RF Module without Decoder/ Encoder?

Hi all,

I'm using some 433Mhz rf modules for a project, I would like to ask, is it necessary to use decoder/encoder if I only need 1 channel signal to be sent and received. ( which mean i only need 1 data line, instead of 4 ) Can I input directly to the input of transmitter and use the output of the receiver to switch on an LED?

At least the receiver isn't designed to transmit statical on/off signals, you should use at least square wave modulation. In addition, it's better to transmit on/off commands than to power the transmitter for extended times, both in terms of power consumption and disturbing other RF services.