Signedplate on top of lid: SIGNAL CORPS U.S. ARMY / VACUUM TUBE DETECTOR SET / TYPE S.C.R. 55 / ORDER NO. W-40283 / SERIAL NO. 568 / MADE BY / WESTERN ELECTRIC CO., INC.
Historical AttributesAccording to the 1918-199 Annual Report of the Chief Signal Officer to the Secretary of War, this type of vacuum tube detector (SCR-55) used with the SCR-54 receiving set. It was thought that a vacuum tube detector would eliminate some of the difficulties of the SCR-54 set and give increased sensitivity and when used in combination with a two-stage amplifier. This type of set was designed in the summer of 1917, being then designated as the AR-5. Samples were used by the American Expeditionary Forces in the fall of 1917. Favorable reports were received in January 2018, but the military concluded that crystal detectors were sufficiently sensitive.
This particular example was used in Harvard's Cruft Laboratory.
ProvenanceMade for U. S. Army Signal Corps; used in Cruft Laboratory, Harvard University; transferred to CHSI.