Riches are not embarrassing.
What a great offer from MRAM, but I think you can be spared the effort it would take to duplicate and post the lit, and here's my ultra practical thinking, unless someone convinces me otherwise...
The TCU-30 Coupler came with a schematic, and RFB has sent very detailed setup instructions, and unless there is more to know than those two things, a copy of the Instructions would probably be redundant.
Another advantage came in the fact that Radio Systems has the manuals posted online for the TR-20 Transmitter & CP-15 Coupler, and an additional CP-15 Coupler Manual.
Therefore, as far as I can tell, I have all the literature that will be needed.
By the way, how do you employ the TR-20?
It appears that Radio Systems no longer sells the Tr-20.... why would they discontinue it?
"t appears that Radio Systems no longer sells the Tr-20.... why would they discontinue it?"
Old model...in comes a new model with newer components, newer design, etc etc.
Ironically...those older RS units sure do have a striking similarity in the circuit designs and components as do the LPB units..including the couplers.
The older RS units show up on auction now and then as well.
The thing is...these two companies..back in the day and in their prime, were doing very well selling these things, but they were not selling them to the everyday joe putting up a Part 15 station at home. They were sold to colleges and universities and drive-in movie theaters and amusement parks and national parks like Carlsbad Caverns and Yellowstone...tourist/visitor info stuff..then along came the TIS(k) TIS(k) stations around the time of LPB's steady demise and eventually RS being the only player, and by that time the colleges and universities moved on to licensed non-commercial FM and sold off their LPB or RS stuff.
RFB
If there is a "bug" on my website is it likely caused by some file or code slipped onto my website?
About a year ago I found that almost all of my html pages at the site had some unknown code added which I knew nothing about. I still don't know what it did, but I erased every instance of it.
I will do another sweep to see what there is to find.
Of course now there is another enemy of the average website besides all the civilian and nationalistic criminals, and that is our "own" nation, be it in military or statutory form, selling our organs to the highest bidders on the world market.
Any idea where I should be looking?
Carl, I'm not using the Radio Systems Phase II transmitter at this time.
The Phase II came from a University somewhere around the east coast. I bought it to try out Carrier Current. The University listed several of these on Ebay. They were part of a network of Carrier Current stations they operated. The one I bought as mentioned previously was crystaled for 640 kHz which locally is the AM station WHLO in Akron, Ohio. Cost: $125
I obtained a parts kit from Radio Systems to move the transmitter to the upper end of the BCB and put it on 1500 kHz. The kit contained the torroids and capacitors for the output network. The crystal was also included in the purchase. Cost: $125
Some time after, I picked up a TCU-30. I haven't made a serious attempt at Carrier Current yet, simply putting an AC line cord on the neutral and phase 1 input and plugging it into an AC outlet. Cost: $205
So, for now the pair are just hanging on the wall in my shack.
I manage our City's AM TIS WQGD298. I employed the Phase II transmitter briefly at the station when the ISS transmitter was down for repair. The City sprung for the crystal on 1650 kHz and the transmitter performed perfectly. It was on air there for about a month.
Dear Employer:
Your transmitter is down for service, but I just happen to have a transmitter that can keep you on the air while I fix yours.
That looks good as a plus of having you as their fixer person.
I do hope they understood and appreciated what had taken place.
In the pre-planning stage as we get set to install a carrier current system, made much easier by all the good help from members here at part15.us, we are reviewing our frequency selection in light of two facts:
FACT 1: All the literature says that carrier current works best down below 800kHz, the lower the better;
FACT 2: For operation above 830kHz the low pass filter in the transmitter output stage must undergo the changing of five parts, because the transmitter is presently wired for low band operation.
THEREFORE, I am wondering two things:
THING 1: Am I absolutely sure there isn't a spot on the low band so we could avoid changing five parts?
THING 2: As long as we are changing the output low pass filter maybe we could install three filters with a selector switch for low, medium and high band?
ANYWAY, let's retrace our low band frequency search:
520 Many AM radios will tune 520kHz, however the carrier current rule, 15.221, only allows 525 - 1705kHz;
530 This is often used by TIS (traffic information service) and was used locally by an Illinois traffic service, but lately is bringing the audio from a licensed station on 1430kHz. It doesn't matter either way, however, because there's only one guard channel above this frequency;
540 Usually blank, but directly adjacent to a powerful station;
550 local 5kW station;
560 open, but too close to 550;
570 usually open, with an occasional time station from Cuba;
580 open, but crammed by..
590 1kW local station directional toward here;
600 blank;
610 blank;
620 blank;
630 5kW local;
640 blank
650 WSM 50kW Nashville TN;
660 blank;
670 blank;
680 blank;
690 local 1kW
700 WLW 50kW New Orleans LA;
710 blank
720 blank daytime, WGN Chicago night;
730 1kW just out of town daytimer;
740 blank;
750 blank;
760 blank;
770 10kW local;
780 WBBM 50kW Chicago IL;
790 blank;
800 blank;
810 blank;
820 blank;
830 WCCO 50kW Minneapolis MN;
840 blank;
850 5kW daytime only one-mile away.
What about 800kHz? Maybe that could work.
NEVER MIND. I just went to 800kHz and found a blaring phantom of the 5kW nearby station on 850kHz, whose HD Radio buzzsaw extends over 830, 840, 860 and 870kHz.
740 might be good. The out of town station at 730 is far enough away that probably no one here listens to it.
Well all of the literature at the present time was written years ago, some as much as 30 years ago and more, when the grids were configured differently. Even at those times, there were CC type baby monitors and in-home intercom systems running on 1.7Mhz and some even as low as 1.2Mhz.
Now those systems worked just fine on the electrical wiring and they were not 800Khz and below (.8Mhz)
In some cases, a CC system will perform better on the upper band, or the middle band and sometimes not work well at all on the low band. This is what I have been saying for the last several months that CC systems is a science in flux, meaning that there is no one solid gold rule or technique to ANY CC installation. They will ALL be different and require different approaches, even when selecting a frequency to operate on. In some cases, operating in the low band works, while in others, the mid band or upper band works better.
To avoid the swap out of filter parts, I would find you a frequency on the low band first and install the system and begin tests. You have from 530 to 830 to experiment with the current filter in the TX. Your list shows PLENTY of open low band channels available. Make it easier on yourself while you learn the ropes of a CC system and work with what you have on hand and conduct tests. Then if you see a need to move to the mid band or upper band, at that point make the change. Be a shame to go through all that work of changing out filter parts, the costs, downtime or risk of messing something up, and find out that change was not a good idea because the change to mid or upper band doesn't work with your grid configuration! All that work for NOTHING!
There is an old saying in the engineering field: "why make more work for yourself?".
About 80 percent of LPB's orders were for transmitters built to operate in the low portion of the band..ie 530 to 830. It allowed the signal to travel down the buildings wiring more efficiently and gave a cleaner signal at the reception ends, especially if there were a lot of splitters and booster linear amps working against high inductive loads such as elevator motors, space heaters, air conditioning compressors and florescent lighting. These things wreaked havoc on CC installations. The low portion of the band is somewhat less prone to these inductive loading problems, but it all depends on the location of these external loads on the electrical system and where the CC system is injecting the signal onto the electrical system.
It's a big venture, MUCH bigger than a simple dangling wire from the roof or taped to a window or tuning up a 3 meter outdoor antenna. And the solutions are NOT going to be written down in some tech note somewhere. Most of what was discovered from site to site was kept to either the person installing the systems, or the owners of the systems and chances are those notes are long gone and buried in some land fill somewhere. This is why we see very little information about CC on the web, or anywhere else.
Basically these days, CC must be relearned and re-documented as it once was back in the hey day. We can use that literature from decades ago as reference, good starting points. But most of it is so outdated, that only bits and pieces of the old literature is applicable for today.
Get ready to go to school..YOUR own school..because class is about to begin and guess who is the teacher....YOU! 😀
ADDED: You will also find that it is NOT necessary to operate that transmitter at it's full output power. It may only take a couple watts or so, perhaps a little more. But the thing to always remember is that a CC system does not rely on large distances of air between transmitter and receiver. The signal is riding on the power lines which run into people's homes and businesses. It's like taking your 3 meter antenna and putting it next to everyone's radio via the power lines. So naturally you won't need to shove so much signal down the lines and saturate everyone's radios within the first block! Start with a couple watts or so and work from there until you find a good enough power setting for good coverage. Even the LPB manuals state this..and the inspecting FCC agent will also advise you that you only use just enough power to get a clean signal but not so much your saturating radios all over the dial and jamming up the cable system or POTS with intermod. Remember, their lines are right below the power grid lines your signal is on and if too much signal is there, can and WILL make its way into the cable distribution line as well as the telco cabling.
RFB
"THING 2: As long as we are changing the output low pass filter maybe we could install three filters with a selector switch for low, medium and high band?"
When your TX 2-20 arrives, look around that final amp module and where the filter parts are. Do you see room in there for 3 sets of filters and the inter-connecting for a switch which will have to have 3 x 2 plus 1 contact points?
NOPE!
Besides that, putting so much cluster of inter-connecting lines to 3 filters via a 3 position switch which must have 3 in and 3 out plus 1 common ground contact will create nothing but a cluster of potential pathways of the high RF level in that area, seriously affecting the impedance of both the final elements as well as the output point going to the small coax which feeds the So-239 jack on the side.
The BETTER approach..which I have already done, is to build 3 filters onto 3 double sided full plated PC board and use dead bug or Manhattan style construction and feed-through PC mount studs so each module can simply be inserted onto the PC mounting studs already present on the final amp module.
Space the new feed-through studs on the new boards so that the entire thing simply slides into the existing studs, like as if plugging in a module into a pattern of holes on a board.
Works great and is useful for the testing phase to find the right portion of the band to work in...and saves a lot of headache on soldering and un soldering of those filter parts, and prevent a solder mess or over-heating of the existing studs and their soldering. It also keeps the filter toroid parts close to the ground plane of the final amp module, which DOES play a role in the filter's effectiveness AND characteristics. So you will want to keep that in mind regarding that filter section. Some of the transmitters will have those toroid transformers standing on their edges, and others will be laid down flat on the ground plane surface of the final amp module, all of which plays a role in how that filter functions.
RFB
You said there are a lot of open channels on my chart......
But, did you not also say at one time that there must be 2 guard channels on either side?
If I used 530 as you suggested, there's only one guard channel at 540.
On the other hand I do plan to try 570, even though there's only one guard channel on either side.
And I do want to run it on the low power side, to draw very little attention. I will start be having that "out of town sound."
I had not previously realized there could be induction into phone and cable......yikes.
"But, did you not also say at one time that there must be 2 guard channels on either side?"
I stated the standard MW band channel separation between stations is 30Khz, and that it would be ideal to follow that same channel spacing...ie "guard" space on each side of your operating frequency. It does not, nor did I mean that a CC system must follow that standard, but is as I put here and before...ideal.
But sometimes we do not have 30Khz of headroom above us or 30Khz of catch net below us, so we have to "improvise" and "overcome" and "adapt" and be nice and find a frequency which will cause the least interference, both co-channel and IF intermod, as well as the cable and telco systems.
"I had not previously realized there could be induction into phone and cable......yikes."
Well let's think about all of this for a moment.
Where are those power grid wires?
Where is the cable TV distribution line?
Where is the telephone system cabling?
Yes yes, some of that these days run underground..especially in big cities. All the same however, they all are in close range of each other along their distribution paths from source to end user/customer.
Now let's throw in "inductive coupling", which does happen even with a piece of wire strung off the roof or in a window pane.
Put two and two together and what do you have?
BTW..CC works by "inductive coupling". :p
So you see...CC is not as simple as it seems or as simple as stringing up a wire across a wall held up by pictures over the hallway entrance or connecting to a window pane frame. In such cases, inductive coupling does occur but at a very small level...ie wrapping a 10 foot wire that came with your AMT5K around an extension cord plugged into an AC outlet, or that same wire sending signal through your house while that signal passes through walls and wiring catching that signal like catching a school of fish with a drop net.
In a REAL CC system, your using a device specifically designed to inductively couple your signal onto the electrical wiring in a MUCH GREATER efficiency factor than the wrapped wire around the extension cord or through the air capture of a nearby signal. Therefore, the chances of causing interference to other services such as cable TV distribution and telco systems is even greater.
Like I was saying....class in session.
Anyone else wish to sign up for the class? 😀
Carl, the best approach per your frequency chart is to begin on a frequency that has at least 20Khz above spacing from your intended frequency of operation, and begin with low power settings, say 5 watts or less so you can tune up without overheating the load resistors in the coupler as you tune, and to keep from shoving too much RF down the lines as your trying to measure any interference. It could be too much RF power that can cause the problem, so start out with low levels and create a chart or graph for good coverage power levels versus power levels making everyone's phone's sing and dance...along with their tv's! LOL.
RFB
Based on good advice and from general life experience, we will start out with 2-Watts, this transmitter's lowest setting.
At 570 there will be an empty channel 10kHz wide on both sides.
"Brought to you by The Electric Company."
ADDED NOTE LATER THAT SAME EVENING -
11:40 PM CST the Cuban Time Station is banging in at 570kHz, louder than ever
Hi Guys!
I've been reading this with great interest.
Again, it goes back to my good good friend in New Jersey.
I am beginning to sense that his life may be more
over loaded than I thought. He has the LPB RC-6A
and an SS Tran AMT-3000. Both of which are mine,
and as you all know, I've been trying to get them
back. The SS-Tran is my second one, as yet not
assembled. I got it as a spare a couple of years
ago.
It is not like him to be unresponsive. He has
recapped some old radios for me, fixed some ham
gear, and he even built me a wonderful 80 meter
one tube cw transmitter, which is beautifully
made and works great.
I just sense that he is REALLY in the middle of
things - too much life, I guess. Maybe he has
something in his life that really isn't good -
and I just don't know about it.
So I will just keep gently trying to remind him
about the gear. He is SUCH A GOOD FRIEND, I really
don't even want to bother him, if he is going through
tough times. I have known him since 1976. He is
really one of the finest people I know.
So cross your fingers for me. If I could see well
enough to drive, I would just go there and get the
stuff. I would ask my wife, but I know there is
no way she would drive a 200 mile round trip to
pick up a couple of radio transmitters.
Again, keep crossing your fingers for me, and I
will continue to read this thread with great
interest.
Best Wishes,
Bruce, DOGRADIO STUDIO 2
I would use the following frequencies to test and find one that will work.
570
610
670
750
810
You said on 570 some Cuba time station comes in now and then.
I doubt anyone around your area is going to be too concerned about a CC station transmitting on top of it. I doubt that when it does come in via skywave, it would be a problem for your CC system.
RFB
"I'd Like To Be in The Class - I Just Don't Have The Transmitter"
That's ok...no TX required!
When your R6 arrives, then you will be ahead of the game and be able to jump right in and get your CC going!
RFB
The idea of sending intelligent human information over electric power lines seems like an episode of The Outer Limits.
"The wires are talking."
I am having an undress rehearsal (as opposed to a dress rehearsal) this morning for the moment when the LPB2-20 Transmitter & Coupler arrive from Texas. There will be a "ding dong" of the doorbell, I will open the door, and the box and a Fedex guy will be there, or maybe he'll be half-way back to his truck by then, and I'll say "Thanks!" I'll bring the box indoors thinking, "hmm, it's lighter than you'd expect," and set it on a small table while finishing a cup of coffee. Then I'll calmly open it up. If there are crumpled-up newspapers as padding, I'll unfold each page and read it front and back.
To be continued.