Avionics reverse-engineering: 60's Hughes telemetry unit

[D Straney]

Very cool - looks like fairly primitive single-layer slabs, like in the thread, interesting to see that!

I have vague memories of seeing SMT caps in early stuff so went poking around, and here's some reference points:

• ATC patent from '74 on a multi-layer capacitor: https://patents.google.com/patent/US3838320A/en
• SMT caps in a late-70's bug probably made in the US
• SMT caps in a late-70's bug, made by Soviet-controlled Bulgaria
• The Russian R-105 radio (design updated in the 70's) has some nice little ceramic modules with peanut tubes and SMT ceramic caps mounted to them

So considering that SMT caps like that ended up in Russia in the 70's, when they were lagging the US at the time in electronics, I guess it's plausible that they were super-high-end specialty just-introduced in the US in the late 60's.

Oh wait, one more, I knew I'd seen this somewhere - a board from the Saturn LVDA with some SMT ceramic caps!  Surprising how far back that goes.

Or maybe most of the telemetry unit was late 60's parts from similar models, and they only assembled the whole thing with newer VCOs a few years later.  Who knows.

[RJSV]

   Never heard of that:
   'Snap-off Diode'.
   Quick search revealed the diode type can issue a sharp pulse, Upon turn-off, or fast turn-off,  which sounds fascinating, (and useful in function generators).

[Alex Eisenhut]

aka step-recovery diode.

[KE5FX]

Or "Boff diode."