They weren’t being chintzy!

Last night I was watching an episode of Radar Patrol vs Spy King, one of those mostly repetitive movie serials from the late ’40s. I vaguely remembered watching this episode several years ago and mocking the fake radar gear. Didn’t they know what real radar looked like?

The antenna:

The scopes:

The trace:

Turns out they were trying to be accurate, but secrecy prevented them from showing more modern equipment. They were showing a slightly modified version of the prewar SCR-268, which I animated a few months ago. As it happens, the SCR-268 was revealed in the same 1945 issue of Electronics magazine that briefly opened the gate to atomic fission, as I mentioned yesterday.


This early radar installation appeared in a 1945 issue of Electronics magazine, which turned out to be the same issue that momentarily revealed part of the atom bomb before clamping down again. The issue includes a significant editorial on the whole subject of clamping and releasing.

= = = = =

After scrounging around the limited material on the SCR-268, here’s a scene and animation. I’ve followed the one available sketch of a full setup, presumably on a Pacific island.

The SCR-268 was developed in the mid-30s and used in the first year of WW2, then replaced by smaller and less clumsy units. The Brits and Japs were ahead of us in radar, and the Krauts were behind. (Krauts are the supreme engineers. They could have been way ahead of everyone else, but Hitler defunded radar development, with the usual Kraut overconfidence.)

SCR-268 was clumsy in its mechanical form, but its electronic innards were highly sophisticated. It was used for searchlight control and gun control.

Three operators sat in front of oscilloscopes, each controlling one aspect of the system from the same picture. Each had a handwheel driving a servomechanism. One controlled azimuth (side-side), another controlled altitude (up-down) and the third controlled the parallax relationship between the radar and the searchlight or gun.

The three operators worked in shifts, constantly scanning back and forth and up and down over the likely area of incoming threats.

For simplicity, Polistra is only controlling azimuth. She turns the servo wheel back and forth, activating a servomotor that moves the entire mechanism back and forth. The servo also moves the azimuth of the searchlight or gun. She is watching the trace (shown at upper right). The transmitter sends out pulses constantly on the middle antenna, and the received pulse from the two outer antennas shows up later. Here she is trying to find the strongest echo pulse.

= = = = = END REPRINT.

So I need to apologize to those movie producers. They weren’t cheap or ignorant.  They were trying for as much accuracy as they could achieve without breaking the law.

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