The PM 6669 is an economic, easy-to-use counter that meets your most stringent demands for high-precision measurements, reliability and durability. The multi-function PM 6669 offers frequency, period, count totalization, ratios, pulsewidth and frequency difference measurements. Available options for further enhanced functionality include a 1.3 GHz input, battery pack and high-stability MTCXO timebase oscillator plus an IEEE-488 bus interface.