A NEW MICROWAVE TRIODE 



547 



number of round trips or select individually the nth round trip for in- 

 spection. 



Fig. 21(a) shows the complete cycle between successive injected pulses, 

 and the individual pulses that follow cannot be resolved at this slow 

 sweep speed. Fig. 21(b) shows the first 26 round trips resolved so that they 

 are distinguishable. Figure 21(c) shows the first and second round trips 



(a) PULSES RECIRCULATING 

 THROUGH AMPLIFIER 



,b) PULSES RECIRCULATING 

 THROUGH AMPLIFIER 



QUENCHED 



INJECTED PULSE 



(c) FIRST AND SECOND ROUND 

 TRIPS THROUGH AMPLIFIER 



ROUND TRIP 



(d) PULSE SHAPE AFTER 

 100 ROUND TRIPS 



■INJECTED PULSE 



Fig. 21. — Recirculating pulse test patterns. 



\f/\f/\f/*u/ 



402-A VELOCITY MODULATION AMPLIFIER 



Fig. 22. — Recirculating pulse patterns showing Ist, lOlh an 1 103th round trips for: Top: 

 Close-spaced triode amplitier. Bottom: 402-A velocity modulation arapliner. 



through the amplifier, with little or no distortion discernible. Fig. 21(d) 

 gives, to the same scale as the preceding picture, the pulse shape after 

 100 round trips. A little overshoot and subsequent oscillation is now 

 visible, although the whole pulse shape is still not too bad. 



In Fig. 22, these results are compared with the results of a similar test 

 performed on a four-stage, stagger tuned, stagger-damped amplifier using 

 the 402 velocity variation amplifier tubes; the first, the tenth and the 

 hundredth round trips are shown. Little or no distortion is seen at the 



