The attached survey of the classical IEC 60444-2 "phase zero" measurement technique based on the PI-network described in IEC60444-1 vs. the modern error corrected measurement method of IEC 60444-5 may provide a helpful inside into the measurement techniques for quartz crystals. More can be found at https://www.axtal.com/English/Support/TechnicalArticlesPublications/LiteratureaboutQuartzCrystals/ Bernd -----Ursprüngliche Nachricht----- Von: Bob kb8tq via time-nuts [mailto:time-nuts@lists.febo.com] Gesendet: Samstag, 20. August 2022 05:20 An: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com> Cc: Brooke Clarke <brooke@pacific.net>; Bob kb8tq <kb8tq@n1k.org> Betreff: [time-nuts] Re: Custom Quartz crystals Hi In the era that the fixture was used, doing this with an network analyzer wasn’t even a pipe dream. Doing up an adequate set of data with the gear of that era was a long and drawn out process. Getting a measurement with a simple fixture was a second or two. Indeed if 1% on resistance and a tenth of a ppm frequency wasn’t adequate, you might head off to other approaches. Given the make tolerances on the crystals, neither one was a limit to production testing. The biggest limit in reality was the accuracy of the load capacitor. That’s why you never / ever swapped it out. The value that was in there was confirmed by some non-trivially exciting testing with a number of “golden” crystals. Bob > On Aug 19, 2022, at 10:30 AM, Brooke Clarke via time-nuts <time-nuts@lists.febo.com> wrote: > > Hi: > > IEC 444 is a PI-Netowrk measurement method for crystals. It is supposed to me more accurate than the method that uses a physical CL. > The HP 41900A has the look and feel of the linked PI-Network fixture so may just be a re-branded version. > https://prc68.com/I/4395A.shtml#E5100 > > -- > Have Fun, > > Brooke Clarke > https://www.PRC68.com > axioms: > 1. The extent to which you can fix or improve something will be limited by how well you understand how it works. > 2. Everybody, with no exceptions, holds false beliefs. > > -------- Original Message -------- >> Hi >> >> Thanks to a bit of off list coaching from those who’s memory >> (obviously) better than mine :) : >> >> This is the magic test set that Motorola (and many others) got pretty >> heavily into: >> >> https://isolalab.com/pinetwork.html >> <https://isolalab.com/pinetwork.html> >> >> The gizmo is right at the top of the page. There’s a nice paragraph >> next to it and a diagram of what’s inside. >> >> The original outfit that made it ( Cathodeon / Pye ) has been out of >> business for quite a while. They apparently made the fixture to >> support their crystal manufacturing business. Just how many fixtures >> they sold to their competitors …. no idea. >> >> Bob >> >>> On Aug 17, 2022, at 8:17 AM, Bob kb8tq <kb8tq@n1k.org> wrote: >>> >>> Hi >>> >>> One “interesting” way to look at this is a “delta F” test. >>> It’s based on a system that (essentially) always measures things at >>> series. You put the (maybe) 20 pf load cap in series with the >>> crystal and zip off it goes to measure the net result of the crystal >>> at a 20 pf load. >>> >>> Typically you did this by pushing a paddle on a fixture. Yes that’s >>> very specific to one rig up. Turns out that Motorola decided it was >>> a fun thing and we tested a *lot* of crystals that way. It’s been “a >>> while” … but .. fundamental crystals came in at > 400 ppm. Third >>> overtones might be around >>> 30 ppm. Fifth overtones might be around 3 to 5 ppm. >>> >>> No this isn’t for the same crystal or even the same crystal package. >>> It also isn’t for SC cuts, these all where AT’s. >>> >>> … and yes, if I could remember the name if the UK outfit that made >>> the test heads, I’d give them credit for their cute little gizmo. >>> >>> One interesting outcome of testing this way was to spec crystals as >>> some number of PPM off series rather than with a load. Changing the >>> load cap in the fixture was “not done”. AFIK that was very specific >>> to internal Motorola documents. The only time I saw it used >>> elsewhere was on crystals that operated below series. >>> >>> Bob >>> >>>> On Aug 17, 2022, at 5:28 AM, Richard (Rick) Karlquist via time-nuts <time-nuts@lists.febo.com> wrote: >>>> >>>> It is hard to answer your question. The tuning range depends on >>>> the varactor(s) used in the respective oscillators, and the range >>>> of the tuning voltages. >>>> I think I could roughly say from memory that putting in a crystal >>>> meant for the other oscillator would probably result in not being >>>> able to reach 10.000000 MHz. Or just barely reaching it and having >>>> no aging margin. I had to apply a lot of arm twisting to Jack >>>> Kusters to get him to make the series resonant (at 10 MHz) >>>> crystals. I made sure that this was really necessary before going >>>> to war on it. >>>> >>>> Rick N6RK >>>> >>>> On 8/14/2022 3:35 PM, Hal Murray via time-nuts wrote: >>>>> Richard (Rick) Karlquist said: >>>>>> We actually used the upper turnover because the E1938 had to >>>>>> operate at ambient up 85 degrees. BTW, the E1938 crystals had >>>>>> to be calibrated for >>>>>> 10.000000 MHz at series resonance, unlike the 10811 crystals >>>>>> which were calibrated for 20 pF (IIRC). >>>>> How big is the difference between series and 20pF compared to the tuning range? >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe >>>> send an email to time-nuts-leave@lists.febo.com >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe >> send an email to time-nuts-leave@lists.febo.com > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send > an email to time-nuts-leave@lists.febo.com _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com