Train Control Systems TCS 1456 KA2 Keep Alive decoder HO scale NIBTrain Control Systems TCS 1456 KA2 Keep Alive decoder HO scale NIB The Keep Alive (KA) devices are used to supply power to decoders during times of power interruption due to dirty track or problematic track work. KA2 will power an HO Scale locomotive with headlights on for approximately 6 to 15 seconds (depending on the locomotive and the efficiency of the motor). This Keep Alive includes a blue and a black w white stripe wire with which to attach it