The TCU-30 manual I have does include the coupler schematic, parts list and mechanical diagrams along with interface instructions for both the transmitter and output connections to the electrical system.
Tuning steps are also provided and I think there is even a couple of pages of flyers for other LPB products..though not very useful these days, it's neat to see brochures on all the stuff LPB had in these manuals.
RFB
It's almost 11:56 AM CST and a check with the global tracking machine tells that Fedex left Earth City, Missouri, this morning at 8:56 with my 20-lb. load on board. I really made out like a bandit when it comes to weight gain... the money I spent weighed less than an ounce.
Earth City is a name that ought to appeal to Bruce MICRO Dog 2 Studio Radio, the discoverer of the planet Phringus and its inter-planetary cargo conglomeration. Earth City may not have any residential units, unless somebody lives in a storage locker, as I believe it is an industrial park on the west side of the airport, right on the shore of the Missouri River.
The carrier current carrier is on the way.
Has it arrived yet? Is it there yet? Is it hooked up yet?
Has it arrived yet? Is it there yet? Is it hooked up yet?
Has it arrived yet? Is it there yet? Is it hooked up yet?
😀
RFB
Having left Earth City at 8:56 AM and now it's 1:56 PM here, miles to the southeast from there, nothing yet.
But while we're waiting, there is ANOTHER QUESTION, if you can believe that.
Is it possible to put more than one carrier current station from the same location?
What are the ways of doing it?
2:59 PM Truck arrived. Man delivers big box. Carl Blare has door already open. Box is now sitting unopened on the office chair.
What should I do?
"Box is now sitting unopened on the office chair.
What should I do?"
STOP! Take a deep breath. Calm down. Relax. Savor the moment. Take a picture. Run outside and yell "It's HERE!" 😀
Now go hook that thing up and get on the air! 😉
RFB
"Is it possible to put more than one carrier current station from the same location? What are the ways of doing it?"
Not without the use of a combiner to isolate each station's coupler output to the common loading point..in this case the power "hots" or the neutral.
It's the same approach when combining transmitters to use a common "community" transmitting antenna system. The combiner isolates, protects and makes sure each transmitter, or in this case the combiners, see the load properly and not get interference from the other, or cause interference to the other.
As far as I know, LPB never made any sort of combiner for CC systems. But there is a little known trick that some CC stations did use to combine the couplers. LPB made power splitters and these worked great as basic combiners, after a little bit of modification. They are the same combiner toroid assemblies used in the combination transmitters which made their 60 and up higher powered transmitters.
Not sure you want to venture into that just yet. Finding those combiner toroid assemblies and power splitters is even more difficult than finding the deals on transmitters and couplers. But perhaps one will show up soon.
Patience pays. 😉
RFB
Using surgical skills learned on the internet I opened the carton, spent 2-hours removing radioactive packing peanuts that seemed to like my hands and didn't want to go in the waste basket, and found the following contents:
1 - LPB2-20 Transmitter
1 - Radio Systems CP-15 Coupler
Upon careful inspection of both units, I have reached the conclusion they are real.
There will be a long pause while I actually assemble the PLL Circuit Card.
Those darn tapes...err peanuts! 😉
They do get in the way don't they! At least they stuck to your hand and didn't end up all over the floor from a light breeze!
They tend to fly really well with a very light wind! Put's a shame to the card game "52 pickup"!
RFB
"There will be a long pause while I actually assemble the PLL Circuit Card."
Remember that for simplicity and less issues with stray capacitance and inductive effects, build the oscillator to work 'on frequency' instead of one that will be 6 times the operating frequency.
It's a lot easier to build an oscillator that runs at 1Mhz than it is to build one that needs to run at 6 times that frequency. But the choice is yours.
If you build a simple LC network to replace the crystal, you will need to leave A2 in place as well as A3 in place. The LC network, controlled by the PLL, will have to be the circuit that operates the oscillator inside the A2 IC. It is then divided by A3 down to the intended operating frequency in the MW band.
If you build an actual oscillator at 6x the frequency, you wont need A2 as A2 is simply an oscillator throwing square waveforms. Your new oscillator operating at 6x frequency merely needs to feed into A3 for division down to the MW frequency.
If you build an oscillator operating in the MW band, you wont need A2 or A3 at all. Simply inject the oscillator signal onto A3 socket pin 8, or at the "FRQ TP" stud on the exciter board. Follow the oscillator with a good buffer stage for isolation, and after that a good gain amplifier to ensure good drive signal for the balanced modulator IC.
You can even make the oscillator output variable for fine adjustment of the drive level prior to the modulator to peak the modulator's performance and prevent over driving which will cause RF waveform distortion and clipping.
The adventure is just beginning!
RFB
I am off course in my thinking. If the LPB2-20 operates from a crystal, is that not therefore an oscillator by definition?
If the PLL circuit generates the frequency in place of a crystal, is that not the same as having a crystal?
If the transmitter needs an oscillator with the PLL card but doesn't need one with a crystal, that seems odd.
How can I get straight on this?
"If the LPB2-20 operates from a crystal, is that not therefore an oscillator by definition?"
No. A crystal is not an oscillator. A crystal is a PART of the oscillator which makes the oscillator work. Without it, the oscillator would need an LC circuit to form the resonant tank and feedback to attain oscillation.
The PLL..as stated on it's own manual and website and here, does not have an oscillator. You have to add that yourself. The PLL cannot directly replace the crystal without building a replacement for the crystal itself..ie the LC tank circuit.
You can build an LC circuit to replace the function of the crystal and have the LC circuit controlled by the PLL via a varactor diode within the LC circuit. With this approach, you continue to use the oscillator circuit inside the A2 IC chip.
The PLL does not generate it's own frequency..that is why you have to add an oscillator and is why oscillator circuits are contained within the assembly manual. Without the oscillator, the PLL can do nothing on its own. The PLL can be used to control other oscillators. But all the same, the PLL board needs an oscillator to control. It can also control an LC network via a varactor diode which in turn makes an oscillator function, thus controlling the oscillator frequency.
I think your confusion is coming from thinking this PLL board is a direct replacement to the crystal. It is not.
You need something to make either the internal oscillator in the transmitter (A2) to work, such as a crystal or an LC tank circuit. The crystal merely sets the frequency to one frequency and keeps it there. An LC tank allows you to set up the oscillator in the IC A2 to be variable, by means of a tuning cap or inductor, or by control through a varactor diode getting a phase lock from that PLL board.
Either way you look at it, the transmitter needs an oscillator regardless if that oscillator is controlled by that crystal, or an LC tank controlled by the PLL, or an external oscillator controlled by the PLL.
Remember, the PLL board is NOT an oscillator! You have to add that, or make an LC tank circuit to replace the crystal directly and the PLL controls the LC tank circuit via a varactor.
RFB
There is an oscillator within the Big Talker shortwave transmitter. Will that one do the job?
http://www.kdxradio.com/bigtalker.html
The oscillator in that version of the Big Talker can work providing you build an LC tank circuit to replace the crystal and re-arrange it's design a little. It is designed to work around a crystal so the circuit will need to change a little to work off an LC tank.
If that oscillator can go up as far as 1.7Mhz then your good.
Take a look HERE for an idea of a crystal equivalent circuit.
And HERE are some pictures of a wide variety of LC tank circuit equivalents to crystals.
For an even easier example..look at this schematic of a tunable phonograph oscillator circuit. Install a varactor diode at the junction of the inductor and the 33pf cap, and then on to the PLL control voltage lead. Sampling for the PLL can be picked up after the buffer stage.
I recommend you read through this also:
VCO and PLL Oscillator Tutorial
RFB
While waiting for the next thing to happen, whatever that is, I came up with another brilliant question to ask:
WHAT IF one carrier current station were coupled to the mains in the conventional way, i.e., the 2-hots & neutral,"
AND another carrier current station were coupled to the neutral line???
Those two loads would be feeding different parts of the electrical system, so they wouldn't collide with each other.
Of course the two stations would be on different frequencies?
Did I just invent something?