No, Carl. It’s not a problem to send a 20 W radio signal from the Moon to the Earth, because NASA engineers thought of that. They gave the lunar lander, and the lunar rover on later missions, a large parabolic dish to focus the signal into a tight beam. Like this one on all the lunar landers.
This is the s-band antenna on the lunar lander. It was aimed at Earth from inside the lander.
This dish was mounted on the lunar rover on Apollos 15, 16, and 17. It focuses the radio signal into a tighter beam which takes longer to disperse.
And this was one of the receivers!
Picking up a 20w signal from the Moon is easy with the right equipment.
