RF modulator , Audio /video AV (3 RCA) to coaxial converter, convert the separate audio and video signals to into VHF TV signals RF modulatorPower : 220v RF output channels : 3 or 4 RF output impedance : 75 ohm Video input impedance : 75 ohm / 1k ohm Audio input impedance : 13+/-3k ohmsTV to ANT insertion loss 50-606 Mhz: -2 dBSize : 150x80x37mm RF modulator