A 1971 Bendix PPI-1 plan position indicator, pulled from a McDonnell-Douglas DC9, is the subject of a hands-on teardown by Thomas Scherrer. The PPI-1 is the display unit only: no radar transmitter, no power supply, just the cathode-ray readout that would have shown pilots where precipitation and turbulence were strong enough to avoid.
The unit rewards close inspection. The case is engineered for field serviceability, with organized wire harnesses and chunky through-hole components that reflect 1971 avionics build standards. A front-mounted dimming filter and a component shaped like a triangular prism are among the specific details Scherrer works through on camera. That prism is worth watching the video to identify yourself.
This teardown matters because primary-sweep weather radar displays at this level of vintage are rarely documented in this format. The original video runs the full disassembly and is the only way to follow the signal path Scherrer traces through the hardware. If you want to understand how radar returns became a cockpit image before digital processing existed, this is the primary source.
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