[Learadio Model R-3 aircraft receiver, antenna, and peripheral components]

Photograph of a Learadio Model R-3 aircraft receiver, shielded loop antenna, and peripheral components, circa 1931-1939. The caption describes the device's development.

Typed caption on verso: "P. This loop was metallized in an attempt to shield it, but it was found that the metallizing reduced the 'Q' of the loop so much that it was completely impractical. It was also used in conjunction with an attempt to adapt the Model R3 receiver for visual or aural null direction finding and the magic eye (brain?) in the little box to the left was used to indicate the null. This apparatus never worked too well, although it did enjoy some success."

Inscription on verso: "This loop was metalized in attempt to shield it but [illegible] metalizing."