Most of the quartz watches I've owned were off by about 1-2 minutes per month, which I consider inexcusable.
Agreed, the mechanical trimmer is rather problematical, but I'd sure like to see *something *that the sophisticated user can tweak at home. Measurement of the current rate error is probably not much of a problem; I once tried seeing the 32kHz signal in the watch by capacitive coupling to the face, and could detect the signal. I just tried a token attempt on my current watch and failed, but it was a crude, unshielded attempt by merely laying a 'scope probe against the watch face. I was being severely jammed by the local 1230 kHz AM station. Anyway, the idea is to observe the signal's phase drift while triggering the 'scope from a trusted 1PPS source. So now all that's needed is an alternate way for trimming the watch's frequency without opening the case. There must be a way... Dana On Thu, Mar 15, 2018 at 8:13 AM, Bob kb8tq <[email protected]> wrote: > Hi > > > > On Mar 15, 2018, at 1:33 AM, Dana Whitlow <[email protected]> wrote: > > > > I concur with Bill. And even if one keeps tabs on the current watch > error, > > as is the usual practice by celestial navigators, once that error reaches > > or exceeds more than a minute the process frankly gets more clumsy and > > error prone. And if a watch drifts in time very rapidly, one loses faith > > in its > > ability to coast at a known rate between checks against WWV, which > > opportunities are not always available when one wants, due to > > propagation issues. > > > > Whatever happened to the quartz watches with trimmer capacitors > > for setting the rate? > > Trimmer caps to set watch crystals are problematic. They are a source of > error > as well as a set mechanism. You bump this or that and the trimmer moves. > They > also cost money to buy and install properly (no flux in-between the plates > …). > Once that is all done you need a way to set them in the factory. Back in > the day, > yes, we hat line workers who did that sort of thing. We also sold the > crystal in the > watch module (not the whole module) for $2 once upon a time. > > How close do you want to set it? In our case, the set was supposed to be < > 0.5 > ppm of the target. Ideally you needed a design that would do a small > fraction > of a ppm in a typical situation. > > If the trimmer is a normal device, you get about 120 degrees of travel for > the > useful part of the tuning curve. A tune range of 30 ppm for the crystal > and another > 20 ppm for the other parts would not be unusual. Even taking the 0.5 ppm > number, > you are into 120 / 100 = 1.2 degrees sort of set on that little trimmer. > > Bottom line: They went away because they weren’t good enough and they were > to expensive …. Setting a modern “shoot the chip” register based module is > way > more accurate and reliable. It’s silicon so the cost is whatever sand is > selling > for …. > > Bob > > > > > And radio controlled? No way! > > The process is to delicate and marginal to rely upon. Give me a > > good stable free-running watch any day. > > > > I don't like the solar watch concept mainly because one sometimes > > has to go for weeks without an opportunity to expose his watch to > > direct sunlight (or some indoor equivalent) for the requisite period > > of several hours. > > > > Yesterday I was reading the manual for the Citizen ECO series, > > and that thing requires far too much effort and complication to keep > > it working and on time. A good watch must simply work, with no > > maintenance beyond occasional battery replacements (and possible > > gland replacement at battery-change time), and accurately enough > > that the time need never be reset between battery replacements. > > > > I use an old quartz diving watch I bought just under 10 years ago, > > (brand no longer distinguishable), which has never drifted more than > > about 30 sec (usually less) between battery replacements, and I never > > take it off between batteries except when compelled to do so at TSA > > checkpoints. Aside from its LCD's failing I'd be happy to use if > forever, > > but it's getting awfully hard to read these days. > > > > Dana > > > > > > > > On Wed, Mar 14, 2018 at 10:54 PM, Bill Byrom <[email protected]> > wrote: > > > >> On Wed, Mar 14, 2018, at 6:53 PM, Dr. David Kirkby wrote: > >>> What is the most demanding task one would use a wrist watch for? > >> > >> It depends on your job or hobby. > >> > >> During the Apollo 13 rocket burn before their emergency re-entry, Jack > >> Swigert used a wrist watch to time the retrorocket burn which was > >> manually controlled by Jim Lovell. Their normal capsule chronometer was > >> inoperative. This was mostly a differential (time interval) timing > >> measurement. > >> If you needed to determine your location (longitude) and all you had > >> was a wristwatch and a sextant (and software or a table with certain > >> information), the accuracy of the distance calculation would depend on > >> the absolute time accuracy of the watch. At the equator the longitude > >> error due to time error is (40,075.16 km/day) / (86,400 sec/day) = > >> 463.8 m/sec. > >> Amateur astronomers need to know time accurate to about a second or > >> better for accurate osculation observations. > >> Amateur Radio nets and phone, Skype for Business, or WebEx conference > >> calls usually start pretty close to the scheduled time. In some cases > >> people start wondering if the organizer is delayed after about 15 to > >> 30 seconds.-- > >> Bill Byrom N5BB > >> > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> To unsubscribe, go to https://www.febo.com/cgi-bin/ > >> mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
