Hi > On Feb 18, 2021, at 9:39 AM, paul swed <[email protected]> wrote: > > 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.
The AT is a “graph upside down” SC. > 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. So that is not an OCXO anymore. Either it’s very broke or somebody has done a lot of customization on it. Why / when / for what reason? No way to really know. > > 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. Very normal results for an AT that was built as a crystal for an XO. ( = uncompensated TCXO). +/- 1 ppm 0 to 50C is a pretty common spec. > > 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. You would need to get down to around -20 C to see the other side of the AT curve. Bob > Regards > Paul > WB8TSL > > On Thu, Feb 18, 2021 at 7:13 AM Poul-Henning Kamp <[email protected] > <mailto:[email protected]>> 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 > [email protected] | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > > _______________________________________________ > time-nuts mailing list -- [email protected] > <mailto:[email protected]> > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > <http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com> > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
