Level control amplifier for aerial - has gain control over fifty decibels achieved using two variable attenuators and two amplifying stages

摘要

The amplifier has a variable attenuator (15) located between two amplification stages (14, 16). The output of the output amplification stage passes via a coupler (17) to the output (18). The coupler couples out part of the signal and applies it to the control input of the variable attenuator. The control signal increases the signal-to-noise ratio at small to medium signals. A second variable attenuator (13) is coupled to the input of the input amplification stage and comes into operation only after the input signal exceeds a given level in order to prevent the input amplification stage being overdriven. The second attenuator is controlled by the output from a trigger (12) responding to the input signal derived via a coupler (11).