It all has to do with the efficiency of the antenna system including the transmission line. 100 mw (0.1 watts) of actual RF power being radiated from an antenna can produce a remarkably strong signal at 30 feet whether it is in the AM or the FM band. Getting an antenna to respond efficiently in the AM band is a problem unless a tall tower is involved. But for FM, because of the short wavelengths of the frequencies in this band, designing an efficient antenna is easy. This is why the FM part 15 rules put a limit on signal strength rather than power or antenna length.

Dave

Yep- and Firesign Theater, Jack Benny, Fibber Magee, Dick Tracy, my own sick commercial parodies and my friend "Uncle Buddy".

Was it worth it?
Oh yeah.

Kind of late posting to this one. Here is a test run at about 1 watt using a 50 ohm load. I wont admit to using an antenna. I've long since dismantled this station but it worked quite well using an old Panaxis FME-500 + stereo generator & various filters. I'm not advocating operating a station with this type of power with an antenna. Regardless of all the supposed fun you think you'll have, you do run a risk of getting popped no matter how low the risk is. Bottom line, this is illegal with a proper radiating antenna!
http://www.youtube.com/watch?v=Q49CQcTFCwU

Here is another vid I recently shot of a local. He is about 4 1/2 miles off as the crow flies. I do not know this individual or what he is using. I just know the general area to within a 1/2 mile that he broadcast within. Not much room for a serious antenna which has me wondering why such a nice signal considering the wave length and antenna required to transmit a decent signal. But this stations audio is certainly nice and his carrier is spot on in frequency. I have a couple other vids of this station playing on YouTube.

http://www.youtube.com/watch?v=huDgIeqtePA

In this vid it's getting later in the night and DX is starting to take it's toll. Within 45 minutes DX completely wipes him out.

http://www.youtube.com/watch?v=YV3P4NyKPXQ

30W could get out a mile even using an antenna in your basement. Don't ask how I know.

Scott Todd

BTW, for what you want to do, a half watt with an antenna up about 25' should be more than enough.

Scott