Hello I understand ASK modulation but I'd like to know what the jfet does to the circuit to ASK modulate?

Thanks

 

The FET exhibits a decreasing resistance to ground as the gate voltage increases.
Thus as the input signal increases in amplitude the carrier signal is attenuated.
You can consider this an analog multiplier circuit which will amplitude modulate the carrier signal.

 

Wrong forum!!! IMO.

Go to 'general electronics chat' or 'radio & communication'