An image of an SCR-55 vacuum tube detector set with the caption: "SCR Apparatus. SCR-55 Vacuum tube detector set. Photograph taken by Photographer 2623 in March 1918. This equipment was used during World War I. Image numbered 111-SC-2623."

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Size: 7982px × 6302px
Photo credit: © piemags/NSC / Alamy / Afripics
License: Licensed
Model Released: No

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