The biomedical telemetry was a bit complicated (as was everything in Apollo). When astronauts were outside, there were 7 channels of analog telemetry transmitted by FM to the Lunar Module. The Lunar Module converted these channels to an AM signal which was transmitted over VHF to the Command Module. The Command Module converted these to PCM data, which was then sent to Earth over the unified S-band system.

For details, see "Unified S-Band Telecommunications Techniques for Apollo" page 11. https://core.ac.uk/reader/80678138

> Who figured that out? [traveling-wave tube amplifier]

It was Andrew Haeff at RCA in 1933: https://patents.google.com/patent/US2064469

Haeff was something of a prodigy, looking at his other patents. E.g., a 3D volumetric laser scanner from 1964: https://patents.google.com/patent/US3636250A

Dude didn't let any grass grow under his feet, tech-wise.

Hmm, I wonder if that's where late 60s Alan Watts got this idea:

"with the aid of laser beams, we can translate a physical object, let's take a complicated one, let's take a dandelion flower gone to seed a dandelion clock. You take a dandelion clock about so big, it can be turned into a formula passed through channels, enlarged to any size, say this big, and with laser beams, cut in solid plastic in a matter of moments. You can get this reproduction of a three-dimensional object. But the transition between the two was handled simply in terms of pulses."

"Rudolf Kompfner in 1942 —notably after his public announcement in 1946— when he was secretly working on microwave vacuum tubes for the British Admiralty at the University of Birmingham during World War II. But the history of this device is more complex because the traveling-wave tube was, consecutively, discovered thrice independently"

https://hal.archives-ouvertes.fr/hal-01754885/document