Calculation and design of resistance-coupled amplifiers using pentode tubes

RESISTANCE-COUPLED amplifiers employing pentode tubes are used more widely than any other type of voltage amplifier for audio frequencies. In spite of this, no method of analysis is available for correctly calculating the complete characteristics of such amplifiers and design procedures ordinarily followed involve considerable cut and try. The present paper presents (1) an analysis taking into account all of the factors of significance in determining the amplification and phase-shift characteristics of ordinary audio-frequency amplifiers employing pentode tubes, together with charts which make it a simple matter to use the analysis; and (2) a systematic procedure for proportioning the coupling network in the plate circuit when the main objective is: (a) maximum possible voltage gain, and (b) large output voltage.