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Eastern Bloc switches

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Overview

As someone who does not speak any Eastern Bloc languages (although I can read a bit of German), understanding the various Eastern Bloc types is not easy. This is made worse by the cultural divide between the West and the Eastern Bloc. Although unbranded switches, and switches with unrecognised branding, is common to all countries, it is worse in eastern countries where it is much harder to find information without understanding the language.

Known brands

HFO

Country: East Germany (DDR)

VEB HFO produced the B 461 G Hall sensor IC used in both East German RFT TSH switches as well as West German RAFI RS 76 C switches (and presumably RS 74 C).

ИЗОТ

Country: Bulgaria

See:

RFT

Country: East Germany (DDR)

Rundfunk- und Fernmelde-Technik (RFT) was responsible for at least two keyboard switch families:

TESLA

Country: Czechoslovakia

In fact, there is no proof that TESLA ever made either of the above switch types. All that is confirmed is that they produced the Hall sensors that these switches used. The switches could have been made by anyone.

Unitra Dolam

Country: Poland

See:

Unknown types

ПКМ 1Б

ПКМ 1Б (“PKM 1B”) is type of fairly low profile reed switch, whose design was inspired by RAFI’s keyboard switches. The switch has four legs, of which two are the reed capsule terminals and two are for retaining the switch. All switches are marked “ПКМ 1Б”. Some have the reed terminals marked “1” and “2”, and some have the word “ЖРВИ” (if translated as a word, “fat”) written in between these. There can instead be an “M” logo in its place, which may instead be “Ш” if the logo is upside down.

As with many other European-made reed switch types (but not those from Clare) the reed capsule is placed horizontally across the bottom of the switch. Just as with ИЗОТ switches, these seem to also use whatever colour of plastic was available, although curiously the lower and upper shell pieces are normally moulded from different-coloured plastics. The plunger is typically colourless.

A photo marked “размен 14*14 мм” shows the switches placed in alternating orientation to accommodate the asymmetric shape, but suggests that this is may be a keyboard with reduced spacing instead of the normal 19.05 mm spacing, with 14 × 14 mm keycaps.

These seem to be centred around Ukraine, based on where they were previously listed for sale. They are found in the “ЕС7927” (“ES7927”) keyboard or computer. Here, too the switches appear to be placed in alternating orientations.

Outer plunger

These switches have the plunger on the outside, that slides down over the shell. The reed capsule is placed off-center and vertically. The keycap presses down onto the plunger and is the exact same width and depth as the plunger. In many cases they are relegendable. Examples: