"The 257\/01 is a modulation meter from Wayne Kerr. Modulation meters measure degrees of modulation in a modulated signal.","Additional Features:","Simplify the measurement of amplitude and frequency modulation on signals in the range 1.5 MHz to 2 GHz. By eliminating the need to tune a local oscillator and make level adjustments, the 257 speeds up measurements and reduces errors. Patented circuitry ensures that the meter always locks to the strongest signal available ignoring spurious signals and harmonics. The mains only model 257\/01 is small and lightweight and is ideal for bench use."