BRUEL & KJAER 4409 Instructions And Applications page 33

2. OPERATION
Fig. 2.13. Photo of the Beat Frequency Oscillator Type 1022.
Fig. 2.14. The Automatic Frequency Response Recorder Type 3308 consisting
of a Beat Frequency Oscillator Type 1022 and Level Recorder Type 2305.
The paper drive of the 2305 is mechanically coupled and synchronized to
the 20 Hz-20 kHz logarithmic frequency tuning of the 1022. The Output
voltage from the 1022 is constant withz'n
±
o.3 dB through-out the entire
frequency range.
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