scope:

The main purpose of this Recommendation is to define means by which interface impedance may be measured, rather than to describe precise procedures for pre-processing, stabilizing and operating the tubes or valves to be measured; although the tube or valve operating conditions, under which the measurement of interface impedance may be made, are known to have a substantial effect on the results obtained. It is also objective of this Recommendation to describe means for evaluating the performance of interface impedance measuring equipment with respect to: Accuracy as a function of the transconductance of the tube or valve being measured. Accuracy as a function of the resistance of the interface. Accuracy as a function of the time constant of the equivalent interface network. The measuring methods and procedures described in this Recommendation are designed to provide information on the following cathode-interface impedance characteristics of tubes or valves: The presence of cathod-interface impedance. The equivalent resistance of cathode impedance. The equivalent capacitance of cathode-interface impedance. Clause 7 outlines precautions to be taken and results to be expected under certain conditions of operation of the tubes or valves being measured for interface impedance characteristics.