Conrad was the voice of "Escape" (1947–54), a high-adventure radio series. He played Warchek, a menacing policeman, in "Johnny Modero: Pier 23" (Mutual 1947), a detective series starring Jack Webb, and was in the cast of Webb's crime drama "Pete Kelly's Blues" (NBC 1951). He played newspaper editor Walter Burns opposite Dick Powell's reporter Hildy Johnson in the ABC radio drama "The Front Page" (1948). He was Dave the Dude in the syndicated drama anthology series "The Damon Runyon Theater" (1948); Lt. Dundy in the NBC radio series "The Adventures of Sam Spade" (1949–50); boss to government special agent Douglas Fairbanks Jr. in "The Silent Men" (NBC 1951); and a New Orleans bartender in the NBC adventure drama "Jason and the Golden Fleece" (1952–53).