. The Bell System technical journal . Hartley, Electrical Com-munication, July 1924, Vol. Ill, No. 1. ANALYZER FOR COMPLEX ELECTRIC WAVES 243 TU without exceeding the same percentage of error, or up to 60 TUwith 1 per cent error due to undesirable modulation in the currentanalyzer. Reliability. Use of the heterodyne current analyzer over a periodof two years has proven it to be one of the most reliable means formaking measurements. With proper maintenance, which consistsonly in maintaining constant A and B battery voltages and gridvoltage, and with proper precautions as to shielding and balanc
. The Bell System technical journal . Hartley, Electrical Com-munication, July 1924, Vol. Ill, No. 1. ANALYZER FOR COMPLEX ELECTRIC WAVES 243 TU without exceeding the same percentage of error, or up to 60 TUwith 1 per cent error due to undesirable modulation in the currentanalyzer. Reliability. Use of the heterodyne current analyzer over a periodof two years has proven it to be one of the most reliable means formaking measurements. With proper maintenance, which consistsonly in maintaining constant A and B battery voltages and gridvoltage, and with proper precautions as to shielding and balance,readings can be taken with a precision of 2 per cent. Vacuum Tube Curves Obtained ivith Heterodyne Current Analyzer. Anumber of curves have been added to illustrate the application of thecurrent analyzer, though of course these represent only a small part ofthe field of usefulness for which it is adapted. SINGLE TUBE AMPLIFIERoTUBE: 0 113013 OUTPUT OF FUNDAMENTAL, 2ND AND 3RD HARMONICS INTO 3000* AND 16000^ LOADS. ETb =240 -Gr = 60. .4 5a. .3 ° I/)lu .2 fc .1 d I& 20 24 MILLIAMPERES 26 32 3<i 40INPUT INTO (bOO** Fig. 11 The first set of curves, shown in Fig. 11, were taken on an O tube(104D) to show how the fundamental current and the second andthird harmonics produced in the tube changed with increase in theinput amplitude of a single frequency. Two sets of curves are shownwhich were taken for two values of load impedance, one being equiva-lent to the normal tube impedance and the other being six times aslarge. The output currents have all been computed to show the equiv-alent output into 600 ohms which is a common reference standard ofimpedance used in telephone work. 244 BELL SYSTEM TECHNICAL JOURNAL The second set of curves, shown in Fig. 12, were taken with anL tube (101-D) but with two input frequencies oi Q = 5,000 andP = 13,000 cycles appHed simultaneously. The measurements in o % o 2 \.2 SINGLE TUBE AMPLIFIERel TUBE # H45S3OUTPUT OF TWO 2ND ORDER MODU
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