Carrier-Current really works!

After reading this milestone by Ultanium I can't wait to get on carrier current. Everything else is put on hold while ground rods go in and coupler and transmitter somehow become materialized.

I'd stay up all night and work on it but don't have any of those things yet. Oh heck, I won't let that stop me. I'm staying up.

Thank you for those nice comments. I am extremely excited that your system is operating and doing its job the way it should be!

Its all a learning process. And as I stated on Carl's LPH show, and on the telephone, each location will be different, with its own unique circumstances to overcome. And sometimes the solutions are in plain sight, but not easily recognized or discovered due to the frustration factor.

Your site is very unique in that it presented its own list of problems which could not be known until the system was put in place and tested. (REAL WORLD TESTS)

We took the real world situations for the site and found the answer in a simple solution and resolved not only the station coverage issue, but also several induced interference issues on other services.

It was a pleasure to assist you with the station and I could not be happier! Another CC station begins its adventure in serving the public interest!

BRAVO!!!!

What is learned here can be passed on to others so they too can pass on what has been learned.

RFB

any hints for someone in an apartment who can't get a good separate ground outdoors?

Question for kc8gpd... if there is a basement you can get to check the floor and watch for openings in the concrete floor. If it's a dirt floor you're ready to consider a ground rod in the basement.

In my basement there is a 1-foot diameter hole in the concrete right into the earth where an old abandoned pipe was previously located.

Before sinking a ground rod in the basement the following safety checks must be made. You must avoid punching a hole in a sewer line or pipe-line, and a plumber, electrician and maybe a gas system installer should be consulted.

The final question is, is there any reason that a ground rod in the basement floor would not be recommended for radio purposes?

"The final question is, is there any reason that a ground rod in the basement floor would not be recommended for radio purposes?"

None at all. Ground is ground, outside or in a basement. In fact it is better in the basement as you have a head start in depth from the basement itself. The deeper the ground rod is, the better moist dirt you slam the thing into, in turn better conductivity for the return path.

Same is true if you hammer in a 20 foot ground rod. It goes deeper into the dirt for not just more surface area to make contact with the dirt, but into the better dirt deeper below the surface. It has more moisture and if we examine elementary electrical physics, water conducts...as does something moist...including dirt.

This is why there is recommendation to all Part 15 3 meter stick operators to keep that ground system in check and often recommended to water it like watering the yard.

They say that water is not good for anything electronic or electrical. But in the case of getting the maximum ground conductivity out of a ground rod and radial system, water and moisture in the dirt is your savior.

RFB

In apartment situations the options are incredibly limited, especially if you are anywhere above the ground floor level.

I have seen some apartment situations where the person would sneak and install a ground line and run that out the window to a ground rod hidden behind a bush or shrubs. Late night and the cloak of darkness aids in this endeavor.

Or simply ask the apartment management permission to install one. If done the right way, they may say go ahead. But do not expect a miracle yes from them, as most of the time they wont let you do that.

Hence the sneak and stick approach, which in of itself has its own risks and rewards.

No there really isn't much wiggle room in an apartment situation for a good isolated Earth ground. It is highly probable that your ground and neutral on the power wiring, the cold water pipes and even phone and cable are all tied in together at the service drops with a ground, meaning that those things are all tied to the same common point at the service points. They all become the same ground..which will not work for an isolated earth ground.

But this does not mean your out of luck. There are several connecting configurations for a CC system in just such situations as yours that will still be effective. Depending on exactly where the power utility and the common grounding point is located, you may be able to get away with using the 3rd lug wire in your apartments wiring, which is the power grid's earth ground, as your neutral return and the neutral line on the power grid for the main connection to the coupler output.

The common ground connection point may be outside at the meter cluster, or even internal to the step down behemoth transformer sitting on that slab tucked away over in the corner of the lot. If that is the case, then there is plenty of distance between you and that common ground connection point, in turn meaning that the 3rd wire (ground) of the power wiring will be far enough away that it can still serve as an adequate return path for the neutral coupling method.

The last ditch option would be to locate the coupler unit somewhere outside and nearby so that you could slam an isolated earth ground rod and couple to the neutral. This still involves running the transmitter coax somewhere and permission to do that. It also puts the coupler unit into an inconvenient place where you may not be able to access it when you need to. But given the limit in options, it may be a good exchange for less than optimum access to the coupler for a huge increase in CC system performance. A trade off.

RFB

If I understand this correctly the "isolated ground" is usually a stake located some distance from the service ground. This requires a ground lead connection to the stake. Doesn't this ground lead radiate and if so does Part 15 field strength limits come into effect?

It would seem that this would put a practical limit on the power used for the transmitter which would depend on the particular installation and the operator would need to assess the field strength at the transmitter site.

Neil

"If I understand this correctly the "isolated ground" is usually a stake located some distance from the service ground. This requires a ground lead connection to the stake. Doesn't this ground lead radiate and if so does Part 15 field strength limits come into effect?"

It can if it is too long. This is why I state, as well as LPB, that to have a working neutral loading CC system, that isolated ground connection MUST be as short as possible. Not only does this prevent a long ground connection turning into a radiator, but puts the signal where it belongs, on the power grid wires. And the shorter that ground connection is, the better performance you will get for the return path as well as coupling efficiency onto the power line or the neutral line.

Adding to this, we can look back at situations where too much ground connection, be it a wire or water tower, becomes more surface area than the rod intended to be the radiator and in turn the whole system works in reverse, making that ground connection the radiator instead of the stick or power lines.

But even if you coupled to the "hot" lines, the neutral connection in this configuration, if too long, can also become the radiator instead of the "hot" lines, totally wiping out the whole concept of carrier current. The concept is confining the signal to a specific area or along a length of power line or leaky coax. In order to do this with power lines or neutral lines, the ground connection should be as short as possible. When this is observed, it wont matter how long the feed connection length is as that length becomes part of the overall length of the neutral grid, and is where we want the signal to be and not on our ground connection.

When the LPB tech manual and I say "Isolated Earth Ground", that does not mean you connect up to the power grid's ground or any other utility ground connection whatsoever. You install your own ground system, comprised of ground rods, ANYWHERE within close range of the coupler. The shorter distance the better. And your isolated ground does not have to be a mile away from a power pole or utility drop. Minimum distance I have found to be workable is 5 feet from an existing ground rod tied to a utility or city water pipe.

For his location the distance between his new isolated earth ground rods and the ground point he tried before..the one that has everything tied to it and does not work, is roughly 6 to 8 feet distance and around a corner of the building. More than adequate to create an isolated ground.

"It would seem that this would put a practical limit on the power used for the transmitter which would depend on the particular installation and the operator would need to assess the field strength at the transmitter site."

His next step, now that the system is installed correctly and working like it is supposed to work, viable field strength measurements can now be made. He will be required to keep a record of this measurement on site. CC stations established prior to 1989 are "grandfathered", such as mine, and are not required to keep a record, but still must meet the limit called for in 221 and 209 for out of band harmonic emission.

With a properly installed CC system, and depending on the frequency of operation, he may find that as little as 2 watts will not only give him the coverage expected in neutral loading, but will also be very close to the maximum 15uV/m 47,000/f limit.

In some cases such as his location and the power grid layout, the power grid is so clustered together that even at 1700 there is still not enough distance between these power lines from one block to the next. It won't be easy to find that distance point of measurement without overlapping into the next power line and so on. The measurement will be tricky but not impossible. This is why for his location and power grid layout, it would be better to operate at the lower frequencies which gives him a greater distance allowance for the 15uV maximum limit point. At 580 this is 81 meters, or 265 feet. So that means ANY power wire carrying his signal, the signal can reach out to 265 feet FROM the line and at that 265 feet point, the signal cannot measure above 15uV.

They do allow for a +/- variable, but not a massive ridiculous amount. Besides, why would you want to cram too many watts into the system and potentially cause interference to other services on those poles..such as cable tv services, telephone services and BPL services. And not only that, you end up over saturating receivers in close range to the TX point.

The system works on inductive coupling. There is no direct connection between the transmitter and power grid. The system relies on the power lines or neutral line to deliver that signal directly into homes and business buildings. The radio receiver, plugged into AC power, will get more of the signal from the power cord than from the power line outside, and is why there is no need to cram signal on the grid. At most, when he changes over to 580khz, 2 to 4 watts will most likely all that will be needed, perhaps even less.

RFB

i was going to fix the cunningham and run it at its absolute minimum on the low end of the band. this should be within limits. we have concrete/brick reinforced multi story building with a parking garage below us.

i was going to use the cable tv sheild as my ground and the neautral.

i figure if there are no issues within my apartment there shouldn't be anywhere else and there should be plenty of distance back to common ground to load up the neutral properly

"i was going to use the cable tv sheild as my ground and the neutral."

That is a good approach. Check the continuity between the cable shield ground and the neutral buss bar in the breaker box. Hopefully it will present some resistance instead of a full continuity. But the couplers can tune even with a .5 ohm inductive load. Start with 1 or 2 watts and tune up for best vswr on the coupler. Place the coupler as close to the nearest cable outlet that is nearest the neutral coupling point. This will help keep that return pathway to the coupler as short as possible for maximum signal injection onto the neutral buss.

No doubt this will give you full building coverage and then some! Quite possibly even over into the next building without having to run a repeater or splitter at the TX point feeding two couplers.

RFB

woah. i was under the impression that carrier current is only really effective inside the building you are using to transmit. boy was i wrong!

why dont standard field strength limits apply when doing carrier current? why is it legal to be covering an "entire town" using carrier current?

also, where are you guys finding super cheap transmitters with enough power for carrier current? 😀

I fully understand how and why CC can achieve exceptional range when a separate ground is used with neutral injection. But, seems to me that this isn't really carrier current as intended, rather, it's a long wire antenna.

Carrier current, I thought, relied on the fact that using the HOT and NEUTRAL would act somewhat like a balanced line and as such radiate a very short distance from the line. Reception was based more on being "connected" to the line or at least being in very close proximity to the line.

Are there any definitions in the RULES that define neutral injection as an acceptable method?

"woah. i was under the impression that carrier current is only really effective inside the building you are using to transmit. boy was i wrong!"

The two main ways to run a CC system is coupling to the "HOT" lines or the "NEUTRAL" line.

When coupling to the "HOT" lines, the RF path is completed when the "NEUTRAL" line is connected to the neutral return in the coupler. In this way, the signal is riding on the electrical distribution wiring inside the building.

When coupling to the "NEUTRAL" in the breaker box, the RF path is completed by installing an isolated Earth ground with grounding rods and connected to the neutral return in the coupler. The signal is riding on the power utility neutral line, and can in some cases cover an entire small town.

"why dont standard field strength limits apply when doing carrier current? why is it legal to be covering an "entire town" using carrier current?"

There are standard field strength measurements that apply. It is 47,000/F = 15uV @ 30m. F is the frequency of operation. (15.221) Outside band emissions must be 20db down of the fundamental. (15.209)

It is legal because the signal is limited to the electrical line. It can emit from that line at the specified signal strength and distance per operating frequency.

For example, 580 Khz would spot your measuring point at 261 feet from the emission source...the neutral line. at 261 feet, your signal cannot exceed 15uV.

Now if the power grid distribution is configured in a certain way, such as it is in newly installed CC system by the Op of this thread, that neutral line is obviously a common neutral line spanning across the entire community. It is a small community, and this kind of power grid configuration where the neutral line covers a larger area than it would in a large city, is the reason why this CC system can cover the whole area.

Anywhere along the length of that neutral line that signal cannot exceed 15uV at 261 feet. It does not matter that this line is branching off in different directions covering the whole town, as long as that signal never emits off any of it exceeding 15uV at 261 feet.

Since the neutral line is the power grid current return, as well as the residents and businesses electric service return, the signal gets right where we want it, into the homes and businesses, and 261 feet off that neutral line wherever it happens to be at.

Super cheap? LOL!!! They are not super expensive, but certainly not super cheap either. A new CC system would run about 1,300 or so for both a transmitter and coupler. Extra costs would be ground rods and grounding wire to create the isolated ground system.

Radio Systems makes the currently available units. But you can find the famous LPB series on auction sites or at ham fests or the very rare old drive in theaters that used a CC system for the audio.

The LPB series used for CC vary in model by power range. There are LPB solid state models and tube models. There are also LPB couplers, the best one they ever made was the TCU-30. The LPB series was and still is the very best CC systems ever made. Unfortunately the company no longer exists so auction sites and lucky finds are your only hope there.

RFB

"But, seems to me that this isn't really carrier current as intended, rather, it's a long wire antenna."

Define the difference in the result of that signal emission in a leaky coax arrangement to loading a neutral line while meeting both field strength measurement limits. Better yet, define the difference in "intended" between them as well.

It is really carrier current. Where it seems to you for the confusion is that carrier current only applies to injecting RF energy onto the hot wires, which hot wires are both inside buildings and spread out all over a city. So going by your confusion, coupling to the hot lines isn't carrier current too unless there is a transformer in the way? Well I know of many electrical service runs that extend for 2 or more blocks in rural areas where those transformers are spaced by quite a distance. Does that mean its not carrier current either?

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. Or if the grid was wired so that the neutral line was a common (continuity) conductor all over the city, that CC signal on the line would cover the whole city just as the leaky coax would. Both methods have their field strength limits in the signal emitting off that line or coax.

"Are there any definitions in the RULES that define neutral injection as an acceptable method?"

Nope. And there aren't any definitions in the RULES that define neutral injection as an unacceptable method either.

And no where can I find any RULE that says a CC system MUST be intercepted by a transformer and cannot bypass a transformer or cannot use its own isolated ground with ground rods.

"radiate a very short distance from the line. Reception was based more on being "connected" to the line or at least being in very close proximity to the line."

A CC system coupled to the neutral line IS radiating a very short distance from the line! 261 feet at 580khz is a long distance to you? As to being "connected" to a line, well I cant think of any more direct connection to the line than a radio's power cord return wire plugging into a power outlet socket with this same return wire connected in the breaker box at the NEUTRAL line connected to the service drop NEUTRAL line connected to the utility pole distribution NEUTRAL line running across town, or split up and only running a few blocks.

A good way to eliminate confusion is to study the origin and history of carrier current and its intended purposes. You will find that this new CC system and mine are no different in application, installation AND intended purposes to any previous CC system.

RFB