PULSE MODULATOR TUBES 



829 



resulted in operation of the cathode at somewhat higher than normal tem- 

 perature under rated conditions. The ratings of the 715A tube are given in 

 Table I. 



U 



Fig. 8 — The 5D21 vacuum tube. 



The 715B Tube 



Some applications developed which required a peak pulse current slightly- 

 greater and of longer duration than that for which the 715A was rated. 

 Meanwhile more experience with the 715A and improvements in processing 

 techniques indicated that a higher peak current rating was justifiable pro- 

 viding the grid temperatures were not increased. 



