The 4 MHz Collection

4 MHz collection

Gathered, here, are some of the rarest watches I own. There have been quartz crystal oscillators with 8 kHz, 16 kHz, 32 kHz, 196 kHz, 262 kHz, 2.4 MHz and 4.19 MHz frequencies in fairly common production (some more common than others) at various stages in the relatively short history of quartz watches. The least common frequency (of the commonly produced frequencies) was probably 2.4 MHz, found in three movement variations from Omega. 4.19 MHz watches are generally less well-known than the 2.4 MHz watches made famous by the Omega Marine Chronometer, however there have been at least three distinct Citizen movements in this frequency as well as one from Junghans, one from Casio and a prototype from Omega.

High-frequency oscillators do not seem to maintain rates quite as flat as those of thermocompensated movements (though one of my Casios is challenging that assumption, right now), but their thermal performance is a lot better than you'd find in lower-frequency oscillators. If calibrated properly for the average temperature that the watch will likely experience throughout the year, a high-frequency watch will run slightly slow in the winter and slightly fast in the summer, averaging out at an impressive overall SPY value. In 1975, Citizen's cal. 8650 Crystron 4 Mega was spec'd to 3 seconds per year. A rate that would remain unsurpassed for roughly forty years, until Hoptroff and Morgenwerk each brought out watches with self-learning, thermocompensated movements.

The performance, in seconds-per-year, of my 4 MHz watches from mid-March to mid-July, 2016 (click on the graph for more details)


Omega prototype, cal. 1522. One of two prototypes produced in 1975.


Crystron 4 Mega, cal. 7370. Produced in 1979 and rated to 5 seconds per year.

Crystron 4 Mega

Exceed 4 Mega, cal. 1730. Of unknown date and spec., this Exceed was likely produced later than the Crystron 4 Mega; possibly into the 1980s.

exceed 4 mega

SP-400, module 75. Produced in about 1980 and spec'd to 15 seconds per year.


SP-400G, module 75. Produced in about 1980 and spec'd to 10 seconds per year.


SP-410, module 75. Produced in about 1980 and spec'd to 15 seconds per year.


What's missing - Junghans MegaQuarz, cal. 667.26; Crystron 4 Mega, cal. 8650