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Professional and personal files including Armstrong's correspondence with professional associations, other engineers, and friends, his research notes, circuit diagrams, lectures, articles, legal papers, and other related materials. Of his many inventions and developments, the most important are: 1) the regenerative or feedback circuit, 1912, the first amplified radio reception, 2) the superheterodyne circuit, 1918, the basis of modern radio and radar, 3) superregeneration, 1922, a very simple, high-power receiver now used in emergency mobile service, and 4) frequency modulation - FM, 1933, static-free radio reception of high fidelity. More than half the files concern his many lawsuits, primarily with Radio Corporation of America, over infringement of the Armstrong patents. Litigation continued until 1967. Other files deal with his work in the Marcellus Hartley Research Laboratory at Columbia University, 1913-1935, and with the American Expeditionary Forces in France during World War I, his Air Force contracts for communications development, Army research during World War II, the Radio Club of America, the Institute of Radio Engineers, FM development at his radio station at Alpine, N.J., the use of FM in television, his involvement in Federal Communications Commission hearings and legislation, and his work with the Zenith Radio Corporation. Also, letters to H.J. Round

Correspondence, manuscripts, documents, memoranda, notes, reports, photographs and printed materials. The Klachko papers are almost entirely made up of her research notes for her biography of Admiral Benson. The material covers all aspects of his life, including his early naval career, his tenure as Chief of Naval Operations, and his Chairing of the U.S. Shipping Board. The catalogued correspondence are mainly replies to Klachkos̀ appeal for information about Benson, the naval and political milieu of early 20th century, and help to publish, review and edit her growing manuscript. Among the catalogued correspondence are: Norman Angell, Walter Lippmann, Edward House, and Eleanor Roosevelt. The catalogued manuscript is Klachkos̀ bio of Benson bound in 5 parts. It is interesting to note that her final manuscript draft is 1038 pages whereas the published biography merely numbers 268 pages. The rest of the collection is comprised of photos of Benson and other important naval and political figures of the time, and Klachkos̀ extensive research notes.