. The Bell System technical journal . 61 + 6(1) ^Of^VALUES OF 0 LOCUS OF 6(1) FOR- VALUES OF 0 LOCUS OF 62+6 (J) FOR- VALUES OF 0 Fig. 7—Vector diagram of input voltages to balanced modulators of the automatic tuning device. the applied radio frequency voltage increases, the mutual conductanceof the modulator tube decreases and consequently a greater amountof 60-cycle current flows in the plate circuit, the phase of which dependsupon which tube has the higher mutual conductance. The voltagecoil of the watt-hour meter is permanently connected to the supplylead. When the frequency of the carrier
. The Bell System technical journal . 61 + 6(1) ^Of^VALUES OF 0 LOCUS OF 6(1) FOR- VALUES OF 0 LOCUS OF 62+6 (J) FOR- VALUES OF 0 Fig. 7—Vector diagram of input voltages to balanced modulators of the automatic tuning device. the applied radio frequency voltage increases, the mutual conductanceof the modulator tube decreases and consequently a greater amountof 60-cycle current flows in the plate circuit, the phase of which dependsupon which tube has the higher mutual conductance. The voltagecoil of the watt-hour meter is permanently connected to the supplylead. When the frequency of the carrier at intermediate frequencyis too high, the phases will be such that the watt-hour meter runs inone direction, and when the frequency of the carrier is too low thewatt-hour meter runs in the other direction. A very small condenseris substituted for the registering mechanism of the watt-hour condenser is connected to the beating oscillator circuit and thewhole circuit arranged in such a manner that the watt-hour meter runs. 500 BELL SYSTEM TECHNICAL JOURNAL until the beating oscillator gives the proper frequency, when theaction stops. Since this automatic tuning unit holds the carrier at intermediatefrequency in a fixed relation with respect to a crystal filter, which maydrift slightly in resonant frequency from time to time, and not insynchronism with a local carrier oscillator, it is necessary that a sepa- INCOMING CARRIER400 Kc. LOCAL CARRIER400 Kc. + A 90°PHASESHIFTER AMPLIFIER AMPLIFIER AMPLIFIER AMPLIFIER BALANCEDMODULATOR AOO BALANCEDMODULATOR TWO PHASE SYNCHRONOUS MOTOR )IC ON + B Fig. 8—Schematic of automatic synchronizing equipment. rate mechanism be provided for synchronizing the local carrier if alocal carrier is to be used. A schematic diagram of the circuit fordoing this is shown in Fig. 8. The reconditioned carrier at inter-mediate frequency is introduced through amplifiers to two balancedmodulators. The output of the local carrier os
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
