Simple 0.5W 10m AM transceiver

Hello, I have found this transceiver in a site, I do not know if it works and also no other info about it.
Could you please tell me how does it work and if it will be able to output 0.5W as the person that posted it says?
Also is there any way to replace the carbon microphone with something else? (transformer?LDR?dynamic microphone?)

0.5W ! I don't think so!

The MPF102 is only rated at 20mA max drain current so the DC input power can't be more than 180mW. In practice, as all the transmitter current flows through the microphone itself, the power would be considerably less. My guess would be 20-30mW at most.

In transmit mode, Q2 works as a constant current sink with the resistance of the microphone controlling the current. To be honest, you could probably remove Q2 and not notice much difference as all the 'PA' current passes through the microphone anyway. It will only work with a carbon microphone, if you want to try with a different type you would have to replace it with a resistor (~100 Ohms) and drive about 1.5V of audio across it from an AF amplifier.

In receive mode it is a simple superregenerative detector with a quench oscillator running at about 2.7MHz. R2 sets the oscillation threshold.

It should have a capacitor across supply and each ground, without it, the tuned circuit (T1/C1) will shift frequency between TX and RX. I also have reservations about the reliability of Q4, especially if the quench oscillator stops.

Quite possibly it transmits more power in receive mode than TX mode !

Brian.

For me looks like an AFD circuit...

What does AFD mean?

https://en.wikipedia.org/wiki/April_Fools'_Day