In a color TV receiver incorporating automatic kinescope bias (AKB) control circuits, a first train of monolevel pulses with timing suitable for retrace blanking purposes and a second train of monolevel pulses with "backporch" timing appropriate for burst gating purposes are applied to a circuit serving to generate at a first terminal a train of bilevel pulses exhibiting a first voltage level during periods of overlapping of the pulses of the first and second trains, and exhibiting a second, lesser voltage level during the remaining, non-overlapping portions of the pulses of the first train. A resistor interconnects the first terminal with a second terminal. A keyed voltage source, responsive to a third train of monolevel pulses timed to indicate recurring kinescope bias control intervals, develops a voltage of a third level, intermediate the first and second voltage levels, at the second terminal during the recurring control intervals. The keyed voltage source exhibits, during the control intervals, an output impedance significantly lower than the impedance exhibited by the interconnecting resistor. During periods intervening successive ones of the control intervals, the voltage source is effectively disabled and exhibits an output impedance significantly higher than the impedance exhibited by the resistor.
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