Lee de Forest
Hogan was born in Philadelphia, constructed his first amateur wireless station in 1902, began his career in 1906 as a laboratory assistant to Lee de Forest, and in 1907 participated in the first public demonstration of the audion tube (triode). From 1908-10 he attended Sheffield Scientific School at Yale University, leaving without a degree to join Reginald Fessenden's National Electric Signaling Co. (NESCO) at Brant Rock, Massachusetts, where he served as a telegraph operator.