Absolute FM1007 FM Modulator with Digital LED Display
This is a nice unit.      You plug your car's antenna into a cable on the transmitter and plug the transmitter into your radio.  The power is supplied through two wires (+12V and Ground) and the audio is plugged into RCA connectors.  The control panel allows you to turn the unit on/off and set the frequency.  The frequency range only goes up to 99.9 MHz, but you can use almost any setting you want below that.  The unit disconnects your car's antenna, when it is on, and connects the transmitter directly to y