1-53of a triode to the input. This effect is a prime-limiting factor in applying triodes. It is a major reason whytriodes are seldom used—especially at the higher frequencies.MU AND TRANSCONDUCTANCEare measures of tube efficiency. Mu (µ), or amplificationfactor, is a measure of the amount that plate voltage varies in relation to variation of the input voltage.Mathematically, mu (µ) is expressed asTRANSCONDUCTANCE, on the other hand, is a measure of the amount of variation of platecurrent caused by a variation of the input signal. Mathematically, it is expressed as:TETRODESwere developed to compensate for the effects of interelectrode capacitance. Placing apositively charged screen grid between the control grid and plate has the effect of adding a capacitor inseries with the capacitance that exists between the control grid and plate. This reduces total capacitancebelow the value of either capacitor as shown by applying the formula: