ANALYZER FOR COMPLEX ELECTRIC WAVES 



235 



Because of the wide range of frequency over which the amplifiers will 

 be operated, resistance, rather than transformer coupling, was chosen 

 as the most reliable form of interstage connection. Due to the large 

 step-down in impedance necessary between the first amplifier and the 

 coupling resistance of the second selective circuit, a transformer having 



46 



44 

 40 

 36 



h 

 I 



z 

 o 



z 





32 



26 



24 



20 



16 



12 



8 



19000 



ZQOOO 



Z 1.000 



FREQUENCY - CYCLES 



Fig. 4 — Discrimination curves of heterodyne current analyzer 



a high step-down ratio was used. The output of the second amplifier 

 also works into a transformer through a fixed resistance and potentio- 

 meter as shown in Fig. 5. The purpose of the fixed resistance is to 

 maintain a more uniform output impedance as the potentiometer is 

 varied. Though the two amplifiers are almost identical in their cir- 

 cuits, they differ in the plate voltage. The first section is operated at 

 16 



