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Fujitsu FES-9 Series



FES-9 Series is a family of reed and Hall effect switches from Fujitsu. FES-9 is a reduced-height version of FES-8. FES-9 was possibly introduced around 1977, if the timeline chart in the Fujitsu magazine is accurate in this respect. In the FES-8 and FES-9 overview, Fujitsu described FES-9 Series as “Low Profile Keyswitches” and wrote that FES-9 Series is “virtually the same keyswitch as FES-8 Series except for lower height.” The operating forces given in the December 1978 advertisement in Computer Design magazine for the linear and tactile types match the FES-8 force curve.

FES-9 is the result of making a number of changes to reduce excess height, without making any drastic changes. These changes appear to include removing the “feet” from the reed carrier, shortening the base, and shortening the plunger. The switches are still damped. The absence of further specifications indicates that all the details given for FES-8 also apply to FES-9, including the option of solid state sensing and tactile feedback (for which the protrusion in the plunger remains present). Height from the PCB including the keycap was advertised as 35.3 mm (1.40 inches, given erroneously as 1.29 inches), a reduction of around 25% over FES-8.

FES-9 switches can be seen in MouseFan’s N860-9201-T001. This is indicated by the 9000-series N860 code. They can also be seen in a 1978 advertisement in Computer Design magazine, alongside FES-8; sadly neither series is named here.


Operating force 50±15 gf (linear, full travel)
70±30 gf (tactile peak)
150 gf maximum (alternate action)
90±30 gf (linear LED illuminated, full travel)


It appears that FES-9 uses the same part number format as FES-8, with the only change being the leading digit changing from 8 to 9. FES-9 is very rare, so only one part number has been observed to date. (MouseFan did not think to document the part numbers of the switches in his keyboard.)

Part number Variant Found in
933001 Momentary tactile, reed B06B-1430-B003A (1992)