Early Broadcast Equipment
RCA 510-A Television Equipment Cabinet
This unit is a camera control unit for a RCA television camera. It was made as part of a mobile package that RCA sold to radio stations in 1939 who wanted to experiment with television. It appeared in a 1939 catalog of RCA broadcast equipment as model 510-A and was called a Picture Equipment Cabinet. It contained a video monitor with a 12 inch screen and a 2 inch waveform monitor. It connected to a model 500-A iconoscope camera and contained all of the support circuitry needed to make the camera work. The 500-A/510-A formed a complete studio/transmitter facility. The 510-A actually had an RF oscillator/modulator included to transmit to nearby receivers
One of these setups was sold to KDYL in Salt Lake City. It is likely that this is the arrangement that was used at the 1939 World's Fair. Here is another link from Maurice Schecter. The same equipment was used in a postwar demonstration in San Antonio, Texas
Notice the connector on the chassis for attachment of the camera cable. The telephone handset was added in the field, and its purpose it unknown.
(Pictures courtesy of the Collection of Historic Scientific Instruments at Harvard University. Information courtesy of Darryl Hock)
The pictures below are from a 1939 RCA broadcast equipment catalog
(Courtesy of Darryl Hock)