GAS-DISCHARGE TRANSM IT-RECEIVE SWITCH 



75 



721 A tube. It should be noted, however, that the 724B tube frequently 

 reaches the end of its useful life as a result of its failure to provide adequate 

 receiver protection before serious loss of recovery occurs. 



The ATR, if one is used, can also contribute to poor recovery as may be 

 seen by referring to Fig. 30. These data are not necessarily representative 

 since it is possible to adjust the length of line between the magnetron 



10 20 50 



TIME IN MICROSECONDS 



Fig. 27 — The dependence of the recovery time on the ambient temperature for the 721A 



tube 



and the ATR junction so as to minimize the effect. Nevertheless the effect 

 is important and should not be overlooked. 



Low-Level Loss. An analysis of the low-level loss must take into account 

 two components of loss, the first resulting from power loss in the TR cavity 

 itself and the second resulting from the fact that some power will always 

 be absorbed by the transmitting branch of the system. 



The relationships existing between the low-level loss adjustment of a TR 

 box and its other performance characteristics have already been discussed. 

 One aspect of the problem, not previously considered, has to do with the 

 dependence of the performance on the Q of the cavity. This is clearly shown 

 in Fig. 15 which has already been referred to in a different connection. From 

 this aspect, at least, the higher the Q of the tube and its associated cavity the 



