This short writeup doesn't include any information about who was operating the radio transmitter at the Fairmont Hotel. However, a year later the Leo J. Meyberg Co. began regular broadcasts from the hotel over its experimental station, 6XG.
Radio News, March, 1920, page 500:
AMERICAN LEGION COUPLES DANCE TO MUSIC BY RADIO.
National history in music transportation was made at the grand ball of Oakland, Cal., post, American Legion, in celebration of Lincoln's birthday at the Civic auditorium recently, when hundreds of couples tript the fox-trot to music conveyed by "wireless" from the Fairmont Hotel orchestra in San Francisco. The strains of the orchestra carried clear across the bay furnished a jazz melody which could be heard all over the big auditorium dance floor.