A modulation device especially suitable for use in a joint TV reception device for tuning the input video and audio signals to various TV channel frequencies. The device includes a modulator for modulating a carrier wave with the video and audio signals to provide a modulated signal, a mixer for mixing the modulated signal with a local oscillation signal to provide mixed signals, a wide band amplifier for amplifying the mixed signals and a variable low-pass filter for filtering the amplified mixed signals to provide a TV broadcasting signal of desired frequency. The device further includes a control device for controlling the frequency of the local oscillation signal and the cutoff frequency of the variable low-pass filter so as to cancel a higher harmonic component from the output signal to avoid undesirable inteference.