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Originally Posted by Don Lindsly
I suspect this schematic is a joke or a classroom exercise. There are several things "wrong with this picture". 1. The antenna circuit feeds the grid of the video amp. Where's the detector? No RF or IF gain at all says there's just not enough dBs to get anything done. The video output taken off the screen grid. The horizontal oscillator/output would be modulated by the video and the reverse.
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The cathode and G1 of the first tube looks like a Hartley local oscillator of the sort found in AA5 AM tube radios. Maybe the oscillation is partly locked on the signal's carrier and creates a synchronous detector? As for the horizontal oscillator, usually max RF on the carrier happens on sync tip. Which would be a big pulse when detected. Maybe that could "tickle" the feedback circuit between G4 and the plate of the tube? And create the horizontal deflection waveform and high voltage? But where does the vertical come from? Oh wait, it just assumes the vertical is the same frequency as the powerline, and you have to twiddle the hold knob to phase it in.
The sound is fairly straightforward, just an FM ratio detector detecting the FM subcarreir off the video.