CTC13 is, like CTC1, rumored to have existed only as a developmental color set. No longer a rumour, the CTC13 was designed and built in 1962 as the progenitor of 21-in. round RCA color television sets that eliminated the safety glass that graced all color sets to that time. The CTC13 was never marketed. RCA did sell two more vintage round sets, the CTC15 and CTC16, both of which were available with implosion-resistant CRTs such as the famous 21FJP22.
There is no schematic record of the CTC13. However, one of the four CTC13-based sets that RCA built has survived along with its developmental implosion-resistant CRT. Even more amazing, the set still works. Truly a wonderful
of our color television heritage.