FIELD: magnetic recording equipment. SUBSTANCE: device records zero beat signals which are output by signal mixer. First input of signal mixer receives signal of crystal clock oscillator, which is passed through crystal filter and first amplifier. Second input of mixer receives signal from microphone, which is passed through second amplifier and level clipper. Signal at output of mixer may be indicated by arrow pointer, oscilloscope or listened by means of head phones. Reference frequency signal from output of crystal clock oscillator is recorded to cassette by means of tape recorder with precisely set speed of magnetic tape. Said tape can be used as reference tape. EFFECT: autonomous design without electric connection to apparatus to be tuned. 4 cl, 1 dwg
