Harold D. Arnold

Harold DeForest Arnold (September 3, 1883 – July 10, 1933) was an electronics engineer and pioneer of radio communication and telephony.

His earliest work was in the development of a vacuum-tube based amplifiers beginning with improvements to Lee De Forest's triode “audion”.

He worked on innovations that made it possible to demonstrate the first radio transmission between Arlington, Virginia, and Paris, France, in October 1915.

He developed and refined manufacturing techniques for vacuum tubes, oxide coatings for filaments, and other innovations for reliability and ease of replacement.

[5] One of his last projects was in the transmission of high quality sound, with the collaboration of Leopold Stokowski, conductor at the Philadelphia Orchestra that resulted in a live broadcast of a concert at Constitution Hall over telephone in April 1933.