. The Bell System technical journal . d rectifier shown in the vector diagram as E^ and Ei . In additiona portion of the IF signal voltage which appears across the primary windingis also applied to each element of the balanced rectifier. At resonance, theprimary and secondary voltages assume a quadrature relationship as indi- 806 BELL SYSTEM TECHNICAL JOURNAL cated. The vector relationships for frequencies above and below this reso-nance, as shown, result in an amplitude change across the rectifier 69b illustrates a typical rectified voltage versus frequency character-istic of s
. The Bell System technical journal . d rectifier shown in the vector diagram as E^ and Ei . In additiona portion of the IF signal voltage which appears across the primary windingis also applied to each element of the balanced rectifier. At resonance, theprimary and secondary voltages assume a quadrature relationship as indi- 806 BELL SYSTEM TECHNICAL JOURNAL cated. The vector relationships for frequencies above and below this reso-nance, as shown, result in an amplitude change across the rectifier 69b illustrates a typical rectified voltage versus frequency character-istic of such an array. The location of the actual crossover zero voltage pointis determined only by the resonance of the secondary circuit over the limitedrange under consideration here. The primary resonance contributes essen-tially only to the symmetry of the voltage output versus frequency charac-teristic. The introduction of the time constant elements in the detectoroutput circuit integrates the pulse output and are chosen with due regard. Fig. 69.—Operation of the AFC circuit—vector relationships in input circuit and out-put voltage vs. frequency characteristic. to the maximum frequency rate of change which this circuit must d-c amplifier shown is normally biased to operate at gainconsistent with stability, to produce the maximum sensitivity to frequencychange and to accordingly achieve the least threshold deviation from theideal tuning condition. Provision for disabling the AFC circuit is includedto enable initial manual adjustment of the beat oscillator repeller the circuit shown here, failure of the AFC circuit proper will result inthe return of the rc[)cller potential to that value originally selected by initialtuning and further manual control may be used. It is often convenient to describe the effectiveness of an AFC circuit interms of its pull in range and its hold in characteristics. Pull in THE RADAR RECEIVER 807 will be defined as t
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