Radio Amateur News, May, 1920, page 642:
RADIO TELEPHONE AT DAYTON, OHIO.
The amateurs of central Ohio have recently taken great pleasure in listening to the wireless telephone at McCook Field. This is a government flying field that is making tests on all kinds of aeroplanes and their equipment. We often hear them talking from the ground to an aeroplane in the air. They have a powerful set that is plainly audible here in the city on a galena detector. The sending range of their set is about one hundred miles taking in Cincinnati, Columbus and Indianapolis. On Friday nights they talk to the amateurs with the purpose of finding the range of their set. Upon hearing them any amateurs having transmitting sets are supposed to answer them by wireless telegraph and those that have not are requested to send in a post card to Radio Laboratories, McCook Field, Dayton, Ohio. They send on Friday nights between eight and ten o'clock on about two hundred to three hundred meters. Their call is M. C. F. Music is sent out with a Victrola and also by having people sing. The talking is not continuous as they frequently are obliged to stop and allow the appartus to cool off. The present station is a temporary one but it is understood that in a few weeks a much more powerful station will be installed to operate permanently.
Contributed by WM. T. PRATHER.