All right, I have seen many posts over the years suggesting carrier current as a viable Part 15 broadcasting alternative. Many have talked about the rules and have provided information on how to do it.
I would like to hear from at least one person who has actually tried it. What was your experience? Did it work? Did it hum? Let's get a real discussion started on this topic.
My only carrier current experience was long ago in college. The campus AM station was carrier current. It always hummed everywhere on campus. There was also an FM station on campus that was favored because it didn't hum.
PhilB
Phil and All,
Many years ago I was the Chief Engineer (big title for an engineering student) for the campus carrier current station at the Univ. of Cincinnati (WFIB). I built one of the tx. and maintained the others. We had one in each dorm. These were all vacuum tube devices which fed directly into the "hot" side of the 120 V. lines in the dorms. These provided good signal strength without hum. Our biggest block to high quality audio was the leased telephone lines which low pass filtered the audio. Other than the band limited audio, the signals were very good.
But, the world has changed. Back then the only nonlinear load on the AC lines was fluorescent desk lamps and those were rare. Today, with lamp dimmers, switching power supplies, lots of fluorescents, and other non-linear devices providing high order mixing of a carrier current signal with the 60 Hz. power signal it is hard to imagine a hum free CC system.
Now I defer to the recent experience of other posters.
Neil
At my old QTH in Southwest Washington state I tried loading the neutral side of the AC in my apartment complex.
I used an iron powder rod 1/2" X 6" wound end to end with 22 Ga. lacquered wire with a tap every tenth turn over half the length and a tap every three turns over the remaining length.
I was using a Gizmo transmitter which also had a bank of switchable capacitors at the output terminal.
I "tuned" it using the millamp current setting of an analog VOM and tuned for the greatest current flow to the neutral side.
I did not have access to a ground as I was on the 2nd floor.
I was able to pick up a signal throughout the six units in my building in the complex, and out to around 200' away from the building, but the complex had underground wiring between buildings and transformers between buildings, so I didn't get out of my building.
Each apartment had fluorescent lights in the kitchens and bathrooms, but I don't recall hum being a problem on the neutral side.
After a bad windstorm that blew a bunch of siding off the buiding, I saw that the building had foil backed insulation, too, so I was in a bit of a Faraday cage myself.
I was able to cover more of the complex (8 buildings) with a 3 meter coil loaded whip on the sundeck, so I used that instead.
Experimental broadcasting for a better tomorrow!
I had a 5 Watt Tube transmitter running as the secondary transmitter for my neighborhood in Manteca.
I was able to get slightly below legal output (a friend of mine had the equipment to test this stuff) just inside the area. The sound was incredible (Tubes are beautiful sounding things), and the quality was excellent.
One thing I did note, and I don't know why (I am not an rf engineer), is that just before the point of being "not legal part 15 CC", the signal dropped to nothing.. really fast. One spot it's a great signal, two feet over, nothing at all. I guess thats a good thing - I just thought it was odd.
5 Watts, with the way my subdivision was wired, worked perfectly. It didn't go past legal limits from house wiring, and it covered the whole subdivision since our xformers were wired to bypass in case one blew up. The xformers surrounding (leading out) immediately killed the signal.
I used carrier current once, back in the early 90's. I'm in a location that was somewhat rural at that time, and my signal went nowhere..not even the closest house could receive it.
I later learned that the large transformer out back was stopping the signal. I had not heard of neural injection back then. Also, being legally blind and NOT an electrician, someone else did the installation of the coupler.
The transmitter was an ancient LPB that used tubes and two fans to stay cool. It was not the neat looking box units you see now..but it did have a good sound to it. I kept the thing running for about four years before donating the xmitter to a remote campground.
I had fun with it, though. My baby sister, who was a young teen at that time, and I used to do a live show together every Friday evening.
Our on-going punch line: "There are lightbulbs out there stronger than us."
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I have a Radio Systems Phase II transmitter with an LPB TCU-30 carrier current coupler. The transmitter will put out from 0 to about 12 to 15 watts.
I tried both neutral and hot side coupling to the AC line and tried various power settings from 2 to 10 watts.
The transformer that feeds my house feeds both sides of the street for about 400 feet. That probably covers about 12 houses.
From 2 to 10 watts, I had excellent coverage within my house. Driving up my street the coverage was static free the length of the 120 v power lines. Past either end, the signal fell off very quickly and disappeared less than 100 feet from either end of the 120 v lines.
I didn't check with the neighbors to see if they could hear it but it would seem that as steady as the signal was on the street, it would most likely be received in their houses.
I'm not using the carrier current setup at the moment, rather I have a Talking House Transmitter using the Talking House remote antenna tuner with an 8 foot whip antenna.