Developing a combined T-R shutter tube duplexer

The tube to be described was developed to fill the need in microwave systems for a single light weight unit which would assure complete crystal protection. The design objectives were standard TR functions with a 40db insertion loss at standby condition with low power requirements and a minimum of weight and volume increase over the values of a normal TR tube. An entirely new principle was conceived which permits installation of the shutter within a normal TR tube body. This new shutter has an insertion loss of 40 to 60db in single tubes and up to 90db when incorporated into a dual tube with matching hybrids to form a TR shutter duplexer. By new magnet design techniques, the total weight increase was held to about 2 ounces for a three element X-band tube, and power consumption to about 3.9 watts. The design is such that, in case of power failure, the shutter automatically closes to present the high shutter insertion loss in front of the crystal, which makes it an inherently failsafe device.