812 



BELL SYSTEM TECH NICA LpOURNAL 



is determined primarily by the constancy of the reference voltage derived 

 by the use of the gas-discharge tube. By incorporating wide frequency 

 band characteristics to the looj) gain elements, the maximum rate of change 

 of regulation can be extended, and this circuit becomes very effective in re- 

 ducing the fundamental and harmonics of the primary supply voltage. The 

 effective impedance of a radar receiver power supply of this type is of the 

 order of one ohm, a factor of extreme importance in reducing the unwanted 

 interaction between the various receiver components by coupling due to 

 this common impedance. Other variations in circuit arrangement for 

 regulated power supplies are occasionally employed, the most common of 

 which involves the use of a vacuum tube as a shunt regulating element as 

 contrasted with the series arrangement shown here. In certain low-current 



SERIES 

 REGULATION TUBE 



Fig. 72. — Simplified circuit schematic of low-voltage power supply — Series regulation 

 type. 



applications the use of gas-discharge tubes of constant voltage characteris- 

 tics are occasionaUy employed in a shunt circuit configuration. 



Figure 73 illustrates the equipment arrangement of a radar receiver power 

 supply as employed for an airborne radar bombing system. In this example 

 is included one non-regulated and three regulated rectifier power supplies 

 with output voltages of +600, +300, +120 and -300 volts available for the 

 radar receiver. The forced ventilation feature shown here is required to 

 prevent extreme temperature rise of the components under high altitude 

 conditions in the presence of considerable heat dissipation by the rectifier 

 and series regulating circuits. Each power supply is designed as a separable 

 subchassis within the over-all enclosure to provide for ease in manufacture 

 and testing of the unit. The weight of this complete unit as installed in a 

 military aircraft is approximately 50 pounds. 



