590 



BELL SYSTEM lECHNICAE JOVRNAE 



supplying the grids is lower than in No. 2 the effect of grid modula- 

 tion is still less marked on the oscillograph and the rise of third har- 

 monic in the analysis is less rapid. This amplifier was designed for 

 an output of .365 watts. The results show that this is obtained at 

 the expense of the introduction of about 2% third harmonic. 



The No. 4 amplifier is equivalent to the last stage of the No. 1 

 amplifier both using about 850 volts anode potential and 27 volts 



.5 6 WATTS 



.86 NA/ATTS 



I.075 WATTS 



I ^ 



I 36 WATTS 



Ci 



I.TI WATTS 



Input Vultage > 



pig_ 17 — Amplifier No. 4; 200 c.p.s. input; load 4,000 ohm resistance 



grid bias which in the case of the No. 4 amplifier is obtained from a 

 resistance drop in the anode circuit. The harmonic analysis curves 

 shown in Fig. 10 indicate somewhat less second harmonic at low out- 

 puts which is probably due to the smaller number of stages. Third 

 harmonic is approximately the same in the two cases. The oscillo- 

 graph figure shows a somewhat larger output l)efore grid modulation 

 takes place but the difference is not great. 



