FR Electronics was a subsidiary of Flight Refuelling Ltd (now Cobham plc) that produced electronic components. This included reed keyboard switches. Cobham no longer have any record of these switches. Switch production was moved to Reed Relays and Electronics India Limited (RRE), a joint venture with FR Electronics that lasted for 20 years until FR Electronics left the market. RRE were able to supply some old stock illuminated switches (which they called RKS 80-1AL instead of RSM82-1AL) but they too have no details left on this product range.
RSM62 has never been observed. RSM62 and RSM82 were described together in an advertisement in Electronics Today International, June 1983 page 65:
Keypad and keyboard range
FR Electronics manufacture a range of keyswitch products which use the RSM62 and RSM82 reed switch type keyboard switches.
It is claimed that the reed switches offer long electrical life and high reliability with a maximum of flexibility. The anti-rotational four-bearing plunger design is used to minimise sideplay and give smooth action. Illuminated and non-illuminated versions are available with single pole or double pole normally open functions. A full range of coloured keytops is available and alternative characters can be supplied on request.
RSM82 is a low-profile reed keyboard switch. It was advertised in 1977 as being 0.7″ tall including the plunger, but RSM82-1A measures 0.89″ instead. The advertisement in Wireless World, March 1977 (page 82, PDF page 84) reads:
The RSM82 series is a range of low profile keyboard switches which utilize reed switches for reliability. Single pole and double pole switches are available, with or without latching, and an illuminated version may also be obtained. Each unit is designed for p.c.b. mounting and is 0.7in high from the top of the plunger to the base. A large range of button tops, space bars and mechanisms is also available.
The only fully confirmed model is RSM82-1A, which is single pole. RSM82-2A is likely to be the double-pole version.
Unitra Dolam M-24-112 is largely the same design, and one series will be based on the other.
RSM83 series is not confirmed from literature, but RSM83 switches were used in Racal receivers. It seems to be simply a heavier weight version of RSM82, from experience.
Only one keyboard has ever been found with these switches, a 1988 Plessey Displays keyboard. The photos for this are all lost now, so it can no longer be examined for clues.