[time-nuts] Old Crystal.

[Bob kb8tq]

Hi

Missing step from that YouTube video:

Stuff a fixed resistor into the 150B and calibrate the Rm per the manual.

Without that, your resistance numbers can be pretty far off.  In a production
setting some of the Saunders gear got “calibrated” (or at least checked)  each 
time the frequency band was changed …..

http://ftb.ko4bb.com/manuals/73.64.254.239/Saunders_and_Associates_Crystal_Impedance_Meter_150B_Service_Manual.pdf <http://ftb.ko4bb.com/manuals/73.64.254.239/Saunders_and_Associates_Crystal_Impedance_Meter_150B_Service_Manual.pdf>

Section 4 ( Operation ) 

Paragraph A ( first step in operation) … Calibration Resistor. 

( and on from there).

The approach for the other Saunders stuff is similar, but the details change
a bit from model to model.

While they like to talk about super duper fancy standards. Check it with
a 51 ohm 1/8W carbon comp and see what you get. Compare that reading
to what your 3456A says …..

Fun !!!

Bob

> On Mar 1, 2021, at 10:38 AM, Azelio Boriani <azelio.boriani at gmail.com> wrote:
> 
> 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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