Here is a little history I found by googling:
http://earlyradiohistory.us/1963hw23.htm"After the laboratory was moved to Anacostia, its staff was increased by several radio engineers and it was assigned the additional functions of design and development of complete aircraft radio systems. Two transmitters, the SE 1375 and SE 1385, which later became the backbone of naval airborne communications, were designed and developed. Both of these produced a clear 500-cycle note and neither was voice modulated. The SE 1375, 20 watts, which used four three-element tubes and operated on frequencies between 570 and 750 kc., was designed by Mr. F. B. Monar for use in small aircraft. The SE 1385, 500 watts, which used two 50-watt three-element tubes and covered the frequency range, 300-600 kc., was designed by Mr. L. A. Gebhard for use in large flying boats. One of the first radioteletype transmissions from aircraft to ground was made utilizing the SE 1385. It also became the transmitting component of the first aircraft radio transmitting system given a model designation, the GA. "
The transmitter appears on this list also:
http://pages.cthome.net/fwc/OLD-NAVY.HTM
