THE L3 SYSTEM — AMPLIFIERS 



911 



01 23456789 



FREQUENCY IN MEGACYCLES PER SECOND 



Fig. 18 — Relative levels of signal voltages in line amplifier referred to voltage 

 at grid of lower triode. Thermistor at mid-range value. 



relative magnitudes of the noise sources are shown on Fig. 19, which 

 gives the noise at ampHfier output as a function of frequency. 



Comparison of the grid to cathode voltages of VT2 and VT4: shows 

 that the former will be an important modulation contributor, since the 

 driving force on these tubes is nearly equal, particularly at low fre- 

 quencies. Typical amplifier modulation values are given in Table III. 

 Computations using the measured feedback and the performance of 



UJ < 



Q5 

 ...ID 



0.2 



0.3 



0.4 0.6 0.8 1.0 2 3451 



FREQUENCY IN MEGACYCLES PER SECOND 



Fig. 19 — Thermal noise at line amplifier output. 



