[time-nuts] AN/URQ13 reference AT cut crystal?

[paul swed]

The conversation may have strayed a bit.

Do need to address one comment that the crystal is a junk box unit. Its
sealed and is a FE crystal. Granted as is, it just may be junk. But it
originally most likely wasn't.
Well a good/bad test last night.

Manually controlled the oven temp and strange results. Looks like a SC xtal
but flip the graph upside down. Also with a heater supply voltage of 15
Volts it can never get to 66 C or more. With 15 V it hovers at 40 C. Needed
to go to 20 V. Heater is 140 ohms total.

At room temp the oscillator is 4 hz high then drops .6 hz below 5,000,000
Mhz at 66.5c.
But then the frequency started going back up at 67c and just kept going.
Even with the oven heat off it kept going up. After a hour and the temp
dropped to 60C it was +4.5 Hz.
Sort of totally unexpected results.

I plan to restart the test tonight or tomorrow and slow the warm up down
even further as I do believe the turn over point was hit. But the upside
down U shaped curve made no sense. Also I do not recall seeing a crystal
curve that looked like an upside down U.
Regards
Paul
WB8TSL

On Thu, Feb 18, 2021 at 7:13 AM Poul-Henning Kamp <phk at phk.freebsd.dk>
wrote:

> --------
> Bob kb8tq writes:
>
> > Turning an “idea” into a production capable part involves making many
> > batches of test samples. Think in the thousands of batches and hundreds
> > of parts in each batch. You have a “search” process at the blank chopping
> > level. You also have a search at the resonator fabrication level.
> Getting the
> > chopping part right is only a small part of the whole process….
>
> I realize this used to be a manual process, but today I would expect
> that you could automate a lot, of not most of it, if you wanted to ?
>
> It would still be a lot of work, and very expensive, but like
> biochemist trying out hundred of thousand compounds from their
> "libraries", robots really lower the cost.
>
> The real question must therefore be, if anybody reasonably expects
> there to be any superior "new" cuts to find in the first place ?
>
> What properties would you program a quartz-crystal-prototyping robot to
> search for ?
>
> Which parameter(s) of current crystal-cuts are "their weak point" ?
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
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