Below is a slightly edited email from the man himself:
Not knowing how much you know about this stuff, I'll try to go easy on the technical details. I was asked by my Department Chairman, Dr. Finley W. Tatum, about 1963 to see if I could help the students who were trying to get a campus radio station going. SMU had somehow acquired an FM transmitter which the students had operated illegally at some point in time. The FCC had told them to cease transmitting to avoid fines. I heard about carrier current radio and proceeded to help with the acquisition of equipment which would allow that kind of operation.
Working under the Student Publishing Company, we bought some low power AM transmitters in the 10-watt range. (I am not sure what the old FM equipment power was, but 250 watts sounds about right. I don't even know what frequency it was on, because I wanted nothing to do with illegal operation.) Our source was the "Low-Power Broadcast Equipment Company" or something like that.
The way carrier current works is that you couple the output from the transmitter into the power lines of a building, using capacitors with sufficient voltage rating to keep the 60-Hz. Power from getting into the transmitter. For any radio that is non-battery operated, the radio signal simple travels up the power cord into the radio. For radios that run on batteries, it works as long as the radio is near any electrical cord, lamp
cord, or wall outlet.
We were using Part 15 of the FCC Rules and Regulations, which allows anyone to operate without a license if they (1) don't interfere with a licensed radio station, and (2) don't radiate more than a certain level of radiation intensity for more than a certain fraction of a wavelength from the antenna (which was the power lines in the buildings). I chose a low frequency on the AM dial in order to have a longer wavelength and hence a longer distance for the maximum fraction.
A problem that you have when you use power lines for antennas is that the radio frequency won't cross a power transformer (from one building to another). Therefore, we had to lease telephone lines from the Umphrey Lee Student Center studio to each dormitory where we wanted to make our signal available, and we had to buy a transmitter for each dormitory. I used metal brackets to mount the little transmitters on concrete pillars or walls in the basement of each dorm.
SMU's buildings are connected by utility tunnels throughout the campus. I was concerned about radio signals sneaking into a nearby building through the tunnel system between dormitories that were situated close together. So to prevent interference between transmitters via the tunnels, I offset the frequencies slightly. We started up in 1964, so we advertised AM 64 (640 K-Hz), but it was 64 on many radio dials. Some dorms had transmitters that were actually 640, some 650, or some 660. I would use the different frequencies for dorms that were close. Also, I very carefully drove around near all of the dorms that had our signal, and tried to pick up our signal on my car radio. I could not, so I figured that we wouldn't get any complaints from anybody passing by.
We filed a notice with the FCC that we were using carrier current transmission and requested the call letters KSMU. Never heard from the FCC, so we did it anyway.
The system worked amazingly well. Students sold ads to local businesses to support the cost of the leased lines to each building and for subscriptions to record providers. The format was most "light-modern sounds" such as Ray Coniff. They also had some rock and roll, but none of the hard stuff. The Student Publishing Company was good to us in terms of new equipment, tape cartridge players, and other incidentals. I recall that Mark McKinney was the first student Station Manager, but he graduated about 1965 or 66. I don't remember who followed him. The Stations Manager took care of programming, sales, broadcast format, etc. I just did the technical stuff.
I accepted employment with Humble Oil & Refining Company (later known as Exxon) and left SMU in the summer of 1968. I later returned to SMU in 1980 and have been teaching there ever since.
H. Charles Baker, Ph.D., P.E.