RCA CTC-5
(click on picture for high resolution image)
The CTC-5 was introduced in 1956, and has a 21 inch round picture tube. It came in several cabinet styles, including this console version named the "Whitby". More information on the CTC-5 is available at Ed Reitan's site. Click for a schematic diagram, advertisement or an article about 1957 RCA color sets.