Cold cathode gas filled tubes have been extensively applied as electronic switching elements in the telephone system. In general, these applications have been limited to control circuits. The usefulness of these tubes can be further extended by making them capable of carrying voice frequency signals. The transmission properties that are required of the tube for this use are considered. It is shown that troublesome oscillatory noise can be eliminated and that the insertion loss of the tube can be reduced to a low value. Furthermore, by a special design of cathode a stable insertion gain of a few db may be realized. Other requirements on bandwidth, power and distortion are satisfactorily met. Thus, these tubes are potentially useful in coordinate type switches in which voice frequency signals must be rapidly switched.

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Cold cathode gas tubes perform both switching and memory functions in telephone switching systems. One measure of the performance of a switching diode is the switching voltage gain, defined in terms of the characteristics of the device. Some of this gain must be sacrificed in order to increase the switching speed in a way which is analogous to the gain‐bandwidth property of a conventional amplifier. In this paper, methods of achieving a high switching‐voltage gain are described in terms of the gas discharge processes. An example is given of an application of these principles to a tube for use as a switch in series with the talking path in an electronic telephone switching system.

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