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BELL SYSTEM TECHNICAL JOURNAL 



to the amplitude of the interference, and increase linearly with the 

 order of the harmonic. These relations apply to harmonic generators 

 which produce sharply peaked waves in general, and are not peculiar 

 to the magnetic type. 



Neighboring modulation products involving the interfering com- 

 ponent q more than once have much smaller amplitudes in normal 

 circumstances than the product considered above. Because of the 

 tuning in the input mesh, interfering components far removed in fre- 

 quency from the fundamental are greatly reduced and the most 

 troublesome interference is likely to be close in frequency to the 

 fundamental. 



It may be noted that where the interference is produced by amplitude 

 modulation of the fundamental, so that two interfering components 

 enter the input, the distortion produced may be approximated by 

 doubling the amplitudes of the side-frequencies produced by one of the 

 interfering components. If the disturbance is the second harmonic of 

 the fundamental, the effect is nearly the same as that for constant bias, 

 and the relations (5) may be used if h is taken as the amplitude of the 

 second harmonic magnetizing force. 



4.4 



Fig. 10 — 73rd and 74th harmonic amplitudes as functions of direct current flowing 

 through non-linear coil. Ordinate is ratio of harmonic amplitude with bias indicated, 

 to that of 73rd harmonic with zero bias. Abscissa is harmonic number multiplied by 

 the ratio of bias to fundamental. Dashed lines calculated from eq. (5), full lines 

 measured. 



To illustrate the effects of d.-c. bias, Fig. 10 shows the amplitudes of 

 the 73d and 74th harmonics of 4 kc. as functions of the parameter 

 nQ/Hi. The agreement between measured and calculated values 

 indicates that the most important effects of bias have been included in 

 the simple analysis. 



