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BELL SYSTEM TECHNICAL JOURNAL 



opened unit, connect the panel apparatus with the "A" and "B" 

 batteries, and with the modulator. All of the panels are provided with 

 a metal strip, such as shown along the top and bottom edge, which fits 

 into a groove in the case and thereby provides better shielding between 



each of the units. Since each unit of the analyzer is provided with a 

 separate shielding case, two sheet iron walls are interposed between 

 any pair, forming a double shielding to electric fields occurring within 

 the analyzer. The complete unit of two sections is very economical 

 in space as the overall height, width and depth of each section are only 

 36, 19 and 12 1/2 inches respectively. 



Characteristics of Complete Current Analyzer 



The successful operation of the heterodyne current analyzer depends, 

 of course, upon knowing its limitations and its reliability. Under 

 limitations may be grouped sensitivity, selectivity and modulation in 

 the analyzer itself; and under reliability, the limits within which 

 readings can be repeated. 



Sensitivity. The sensitivity depends upon the coupling resistance 

 used in the two amplifier units, and increases with added resistance 

 so long as this is only a few ohms and small as compared to the total 



