FR Electronics RSM 82-1A
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FR Electronics RSM 82-1A is a reed switch, using a design very similar to Unitra Dolam M-24-112.
The base of the switch has six holes for terminals: four for two reed modules (likely providing DPST rather than double-action) and two for illumination which line up with channels in the centre shaft that hold a lamp. An FR-branded illuminated version has never been seen, but the RRE illuminated counterpart is RRE RKS 80-1AL.
"1A" likely indicates 1 form A (SPST NO); whether "RSM" or "RSM 82" indicates the name of the series remains unknown. The DPST version is presumably RSM 82-2A.
The base of the switch can be removed by prying open the switch using a thin blade.
The reed unit terminals appear to push into the base of the switch from the outside, making the reed assembly non-removable. The reed capsule itself is attached to the terminals using a seemingly invisible amount of solder, or some other visually non-detectable process.
- Plessey Displays keyboard, ca. 1984