Something I've wondered about Apollo?

:) not unless they were very wealthy.

Today, a satellite dish capable of doing that would be a simple project. But that kind of low cost equipment didn't exist then. Nor a lot of the other stuff we take for granted--satellite radio, GPS systems, etc.

There were communications satellites--but the first (Telstar) was launched in 1965--just 4 years before Apollow 11--and asatellite dish able to pick up its signal (from 1/10 the distance) was a big--and very expensive--piece of equipment then.

I know what you're trying to ask: You're asking about the Apollo missions and if the radio communications between the astronauts on the Moon and personnel at Mission Control in Houston could have been intercepted by "ordinary" people outside of NASA. I'll have to guess here, but I'll have to say no. These communications would have been in the microwave range, meaning that you would have needed a "dish" antenna to intercept the signals. Shortwave, for example, probably wouldn't work as most of those signals "bounce" off of the ionosphere. Although "dish" antennas are a dime a dozen these days, they were certainly not common back in the late 60s and early 70s. The government used them, but they weren't available at the consumer level. You would have also needed a radio that received signals in the microwave range, which also weren't available to the consumer. Also, the signals may have been "scrambled" (electronically modified) so that the Russians, for example, wouldn't have been able to intercept any information that may have been classified. Remember that this was during the "Cold War" when we were having an arms race with the Russians. We were also having a "space race" at the time. The Russians were the first to send a man in space, but we were the first to put a man on the moon. If there are any "Hams" (amateur radio hobbyists) out there, maybe they can confirm that this wasn't possible back then. It would have been really cool to intercept these communications, and I probably would have done it if possible! :-)

I don't know of any "signals coming from the moon". But I'll play along.

Let's assume equipment was left behind, say even that it was radio equipment.

Was it battery powered? Probably. If that's the case, the batteries puked long, long ago. There were 6 landed Apollo missions, I think the last one landed in 1973. Batteries don't last nearly that long on earth where there aren't significant cosmic rays and the difference between sun and shade temps isn't anywhere near 400 degrees.

Was it powered by solar arrays? If so, those arrays would have been fried by cosmic rays and miniscule pieces of dust that slammed into them and tens of thousands of miles per hour over the years. Wouldn't have that problem on earth, but solar arrays have a pretty short lifespan in space. They have to do a lot of maintenance, upkeep, and replacement on the ISS periodically to stay ahead of the damage.

Now........the radio signals used at the time were also exceptionally weak. It took very high-end receivers to capture and magnify them. Not something the backyard radio freak would have made at the time. Probably could be done by the enthusiast now, but then, for the aforementioned reasons, those signals were silenced probably decades ago.

The russians certainly picked up those signals. I don´t know about amatuers at the time but a few weeks ago a woman picked up a live feed from the spaceshuttle on her babymonitor... It certainly would have been possible to pick up the Apollo transmissions. A lot of ham radio operators picked up the Sputnik for instance.

OK, amateurs may not have done it, but hundreds of professionals would have done.

Recall that the Australian radio telescope was monitoring during the time the moon was not visible from Houston. You have to ask whether these guys were paid to keep quiet, if it was a hoax.

Of course, they weren't.

Please don't fall prey to really ignorant and silly conspiracy stories

My father apparently did, during one of the moon landings (but not the first!) With some of his friends they rigged up a 200m antenna with copper wire.

Sorry, but that was way beyond my electronics abilities at the time. Heck, it's STILL beyond my electronics skills! 8^)

No... but the Russians and Chinese did.