1322 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1953 



Table I 



Source of Loss 



Sustaining stored energy in resonant circuit 



Output load 



Region 1 of collector operation 



Loss in emitter 



Margin for stability of adjustment 



Total, Wt 



This would be 1920-ohms, 1400-olims and 1045-ohms respectively. For 

 purpose of illustration the average value is plotted on the characteristics 

 of an average transistor in Fig. 4 along with —R2 for the transistor. It is 

 evident from this that —R2 is lower in value hence the circuit will os- 

 cillate and build up to the required voltage. Minor corrections in the 

 emitter current would normally be required in order to meet test require- 

 ments. The potentiometer that is shown in Fig. 2 provides the means 

 for adjustment. 



The oscillogram shown in Fig. 5 illustrates the condition described 

 above. The characteristics of the transistor used are shown in Fig. 4. The 

 oscillogram is a multiple exposure from which Rl, —R2 and RS (see 

 Fig. 3) for several values of feedback may be obtained. The normal 

 condition of adjustment is illustrated in Fig. 6 with normal load. Four 

 times normal load is a test condition. 



When the extra load that is applied during test is removed the output 

 voltage should go up since power input exceeds the power expended. 



o 

 uj h 



■13 



-12 -II -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 



COLLECTOR CURRENT, Ic^ IN MILLIAMPERES 



Fig. 4 — Characteristics of representative 1729 type transistor with negative 



resistance values plotted for the average condition given in table. A load line is 



also shown for the average condition. In plotting -R2 a line is drawn from h = 0, 



1 414 X 2 

 Ec = 16 to point corresponding to maximum h . Maximum le ^ WeX ' 



at Ec ^ 1.5 volts. We is loss in emitter circuit given in table . 



E., 



