Devices that allow the modulation of an Audio / Video signal (e.g. coming from video recorders, cameras, SAT receivers, etc.) in an analog RF channel. The output channel is controlled by PLL. The levels of video and audio signals are both adjustable by trimmer. Equipped with coaxial attenuator (0÷20 dB) to adjust the output level. The self-powered modulators with SCART are available with mono or stereo audio, while all other models are available in the only version with mono audio.