First American radar

Rehashing from two weeks ago:

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.

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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.

The altitude operator was also watching the strength of the received pulse, controlling a servo motor that turned the antennas and lights upward and downward.

The parallax or range operator was watching the distance (time delay) between the sent and received pulse, setting the searchlight and gun to be more ‘cross-eyed’ with the radar when the received pulse was nearer.

I’m showing the searchlight turned on for clarity, but in reality the light would be turned off until the officer in charge decided it was time to fire. Then the light captured the aircraft and the guns were fired. The enemy wouldn’t know he had been seen until just before he was shot.

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Graphic sidenote: Is that a UFO or Smokey Bear?

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