NEW SINGLE CHANNEL CARRIER TELEPHONE SYSTEM 169 



The power supply circuit, which is shown in Fig. 5, operates from 

 an alternating-current source of 100 to 130 volts, 50 to 60 cycles, and 

 requires about 50 watts. It supplies alternating current for the fila- 

 ment supply, 160 volts direct current for plate supply and 24 volts 

 direct current for relay operation. Provision is also made for direct 

 operation from 24-volt and 130-volt central office batteries. 



The equipment for a terminal is mounted on two panels. One of 

 these, shown in Fig. 6, is 15j inches by 19 inches in size and contains 

 all the apparatus except the line filter circuit. The second panel, 

 shown in Fig. 7, is 3| inches by 19 inches and contains the line filters, 

 and other equipment which is required for balancing purposes. 



Fig. 7 — Line filter and balancing panel — front view. 



Repeater 



A schematic of the repeater is shown in Fig. 8. The amplifiers are 

 the same in design as the transmitting amplifier at the terminals. 

 Two sets of line filters are required and are identical with those used 

 at the terminals. The a-c. power supply circuit is substantially the 

 Same as the one used at the terminals except that the 24-volt supply 

 for relay operation is omitted. The power required for operation is 

 about 35 watts. 



The complete repeater consists of three panels — -the repeater panel, 

 which is 10| inches by 19 inches, and two line filter and balancing 

 panels. The repeater panel is shown in Fig. 9. 



Transmission Performance 

 Line Considerations 



In outlining the transmission performance of the system, it is 

 necessary to consider the characteristics of the lines as well as those 

 of the equipment. At carrier frequencies the line losses and the 

 variations in these losses with weather are considerably greater than at 

 voice frequencies. This is illustrated in Fig. 10, which shows the 



