page_title: SCR-270
section_title: Deployment and Incomprehension
hierarchical_section_title: SCR-270 / Deployment and Incomprehension
caption_attribution_description: English: Original Caption: Radio set SR-271-D at Evans Signal laboratory show shelter for components and operating personnel, 100 foot tower, and antennae modified for PPI display. IFF antenna is shown top center on radar antenna. This is the non portable version of the SR-270 which was otherwise identical in capabilities and equipment to the SR-270. alteration- this version has a border cropped which credits the photo to Lieutenant Zahl. Original at the above location. This photo is credited to First Lieutenant Harold Zahl, who pioneered Radar use by the Army air corps. The photo appears in a paper by him from the period. these photos would not have been saved were it not for Dr. Howard W. Andrews, who had the foresight to preserve them along with Lieutenant (Dr.) Zahl's papers for posterity. Credit and thanks to H.W. Andrews for preseving these photos.
context_page_description: The SCR-270 was one of the first operational early-warning radars. It was the U.S. Army's primary long-distance radar throughout World War II and was deployed around the world. Its also known as the Pearl Harbor Radar, since it was an SCR-270 set that detected the incoming raid about 45 minutes before the December 7, 1941, attack on Pearl Harbor commenced.
  Two versions were produced, the mobile SCR-270, and the fixed SCR-271 which used the same electronics but used an antenna with somewhat greater resolution. An upgraded version, the SCR-289, was also produced, but saw little use. The -270 versions were eventually replaced by newer microwave units based on cavity magnetron that was introduced to the US during the Tizard Mission. The only early warning system of the sort to see action in World War II was the AN/CPS-1, which was available in mid-1944, in time for D-day.
context_section_description: The non portable version, the SCR-271-A, s/n 1 was delivered to the Canal Zone and began operation in October 1940 at Fort Sherman on the Atlantic end of the Panama Canal. It picked up airliners at 117 miles (188 km) in its initial test run. The second set was set up on Fort Grant's Taboga Island on the Pacific end of the Canal by December 1940, thus giving radar coverage to the vitally important but vulnerable Panama Canal. Westinghouse quickly ramped up production, and produced 100 by the end of 1941.
  Operators of sets that were sent to the Panama canal, the Philippines, Hawaii and other strategic locations were all gathered for an air defense school at Mitchel Field, New York in April 1941. The school was the culmination of efforts begun in 1940, when the War Department created the Air Defense Command headed by Brig. Gen. James E. Chaney.  Chaney was tasked by Hap Arnold to collect all information on the British air defense system and transfer the knowledge as quickly as possible to the US military. Air Marshal Dowding, one of the designers of the Ground-controlled interception (GCI) air defense system used during the Battle of Britain, was at the school and discussed with the American generals the design and urgency of establishing the Hawaiian system, in particular emphasizing the need for thorough radar site coverage along the coasts.
  Despite the high level attention and the excellence of the school in training on the use of the SCR-270 and its integration and coordination with fighter intercepts, the army did not follow through on supporting the junior officers who were trained at this session. Air defense required direct control of assets spread out over disparate units; anti aircraft guns, radars, and interceptor aircraft were not under a unified command. This had been one of the primary problems identified by Robert Watson-Watt prior to the war, when a demonstration of an early radar system had gone comically wrong even though the radar system itself had worked perfectly. Dowding was well aware of the importance of a unified command, but this knowledge did not result in changes within the U.S. Army structure.
caption: Non portable version: the SCR-271 at Camp Evans[3]
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