My Timex Indiglo looses about a second a month. I think that's pretty good for a <$30 watch I got at Walmart. Al <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

Hi Most (as in the center of the distribution) afordable watches are calibrated to run fast. There is info on this in the archives. A pretty typical target is 10 seconds a month. Yes, we used that as a target back in the 70’s but it’s still pretty common. You have to get lucky to find one that is dead on time. Some math: 2,592,000 seconds in a month. 1 second is about 0.4 ppm. Your typical watch crystal moves about 20 PPM over 0 to 50 C. The curve is a parabola with a tolerance on the inflection point. So 10 seconds a month comes out to around 4 ppm. With the temperature out around 20 ppm, you need a fairly stable / consistent environment to hit even that sort of number. Yes, you could play compensation games, but doing so only works to the degree that the crystal matches some ideal curve. ( = you get a pretty limited gain with low cost crystals and no testing). Bob > On Mar 6, 2018, at 3:02 PM, al wolfe <alw.k9si@gmail.com> wrote: > > My Timex Indiglo looses about a second a month. I think that's pretty good > for a <$30 watch I got at Walmart. > > Al > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> > Virus-free. > www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> > <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.