Curious Marc Fixing a US$33,000 HP 3GHz Signal Generator he Bought for US$150

This thing is amazing. It has a tiny spherical Yttrium iron garnet crystal resonator in a box to generate microwave frequencies:

 

It's part of the Apollo communications system. See Apollo S-Band Communications and their Soyuz/Apollo Space Hardware playlist.

See Robot Languages and Another Lunar Lander Fail and the AI Robot Apocalypse.

With modern equipment (including a Spectrum Analyser that takes 10 minutes to boot up Windows, because it calls out to Microsoft to check licences, ...) 

And it goes on, ... their transmitter/receiver pair had been retuned, probably as part of the GEOS3 program. See https://podaac.jpl.nasa.gov/GEOS-3

Reverse engineering the up-data link test system:

 

11:31 They had two switches: essentially to prevent the Russians from sabotaging the mission by reprogramming the space ship in flight!

 

3:10 NASA at some point afterwards switched the sub-bit encoding, ... nobody knows why, ... Discovering the weird missing inductors in the modem:

I wonder whether maybe this is because the ISS actually uses the same S-Band system, and they didn't want people to be able to hack the ISS? 

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