The Motorola Transistorized AC Voltmeters offer many advantages not found in a-c vacuum tube voltmeters. Small physical size, light weight and full transistorization permit complete portability for field use. The absence of heat producing elements, such as tubes and transformers, lessens the need for frequent recalibration and increases component life. The Model 51051C is battery operated. The Model S1053C in addition to being battery operated, contains an a-c Power Supply which operates from a 117va-c, 50-400cps source. A detachable power cord is supplied with the Model S1053C The SKN6009A 230/117 Volt Adpater Cable Kit {an op- tional item not furnished with the standard Model S51053C) permits operation from a 230 volt, 50- 400 cps power source.