Here are the results of a series of temperature tests I performed on some of my watches. The watch set contained both thermal-compensated and non thermal-compensated watches. The thermal-compensated watches included watches that used microprocessor based compensation (Citizen Chronomaster, Grand Seiko, Longines VHP) and watches that had increased quartz frequency (Omega Marine Chronometer and Seiko Perpetual) as the method of compensation.
The set of watches was held in a constant temperature chamber at either 82 or 92 deg. F for a period of about one month per temperature level. The drift of each movement with respect to the time signal from NIST was computed for each watch using a stopwatch and multiple time measurements. The clock used as the reference was a PC based clock which was synchronized at 2-minute intervals to the atomic clock at NIST. The drift of the PC clock over the 2-minute period between synchronizations was never observed to be greater than +- 0.03 sec. The estimated accuracy of the manual timings were estimated to be in the range of +- 0.05-0.07 sec. This was determined by observing the deviation among 5 timings taken one after another.
The temperature chamber used to maintain constant temperature conditions was a converted egg incubator (but that’s another story in itself). The temperature was easily maintained within +- 0.1 deg. F during the testing.
The first attachment shows the results sorted by the absolute value of the change in accuracy using 82 deg. F as the reference. The second attachment shows the same information but sorted by the absolute value of the accuracy at 82 or 92 deg. F.
The watch labeled “Walmart” was indeed a $7 Wal-Mart watch put into the set to provide an example of the performance of an inexpensive quartz movement.
As to what the data means, I will let the good members of the HEQ forum chew on that for a while. I have my own ideas, let’s see if you come up with the same conclusions.