The vacuum tubes used by George Cannon in 1916-1917 were provided by Lee DeForest.
Radio Broadcast, November, 1924, pages 81-82.

WHAT  Our  Readers  Write  Us
Who  Was  the  First  to  Broadcast?
EVERY once in a while the discussion starts about who was the first to broadcast. Mr. Cannon's letter raises a point which should interest other experimenters who were carrying on wireless telephone tests about the same time as he was. We suggest that those who are interested write Mr. Cannon directly. Without entering into the discussion ourselves, it is interesting to recall that Dr. Lee De Forest was carrying on experiments with wireless telephony from a studio at 103 Park Avenue, New York, in the spring of 1908, when he broadcast "Cavaleria Rusticana" from the stage of the Metropolitan Opera House. [NOTE: The broadcast of Cavalleria Rusticana and I Pagliacci actually occurred on January 13, 1910].

    Doubleday, Page & Company,
        Garden City, L. I.
    One hears off and on quite a bit of discussion as to who really ran, in a practical manner, the first broadcasting transmitter.
    This interests me, as I have quite an inclination to believe that this station handled the first phone of this type. During the months of December, 1916, and January and February, 1917, I ran quite a regular schedule from 9:30 p. m. to 10:30 p. m. Press was broadcast. Phonograph records were sent out and several instrumental artists contributed.
    The range of transmission was about two hundred miles maximum. The modulation compared very favorably with that of the stations of to-day. There were only about a dozen special tubes in existence I believe, and the ones I used would now be rated at about fifty watts. Our efficiency was low, naturally.
    I have numerous documents to prove the above contention and wonder just where my station ranks among the first of broadcasters.
GEORGE C. CANNON,                
Radio Station 2ZK                
183 Drake Avenue,            
New Rochelle, New York