Bob kb8tq <kb8tq at n1k.org> wrote:
>
> Hi
>
> > On Mar 1, 2021, at 3:32 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
> >
>
> A while back I got drafted into writing the code and validating the procedure
> to do this commercially. With care, it can be done and the results are quite
> good. As you would expect, there are various gotcha’s you run into.
>
> Along with the network analyzer (resolution and noise) , it depends a bit on the
> crystal you are looking at. High Q low frequency crystals are a challenge for the typical
> network analyzer. Something like a 150 MHz fundamental is generally pushing
> things like test setup (…. rigid cables are a good idea)  more than the analyzer.
>
> Yes this assumes you are looking at “real” ( = expensive) analyzers rather than
> the low cost stuff. There is a reason people pay for those great big boxes …. :)
>
> Fun !!
>
> Bob
>
> >
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>
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