This is what Steve has to say about this mod...
Now, I'm not here to do any bashes, battling or argue the finer points.
You've already got some of my work posted here as variants.
So I as like Toll-Free - ,lay no claims to the mod, only to try and break it down,
So even I could understand it.
In the CB Tricks days, I did up a thread about Asymmetrical Mods, both in method and ways others have already started doing to try to make more "swing". The above was included in that thread.
Much of what was in that thread has already been discussed in other threads here - so all I'm trying to do is add some more "latest news" as I have time for.
Because what the above does, is similar to what we have been applying in other portions of this thread.
The best way I can describe this event is similar to a stream of water flowing out of a waterfall into a pool - if you got a waterwheel and inserted it into the falling stream - you capture energy as is falls,(potential) the weight of the water (kinetic) as well as it's length of fall before it's used (momentum) - this concept needs to be kept in mind when I elaborate.
The output of the modulation transformer - before D8 is very complex and contains negative going energy that can cause cutoff - so the use of D8 as a spike diode is for the purpose of reverse bias prevention. It does nothing else - it removes energy that is flowing in the wrong direction - and that information is lost. All that is left is a DC bias (and forward Audio components) being sent to the Driver and Final in it's place.
•As points to remember
•The use of the Resistor - Divider Network keeps the Capacitor charged to 1/2 the supply rail that the Audio Amp uses and follows the output "sags" that occur when you are using the Limiter. If you so choose, these resistor values can more closely match your limiter "divider" supply as for limiter action will affect the output of the Reactance Modulator.
•The Dividers power capacity is dependent of the resistor values so it will charge at a slower rate using higher resistor values - adjust accordingly when you are working in the proper bias values to allow the "soft clipping" when the Modulation levels are heavy - for the Average and RMS power levels will appear to "drop" - so the use of the right resistance helps to provide the lower-range (as in the bottoming out of the Capacitors reserve charge before it can recover similar in operation to the AM Regulation sections "Gain Cell" capacitor).
•Please take heed: This tap section does not need D3! You already are tapping this area for power anyways, because where the "keep alive" circuit goes, is to the Asymmetrical Resistor TEE's shown earlier as Variants - in the above graphic, these apply as Variants 2 or 3.
- Let's take the focus off of D8 for the moment; think of the output of the transformer as that falling stream of water - most goes straight out - has a positive flow towards the Driver and Final. But as always, there is a DISPLACEMENT of energy that is demanded back through the Output of the Reactance Modulator - so the stream going out is not always "steady" there are "Bursts" of energy that force the water out at a greater pressure (Voltage) and in doing so, the remaining Volume (Current) is reduced because of the capacity the water channel is in size (AWG gauge as well as Reactance in Turns of the coil) so there will be moments of NEGATIVE pressure that seems to make the water stop or CAVITATE - which is the reason for D8 - to prevent this Cavitation from damaging the Driver and Final.
So, the output of the tap, has not been "tied" to anything except output - so it's negative energy can be captured in a capacitor and stored for brief moments.
This is what I'm referring to a the negative swinging energy that is being converted into a pool of energy that is captured - we can't do anything with the audio information within the waveform being so negative that applying it would cause severe damage - so it's energy is then stored - converted into a working bias...
That is the purpose of the Diode strapped parallel across the storage cap. So as this Negative Energy tries to extract itself from the capacitor - that energy is lifted/pushed into the falling level of power that this negative spike is inducing into the output side of the circuit. So the power level falls - if only briefly. The Diode prevents the capacitor from getting damaged by reverse bias current at the output of the Modulators own tap. The twin Resistor divider then provides a replenishment to the pool of energy we want for the capacitor to have to pull from for the next negative going spike.
Remember the Limiter discussion - and how the Diode only conducted when the level of audio (average or RMS - Peaks too) drops below a set point that was set by a resistor divider network. This energy was stored in a series of capacitors to act as a reservoir or pool in which the Limiter Transistor used and took energy away (audio) from the Mic amps input line from the microphone as a means to equalize a potential difference between the Limiters Base and Capacitors connected to it and a ground potential - it uses negative energy as a means of power, as a limiter; to limit or pull power from another source - in this case - the Audio from the Microphone.. Power can be present for a moment of time before being bled off from by a resistor and capacitors (bank) to feed this energy back into ground or pull from a feedline containing Microphone audio that is going into the Mic Amp - the resistor in the circuit just after the diode along with the values of the capacitors - developed the timing as well as the energy levels the Limiter worked in.
The above circuit - and it's location in the circuit - output from the Modulation transformer - allows us to tap into this negative-going energy as a means to generate an OFFSET voltage that can power another device or generate an increased bias potential to help remove or prevent - cutoff - by summing the voltage present - storing it in a capacitor - and then when the energy potential difference - the power level in the output of this circuit at the junction of the storage capacitor and D3, is less than the energy stored in the capacitor - can allow it, that energy- to be released back into the audio line.
- But that is why we don't need D3 in the circuit, we take it out because of both our limiter divider, as well as our Resistor TEE are positioned to provide a transfer of power into the TX chain for reserve energy that can be imposed onto the RF as it tracks down the chain and has audio applied to it from each collector the TX Chain has from the starting - injection - point we chose.
This is a lot like how a Limiter or Automatic Noise Limiter would function. It blanks out a negative-going power spike by prevention of the reverse-bias condition by storing the energy into a capacitor and then releasing it back into the Audio BIAS line that goes to the Driver and Final. In he ANL system, this is a similar function as it "blanks" out the noise spike using the energy stored in the capacitor.
What the Mod does is utilize the Spike diode as the means to provide the forward power, with the negative-swing energy that is part of the Phase Modulation occurring in the transformer - the audio frequency energy - as it's vectors - that would swing negative - and damage the Final. Now - is given a chance to be restored as some captured energy, although it's frequency component is gone, the DC shift the energy has in the vector is kept as part of the charge that the capacitor takes in BELOW the reference voltage and even below the Board Ground.
