Is there anyone heard of this? If so how is it done? and what are the pros and cons? Im going to be setting up a station soon.
I don't know anything firsthand, but here is an excerpt from "The Big Antenna Book" by Cunningham.
http://www.filecrunch.com/file/~li7xra
by MRAM 1500 kHz
Basically "neutral loading" involves coupling the RF to the neutral side of the line referenced to a ground separate from the AC power system. This allows for some impedance to develop between the neutral and the gound point used. This is necessary since the AC neutral and ground normally end up tied together at some point which results in a very low impedance the coupler can't work with.
Normally, carrier current systems couple the RF to "hot" side of the AC line referenced to the "neutral" side of the AC line. Commercially made couplers may be setup to couple to single, split or three phase power lines.
There is no hard fast rule for carrier current distribution and what may work here doesn't work well somewhere else so lot's of trial and error may be involved to get a good working system.
The catch is your signal must still satisfy FCC rules regarding carrier current operation whereby the signal strength must be at or below the maximum limit a specified distance from the power line. This works OK in a building or group of buildings serviced by the same transformer but generally not as well as a system using an antenna under Part 15.219.
Try the PDF reading room, here:
or the LPCC page here:
Experimental broadcasting for a better tomorrow!
Mram1500 gave some good information. I will add that it depends quite a bit on your situation. My CC experience was in a college dorm where the feed was 3 phase. I coupled a 25 watt tx. into one hot side of the line and tuned the old tube rig for max drive and min plate current. It worked great (or is it greatly?). The campus plant engineer would not go a along with caps. to the other two phases to couple the RF (good decision...as I learned more about power distribution I realized he was correct). The distribution must have been such that each phase appeared on each floor though not to each room, but nonetheless, the signal could be received all over the dorm. It was not necessary to have each outlet in each room on the RF feed, there was enough radiation to cover this dorm. We had all dorms covered in a similar fashon and it worked well.
I think it is going to be a matter of try it and see what works.
Neil
My take on the sparse information in the LPB Neutral Loading Option shown in: http://utopianetwork.home.comcast.net/carrier/ccneut.pdf is that you just plug the transmitter into a wall outlet and it will feed the signal to the neutral terminal. The transmitter ground is shown as being separate. The neutral terminal on an outlet is connected directly to the building ground rod back at the breaker box. So the load resistance will be the difference between where the transmitter is grounded and the building service entrance ground, probably just a few ohms. This is essentially a direct short. However, if the outlet is a significant distance from the service entrance, there will be an unknown amount of RF impedance, depending on a lot of factors. For signal strenth, the longer the run, the better. Not a pretty setup.
Old time full blown carrier current campus systems distributed the RF by coax to each building. High current RF inductors were inserted in series between the power feed to the building and the internal wiring. The RF from the coax was then coupled to the hot legs on the internal wiring side of the inductors. This is best for efficiency and for preventing the signal from radiating from the overhead power lines. But, this is still extremely inefficient because the signal is attenuated by the internal building wiring hot lead to ground capacitance. The transmitter needed to run at fairly high power to overcome the losses. And, talk about hum!
PhilB