Decades ago this would have been a free-running LC tuned circuit, then as technology advanced it was replaced by a digital phase-locked-loop frequency synthesiser and most recently a DDS, or Direct Digital Synthesis chip in which the waveform is produced directly by a DAC.

The phase-locked loop PLL remains a popular choice due to ICs such as the Si but is rarely constructed from individual chips as it once might have been. A PLL is a simple circuit in which one oscillator is locked to another by controlling it with a voltage derived from comparing the phase of the two.

Combining a PLL with a set of frequency dividers creates a frequency synthesiser, in which a variable frequency oscillator can be locked to a single frequency crystal with the output frequency set by the division ratios. The code can be found on GitLabshould you wish to try for yourself.

#169 Phase Locked Loop PLL Theory Supplemental with CB Radio Simulator

It would be interesting to see how good this synthesiser is at maintaining both a steady frequency and minimal phase noise. Meanwhile if PLLs are new to you, we have just the introduction for you. The Arduino and the Raspberry Pi were designed with set top boxes in mind. Thy both have everything needed to control a tuner. No jitter or harmonics.

cb radio pll chip

The box is controlling a tuner. Neither the Raspberry Pi nor the Arduino were designed with set top boxes in mind. I built a PLL for a 80m receiver around a 16F84 some 15 yers ago. I love this. I wonder what the drift is like. The drift of a synthesized VFO depends solely on the stability of the crystal oscillator it uses as a reference. So what do you need to finish the project?

Is this just a reciever then? Can it transmit does it need an amplifier? This is just a variable-frequency oscillator, or VFO, which is a fundamental building block for both radio transmitters and receivers. You need all the other building blocks, which can include RF amplifiers, audio amplifiers, mixers, and intermediate frequency amplifiers and filters, for starters. The VFO is considered one of the most challenging parts in a transmitter or receiver, because it needs to be adjustable, but once adjusted, is expected to remain at the same frequency over a period of time and over a range of temperature, which are significant hurdles in their design.

The wider the tuning range required, the more difficult it is to achieve high stability in simple oscillators. The phase-locked loop offers a relatively simple way of producing a variable yet stable oscillator. This site uses Akismet to reduce spam. Learn how your comment data is processed. By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies.

Learn more. The internals of a PLL frequency synthesiser. Image by Chetvorno — CC0 A PLL is a simple circuit in which one oscillator is locked to another by controlling it with a voltage derived from comparing the phase of the two.

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Report comment. OK, then one 74xx74 can be used as FLL allowing for any ratio. Leave a Reply Cancel reply. Search Search for:. Hackaday Links: July 12, 28 Comments. Hackaday Made Me Buy It!Maxon Chassis.

The chip cannot be modified except the LC SBB chassis which can be modified with an external oscillator and mixer. No chance of modification. The MB is used in the popular Uniden chassis.

In the Export versions it has a pair of MC binary Adders connected to it, this enables more Ncodes per mixing crystal. Modification can be done by changing the loop mixing crystal or controlling pin 10 on the MB Used in alot of the newer Uniden 'clone' export radios.

Also has a pair of MC binary adders to increase Ncode range. These two chips were paired to form a PLL. If these are combined they make up a 8 bit binary counter. The AM models use a loop oscillator singnal and can be easily modified. Does the same functions but in one chip. This radio is useless without the mike controller. It uses a single Models include:- U.

Models: Lake U. This chip is a phase comparator and programmable divider only. It is used in conjunction with the MSL programmable divider. Modification is done by useing an external oscillator to replace the doubled 20 Mhz mixing signal coming from the 10 Mhz reference divider.

This chip is the same as above,the only diference is that this one uses a This is the most popular PLL ever made! Used in both U. Due to large number of radio's using this chip I have not listed them.

This Pll is now fitted to Unidens that say "Made in Malaysia" on the back panel. This chip is a clone of the MB with a few changes. The resistor near Pin9 needs to be removed and a jumper wire with a ferrite bead put in its place to reconnect power to pin 9.

As this radio is not as broadbanded as previous Unidens it might not be worth the expense of the new chip.Within the local cast of characters who made up the CB radio hobby in our area, there comprised a handful of people who were not only technically curious about the inner working of their radios, they were always looking for new and innovative ways to improve their radio's performance and capabilities. More power, and louder modulation were two of the biggest areas to pursue these goals.

cb radio pll chip

Another area which was extensively explored, was frequency expansion. It was desirous for the high performance radio operator to have more channels than the "common folk" had, whether simply for a private escape channel, to increase one's DX opportunities, or simply for local bragging rights.

But the pursuit of these expansions were usually not all that easy, or cheap. In the early 70's, the typical 23 channel radio generated its frequencies by mixing different combinations of crystals. In order to expand frequencies on these rigs meant that you had to either add additional crystals for more channels, wire in a VFO to add continuous wide range tuning, or experiment with other tricks like expanding the clarifier range or reversing mixer crystals. While all of these solutions were popular, none were a clean simple operation to perform, nor were they inexpensive.

And when you were a strapped for cash teenager, expense was a definite consideration. But those were the limitations of the crystal synthesized radio of the 60's and early-mid 70's.

So it should be no surprise that most people had only a limited number of extra channels to sneak away to. But advances in technology were about to change all of that in a big way. And the CB band would never be the same The first hint that something new and different was about to hit the market came about in the timeframe. The Hy-Gain and a couple other radios hit the streets sporting a new high tech "digital" synthesizer.

A handful of I. As time progressed, other manufacturers followed with similar PLL schemes as well. It would seem that most of the major manufacturers were experimenting with this new technology on at least one model in their radio stable. At first, most of us looked at these "newfangled" PLL circuits with disdain. They could not be modified in the usual familiar way to get the expanded channels that we were all used to running on.

Even trying to put channel "22A" in the blank spot did not yield the same results as we expected. But our dismissive prejudice, based on nothing more than ignorance toward the PLL, only blinded us to their ultimate potential, even if the early units were not nearly as capable as later designs. But soon people started accidentally discovering some strange behavior on some of these newfangled PLL rigs.

It was discovered that when the channel selector dial was wiggled carefully between certain channels of their radios, new channels would appear that were outside of the 23 channel band plan. Several RC channels, as well as future channels 24, 25, 26 and 27 were among those channels discovered. All of a sudden, the PLL became interesting, and those techies among us scrambled to discover what other secrets might lie within that mysterious circuitry.In view of its usefulness, the phase locked loop or PLL is found in many wireless, radio, and general electronic items from mobile phones to broadcast radios, televisions to Wi-Fi routers, walkie talkie radios to professional communications systems and vey much more.

CB PLL Modifications List

The phase locked loop take in a signal to which it locks and can then output this signal from its own internal VCO. At first sight this may not appear particularly useful, but with a little ingenuity, it is possible to develop a large number of phase locked loop applications.

The key to the operation of a phase locked loop, PLL, is the phase difference between two signals, and the ability to detect it. The information about the error in phase or the phase difference between the two signals is then used to control the frequency of the loop. To understand more about the concept of phase and phase difference, it is possible to visualise two waveforms, normally seen as sine waves, as they might appear on an oscilloscope.

If the trigger is fired at the same time for both signals they will appear at different points on the screen. The linear plot can also be represented in the form of a circle.

cb radio pll chip

The beginning of the cycle can be represented as a particular point on the circle and as a time progresses the point on the waveform moves around the circle. The instantaneous position on the circle represents the phase at that given moment relative to the beginning of the cycle. The concept of phase difference takes this concept a little further.

Although the two signals we looked at before have the same frequency, the peaks and troughs do not occur in the same place. There is said to be a phase difference between the two signals. This phase difference is measured as the angle between them. It can be seen that it is the angle between the same point on the two waveforms. In this case a zero crossing point has been taken, but any point will suffice provided that it is the same on both. This phase difference can also be represented on a circle because the two waveforms will be at different points on the cycle as a result of their phase difference.

The phase difference measured as an angle: it is the angle between the two lines from the centre of the circle to the point where the waveform is represented. When there two signals have different frequencies it is found that the phase difference between the two signals is always varying. The reason for this is that the time for each cycle is different and accordingly they are moving around the circle at different rates.

It can be inferred from this that the definition of two signals having exactly the same frequency is that the phase difference between them is constant. There may be a phase difference between the two signals. This only means that they do not reach the same point on the waveform at the same time. If the phase difference is fixed it means that one is lagging behind or leading the other signal by the same amount, i.

A phase locked loop, PLL, is basically of form of servo loop. Although a PLL performs its actions on a radio frequency signal, all the basic criteria for loop stability and other parameters are the same.

In this way the same theory can be applied to a phase locked loop as is applied to servo loops. The basic concept of the operation of the PLL is relatively simple, although the mathematical analysis and many elements of its operation are quite complicated. The diagram for a basic phase locked loop shows the three main element of the PLL: phase detector, voltage controlled oscillator and the loop filter. In the basic PLL, reference signal and the signal from the voltage controlled oscillator are connected to the two input ports of the phase detector.

The output from the phase detector is passed to the loop filter and then filtered signal is applied to the voltage controlled oscillator. Here the phase of the signals from the VCO and the incoming reference signal are compared and a resulting difference or error voltage is produced. This corresponds to the phase difference between the two signals. The error signal from the phase detector passes through a low pass filter which governs many of the properties of the loop and removes any high frequency elements on the signal.

Once through the filter the error signal is applied to the control terminal of the VCO as its tuning voltage. The sense of any change in this voltage is such that it tries to reduce the phase difference and hence the frequency between the two signals. Initially the loop will be out of lock, and the error voltage will pull the frequency of the VCO towards that of the reference, until it cannot reduce the error any further and the loop is locked.

When the PLL, phase locked loop, is in lock a steady state error voltage is produced.

cb radio pll chip

By using an amplifier between the phase detector and the VCO, the actual error between the signals can be reduced to very small levels.But what gained the XLR a devoted following was audio quality combined with a particular amenability to postsale modifications. Trucking is a solitary endeavor, and two-way CB radios provided a means of creating a community.

Also, at the time, trucker pay was often dependent on how quickly goods were delivered. That encouraged truckers to drive much faster than the speed limit, which the federal government in reduced to 55 miles per hour 89 kilometers per hour.

Other motorists caught on and began buying CBs for the same reason. Truckers also had a culture of modifying their equipment. Common CB mods included whip antennas and hacks such as additional power and stronger modulation, but those willing to dig into the innards of their radios figured out it was also possible to add more channels.

Prior to or so, adding channels to CB radios was expensive and involved the painstaking business of installing and calibrating crystals. Crystals then were the traditional, inexpensive way of generating and maintaining a frequency in a small radio transmitter.

Right about that time, however, radio manufacturers started replacing the crystals on their basic CB radio models with silicon-based phased lock loop PLL oscillators. Basically, a PLL used a voltage-controlled oscillator to establish a base frequency, and other electronics to compare that frequency to another one generated by one or more crystals. With a variable frequency divider between the voltage-controlled oscillator and the phase detector, the radio-transmit frequency was determined by the divider.

Truckers soon discovered that the PLLs were programmable, and that the process of programming them to support additional channels was cheap and easy.

PLL Phase Locked Loop Tutorial & Primer

The chip is visible at left, above the green switch housing. Truckers eventually found the uPD could be reprogrammed to support channels—many more than any other PLL, and fantastically more than the 40 channels the FCC had set aside for commercial CBs.

But so, too, did the offerings from a couple of other manufacturers that also used the Uniden hardware. The XLR had another advantage, though, that appealed to the truckers who enjoyed tinkering. It was one of the few CB radios built with an audio-clipping circuit. For those willing to spend a little extra time tuning their radios, the XLR would deliver some of the best sound quality it was possible to get out of CBs.

Not only did the XLR became one of the biggest-selling CB radios, its introduction helped make the all-time high mark for CB sales in the United States, with 13 million radios purchased that year.

Unfortunately for truckers, the channels they added operated above the maximum frequency the Federal Communications Commission had set aside for CB radio the official range is between Users who had a legal right to use those frequencies complained to the FCC about incessant interference from CB users.

The FCC began levying hefty fines on truckers caught illegally using those channels; some truckers were said to have lost their jobs. In response to the FCC crackdown, Cobra discontinued the model in Enter Here.The uPD The Injecting the You could also screw with the down mixing PLL feedback loop.

This will be a easy to recognise by a low pass filter between the mixer and the PLL chip pin The signal is about 1MHz. Injecting a stable frequency into this pin of the PLL will also change the output accordingly.

Injecting KHz will put you on ch15 NZ call channel. Pin 20 changes the step size from 10KHz to 5KHz.

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Mod sent in by Trash C or TC These PLL's use a rather complex mixing system that makes them just simply a pain in the arse and not worth the effort of modifying.

They have internal ROM channel select that limits the choice of channels through the normal channel select. I think this chip is what is used in the Pearce Simpson Cub or Lankar.

I had a mod for this chip, it seems to be pin 11 de-earthed, but it has no other notes to describe what it does. It's worth a try if you have nothing else to do.

The arrangement of this PLL in circuit is rather messy and frequency shifts are everywhere. Any modification to any part of the circuit like the If you wanted to xtal lock your radio onto one out of band channel, then you could have two xtal oscilators made, one 13Mhz and one 16MHz and inject the 13Mhz into the transmit doubler and the 16Mhz into the receive mixer.

Ground the "Mode Select" - Pin 14! If it is already earthed, then you're in business. Pins 1 to 8 are simple binary select. If "RF Inhibit" pin 24 is connected, then cut the track.

That's the simple mod Welcome to the big league. Instead this PLL has an interesting feature.

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It has two dividers, one is a reference divider the other is the program divider. This is what you normally program through pins 1 to 8.

Nothing special there!

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What is special is that in most PLL's these dividers don't have an output to the real world, instead the signal is processed internally and it pops out the arse end of the PLL as a DC voltage that you average garden gnome won't notice or care about. This tells the VCO what frequency it should be oscillating at. This is your chance to rebuild part of the PLL for your own evil purposes.

The reference divider is rather un-interesting and is probably best left alone, but what you do to the program divider, you can also do to the reference divider later. Think of it like front and rear gears on your bicycle. The reference divider is probally only something small like divide by 2,3,4,5.A few switches to open or close power to the input lines on the PLL could do wonders to get your CB going out of band either up or down from the legal Govt 40 Channels.

And if you were smart enough to fit ThumbWheels on the BCD logic lines you could even have a cheat sheet that gave a three digit number that corresponded to a frequency.

This list has been copied from the websites credited below, but I have seen this list on many sites, so can not say who originally created it for the good of all operators. One of the reasons I put it here was to see if anyone can come up with a circuit diagram or correct alignment info on the Pearce Simpson Super Bengall MK These were replaced with other similar but not same permeability slugs that I hope will tune in OK.

Any advice appreciated. Super Bengal Mk II: sim. Use at your own risk.

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If you use it to break the law, then YOU, indeed, have broken the law. Skip to content. By Greg 43AX Jul 12, CB Radio's Featured. J May, J Jul, CB Radio's Stoner Pro J Jun, You missed. May 7, Jul 13, Jun 2,


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