Apollo Spacecraft S Band Communication System, Part 18—Reverse Engineering a Mystery Analogue Module

The only thing worse than restoring half century old electronic equipment without schematics or operating instructions is when it has missing parts. To get the ground-to-spacecraft data link running as it was intended requires an X-ray machine, knowledge of the internals of passive components, a bench full of candidate parts, and knowledge of the behaviour of real-world inductors which many engineers of the digital age never learned or have forgotten.