I am interested in any description of the electronics on Syncom-3, the first geostationary satellite. I've been able to find quite a bit of general information. There was a pair of 2 Watt TWTs and somewhere there were five stages of clever diode frequency doubling to get up to the 7 GHz frequency. But I've not been able to find out if it was all vacuum tubes, for example, or if there were any transistors used. Was there a computer or state-machine of any description? What type of memory elements (if any) were used. Latching relays, Core memory, etc. These are the links I've seen so far: https://en.wikipedia.org/wiki/Syncom https://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1964-047A https://space.skyrocket.de/doc_sdat/syncom-1.htm http://web.archive.org/web/20101111082736/http://www.boeing.com/defense-space/space/bss/factsheets/376/syncom/syncom.html
You may want to read this technical report by NASA.
By searching "transistor" in the pdf, I have found this:
[...] the frequency multiplication is accomplished in eight doublers, of which all but the first involve the use of varactor diodes connected push-push in efficient duo-mode networks. The first doubler uses a conventional transistor circuit [...]
And this for "memory":
A psi tracker is used in the input circuitry of the synchronous controller servo. This functions as a memory circuit to ensure controller lock-on if for some reason psi pulses from the spacecraft are lost. It also discriminates against noise and spurious signals from the telemetry receiver that might otherwise break controller lock-on.
(There were also other results for transistor and memory).