... when you said "On these - it may not be as easy - for they did set these up with circuits that "hang up" if they have no place to go - so if you remove a part - that may make matters worse and the radio won't even work at all."
That is what my former boss would say.
And as you look thru the Schematic, there are a few "time bombs" in them - referring to If you do this - You get This.
So I'm cautioning you it is easier to "tack on" a simple resistor than to remove the part - why? They have an epoxy "Seat" to keep the part in place while wave-flow soldered. then they spray a epoxy sealant on the board - that's the shiny stuff to keep it sealed from the factory.
When you try to remove it can scorch the board and you have to repair the pads.
This is the "time bomb" I'm referring to...
See Feature Toggle?
That is driven by Logic setup - so they can control how the part toggles on or off...
IF the VCO ever quit or something, it thinks, has gone astray
- MICMUT engages and kills audio to TX with.
There is more...think back to the days of using R131 approach to the AMC but keeping the ALC working...
But todays version is a little different
They still use PNP to "invert" the signal used to drive the Limiter.
But how it collects the power to do this - is what I am concerned about...
That "envelope controller" part where when you raise or lower the DC Bias for carrier power - that circuit "follows" the Bias line and applies the drive needed to maintain Limiter control in both ALC and AMC - Note AMC Enable - that is how it selects the Envelope - Off, the AMC follows Envelope - ON? Then the Radio is expecting FM or SSB - no need to use envelope control.
So to me I would NOT do the mod unless you have a pot of 20K and you are able to "tack" solder on the two leads to the board as a means to make a shunt one lead (wiper arm) to that resistor the other lead side to ground then install a 220OHM in series as a current buffer resistor to protect the pot as well as give you a SOLID leg lead to tack on with.- to the 1K part and adjust - pare down the signal drive and observe the results - because if you can reduce the signal drive - you can make the limiter work less on the audio signal.
You can even use a DVM Test lead tip for the probe leg - just use this setup to locate and verify the Limiter will act on your level - not the OEM full force design.
The Cobra 148 and others - remember those discussions - the Resistor Divider it uses provide the Threshold and Drive level the PNP used to push against the Limiter and the Audio in the Mic Line arriving to the Mic Amp.
In the above Pic graphic, locate the AM MOD Tap and see the diode, but then too - look at the part it's buffered before it arrives to the PNP - a 470 ohm resistor - so it's going to act hard and fast to pull energy from that dropping bias the extra mod does to the AM Mod line. So I'd try to locate that PNP and look for the 471 resistor off it's Base lead and tap that and adjust the Pot to try and drian off power the AM Mod line sends to the Transistor - do the tap between the 471 (470 Ohm) and the BASE lead. Because - they use that 470 ohm resistor to buffer the Base so design your Resistor Divider starting there...
But its in finding the right spot to attach or remove - is what your need to be careful with.
Don't do the mod if you're not comfortable.
