Effects associated with the thermal response of the T1 telephone transmitter

The thermal response of the T1 transmitter, when excited by a bias current, is analytically obtained. The thermal expansions which produce a decrease in electrical resistance are described. Good agreement with experimentally measured temperature rises and displacements is demonstrated for the early time transients during which the resistance change occurs. The displacements which produce “thermal packing” are found to be a stronger function of the thermal expansion coefficient of the dome electrode than of any other part of the transmitter assembly.