QST, September, 1920, page 44:

    Young & McCombs, Rock Island, Ills., announce that about Sept. 1st they will have a new C.W. transmitter in operation at 9BY, with a power of 550 watts, and will give radiophone concerts every Thursday evening, 7:15 to 9 o'clock, with a fifteen minute intermission at 8 p.m. for 9ZS' time signals and weather report. The latest phonograph music will be played on amateur wave lengths, and a report of their signals will be appreciated. They also operate station 9BC, using a deForest radiophone with eight bulbs, operating regularly over 200 miles.