When the Apollo astronauts made their way to the Moon, their communication equipment had a transmission power of a mere 20 W, which the sensitive receivers back on Earth managed to pick up. But this isn’t just any amplifier, it’s a Traveling Wave Tube amplifier (TWT), as [Ken Shirriff] explains in a recent article.
The most fascinating thing about these TWTs isn’t just their role during the Apollo missions, but the fact that even today this type of vacuum tube is still among the most efficient and compact types of RF amplifier. As a result today’s high-tech satellites still commonly feature these devices.
As always, [Ken] entertains and enlightens us with how the TWT and the rest of the amplifier system worked.