Irregularities in loaded telephone circuits

The development of long distance telephone transmission has made the question of line irregularities a matter of great importance because of their harmful effect in producing echo currents and causing the repeaters to sing. The structure of coil-loaded circuits permits the calculation of the probability of obtaining an assigned accuracy of balance between line and network when certain data are known or assumed regarding the accuracy of loading coil inductance and section capacity. Formulae are given and the results of calculations compared with measurements made on circuits of known accuracy of loading.