speed settings

[ronaldheld]

Does anyone remember or can find the default speed or the one used for wearing it 1/2 a day and then off the wrist 1/2 a day?

[clockace]

are you refering to the mkIII/IV's? i have 2 that are running 1@600, the other @ 698. both are keeping excellent time [w/in less than 10 secs/yr]. why one is 600 the other 698 i don't know other than the qc may be slightly different. i have not found any difference whether i wear it frequently or not often. maybe just these 2?? peter

[retroleds]

I have one that seems to hold very good time at 648. It lives in the curio cabinet, so I can't vouche for any "on wrist" vs. "off wrist" difference.

[ronaldheld]

Yes I should have posted Mark IV. Going from unworn to worn should make a non trivial difference in averaged rate,

[charger105]

Hi ronaldheld.
I don't think the setting of one MkIV will have any bearing on what another should be set for.
My understanding is that the frequency adjustment compensates for oscillator circuits which are all slightly different (depending on the individual quartz crystal, capcitance of conductors in close proximity and capacitance inside the chip(?) etc.).

I think you are right though, you should be able to find a setting value which is suitable for half on the wrist and half in the box use......it'd just be a different value for different watches.
Rgds,
Andrew.

[rewolf]

Hi ronaldheld.
I don't think the setting of one MkIV will have any bearing on what another should be set for.
My understanding is that the frequency adjustment compensates for oscillator circuits which are all slightly different (depending on the individual quartz crystal, capcitance of conductors in close proximity and capacitance inside the chip(?) etc.)....

This is correct. Thy individual crystal tolerances are the biggest contributor.

If you have the ideal setting for a given watch in off-wrist state, it is theoretically possible to derive the value for 1/2 on-wrist state (like "increase / decrease by 5" or so).
The theoretical temperature behaviour af a standard 32kHz crystal is depicted here: http://dwf.nu/viewtopic.php?p=25336#25336.

But maybe the simplest way to find out is to wear the watch for a week and then re-adjust it. IIRC the Synchronar manual states how many increments to adjust for a given measured deviation.

Edit: found the Mark IV instructions:
The crystals we use run at their highest frequency at 75°F (23.8°C) and slightly slower at temperatures above or below this point. Therefore, depending on the wearing habits, climate, etc., a different optimum setting will be fond. Normally a setting of 48 seconds per year is required for a watch being worn every day versus one held at 75°F. This amounts to 6 digital increments on the speed setting scale.
That is, using elementary math:
- 1 increment means 8 seconds per year,
- 1 increment means 0.67 seconds per month,
- 1 increment means 0.15 seconds per week,
- 1 second per week means 6.5 digital increments,
- 1 second per month means 1.5 increments,
- 1 increment means 0.25ppm,
- 1ppm means 4 increments,
etc...

[J Thomas]

[ronaldheld]

Thanks for all of the comments, rewolf good information with the rate listing. I suppose that I will just have to wear it and see how it works out, probably starting next week.

[ronaldheld]

What is the best technique for getting the seconds to zero based on an external reference?

[charger105]

Hi ronaldheld.
The seconds start from zero upon release of the setting switch. So, set the time to the upcoming minute, and hold the switch in position until your external reference ticks over to the new minute (at which time you release it ).

Rgds.

[clockace]

and on the mkIV you use right switch away and left switch away. left switch away advances minutes. when at the next upcoming minute release left switch still holding right switch away. at the time beep release the right switch. secs start at zero then. peter