Casio SP-400G

Module 75

Factory Spec. 10 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, 40,000 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-400G, Casio also released the SP-400 (15 SPY) and the SP-410 (15 SPY).


Parent Company Casio Computer Co. Ltd
Brand Casio
Model Series unknown
Model Name unknown
Model Number SP-400G / H103G
Case Number unknown
Serial Number 809150
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
  Day, date (not perpetual)
Timing Results Basic data  &  Further details
Images Photos - Large File Sizes!
Documents User manual