350 



BELL SYSTEM TECHNICAL JOURNAL 



0.4 0.8 



Fig. 4 — Lower side-frequency voltages in an iron dust coil. 



order products plotted against the fundamental current of higher 

 frequency in each instance. For these measurements the current of 

 one frequency was maintained at some fixed value and the amplitude 

 of the other one varied. Both sum and difference products, but with 

 different fundamental frequencies, are exhibited. The upper side 



a. 80 



13 40 

 UJ 



ffi 



8 _ to 12 



I IN MILLIAMPERES 



Fig. 5 — Twenty-five kc. third order product of 9 and 7 kc, iron dust core. 

 ^„ = 24.5, V = 0.18, Lo = 4.54 mh., // = 38.9 /. 



