I am doing a circuit for an AM transmitter and receiver. I extracted it from http://www.pyroelectro.com/projects/pyro_rf_receiver_27mhz/index.html.
I have already done the transmitter, and the antenna seems to irradiate as there is some interference with other devices. However, my question in this part of the circuit is if the indcutor L3 (the one right before the antenna) is needed, and why? can I change its value?
On the other hand, I have also done the receiver; however, it does not seem to receive anything. It is important to say that I tailored the design so that I could use a 20MHz carrier. In the transmitter I used a crystal of 20MHz, and in the receiver (tank circuit), I used an inductor of 10uH and a combination of ceramic capacitors of around 6.66 pF. I suppose I do not detect anything because I used a choke inductor (those that are fabricated and come in a green package), and I did not made my own (I did not made my own as I have no way of meassuring it). Also, I do not see any envelope detector on the receiver... which part in this circuit acts as the envelope detector. And finally, why does it not work? I really appreciate your answers