George Risk Industries Series KB

Contents

• Overview
• Design
• Product range
• Models
• Series KB-LED
• Documentation

Overview

GRI Series KB is a series of tall, cylindral reed switches (1.75″ from base to keycap centre), secured with a nut onto a threaded leg. They support double-pole and normally closed configurations and lamp illumination; the rated lifetime is 50 million cycles.

The age of these switches is not known. Keyboard model 2-103-001-A-10 contains ICs from 1970, suggesting that the switches are going to date back to no later than the very early 1970s. Those switches were unfortunately not date-stamped.

In February 2022, George Risk noted that KB and KBLP switches are still manufactured.

Design

The plunger is divided into two parts. An inner plunger is fully contained within the body of the switch. A second plunger snaps into a shaft above this, and the keycap attaches to this part. The removable plunger style seems to be specific to the width and style of keycap, although this does not seem to be encoded within the part number of the switch itself. Tentatively, it appears that illuminated plungers are ivory coloured, while non-illuminated plungers can be grey or black. Normally, non-illuminated plungers are black, but in keyboard model 2-103-001-A-10, grey is used for single-unit keys and black for 1.5-unit keys. Although no photos are known that depict this clearly, the lamp appears to be statically positioned within the switch, well below the top of the plunger. At present, there are simply too few known examples to observe. Radwell had an illuminated type for sale, but upon receiving an order discovered that none were left; the single photo depicts the side of the switch and does not show the lamp at all. Another illuminated type shows up in an Internet search, but it was already sold, and the photos do not clearly depict the lamp.

Instead of using a slanted keystem or keycap mount, stepped keyboards are achieved by slanting the entire switch. The base of the switch can either be flat or wedge-shaped, and this determines the keycap angle.

Product range

The part number is stamped onto the switch. The manufacture date is frequently stamped below that, in the form M-YY. Most positions in the part number are treated as optional, and are generally omitted when not applicable or unnecessary. Broadly, the part numbers are the same for KB and KBLP, but some options are not available under KBLP. Most examples follow the schema detailed below. Some older switches do not appear to follow this pattern, and the model numbering scheme may have changed.

The schema is as follows:

KB-T(-K)(-V)-F(-C)(-A)

“KB”

Series name

T

Switch form: 01–06 (see below)

K

Keycap type (where keycap supplied): one to three letters, e.g. J, GM, NNN; see catalogue for details; when all positions are given, “XXX” appears to denote that no keycap is supplied

V

Lamp voltage, or absence of lamp or socket (see below; usually omitted if there is no lamp socket)

F

Force: 01 = 2.5 oz (71 gf), 02 = 4.0 oz (113 gf), 03 = 6.0 oz (170 gf)

C

Keycap colour (where keycap supplied): two to four position alphanumeric, e.g. 09 (white), 11A (fire engine red), 17AL (illuminated canary yellow); when all positions are given, “XXXX” appears to denote that no keycap is supplied

A

Angle: SL = sloped, FL = flat (default if omitted)

Examples:

KB-05-03-FL

SPDT-BM (05), 6.0 oz actuation (03), flat (FL), no keycap or lamp fitting (sold by Radwell)

KB-05-14.0-03-FL

SPDT-BM (05), 14 V lamp (14.0), 6.0 oz actuation (03), flat (FL), no keycap (previously sold by Radwell)

The complete set of permissible forms is given as:

The defined lamp options are:

KBLP part KBLP-05-5.0-02 suggests that KB would also drop the leading zero in 05.0. In fact, “5.0”, “5.0V” and “05.0” have all been seen.

Keyboard 2-103-001-A-10 from circa 1970–1971 contains three switch types, marked as follows:

• KB-01-01
• KB-01-01 6 oz.
• KB-01-0X 6 oz.

These seem to use an older part number system, where the weight was not included. The meanings of these part numbers are not known.

Models

The following models have been discovered:

Where the source is given as “NSN”, the items were found listed on PartTarget. Items discovered solely by NSN code have not been verified, and the part numbers may be erroneous, especially where they are not formatted correctly and assumptions had to be made as to the correct format and thus which fields have which values.

Series KB-LED

This is the LED-illuminated variant of KB. Normal illuminated KB switches take an incandescent lamp. These have their own part number schema, but the part numbers still fall under Series KB:

KB-T-V-F-C

“KB”

Series name

T

Switch form: 01–06 (see above)

V

Illumination voltage: L05: 5 V, L12: 12 V, L14: 14 V, L28: 28 V

F

Force (see above)

C

Keycap colour: OR: orange, GN: green, RD: red, YE: yellow

Documentation

• GRI reed pushbutton switches advertisement, Computer Design, July 1975
• GRI catalogue (2017) part 1 — keyboards, keypads, switches (see the main GRI page for notes on this document)
• GRI catalogue (2017) part 3 — keycaps, ordering instructions
• KB datasheet (November 2021), from the GRI website