Manually gain presettable kinescope driver in an automatic kinescope bias control system

摘要

A television receiver includes a DC coupled video output amplifier for supplying video signals to the cathode of an image reproducing kinescope, and an automatic kinescope bias (AKB) control system for maintaining a desired cathode black image current level. A video processor supplies video signals to the output amplifier via an input network including a manually adjustable resistor for pre-setting the amplifier gain. During AKB operating intervals, a substantially zero voltage drop is maintained across the adjustable gain control resistor so that the setting of the adjustable gain control resistor desirably has no influence on the kinescope cathode bias voltage monitored by the AKB system.