Avionics + mil-spec teardowns

Let's take a look at a signal generator board, with a lot of programmable logic, RAM, and 5 separate DACs: this might do DDS waveform generation for radar transmit pulses.

https://www.eevblog.com/forum/projects/reverse-engineering-some-litton-military-boards/msg5711141/#msg5711141

Take a look at some super-shiny gold & ceramic, which turns out to be a high-bandwidth parallel data acquisition system.  There's a lot of fast op-amps, comparators, and ADCs, plus a dynamic offset-correction circuit with a specialty sample-and-hold chip, but the overall function is still a bit of a mystery (I suspect either imaging or radar).

https://www.eevblog.com/forum/projects/reverse-engineering-some-litton-military-boards/

Surprisingly complex power supply for a traveling wave tube RF amplifier, from the late 70's:

https://www.eevblog.com/forum/projects/avionics-reverse-engineering-spacecraft-equipment/msg5678733/#msg5678733

Couldn't resist the gold packages and paid too much for this board, but it ended up having some interesting packaging & sensor signal-conditioning circuitry:

https://www.eevblog.com/forum/projects/reverse-engineering-misc-avionics-(part-3-raytheon-eas-diehl)/msg5646971/#msg5646971

Found a voice encryption unit from a British military helicopter: the crypto hardware itself was removed (as expected), but there's a lot of interesting interface & digital encoding stuff built out of op-amps/comparators/4000-series logic, and a complex 3D construction scheme with lots of wiring harnesses.

https://www.eevblog.com/forum/projects/avionics-teardown-reverse-engineering-a-(de-mil)-voice-crypto-unit/

I looked at a mystery board made by Broad Reach, likely a general-purpose analog & power I/O board for some kind of satellite's onboard computer system:

https://www.eevblog.com/forum/projects/avionics-reverse-engineering-spacecraft-equipment/msg5577507/#msg5577507

Got some boards from what looks like an old benchtop engineering model of a spacecraft RF transmitter, and worked my way through figuring out what all the circuitry does: https://www.eevblog.com/forum/projects/avionics-reverse-engineering-spacecraft-equipment/msg5565207/#msg5565207

A Hughes Space & Communications box, when reverse-engineered, seems to contain a dual-locked-oscillator FM signal generator, most likely used in a communications satellite for a microwave link somewhere in the 20-40 Ghz range:

https://www.eevblog.com/forum/projects/avionics-reverse-engineering-spacecraft-equipment/

I finally got around to tracing the full schematic of the F-4 Voice Warning generator, and figuring out how the all-4000-series-LSI/MSI control circuitry works.  Apparently it has two different voice samples (low-altitude & cockpit un-latched).  Haven't gotten it to play audio yet, but working on extracting the data from the onboard ROMs...

https://www.eevblog.com/forum/projects/avionics-reverse-engineering-f-4-voice-warning-generator/

Added a writeup about two Westinghouse digital processor boards from aircraft radar systems, an older one from the 70's and a newer one from the 90's:

https://www.eevblog.com/forum/projects/reverse-engineering-misc-avionics-(part-3-raytheon-eas-diehl)/msg5533221/#msg5533221