Casio SP-400
Module 75
Factory Spec. 15 SPY
Thermoinsensitive: High Frequency (4 MHz)
User Adjustable: Yes
This watch has been described as 'the ultimate stealth HAQ'. It looks very much like any other 1980s digital watch. It cost, however, 28,000 Yen in 1980 and while that is not exactly 'luxury watch' territory, it is rather a lot for a basic digital job.
Although it isn't thermocompensated, this watch might still be considered a HAQ due to its 4.19 MHz oscillator (and, of course, its rate trimmer), giving it the promise of very good thermal performance and year-round high accuracy. That would make this probably the only known HAQ to date that is solely digital.
Alongside the SP-400, Casio also released the SP-400G (10 SPY) and the SP-410 (15 SPY).
| Parent Company | Casio Computer Co. Ltd |
| Brand | Casio |
| Model Series | unknown |
| Model Name | unknown |
| Model Number | SP-400 / H103 |
| Case Number | unknown |
| Serial Number | 705364 |
| Approx. Date of Manufacture | 1980 (estimate) |
| Calibre (mvt maker) | Module 75 |
| Calibre (brand) | Module 75 |
| Factory SPY | 15 |
| TC Appproach | Thermoinsensitive: HF |
| Frequency (XO 1) | 4.19 MHz |
| Frequency (XO 2) | n/a |
| Rate Adjustment | User |
| Major Inhibition Period | n/a |
| Minor Inhibition Period | unknown |
| Power | Disposable cell |
| Cell Number | CR2016 |
| Case Back | Press (requires case press for closing) |
| Water Resistance | unknown |
| Features | Digital display |
| Stopwatch | |
| Day, date (not perpetual) | |
| Light | |
| Timing Results | Basic data & Further details |
| Images | Photos - Large File Sizes! |
| Documents | User manual |