They did it. It took 21 episodes to revive my Apollo S-Band transponder and 20W tube amp and reverse engineer and revive the various test fixtures, but they did it. They transmitted B&W (color to come) TV with my vintage microwave equipment.
Earthrise is visible on the screen on the left. But it’s a studio fake! The camera in the back is aimed at the t-shirt with that image. (Jump to that scene)
In this episode, they added my FM Receiver to the Transponder mount and various other elements of ground equipment. It worked like a champ, with everything, even the light bulbs, still functioning 50+ years later.
To save power and bandwidth, the Apollo camera made some unusual design choices. The single S-Band radio link carries data, voice, and ranging information along with the TV signal. It’s 320 lines * 10 fps with a very unusual slow scan and sync signal (short bursts of 500kHz). While good for the unified transponder, the video could not be broadcast or even shared with Houston TV monitors; it required a huge scan converter machine. This was a crude analog converter — they displayed the slow scan video on a screen and filmed the screen with a NTSC TV camera! This led to serious image degradation for everything we saw on TV at the time.
Enjoy! Curious Marc Video, Episode 21.
The setup: “Our repaired NASA PM transmitter, PM receiver and FM receiver on the left, earth side. We’ll only need the FM receiver for this TV transmission experiment. In the middle, an old B&W TV monitor. On the far right, our Apollo transponder, with a period-correct vidicon TV camera sitting atop of the transponder test mount.”
With just 20 Watts, they could communicate with Houston from the moon (across 239,000 miles). And a single antenna combined voice, television, command, tracking and ranging. They even used it to study the lunar surface, with the aid of the Stanford Dish.
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