Welcome to the RFB’s Carrier Current blog. Here I will enter regular, and irregular updates about my Carrier Current station, which operates on AM 1670 using the Motorola C-QUAM AM stereo standard. I started this Carrier Current station back in 1973 and have seen a lot of changes and improvements in Carrier Current broadcasting. Feel free to post any questions about my station, or Carrier Current broadcasting in general and I will do my best to answer them. Enjoy RFB’s Carrier Current blog!
That’s Great!
That’s great because few of us have
experience in this area. Since you
have been doing it since 1973, I’m
sure you have seen a lot of interesting
things.
I was at the University of Connecticut
in 1973. The FM station there was
WHUS, 91.7, Storrs, CT. At that time,
I believe they were about 3,160 watts ERP.
The only way to get on 91.7 was to start out on
the carrier current station – at that time it was
known as WHUS AM, on 640 kHz. I did a half
hour show on Sunday night from 10:30 PM
until 11:PM. If memory serves me correctly,
there were only about 5 records in the studio.
I guess they really didn’t care if you were there
or not and they only left a few records in there
so nothing could be taken. There was an old time
radio show that ended at 10:30 “Gangbusters,”
that was coming from somewhere else. After
11:00 another show came on automatically.
So if you didn’t show up there was a half hour
of dead air between 10:30 and 11:PM.
I am sure nobody was listening. My dorm did
not have a carrier current transmitter in it,
so I couldn’t hear WHUS AM. I went to a
friend’s dorm where 640 could be received,
and it was about 30% hum.
Best Wishes,
Bruce, MICRO1690/1700
Only One I Knew About
The only carrier current I ever knew about in St. Louis was operated by St. Louis U. back in the 1950s, at 590kHz, serving several scattered dorms, call letters KBIL which reflected the famous Billikens Basketball Team. Studios were decent with big Gates console and some giant 16″ transcription turntables and a Magnecord tape recorder. The chief engineer, Harry C., was very sociable and let me hang around as a grade school kid. As the station sort of melted from lack of interest Harry C. gave me an LPB tube transmitter schematic and a few coupler data sheets, then he went on to a lifetime career at 1600kHz 5kW. I went on to operate a part 15 station which many people think I only imagine.
Early Carrier Current Attempts
Carrier Current technology dates back as far as pre WW I when the telephone industry used the technique of sending RF signals on their DC pair wires as a form of private communications links. Later the power companies began to use this same technique for the same purposes, to provide a private communications link across their existing power grids to communicate with sub stations. They also began to use Carrier Current as a form of radio control to these sub stations located in the middle of nowhere, thus eliminating the need to have these sites manned.
In the WW II years, radio communications via intentional radiator was banned for security reasons. HAM’s began to communicate via Carrier Current techniques. A lot of the technology was further improved upon by the HAM’s.
However back in those years it was extremely difficult to couple to the power grids. There were no toroid transformers at that time and couplers consisted of bulk tuned circuits of coils, capacitors and inductors. These early couplers constantly had to be re-tuned due to the nature of the changing inductance on the power lines from one hour to the next, all day and all night long. These early couplers were also quite ineffective in keeping out the induced 60 cycle AC hum, though they did work to some degree.
When the toroid cores came along, it was much easier to null out that annoying 60 cycle hum as well as drastically improve the coupling efficiency. The toroid transformers also provided a means to maintain coupling effectiveness even though the power lines would change inductance during load peak times and low load times.
As we all know, LPB, or Low Power Broadcasting Inc, was the only company around making Carrier Current transmitters and couplers. The engineers at LPB knew what they were doing and created top of the line products that were on the level of Part 73 devices. Today, LPB no longer exists and the only source now is a company called Radio Systems Inc.
LPB equipment can still be found often at ebay and usually in very good shape. But be warned, these items are heavily sought after and expect to be bidding with a lot of competitors and sometimes very high bids, especially now because these items are becoming more rare with each passing day.
However that should not stop anyone from considering Carrier Current broadcasting. A simple 5 watt AM transmitter and a coupler consisting of an inductor coil, a capacitor, variable or fixed, and a fuse is all it takes to inject the RF signal onto the power line. Further experimentation and circuit construction, especially with toroid coils can enhance the coupling efficiency as well as null out annoying 60 cycle hum.
The 60 cycle hum is caused by what is known as “reverse inductance” in the field of Carrier Current. That is…the 60 cycle energy finds its way back into the output path of the RF chain and into the final RF amplifier. This happens most when coupling to the power grid “HOT” lines. Thus a coupler must be designed with a section of its overall circuitry that couples this 60 cycle energy and “null” it before it has a chance to find its way back into the final RF amplifier. Here is where the toroid transformers do the job nicely while maintaining the coupling efficiency of the RF signal.
One way around this annoying hum, especially with simple coupler designs is to couple the signal onto the AC Neutral line. This also bypasses the utility transformers which will be like a solid wall to your signal and prevent it from going further down the power lines. Coupling to the AC Neutral line is far more safe than coupling to the AC “HOT” lines as there is no voltage potentials on the AC Neutral. Although the AC Neutral serves as the return path for the AC power system and return current eddy’s can be measured on it, the effect of these return currents to the RF signal is very light, if any. Often there is no hum at all, and sometimes there is a little bit of hum, but no where near the amount of hum that will be present if coupling to the “HOT” lines.
As time goes on, I will post my experiences and describe my experiments I have done in this field. Carrier Current broadcasting is a great alternative to the familiar intentional radiator system, and allows for the use of far more power from the transmitter because it takes WATTS to inject the signal effectively onto the lines than it does to make a simple 3 meter long whip emit a signal.
Carrier Current is regulated under the FCC Part 15.221 section of the rules. The biggest misconception to date is that Carrier Current is intended only for educational institutions and colleges. This is a BIG MYTH!!
And the reason for the big myth is that in the past, a Carrier Current setup was normally found at colleges and campuses. Well myth is not the rule. In fact, the FCC rules do not contain anything saying a Carrier Current station is only permitted on a college campus. If that were the case, then there would have been hundreds of drive-in movie theaters getting NOUO notices as well as apartment complexes, camping sites and mobile home parks.
Carrier Current does have regulations to follow. For example, its signal must not exceed a certain amount at a given distance based on the frequency used. Most Carrier Current installations favored the low portion of the band because of the longer wavelength and farther distance the signal could be picked up off the power line. However even at the upper portion of the AM band, such as my station which operates on 1.670Mhz, my signal can go as far as 93 feet from that power line. At 670Khz, that signal can go as far as 200 feet from that power line.
This might sound incredibly limited. Well in a way it is. However consider this for a moment. How far does that neutral wire on the power grid go?
Every utility pole has a neutral line on it. Every home has a neutral line going into it. Depending on how the power grid system is configured, that signal can cover an entire community FAR exceeding any coverage a Part 15.209 installation can even dream of, although some Part 15.209 sites can cover an impressive amount of distance, usually that only happens if the conditions are at their peak, but on average, a Part 15.209 setup can muster about 1/2 mile to 1 mile maximum. On good conditions such as a rainy day when the ground is moist, a Part 15.209 setup can reach out to 2 miles and more.
With a Carrier Current Part 15.221 setup, using the neutral line and that neutral line is covering an entire community spanning 5 miles or more, your signal will travel down that neutral wire and right where it needs to be going, directly into homes and businesses tied to that power grid system.
Think of it as a “wired wireless” system. And wherever that wire goes, so does your signal! And what better way to have your signal path take than to be fed directly into your listener’s radio..right there at their power outlet! It would be as if your Part 15.209 100mW transmitter were sitting right next to it!
More to come!
RFB
The HUM-ble Beginnings
As I mentioned before, I started a Carrier Current station back in 1973. I was inspired by reading about the early experimentation done with the technique. I was also inspired due to the extremely limited range I was getting off the intentional radiator setup. I wanted my station’s signal to reach more people. Other than going the regular route of applying for a license to a 250 watt AM station, which even in 1973 was incredibly expensive, Carrier Current seemed to be the answer. And it was!
As with any venture, it must begin somewhere. My first task was to learn as much about Carrier Current technology as I could. I was already well versed in radio engineering so some of the learning curves were already accomplished, but that was with intentional radiators..ie antennas. Transmitting through an antenna and through the power lines are two completely different worlds which require different approaches….drastically different approaches!
Transmitting a signal through a wire or rod is simple, just cut the wire or rod to a wavelength of the frequency intended and there ya go…your on the air. Sounds simple..and basically it is. Even for the MW band which 1/4 wavelength antennas can be as long as 120 feet or more.
However even back in 1973, there were strict limits on how much power and field strength as well as antenna length were permitted without a license. Despite the fact that those limits were less strict than they are today, the limits were there nonetheless, and as it does today, even those less strict limits wreaked havoc with coverage goals.
Come to think of it, and this is through actual first hand experience, I do not see any real difference between the limits of those years past and today.
I won’t waste any time throwing out numbers or figures to compare from then and now, that is not the purpose of this blog. That information can be easily found across the internet as well as in libraries. Let’s just say that back then and today, the limits imposed have and had the same effect…limiting the range of the signals.
There had to be a better way. I felt like I was spinning my wheels trying to peak and tweak and maximize that 3 meter stick. Although a lot was discovered and developed to maximize a 3 meter setup, it still was not satisfactory to me nor was it really helping the purpose for setting up my own radio station.
So the first thing to do was to learn about Carrier Current. Most of my initial information came from Amateur Radio handbooks to extend my knowledge about tuned circuits to change a 50 ohm impedance down to a 1 ohm and less load. Quite a task let me tell ya! Especially when all you had to work with were bulky tuned circuits! Although toroid cores were around in 73, they were rather pricey and I did not work with them much and had just some basic understanding of how to construct a toroid transformer for work in the RF field.
So being limited to bulky tuned circuits, the biggest hurdle to overcome was getting rid of that annoying hum! I spent hours upon hours trying different circuit configurations and designs, all the while trying to maintain RF signal coupling efficiency to boot! It was NOT easy. Sometimes even frustrating..but not so much as to make me give up! Using a borrowed radio rig which was a surplus WWII field radio, I manged to come up with a design that worked well.
After learning how to design and build an adequate coupler unit, the next task was to build a transmitter. Sure I could have simply bought one from LPB, but as with most hobby enthusiasts, budget tends to be the big limiting factor. It is easy to just buy something off the shelf and be done with it. But I was a builder, and engineer who got down to the nitty gritty and got my hands dirty…as well as plenty of soldering iron burns! No pain no gain right? 😀
My first home built transmitter for the Carrier Current station was a two tube design that put out about 3 watts of continuous power, and about 4.5 watts Peak Envelope Power under modulation. This was adequate enough to continue the venture of actually coupling that signal onto the power lines through the home built coupler. Here is where a lot of experimenting came into play..as well as keeping in mind about safety. After all, I had not heard of or known of any technique about coupling to the neutral line at that time.
The initial testing resulted in a few “POOFS”! Good thing for in-line fuses! In my rush to test, I had forgotten about the fact that even with an adequate capacitor of adequate voltage rating, it acts differently at AC and even more so to a changing load impedance! POOF! Damn! There goes another set of caps! Gotta love them fuses though!
I think that at no other time during my entire electronic and RF engineering career I had seen so many blown capacitors and goo all over the inside of a box! POOF!
Well after all the POOF’ing around and learning about the ever changing inductance loading of the power grid, I finally found the right combination of capacitor value and voltage ratings to keep the smoke in them, and a lot less goo out of the box! That was some messy stuff! After doing the final design and build of the coupler it was time to move on to the next step. Field testing!
After reviewing the FCC rules about Carrier Current, I set out to meet those specifications. This was rather easy considering the power line ran about 1 full block then BAM…a roadblock! That darn canister up on that pole was blocking my signal!! What a bummer! I wished I could just climb up there and get it out of my way! It is not that high of a climb….Ya right!
But I was not discouraged by that. I had learned a bit later that it was possible to have the power company bypass that transformer with coupling capacitors. Fortunately a relative worked for the local power company and pulled a few strings to get 5 locations mounted up with these bypass capacitors. YAY!!! Now my signal covered 5 whole blocks!!
This was a victory worthy of a celebration! Break out the party hats and noise makers..in which I did just that. I had a celebration party on the air to bring in the station’s first day of Carrier Current broadcasting!
Once the bypass capacitors were in place, and after the debut party, I began the measurement tests. Everything fell right into place! I was amazed at how easy it was to meet the FCC specification. I noted my measurements and continued on with station operations.
About a year into the station’s operation, I started getting letters from addresses that were more than 5 blocks away. I thought how could anyone past the 5 block area pick up my signal? The power company did not install any other bypass capacitors beyond the 5 block parameter. Well little did I realize until thinking about it, the signal was inducing itself onto other nearby power lines even though they were not physically connected through the bypass capacitors!
At that point I began to expand the system with more transmitters and couplers. I expanded my station’s coverage to the entire town by using two methods, adding more transmitters and couplers at key points, and by the natural induction of the signal onto other power lines not being fed by added transmitters and couplers.
Audio was fed to the added transmitters via an equalized phone line, which was very handy since the telephone company had phone lines on the same poles where the additional transmitters and couplers were mounted. I leased one large loop of equalized line and had the telephone company make sure that loop always followed the path of where one transmitter and coupler was to the next, saving a ton of money.
I began to program local talk programs as well as music from local artists. I even had a program in the morning called “The Trading Post” where the audience could call in and trade items or offer them for sale. This program was incredibly popular, sort of an electronic version of a classified ad’s to a newspaper. Soon after that I began to sell some of the airtime to organizations and advertisers.
The station identified itself as Carrier Current Community Radio, or CCCR. It operated on AM 670.
More to come. Further improvements made to AM 670 CCCR.
RFB
Thank you!
This is really great RFB!
A world unexplored by most of us.
Just to save time – you were great
on the Low Power Hour, and I appreciate
your info on so many threads – the top hat
thread, the lights on the antenna thread,
and others. I also saw the photographs of
your carrier current set-up on Carl’s website!
I can’t thank you enough!
Bruce, MICRO1690/1700
Glad to inform
Thank you Bruce and all here at Part 15.us, with special thanks to Carl Blare of The Low Power Hour for inviting me to be a guest on his program, a well put together, highly informative program! I might have to suggest to Carl that perhaps the program should go 2 hours, especially for topics such as Carrier Current. As I wrote to him in an email after the interview, when he said “we are just about out of time”…it felt like I had just picked up the phone 5 minutes ago!
There is a lot to cover regarding Carrier Current. The pictures only show the end result of what took weeks of planning, testing, configuring, testing some more, re-configuring, pulling hair out, throwing things, saying colorful metaphors muffled by biting the tongue, more hair pulling….almost as much if not equal to making a well designed, highly peaked Part 15 intentional radiator system…which I have one of those as well as I described in other threads with the sensing circuits, auto-peak tuning, lights and day/night function for those lights. It serves as a 3rd backup to the CC system.
I will explain some of the details here in this blog about those pictures on The Low Power Hour website. As describing these details is much easier by voice than typing, I will keep them brief but at least containing enough information to understand what is being looked at on the pictures.
You can click on the pictures themselves to get a much larger version of them with defined points. Simply click on each picture, then when they open, click on the image again to magnify. Here is the link to The Low Power Hour web page: http://kdxradio.com/lph.html (right click on this link and have it open in a new browser tab so you can have a side-by-side window to read and follow along with the images without having to bounce back and forth by left clicking)
Starting with image 1. We see the entire K-ROCKS AM Carrier Current system. Although it could have a more “eye appealing” with appearance, that would not help in the way of system performance. But key safety practices have been incorporated into this layout, which sometimes adhering to safety does not always mean pretty! 😀
In image 1 there are two LPB transmitters sitting on small postal boxes so that the vent holes at the bottom can allow for postive air flow (heat rises through the top vents, cool air pulls in at the bottom vents) through the transmitters. The unit on the left is an LPB TX 2-20 driven by the Chris Cuff C-QUAM exciter board. Pictures of that are within another thread on the forum boards along with a sound sample. On the right is an LPB 25th anniversary special edition AM-25. This unit is also driven by a C-CUFF C-QUAM exciter board. Both transmitters are configured for the upper AM band in their amplifier’s harmonic filter. However I have complete sets of toroid coils and capacitor sets to move both of these units to any one of the 3 segments of the entire AM band that LPB desinged these to work in.
RF power is fed into the LPB TCU-30 coupler unit with a short coax fitted with PL259 connectors. I run these transmitters at 15 watts each under normal operation, but both can safely reach the maximum 50 watts of RF power. However the LPB TCU-30 coupler can only handle about 35 to 40 watts continuous. A second LPB TCU-30 coupler, not pictured, is also on hand to serve as a backup. Running them at 15 watts perserves the transmitters and provides more than enough power to couple the signal onto the power grid and obtain a coverage area of about 4 miles. In some areas that signal, though containing some noise but listenable, was tuned in near the south end of Evansville, about 6 miles away.
The nature of coupling to the power lines does cause your signal to be limited to close proximity of those power lines, but that really does not defeat the purpose because the signal is being fed right into where you want it to be…at the listener’s radio via the power socket, as well as within 200 feet of that power line. For my station’s case, it is 93 feet at operating frequency 1.670Mhz (1670Khz).
A DVM sits to the far right and provides for instant power amplifier bias voltage monitoring. In the LPB solid state series, temperature compensated bias is vital for the matched pair of final power transistors (SD1407’s). Main B+ to the finals operates at 30 volts DC at about 2 amps.
And to the far left is a good ol Ramsey FM 100 transmitter that is also on air at 92.3Mhz. The antenna is a telescoping whip attached to the F connector on the back of the unit. The car sitting on top of it is a dealer’s promotional model of a 1965 Oldsmobile Cutlas which a short production run of those promotional models has an AM radio! The one in the picture does have the AM radio and works very well. 🙂
In between each of the LPB transmitters is an ASMAX-1 C-QUAM exciter board sitting on a piece of wood. It serves as a stand-by exciter. Soon it will have a nice cabinet to call home.
In image 2 we see a closer look at the coupler with its cover removed and a closer look at the point of contact in the breaker panel box. Note how the power grid earth ground buss is mounted with clamps to the breaker panel box, and note how the power grid neutral buss sits on an isolated mounting pad (black in color). This is how the NEC calls for a breaker panel box to be wired.
The power grid earth ground and the power grid neutral CANNOT be connected together in the breaker box, and should not be. Despite the rumor, and mis-informed, the National Electric Code does not permit the power company or any licensed electrical installation company or electrician to connect these two points in the home. The only place where they are connected are at the supply side of the utility, which is up on the utility pole!
And logically so. If lightning were to strike the utility pole, the shortest path to ground at that point is the ground wire ran down the side of the utility pole! I would want that lighting to go into the ground out there at the pole…not in my breaker box!
The earth ground that is wired in the breaker box runs to a totally separate earth ground from the utility pole earth ground, meaning the two are isolated ground paths. Now you see why the NEC codes call for no connecting the neutral and earth ground in your breaker box! The connection for safety is done at the utility pole!
In image 2 we also see the wire providing earth ground for the coupler. This ground is also an isolated ground. It runs from the coupler through a 6 foot long wire, out through the wall, and connects directly to a 8 foot grounding rod. Another wire runs from that grounding rod 6 feet to another 8 foot ground rod, and another 6 foot wire then connects to the water pipe coming out of the ground which provides my home with water service. This entire ground connection is isolated from the earth ground used by the power grid, and helps create a complete RF path.
In image 3 we see a much closer look at the coupler and it’s internal components and connections. The earth ground connection ties to the coupler’s neutral stud. The second stud is the couplers “L1″ connection point. This is connected to the power grid’s earth ground point in the breaker box. Some might be thinking..”huh?..why would you connect one of the coupler’s outputs to the power grid earth ground?”. LOL!! I will explain that in a bit.
The second stud is the coupler’s “L2” connection and is tied to the power grid neutral buss in the breaker box. This is the main line that the signal is traveling on. It is this connection that gets my station’s signal down the power grid and 4 miles of coverage.
Taking a closer look at the connection strip in the coupler we see a ceramic disk capacitor attached to L1 and chassis ground. Here is part of the reason why L1 is tied to the power grid earth ground. This capacitor helps to shunt the small amount of AC noise and hum to the isolated power grid ground as well as chassis ground of the entire system. The output network of the coupler is designed so that each connection, L1 through L3 are isolated via the fuses and 3 coupling capacitors. By connecting one of these L outputs to the power grid earth ground, it will assist in “nulling” out any AC noise and hum artifacts due to return currents on the neutral line right into the isolated earth ground…a safe place for it to go instead of being induced back into the transmitter via reverse coupling effects by way of the coupler itself, which would cause that blasted annoying hum!
This connection configuration also helps the coupler focus more of the signal energy to the neutral line effectively. At the frequency of 1.670, I found this arrangement to work best while maintaining hum-free signal and coupling efficiency. The VSWR meter, at full 30 watts of drive, barely even rises above 1:1, an excellent match!
In fact you would have to turn the calibrate control to full clockwise just to even see any reading on the VSWR or “TEST” mode to check for a good match! With the meter set at full scale, the needle sits right at 1:1, deep in the green!!
Image 4 merely shows the bottom of the coupler unit so we can see how the solid copper wire making the connections are arranged. Nothing special there, well except maybe for the salvaged aligator clip insulators I had to shove and fight to get them to slide onto the copper wire at those bends! They are there so that both the power grid earth ground connection and the netural connection do not contact the coupler chassis. There is no risk of them doing so, but with them insulated from both the chassis and each other, this keeps the VSWR where it is at..1:1…and I LIKE THAT! 🙂
There is absolutely no voltage potentials on any of those copper wires, earth ground (red wire) and chassis. I can safely touch any of them, combination of them at one time and be perfectly safe. The meter also confirms absolutely no voltage potentials here, even at the lowest setting of .2 vac on the DVM! This makes this installation very safe and preferable rather than coupling to the two hot lines carrying 220vac potential across them!
Image 5 shows a closer look at the connecting point for the power grid neutral. As seen, the neutral buss inside the breaker panel is isolated by a large black mounting plate. NEC codes require this to be there!!! This means the neutral return wire is NOT connected to the power grid earth ground in the breaker box! When you go to measure a typical outlet between the ground and neutral and check for continuity, you are most likely getting the “beep” because somewhere else in the house is an appliance or device that internally has these two connected together. That is ok. But at the breaker box..it is a NEC NO NO!!!
Image 6 shows the power grid earth ground connection buss and the coupler connection to this buss. As seen the earth ground buss is directly mounted to the breaker box. But as also seen, there is NO direct connection between this buss and the neutral buss!! That makes both of these buss points ISOLATED! And that can also be confirmed by taking a continuity test…your meter should be reading zero, or for a DVM continuity check, NO BEEP!! If you have a beep..you have a problem, or you could be reading through something plugged in as mentioned earlier that combines the ground and neutral in the appliance or device.
It all looks quite simple doesn’t it. Well like I said, it took weeks of testing and configuring and a lot of coupler adjustments through their complete range of settings to get to this point of where it works. The real neat thing to this arrangement is that if I wanted to operate on the lower end of the AM band, I do not have to change the coupling connections at all, because this arrangement also provides a perfect match for the frequency of 770Khz! So all I would have to do is simply swap out the output filter components on the PA’s, change out the programmable oscillator chip, and re-tune the coupler for that frequency of 770Khz! A process that takes about 5 minutes because I have made the changing of the filter components easy by using soldered in component lead sockets. I simply pull out the parts, re-insert the others…bada bing!
Hope that provides some insight into the K-ROCKS CC setup and some expanded information on the pictures and their details. Feel free to ask any questions..I will be happy to answer them.
Thanks again to Carl Blare, host of The Low Power Hour for inviting me on his program to discuss Carrier Current. I am happy to announce that I have picked up his program and air it on K-ROCKS and it is starting to become a poplular show here in Casper Wy. GO CARL!! 🙂
RFB
Cool!
Too Cool!
Makes me wanna do Carrier Current
An Urge To Purge
It is a very good way to expand on Part 15 219 setups, or make CC the primary and 219 as the expansion fillers. They can both work well together and if done right, can be done inexpensively.
Just like the home built equipment specifications for 219 gear, the same applies for 221. Good engineering practices and common sense are the key to constructing equipment as equal to or even better than off the shelf pre built gear that is often well beyond the reach of typical Part 15 budgets.
Hunting equipment down is not difficult either. Check Ham swap fests, auction sites and used radio gear publications.
No one ever said that “a piece from here, a piece from there” will not work to set up an effective system. Having the biggest best prettiest stuff is not always the best route to go, especially with limited budgets. After all, this is radio, not video…so other than yourself sitting in the studio..who is going to see all that pretty gear flashing with lights and moving meters or led readouts! The audience will only experience what they hear on their radio and in order for that to happen, the focus and investment sould be in the equipment that gets that content to them. Makes no sense in spending 5 grand on a rack full of processing gear when only a fraction of that investment gets put into the system that does the real work…getting your station’s signal into the listener’s radio.
As I mentioned in another thread…I do professional broadcast television and radio engineering consulting and contract maintenance for stations spread over a 4 state area surrounding and including Wyoming. Part 15 stuff is no job too small, so if you need consulting just contact me and we can go from there.
RFB
More CC questions
First, thanks so much for your efforts to educate the community about CC radio. Can you recommend a good CC manual other than the LPB one (which I have)?
I talked to a top engineer at OPALCO, our power system here in the San Juan Islands ( San Juan County, WA), and with some trepidation, I found that every meter panel, along with all power poles, all go to ground. I was thinking that would kill any chance of using CC here until I re-read your articles.
The engineer also stated that they do indeed transmit and receive data on the grid. I’d think that would indicate that if they are able to pass the data, then it should also pass RF signals. However, he said they attach filtering systems every so often to ensure that RF generated by the power is shielded such that it doesn’t induce RF noise outside the lines … IOW, they are trying to maintain clean power. Now, that could mean it might also filter out an RF signal, possibly in the AM band … I don’t know.
What is your experience here? Will it be worthwhile to invest time and $’s into a CC system?
TIA …