Radiation Inc. Logic Modules 1960s Apollo Saturn V, LEM Ground Support Equipment

by Robert Brand 20 Jan 2020

I was excited to see a package had arrived that I was looking forward to receiving. It is not the new technology that we normally see in ThunderStruck, but a hint of the past. As some may know I was involved in support for Apollo 11 as a 17 year old It was a friend in the USA who has sent us some Apollo Saturn V / LEM ground equipment. It is for educational purposes when we give talks. It is simply amazing and I believe that they all work. Maybe we can make a count down timer – I’m serious. I would love to have these modules do more than just be a static exhibit.

According to the documents I have:

8 x NOR-L #503816G1 modules

6 x CSR-L #503819G1 Modules

4 PI-L #503818G1 Modules

and 1 x two speed Switch Module 1007522-021 ACSK-21

An actual piece of Early Space Exploration History
The Radiation Incorporated modules are pulled from a rack that was used as Ground Support Equipment (GSE) for the Apollo Saturn program in the early 1960s. These particular modules was used in support of the LEM (Lunar Excursion Module). Originally obtained from a sale of NASA surplus in the 1970s,

Radiation Incorporated Logic Modules Saturn V - LEM test Modules

Ultra-High Reliability Electronics
Numerous electronic problems were encountered during the early years of missile and rocket development due to the extreme environments. The rocket engine’s high level of force and vibration expected was one of the key factors considered in all Apollo hardware. With manned space flight as the goal, extreme reliability was also called for in GSE design. Radiation Inc. delivered that reliability it in the form of these modules.

These modules were socket mounted and interconnected in panels (see the images below). The panels held large numbers of them to form complex test equipment and other ground support systems needed. There are no ICs in these Radiation modules, rather they are made from encapsulated discrete transistors and other passive components. The push for miniaturisation was on and these modules were the direct predecessors of commercial ICs.

Radiation Inc Test Shelf
Radiation Inc Test Shelf
Radiation Inc Test Shelf Rear
Radiation Inc Test Shelf Rear

Radiation Inc was the company who made the Pulse Code Modulation System for Apollo. And later became Hughes Corporation. These modules were removed from a Radiation, Inc. Model 540 Decom that was used at NASA MSC on the testing of the APOLLO Lunar Excursion Module These modules were the way Digital Logic circuits were built before integrated circuits.

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