An RF modulator is a device for converting a coaxial cable jack on older televisions into a set of RCA-type composite audio/video jacks for connecting newer types of equipment, such as DVD players. Decades ago, when television sets typically connected with a coaxial cable for satellite or TV service, and possibly a VCR as well, a simple coaxial jack was the only necessary connection point. With an RF modulator, older TV sets can still be used with modern AV components.
Connect a coaxial cable to the RF "IN" jack on the back of the TV, turning the coupler on the end of the cable clockwise on the threaded jack.
Attach the other end of the cable to the RF "OUT" coaxial jack on the RF modulator.
Insert a set of composite AV cables into the yellow, white and red composite "IN" jacks on the RF modulator.
Connect the other ends of the composite cables to the AV "OUT" jacks on a component such as a VCR or DVD player.
Things You'll Need
Composite audio/video cables
If the TV is really ancient and has only screw-in connections for the RF signal, then use an RF modulator equipped with two small metal Y-clips. The clips slip underneath the screw heads, which are tightened to hold the modulator securely to the television.
Unplug the TV while connecting the coaxial cable, RF modulator and composite cables.