The Simpson AC Ammeter Adapter Model 653 is a compact, accurate, wide-range instrument. When it is used in conjunction with a Simpson 260* or 270 Multimeter, AC currents can be measured over a frequency range of 50 to 3000 cycles per second. This wide frequency range in general exceeds commercial and military power frequency requirements. The Simpson VOM-plus-adapter concept is completely unique in approach and versatility. Each of the adapter models, of which the AC Ammeter is but one example, provides specific measurement and testing capabilities at a fraction of the cost normally required for separate testers.