Dreher was born in Vienna, Austria-Hungary (now Austria) in 1896, and emigrated to the United States in 1899. Beginning in 1908 he operated a small amateur radio station while living in the Bronx, and in 1916 qualified for a First Class-First Grade commercial radiotelegraph operator's license. He attended Townsend Harris Hall, the
City College of New York (CCNY) preparatory school, graduating in 1913. He then enrolled at CCNY, where his primary instructor was Dr.
Alfred N. Goldsmith. The United States entered World War One in April 1917, and Dreher received his B.S. degree in May, a month early, on the condition that he take a civilian position that aided the war effort. He began employment with the
Marconi Wireless Telegraph Company of America, working on war contracts in the company's test shop in Aldene, New Jersey, and also became a member of the
Institute of Radio Engineers (IRE). In 1919 American Marconi's assets were purchased by
General Electric and reorganized as the
Radio Corporation of America (RCA). From 1921 to 1923 Dreher worked as an operating engineer at RCA's transatlantic radiotelegraph station located at Riverhead, Long Island. In May 1923, RCA established two showcase broadcasting stations, WJZ (now
WABC) and
WJY, at "Aeolian Hall" in New York City. Dreher was initially the facility's chief control operator, but was soon promoted to engineer-in-charge. Drawing on his experiences, he published articles about radio technology and the emerging broadcasting industry, including, beginning in March 1925, the monthly "As the Broadcaster Sees It" column in
Radio Broadcast magazine. ==Sound engineer==