A Wide-Band 550-Megacycle Amplifier

This paper describes a five-stage 550-megacycle amplifier having an over-all bandwidth of 20 megacycles and a gain of 10 decibels per stage. It uses a 2C43 triode in a grounded-grid circuit with an impedance-transforming band-pass filter in the output to give the desired bandwidth. A visual method of alignment with a sweep-frequency oscillator is described, and important design considerations are given. The voltage gain per stage for a wideband amplifier of this type is shown to be G=(μ+ 1)√RL/(Rp+RL[μ+1+(Rp+RL)/Rtwhere Rtis the equivalent shunt resistance between grid and cathode due to transit-time loading and cathode-lead-inductance loading, and RLis the optimum value of load resistance in the plate circuit consistent with the bandwidth of the amplifier and the grid-plate capacitance of the tube.