Spectrum- / Network Analyzer 10Hz - 500MHz The Agilent (now Keysight) 4195A is a combined Spectrum- / Network Analyzer with a frequency range from 10 Hz to 500 MHz. Also has the impedance measurement facilities when used with 41951A. 7.5inch colour display, 2.5-inch disk drive in the front panel. Built-in command structure resembling BASIC for development of automated tests without a controller. Softkey control of graphic pringer or plotter. +/-1ppm accuracy