You run the risk of loading down the circuitry.

You might try using a sensitive AM shortwave receiver to detect a
harmonic of the oscillator. Use an unductive coil around the timepiece.
Then using a signal generator with a very precise reference oscillator
as a BFO, warp the crystal oscillator for a zero beat. If you are at the
9th harmonic (for example) you will improve your accuracy 9 times. Use
WWV to verify your signal generator is accurate as a first step.

Also don't discount the temperature variations of wearing it for 12
hours and then leaving at room temperature for 12 hours. You might find
you have made things worse by adjusting it at room temperature.

Joe

Fred McKenzie wrote:

In article , Isaac
Wingfield wrote:



You're very unlikely to be able to use any kind of frequency counter to
measure the oscillator with sufficient accuracy. There are close to a
hundred thousand seconds in a day. Measuring to one part in 10^5 will
leave you with an error of half a minute a month; not very good at all
for a timepiece these days.



I appreciate the comments. Now all I need to do is to look inside and see
if there is a trimmer. I can see where the slightest error would
accumulate over time.

I have an old Fluke counter (7220) with a low-frequency option. It
phase-locks a higher-frequency oscillator with the input signal, counts
the oscillator and displays it as the lower frequency. It would be worth
a try if I could pick up a strong enough signal from the watch without
warping it.

Fred



--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"

"Follow The Money"