The Photophone Type PB-46
Ribbon Transmitter
(MI-3017, prototype velocity microphone)

Slide show photos courtesy of John Madison

Jim Webb writes:
    “This is definitely a PB-46. It has the large flange on the bottom of the yoke which the early 44-A mics had. It is missing the shock mount that would go with the mic. This is serial number 1030 (Number 30), and my guess is that there were not more than a few hundred made. Since there is little or no literature available, many collectors do not even know it exists. My understanding is that the PB-46 was really the very first model of the (permanent magnet) 44-A (very early thirties), coming after the field coil-driven PB-31. I have never seen documentation on it other than a handwritten note I received from an RCA engineer describing it as such. Its main distinguishing characteristic is that it has a covered terminal block in the back where the cable attached. It was quickly replaced by the 44-A and its variations.”

Photo courtesy of Dennis Schrank.
This mic’s serial number is 1037.