Development of a Circuit for Measuring the Negative Resistance of Pliodynatrons

Pliodynatron oscillators are assuming greater importance in engineering work. As the value of the negative resistance of a tube having dynatron characteristics is a measure of its utility it was necessary to design a test circuit which would quickly and accurately measure this property without recourse to the older and more laborious method of plotting the Ep-Ip, curve of the tube and calclulating its negative slope over the operating range. The test circuit is an adaptation of the Wheatstone bridge.