810 



THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1953 



The power separation filters are basically simple designs, but the reali- 

 zation of the theoretical design was complicated by the following: (1) 

 the components in the low frequency section must pass currents of 

 about 1.5 amperes without change in characteristics, and must with- 

 stand potentials as high as 2,000 volts rms without generating corona 

 noise; and (2) the components in the high frequency section must be 

 such that the loss over the transmission band (300-8,350 kc) is small 

 and stable and of such a shape that it is easily equahzed. To meet these 

 requirements stable inductors and capacitors with a minimum of para- 

 sitic resonances in the band were designed. 



REGULATOR 



PSF 



H 



ARTIFICIAL I I EQUALIZER 



LINE I I (PASSIVE) 



;i 



TEMPERATURE 

 SENSITIVE 

 ELEMENT 



3 



B — 



Fig. 15 — Auxiliary repeater. 



The artificial line shown preceding the input to the amplifier is a pas- 

 sive network to build out the loss-frequency characteristic of a short 

 cable section to be equivalent to the loss-frequency characteristic of 

 4.0 ± 0.2 miles of 0.375" cable or 2.87 ± 0.15 miles of 0.27" cable. These 

 lines are provided in several different sizes, so that, where it is impossible 

 physically to locate the repeater within the specified accuracy of 0.4 

 mile this accuracy can be obtained electrically. The design of the net- 

 work is such that an accurate and stable characteristic is obtained with 

 a minimum number of components. 



The equalizer is a means for compensating for small variations in the 

 transmission characteristics of coaxial cables due to variations in the 

 physical construction of the cable. In the case of the most generally used 

 cable, this eciualizer inserts only a small flat loss. 



The amplijirr is of the feedback type whose gain frequency char- 



