An electro-mechanical MHz range harmonic load pull tuner is made as a cascade of filter sections and independent tuning sections; the filter section includes three parallel series resonant circuits, each set including one inductor and one adjustable capacitor. The tuning section includes three parallel tuning modules; each module comprising three adjustable shunt air capacitors inter-connected using coaxial cables of appropriate length. Each capacitor is remotely adjustable to 10 or 20 values (settings); the tuner creates independently controllable impedances at three (harmonic) frequencies in octave size frequency bands between 5 and 150 MHz. An Error Function-based optimization algorithm allows impedance tuning at three frequencies independently, by optimized searching among the more than 209=512*109 possible combined tuner states. Stepper motors, drivers and control software are used to automate, calibrate and use the harmonic tuner for automated harmonic load pull measurement.