"I know a ham who used to routinely work moon-bounce on VHF, with a rig
powered by a single 9v transistor radio battery. I think he had something
like 60 _milliwatts_ on transmit."

Although the statement does not give all of the facts, I am sure there is an
error. The moon is 250,000 miles away - which means a total distance
travelled of 500,000 miles. The signals must refect off a less than perfect
reflecting surface (moon dust).

I am an amateur operator and have heard signals off the moon. With modern
digital modes, there is an improvement in single signal performance - and if
the station on the other end has a giant antenna (such as the giant radio
telescope in Puerto Rico, used on occasion by amateurs having fun), it is
possible to work moonbounce with a 100 watt rig and a long single yagi.

That is a far cry from 60 milliwatts. There is about 32 db difference
between 60 mw and 100 watts. That would mean the antenna, instead of 15 db
gain for a long yagi would need to have 47 db gain. An antenna that size
might raise some neighbor's objections (blocking the sun). And, operating
it would not be routine, as an antenna with such high gain needs to track
the sun. Might need something about the size of a locomotive to move it.

Colin