The radio station broadcast mainly classical music recordings. One of the station's listeners was the inventor of frequency modulation, Edwin Howard Armstrong. When Armstrong put his experimental FM station, W2XMN, on the air, he arranged to rebroadcast some of WQXR's programming. This ended in 1939, when Hogan and Sanger put their own experimental FM station on the air, W2XQR, just down the dial from Armstrong at 42.3 MHz. In 1941, the station began transmitting from the top of the Chanin Building, where it remained until 1965 when it moved to the top of the Empire State Building. Remnants of the original tower remain on the Chanin Building.