TD-2 MICROWAVE RADIO RELAY SYSTEM 



1055 



cavity with the grid grounded directly to the body of the structure. The 

 cathode of the tube is connected through an internal by-pass condenser to 

 another part of the structure such that a cavity is formed around the tube 

 between grid and cathode. An iris or aperture which is capacity tuned by a 

 screw provides a means for coupling to the input waveguide. A coaxial cavity 

 is formed around the plate which is tuned to the desired frequency by the 

 movable coaxial transformer. The transformer couples the plate cavity to 

 the transducer probe where the signal energy is transferred to the output 

 waveguide. 



Fig. 12 — Transmitter modulator. 



The transmitter modulator is shown in Fig. 12. The oscillator power is 

 applied to the cathode grid cavity through a tuner, a bandpass filter and a 

 waveguide spacer. The IF power is applied between cathode and grid 

 through a network which is mounted within a cyUndrical compartment 

 around the tube socket. The desired output sideband of the modulator is 

 selected by a bandpass filter. Following this filter is a tuner unit which 

 provides a means for adjusting the output impedance for a match with the 

 following ampHfier. A conversion gain of 9 db is reahzed in the process of 

 shifting the IF frequency to the microwave band. 



The modulator assembly is directly connected to the input of the trans- 

 mitter ampHfier, as may be seen in Fig. 8. An amphfier shown in Fig. 13 

 consists of three stages of 416A triodes mounted in cavity structures as 



