It was probably a Ramsey Kit. Although, the company does not recommend
running the units at higher than legal limits, it is possible to
operate some of their transmitters illegally with simple modifications
or by using external antennas.

He was not running it legally at 1/2 watt. The legal power for
unlicensed operation on the FM band is determined by measurement of the
signal strength within a few meters of the transmitter. If he were
operating legally, this translates into a few hundred feet at best and
means a transmitter power of only a few milliwatts (typically in the
6-20 mw range).