[time-nuts] Need a Watch Recommendation

[Dana Whitlow]

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 <kb8tq at n1k.org> wrote:

> Hi
>
>
> > On Mar 15, 2018, at 1:33 AM, Dana Whitlow <k8yumdoober at gmail.com> 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 <time at radio.sent.com>
> 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
> >>
> >>
> >>
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