"I can run a leaky coax all over New York City if I was rich enough and run an AM or an FM station and cover that whole city."
so you can route your own wiring and call it carrier current? why doesn't this violate the 3m antenna rule? can i short the shielding on a coax and use it to make a dipole on my roof and call it a 'leaky coax' system?
i'm not trying to be controversial. i just want to understand at what point we go from one set of rules (3m antenna and 100mW) to another set of rules (unlimited antenna length and 20w in a carrier current system)?
"so you can route your own wiring and call it carrier current?"
If you got the resources to string up wiring in an area or a community or a city, that wiring is carrying the signal. It also carries the RF signal current and the circuit is completed with earth ground. Hence yes it would be a carrier current system.
"why doesn't this violate the 3m antenna rule?"
Because even by the FCC's own rules, which is Part 15.221, a carrier current system is a limited area transmission delivery system. The signal cannot exceed 15uV at the calculated distance of the operating frequency. At 580Khz it is 81 meters or 261 feet away from that wire.
That is NOT any great distance at all. In fact everyone can go look at that AMT3000 range video and tell me 261 feet is a massive distance!
"i short the shielding on a coax and use it to make a dipole on my roof and call it a 'leaky coax' system?"
No, you only end up making a shorted coax sticking through your roof. A leaky coax system is built with specially constructed coax designed to allow a certain amount of the RF energy within it to emit at a specific field strength at a specified distance from that coax. Irregardless of how long that coax is, or that neutral line on the power grid, that signal cannot exceed a specific amount of field strength FROM it..ie emitting off of it.
RFB
in one of cunninghams books he has a poor mans leaky coax that is made by reversing the shield and hot at tx end and sticking a 50 ohm dummy load at the other end.
It works, but not really controllable of the amount of signal emitted off of it.
However there is nothing wrong with being resourceful!
RFB
made a discovery. 1/2 the apartment seems to be on one circuit while the other seems to be another. when the power goes we often loose one 1/2 while the other 1/2 still has power. possibly 2 very long paths back to common ground? or even maybe two independent grounds?
The most normal 2-phase home-type electric setup consists of 1-balanced 220VAC line, with one common (neutral) and one ground.
Each branch of the 220VAC consists of two 110VAC lines which are 180-degrees out of phase with each other.
It is good practice to place all audio/video/computer on one of the 110VAC branches, and leave the other branch for lighting, heaters, refrigerator and everything else.
But the point is that there is only one neutral and one ground.
"when the power goes we often loose one 1/2 while the other 1/2 still has power."
There are always two circuit paths in a dwelling unless it is fed by 3 phase power, highly unlikely in a single dwelling, but your building most likely has 3 phase running to it.
So half of your dwelling looses power and the other half remains powered?
This is very unusual since most installations are fed by the same primary HV feed. When that HV feed goes out, everything should be going out as well, not just half.
RFB
The house next to me on one side is fed by a different power source than I am. When they lose power I usually do not.
When I lose power they usually do not.
We could have a swap deal to provide extension cords over the fence in that situation.
Maybe in a bad storm I might negotiate with them.
"The house next to me on one side is fed by a different power source than I am. When they lose power I usually do not."
Even that is unusual for two homes side by side on the same block. Understandable if the other house was across the street on another block, but right next door?
Very odd. Unless the grid just happens to split and end at the pole in the ally where you have one drop from "grid A" and your next door neighbor is on "grid B".
Just goes to show what a weird world we live in!
RFB.
I ordered a crystal from ICM to get my little CC station down to 580khz, as the old Gittings PLL board I have has stopped working. The station has been running since my original post, and some days the signal is great across town (about 2 miles), and other days its less than a mile. Today I dropped in the new crystal and updated the filter section of the LPB, but my coverage has dropped to maybe 1/4 of a mile despite running at 100% power. I am really frustrated at this point, and am going to try a different location near town to see if I can make this work. I have been tied up with other stuff over the last week (sorry RFB!), but will try some tests over the weekend and see why this thing isn't working.
Tommy J.
"I dropped in the new crystal and updated the filter section of the LPB, but my coverage has dropped to maybe 1/4 of a mile despite running at 100% power."
Placing more grounding rods will help improve that coverage. Key is to create as much of a ground contact at the grounding point as possible. Several ground rods may be necessary as that is also dependent upon the ground conductivity.
Let me know if I can be of further assistance. 🙂
RFB
Does anyone know exactly what I should ask the city to install on the powerline transformer that will allow my RF to come through on the hot side? I asked for an RF bypass capacitor, but nobody seems to know what I'm talking about.
Tommy J.
Mention "Broadband over Power Line" and they might figure it out! 😀
RFB
I'm frustrated with the carrier-current thing, to the point I pulled it all out and put it in the truck to take home, maybe even to eBay. Today I toyed around with an old EDM LED transmitter I had bought & never used. Hooked into a j-pole and set to 87.9, I am getting about a mile coverage from inside my garage. I have no way to test it and see if its 250uv at 3M (that's why I'm hiding inside the garage), but it sure sounds nice! Maybe if I get a few of these and link them together via 5ghz, I can have a legal city-wide FM station? I know I could probably do the same thing with several rangemasters on AM, at least they have the sync capability. Interestingly, the same j-pole with a 30 watt exciter gets me about 7 miles, with the antenna on the ground. I have been messing with this carrier-current stuff for weeks, I'm frustrated..
Tommy J.
AM-580 The Bull!
"I have been messing with this carrier-current stuff for weeks, I'm frustrated."
Well this is a sudden turn of events. What is causing the problem?
I would not give up so quickly when just a couple weeks ago the system was working, though not on the frequency of choice, it was working.
Give me a call and let's see what can be figured out.
RFB