Notice that the radio dial has little triangles-in-circles at 640 and 1240 AM. That's CONELRAD, the old Civil Defense radio system from early in the cold war. Probably early 60s, which correlates with the other estimate of 1962-63 for your entire unit.
The idea behind CONELRAD was, when the Soviet bombers were headed toward us, all AM stations would switch over to transmitting at low power on those two frequencies, thereby depriving the Soviet pilots of clear radio beacons (from powerful stations on their own frequencies) to use for radio direction-finding. The broadcasts on 640 and 1240 would be used to keep citizens informed about the emergency.
CONELRAD evolved into the Emergency Broadcast System, which is now the Emergency Alert Network, and the SAME network, whose mission has expanded to deal with weather emergencies and terrorist attacks.
