360 



DELL SYSTEM TECHNICAL JOURXAL 



Direct currents and voltages are ver>' important factors in the 

 operation and maintenance of amplifier circuits such as telephone 

 repeater and carrier apparatus. The battery supply arrangements 

 for a single tube amplifier are shown in Fig. 6. 



It is necessary in order to insure efficient amplitication without 

 distortion to regulate the currents and voltages to fairly close limits. 

 In practice provision is made for quickly reading the voltages of grid, 

 filament and plate batteries as shown by the voltmeter connection 

 (\') in the figure. The plate current is read by the milli-ammeter 

 M and the filament current bv the ammeter A. The filament current 



Filament ■+■ Plate 

 Battery Battery 



Fig. 6 



is regulated to meet the operating limits by cutting resistance in or 

 out of the circuit with the rheostat R. The same applications of 

 current and voltage readings apply to the more complicated amplifier 

 circuits, although wherever practicable automatic regulating devices 

 are jiroxidcd which reduce the amount of manual testing work to a 

 minimum. 



Capacity Mcasiiremenls. There is little occasion in transmission 

 maintenance work to make accurate direct current measurements of 

 capacit\-. .\ simple (I.e. test, however, has been provided for use 

 I)rimaril\ mi siilisirilurs' Iciojis fur cliecking the condensers in the sets. 



jroof 



Fig. 7 



As shown in Fig. 7 tlu- circuit consists of a 100,000-ohm voltmeter 

 in series with a grounded KlO-volt battery connected to one conductor 

 of a subscribers' loop, the other conductor of the loop being grounded. 



