Greetings!
Ok, to keep this as basic as possible - all points are noted. We attract far more with honey than by using - vinegar...
Now, can we give the guy a chance to get his head around the TX and RX tracking?
Ok, not to go too far into this - much of my experiences in getting RX and TX to "line up" stem from people asking/expecting WAY - WAY too much from the slide the clarifier can deliver.
You achieve better results climbing the mountain step by step than by running up only to stop much farther back than if you had simply walked.
Expenditure of Energy...
How To Live With An Energy Budget...
I hope you know how voltage dividers work...
IF not, then this is all in vain...
The Clarifier simply provides a voltage to a diode that when it's properly biased, exhibits traits like a capacitor - by varying the voltage - that capacitance varies too.
So what is the deal with Voltage Dividers?
The Clarifier is a potentiometer that has a wiper that when moved across a resistor substrate that has a power flowing thru it, that wiper "sees" this power. This power can be pulled from the substrate - and depending upon where the wiper is in distance from the one side of the substrate or the other - you can apply power to one side of the substrate and have it flow out the other side - and the wiper can also pull this power from the substrate - before it gets to the other side. The wipers location or aspect from the power going in and the power flowing out - also allows it to see the power MODIFIED from the input into the substrate - closer the wiper is to the substrate that is getting power flowing into the substrate - means the wiper sees or has the ability to take more power from the substrate, from the power flowing thru the substrate, BEFORE the power travelling along the length of the substrate can reach the other side, or return.
IF you understand the above, then this should be relatively easy to finish.
You just have to understand "impedance" and how it plays a role in the Clarifier's ability to send a voltage determined by the wipers location and aspect to the power source and it's ground (return).
Too little resistance and the circuit becomes unstable and unusable for oscillators.
Too much resistance and the variable resistance has little effect to change the oscillator.
The variables lie in the characteristics of the circuit it sends this power to.
The Varactor changes capacitance by the potentiometer changing the reverse-bias voltage POTENTIAL on the diode. The output of the diode needs to be ISOLATED from the input voltage so the Oscillator can see this AS A change in capacitance not just as a power being applied.
You are trying to make a resistive element a reactive part of a circuit that sees a capacitive value versus a voltage value.
So, the more you ISOLATE the clarifier from sourcing and returns, the less reactive the resistive element (variable) becomes and appears as an higher impedance - and the diode shows itself as more of a capacitive reactance. The resistor is less of an effect and the capacitor takes over in this circuit.
So that means adding resistance to both the SOURCE side, and the RETURN side of the clarifier - with the best results being that range of voltage which makes the DIODE provide the most or largest shift in capacitance for a given voltage range of adjustment.
That is why the clarifier is BUFFERED from both Return (Ground) and the Regulator - or Source - to provide a high resistive reactance or highly resistive impedance variable voltage power to a reverse biased diode (high impedance state is what reverse biasing does, no current flow or power flow thru the diode).
Now to speed this up, they chose the Varactor diode to show its best character they designed the oscillator for - by having roughly 5 volts near center slot as the best - but when it arrives to the oscillator it looks more like a capacitor with a lot of shift in farads (picos').
There's a danger in the "maximum" characteristic of capacitance - for it makes it very SENSITIVE to voltage changes, temperature and its' environment - moisture and vibration.
So, when you talk about "not quite right" there's a lot more to throw at this than meets the eye.
The above has to be understood first before I can even begin to give you other tips and tricks I use to stabilize the circuit.
Ok, step back for a moment and let's look at the PLL's way of looking at things. It too, uses a varactor as a means to mix your voice mixing in with a frequency that passes thru the AN612 (Balanced Modulator) and mix it with another, the PLL's oscillator that the clarifier controls, together to make 27MHz TX and RX you are dealing with.
Well, can we do something? Yes, most people "source" their power to the 8 volt regulator supply that the board uses for just about everything else.
Fine and dandy as long as you don't have too much sags, drags or blips and bumps on the voltage line - pretty much straight forwards as far as attaching the clarifiers' circuit to the mains. But, the problem lies in the PROPAGATION, loading and switching transients and noises prevalent on the 8 volt line. Toys, Modulation Mods and loud mics are just some of the sagging results in radios no matter the size.
Well, the PLL itself has to be aware of these issues too. So, it also has a built in regulator and it keeps itself on frequency by minor adjustments to it's own oscillator and reference.
So, as the PLL tracks this, or senses voltages' changes, it's built-in regulator can control and adjusts its frequency accordingly.
In reference to the above, you can save yourself a lot of trouble by simply re-sourcing the clarifiers' own SOURCING to the same source the PLL uses - and as the PLL will get sags and swings in voltage it's internal regulator will make the changes it SENSES from the power pin feeds 7 and 11 - the clarifier will too but then the PLL will track it better if these swings were more inline with it's own regulator.
So, just tap from the PLLs' voltage regulator or D26.
So that will bring the Clarifier to the point that when the PLL's OWN power supply dips and swings and adjusts, the clarifier will exhibit the same effects and give you more predictable results.
And for best results - you don't MODIFY THE CLARIFIER in any way shape or form except to provide a power source to the varactor - meaning keep all resistor values in place and the only thing you add is the removed diode from D25 and use a 470 ohm to as much as 1K resistor - you pick the value - to help you with keeping center slot you have now so you don't need to delved further into the tank coil mess inside I sent you it's High-School photo of.
So to do this right - I found the "hole" in the board PC-122's had for single point sourcing for Clarifier - only thing is, the voltage was pretty close to the max range the clarifier was already set to - so you needed to still buffer it - I used 470 to 1K and 1 diode I removed from the board D25, from the TX sourcing VR3 TX FREQ ADJ pot was. I put one lead of the 1K to Clarifier that feeds from the ANL/NB switch line and Free end to the BANDED end of D25 you removed from the main board and the other unbanded free end of the diode went to the hole that had 5.6 volts from it to power the PLL's Pin 11 and 7 pins.
It's all there in the pages, you'll see where I had to "cut" on the "Guts" of the front panel PCB to break the RX source from the ANL NB switch that had a "Branch" that fed the Clarifier.
IF you don't want to do that, then REMEMBER THIS:
The RX source feeds the Clarifier, IT IS SEPARATE from the TX.
TX has a variable VR3 that sources from the TX voltage.
So, here's lies the problem that SEPARATES the CB 11 meter realm from the 10 meter Amateur realm. In the Amateur realm radio tuning systems can source from single point references simplifying the tracking problems - CB cannot. CB has to deal with swings and toggle delays and lags due to the toggled switching and the sags and swings both TX and RX side voltage references present to the Varactor.
And I haven't even begun to talk about temperature compensation and precision issues surrounding the composition of both Clarifier and the VR3 pot substrates let alone you can offer the tank circuit offsetting or swamping resistance R119 (6.8K) and raise it to 10K to help improve slide or if you wish linearity and temperature compensation - reduce it to 3.9K - you'll lose slide but it will drift a lot less.
Or even source a 914 automotive bulb and route it close to the PLL and VCO section to warm up the radio with the warmth of its light like an oven and helps bring the radio back to center slot quicker in it's warm-ups. I've done this thru the unused pin on the power plug with the 914 running to dashboard lighting and the bulb simply soldered one lug to ground the other to the pin and turn on the lights (running or regular) to warm up the radio as your drive.
So your "offset" is due to poor composition and temperature drift. Sourcing to one location for power and using one variable - the clarifier - helps you enjoy the radio with less hassles.
DISCLAIMER:
The above is for information only - any losses incurred by using the information is your responsibility - you are liable for any issues, seen or unforeseen - this information can be used to incur damages and liabilities against you if this is used to harm or interfere with communications - intentional or not.
The PC-122, you'll find, is a valuable tool in learning the AM and SSB processing functions we take for granted today - this radio is the simplest way to understand how RF works - and is the predecessor to a lot of the technology we see in CB today.
There's a lot to be said about clarifiers'.
Recommended:
Keep Wattage 3.5 watts or less, if you choose to jumper that's on you.
Trim down Driver and Final 35mA and 40mA respectively.
Look for the holes or parts - discussed in the PC-122 REFERENCES Section and take heed their advice - you'll know why I recommend the Bias values above if you have those parts installed - else you may blow the final and driver quicker if you attempt any increase of power via AM regulator or Modulation, mods.
If you must, drive and amp (metaphorically too) (sigh) pay attention to the Modulation tweaks and Limiter part swaps that can make the radio work far better even a bit cooler - these radios cannot be repaired back to OEM - the parts just are not there anymore so be conservative with any changes.
Attached is some works I have done to help others via CB Tricks. Hope they help you. Just give credits where credits are due. I worked way too hard on these. Didn't get a chance to put them up on my pages, these were posted much later in threads for various reasons.
Regards!
:+> Andy <+:
