Chrominance amplifier control circuit providing simultaneous adjustment of gain and DC level

In a circuit for use in a color television receiver, equipped with a precision-in-line color picture tube containing three electron guns disposed in a line, each gun being associated with a respective picture color and including a cathode connected to receive a respective chrominance signal associated with its respective picture color, the signal applied to the cathode controlling the amplitude of the electron beam produced by the associated gun, the circuit including three amplifiers each connected to amplify a respective chrominance signal and having an output connected to the cathode of a respective associated electron gun, the signal at the output of each amplifier being held at a constant voltage level during each horizontal blanking period by means of a keying pulse, and each amplifier being connected with a respective feedback path including an amplification determining resistance network, the resistance value of which determines the gain of its associated amplifier, the improvement wherein each said resistance network includes at least one variable resistance which is adjustable to vary the resistance presented by said network, and said circuit comprises means connected for coupling such keying pulses into each said resistance network in a manner such that variation of said variable resistance in any respective one of said networks will simultaneously produce, for said amplifier associated with said respective network, a change in the gain of said amplifier and a change in the direct voltage level of the chrominance signal at the output of said amplifier in a direction such that increases in the gain of said amplifier coincide with shifts in the direct voltage level at said amplifier output in the positive polarity direction.