Yo Hal! On Sat, 04 Feb 2017 17:19:21 -0800 Hal Murray <hmur...@megapathdsl.net> wrote:
> g...@rellim.com said: > > Then you have to take aging into account. A 10 year old Mac may > > have difted a lot. Or maybe the crystal got bumped. > > > Also a lot of crystals are now surface mount. The soldering > > process may have bend to crystal a lot. > > Do you have references to any published data? I have been looking hard for a week. All I can find is handwaving. The wikepedia page is typical: https://en.wikipedia.org/wiki/Crystal_oscillator#Stability_and_aging Lists of things affecting the crystal, but no real numnbers. Even the few good data sets I can find are irrelevant unless we know the specifics of you crystal. What cut, frequency, model #, excitation type, etc. All I really know is that I have seen motherbaords with frequencies that are really far off. Have you chronyd on your Mac yet? What does it say your frequency is? > A lot of that depends on what you mean by "a lot". I haven't seen > any good rumors that either age or soldering will shift a crystal any > where near the 500 ppm scale that we are interested in. This says 'low cost osciallators' are 100 ppm. So 500 ppm does not seem that far away to tme. RGDS GARY --------------------------------------------------------------------------- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 g...@rellim.com Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin
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