Apollo 20Watt Travelling Wave Tube Amplifier technology

[RobF]

Have just been reading up on this after seeing a link on Facebook. Might be of interest. We tend to take good communications for granted, but interesting in books and movies that try to realistically portray the Apollo landings there were frequently issues requiring switching between bands and antennae to maintain communications with the earth (or the Command module).

https://www.righto.com/2021/07/inside-20-watt-traveling-wave-tube.html

[Hans Tucker]

Well this was an interesting read .. thanks Rob for sharing. But then I am biased .. I love reading anything technical from the Mercury, Gemini, Apollo and Shuttle era.

[gary]

Hi Rob,

Thanks for the post.

One of the links in there to the Command Service Module (CSM) Functional
Integrated System Schematics Block II Revision K was also interesting to
browse in its own right.

Link :- https://www.ibiblio.org/apollo/Documents/CSM%20Functional%20Integrated%20Sys tem%20Schematics%20Block%20II%20Rev ision%20K.pdf

For example, on the "Engine On-Off" (section reproduced in image below) you
see the use of so-called "Deadface Connectors" between the Command
(CM) and Service Modules (SM).

Extremely reliable, robust connectors designed for the space industry,
they are designed to provide electrical isolation before physical separation
such as in this case where the CM and SM separate prior to re-entry.

[Hans Tucker]

Rather enjoyed going through the schematics .. had a bit of a rise in interest when I reached Section F .. thinking about the root cause of Apollo 13.
One of the best jobs I had in the RAAF was being a Technical Spares Assessor for Aircraft Consumable Spares (ACS) managing Passive, Active Components and Connectors. It was fascinating to read all the MILSPEC's that covered Aerospace Components which included Space Grade components which had their own unique MILSPEC's. Space Grade components had really tight tolerances and additional testing requirements to ensure reliability ... you appreciate why the programs cost $$$$$$'s.

[RobF]

Glad it was interesting Hans and Gary. Knew there were others on Ice with knowledge to get much more out of it than I.

I found the equipment bay schematics particularly interesting. You tend to take complex avionics (astro-onics? :)) for grated when you see the Apollo spacecraft pics, but of course ever single gram of hardware was there for a very good reason.

[The_bluester]

It is interesting having a look at that. I used to work on a RADAR system which used a cousin of the TWT, a multi cavity Klystron. 100W of RF in at the bottom, 1.2MW (Yes, Megawatts, though that is instantaneous power and the actual average power was quite low with a 1.2ms pulse at 750hz repetition rate) out at the top. Basically a five foot tall vacuum tube with pulsed -60KV on the cathode to make it go.