. Multiplex combinations for economic telegraphy and telephony . oises aremore serious in multiplex telephony than in ordinary lines con-taining an instrument at each end of the line, since a very smallstray current induced in one of the physical wires will cause an #17. unbalancing ^ect,and sounds will not only be heard in theparticular main line instrument, but also in the phantominstrument. Where there are a number of wires of various circuitsrunning parallel in the same lead, the electromagnetic andelectrostatic interactions may be balanced up entirely bytransposition of the lines, which c
. Multiplex combinations for economic telegraphy and telephony . oises aremore serious in multiplex telephony than in ordinary lines con-taining an instrument at each end of the line, since a very smallstray current induced in one of the physical wires will cause an #17. unbalancing ^ect,and sounds will not only be heard in theparticular main line instrument, but also in the phantominstrument. Where there are a number of wires of various circuitsrunning parallel in the same lead, the electromagnetic andelectrostatic interactions may be balanced up entirely bytransposition of the lines, which consists in reversing themutual position of wires with respect to each other at certainintervals. To make this transposition, all that is necessaryis to take up slack enough in the conductors to enable them tobe shifted a certain number of pirns to the right or left asthe case may be. This is generally done at the point oftransposition by means of a double grcfve insulator. One schemeof transpositions,used on Physicals containing phantoms^isshown below. Line 1-. If the section of line is sufficient to make the numberof transpositions to come out an even number, 1300 ft. has beenproposed as the best interval between the ;the 1300 ft, intervals must be lengthened out or short-ened, as the case may be, to make the total number come out evenbetween terminating points. If there are more than four circuits 118 on the same cross arm, they are all transposed with respect toone another in the same manner. On the next cross arm above orbelow, the method is the same,except tnat the two circuits in thesame perpendicular plane are transposed at half distances on eachside of the transposition point for the circuits on the referencecross arm. This method is called phantom transposition and ia doneon phantom transposition brackets consisting of a vertical hangersupporting two double groove insulators at a distance of abouttwo feet from each other. If any ordinary telepho
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelephone, bookyear19
