356 BELL SYSTEM TECHNICAL JOURNAL 



terminates at the end of the second section, the third section extending 

 the cable to the San Antonio line. 



Since the number of cable pairs to the San Antonio line was limited 

 to a maximum of six and since the rate of circuit growth over the two 

 lines was expected to be approximately the same, requiring cable relief 

 over the entire distance when the branch to the San Antonio line was 

 exhausted, an objective of six pairs to each line was set up. 



Measurements of crosstalk coupling at 140 kilocycles in terms of 

 inductance and capacitance unbalance were made between each pair 

 and all other pairs in each section and the pairs rated in their order of 

 desirability. It is of interest that this required a total of 854 measure- 

 ments. Those pair combinations whose coupling of the mutual 

 inductance type was high were rated as the least desirable. This was 

 done because capacitance balancing was to be used to obtain crosstalk 

 reduction. The more desirable pairs in the first two sections were 

 connected through to the six pairs in the last section by cut and try 

 method until the overall condition was such that all six pairs were 

 acceptable. By a similar procedure, using the remaining pairs in the 

 first two sections, six pairs to the Houston line were made acceptable. 

 No record is available as to the number of tests made in the cut and try 

 process. 



A cable terminal on which balancing condensers were mounted was 

 installed in the central office building and connected to the selected 

 pairs. This terminal contained sixty-six sm.all adjustable wire wound 

 condensers which were connected between each pair and every other 

 pair. The condensers were adjusted to reduce to a minimum the 

 capacitance component of the crosstalk coupling. 



Buildings 



For the three J carrier systems, four new repeater stations and eight 

 filter huts were needed. The same type of construction was used for 

 all : Concrete foundation with floor slab above grade, double four-inch 

 brick walls with rock wool insulation between but with solid brick at 

 corners and openings, pitched roof with wood framing, fire resistant 

 wall board ceiling, fire resistant composition shingles, and heat insu- 

 lation above ceiling and below floor slab. 



All of the racks for equipment in the unattended repeater stations are 

 arranged in three rows with power, repeater, and line equipment in 

 separate rows within a floor space of 17 feet by 16 feet which will allow 

 the ultimate installation of six repeaters in each building. The 

 entrance cables from the terminal poles enter from iron conduit through 

 the floor and are racked and spliced on the side wall adjacent to the 



