SPARK GAP SWITCHES FOR RADAR 



597 



Sufficient tubes were manufactured to sup{)ly apj)n)ximately 3000 radar 

 equipments. 



Fig. 22 — Western Electric 1B29 spark gap tube. 



W.E. 1B31 



The 1B31 fixed gap was also an aluminum cathode gap, with a gap spacing 

 of 300 mils and 24 inches of 75% hydrogen and 25% argon. An exterior 

 and a cross-sectional view are shown in Figure 23. This gap was developed 

 for an airborne radar. This modulator was required to furnish a peak power 

 of 230 kilowatts to a W.E. 2J53 magnetron. The modulator was also to 

 I)rovide a range of pulse durations and repetition rates extending from 0.25 

 microseconds at 1600 pulses per second to 5.0 microseconds at 200 pulses 

 per second. 



In order to meet these requirements, two 1B31 tubes were used with a 

 peak switch voltage of 8 kilovolts and a peak current of 75 amperes. By 

 using a 300 mil spacing, a life greater than 500 hours was obtained at 200 

 pulses per second, 5 microseconds and 75 amperes. The other operating 

 conditions were less severe from the life standpoint. 



The wide spacing used meant a considerable increase in the size of the cath- 



