FIELD: physics.
SUBSTANCE: invention relates to applied physics and can be used in making electron paramagnetic resonance (EPR) spectrometers. Spectrometer comprises signal 1 and heterodyne 2 microwave generators, measuring attenuator 3, mixer for reference 4 and signal 5 channels, circulator 6, measuring resonator 7 with its resonance frequency tuning element 8, reference amplifier 9 and 10 signalling channels, phase-frequency discriminators 11 and 12, frequency dividers 13 and 14, synchronous detectors 15 and 16, reference generator 17, frequency synthesis device 18, three-position switch 19, pulse modulator phase 20, alternating current amplifier 21 and pulse demodulator 22.
EFFECT: technical result is high accuracy of automatic frequency tuning system of signal generator and resonant frequency of resonator.