[Lear Developments aircraft transmitter]

Photograph of a Lear Developments aircraft transmitter, circa 1931-1939. The verso caption notes that this transmitter was developed for the Flight International Corporation and describes the device's components and specifications.

Typed caption on verso: "K. This is an aircraft transmitter designed for International Flight Corporation and was the first transmitter, I believe, that was ever designed to have a rotating turret type of coils where the coils were changed from frequency to frequency. The knob at the top of the transmitter was for the purpose of rotating the drums which enclosed the coils. This latter was adopted by Bendix and RCA and provided the basis for the magic brain, from [handwritten note: 'sic'] which I furnished the basic idea to RCA in 1935. You will note that there were 400V and 1500V positions on the switch which would make it possible to tune up the whole transmitter on low voltage and then switch over to high voltage to get high power output. There was also a high power switch and a low power switch so that the unit could be used for transmitting under either condition."