so.. I tried the npc

[Slowmover]

The NPC-RC - started out as a whacky way to show forward swing on a meter to impress ones' self in thinking they did something "KEWL" to their radio. (Circa 1990's)

Then as time progressed others took to the task to provide actual provable theories which turned into practice

(If this looks like I favor the mod - no, I'm not a real big fan of it but
- "When In Rome...Do as the Romans Do.")
​

It's when you see and know the effects this mod does to the audio envelope - it does not turn this into a "Louder" radio - it shoves (by apparent action) moves more voltage into the carrier power by changing the way the Regulator recovers from the negative swing - it gives an apparent effort to help (Help? Well, not really, just keeps the ,limiters from engaging) the radio provide greater larger, higher voltage peaks which is the Audio Envelope along with RF carrier - between these two - you "see" a forward swing - but not necessarily "Louder" audio - just envelope containing those voltage peaks.

What's been "trimmed off" is the part of the Audio signal that sinks below carrier power level.

• You need to dwell on that for a moment - Symmetry versus Asymmetry
• - because that "negative" swing is why people say you have to adjust the "resistor value" to recover some of that negative energy that ADDS Audio Punch to the radio that the NPC-RC REMOVES - it lessens those "troughs" - flattens them really - and the receiving side can't recover that missing information - it's simply lost during the conversion done at your radio.
• - it's not their fault in what they hear; for you did the conversion to your radio and that information contained in those negative sides, are lost forever..

Why?

• You don't "Fully modulate" those peaks unless you "trim" the mod per your power levels you use, and if you're going to do that, might as well run the radio between 2.5 to 3.25 watts - you achieve the same effects only you have 100% Fully modulated signal going out running without that NPC-RC.
• Limiter action - by default, in these lower power levels is not only fully adjustable - it can be "fully defeated" just by running lower carrier - the AMC and ALC don't have to struggle with the dynamics as much.
• To some that is their "smoking gun" and last-line of defense - in getting their words out - run it into an amp to do the rest - as best as possible.
• I have known this for some time and have taken flack for even making the suggestion of using a higher ohmic resistor value to restore the audio signal - That includes Punch
  • - there are many that are "Stiff necked" when it comes to understanding that Hi-FI and NPC-RC are NOT compatible methods to combine together in audio processing.

So, yes, you're right to hold back and not destroy the audio you are producing in a properly tuned radio.

Think about this for a moment...

• Do you see any "stock" radios using the NPC-RC?
• Seriously do you?
• You think that with all the hype - benefits and retirement package this mod tends to supply for those that use it - you'd think, for one minute, that all those crazy Asians would let this simple mod money-maker method be ignored and let a performance-based selling point pass them by?
• Otherwise the mod would be used by Qixiang and Uniden and Cobra - with CRE and Alan doing more business by using such mods - it simply would be used by now.

They don't...why? - Read above...you lose too much Audio Signal in the "NPC-RC the BW way" because the 100 ohm resistor described in the mod, takes away all the slope of the negative peaks and FLATTENS it .

• - you lose 50% of audio envelope this way - by using this value in his method is what turns off the limiter action in most radios.
• When you trim, increase that resistor - you then "offset" the envelope slope losses and slow down the "clamping effect" the Diode would otherwise perform on the audio, on it's own, had there been no resistor installed in the first place
  • - IF you had done just the diode - you already know how that sounds.
• The trimming also brings back some of the negative peaking the Audio Envelope has, then Realize this; the reason why the Limiters have to fiddled-defeated or otherwise played to restore the swing is because you're restored some of the negative peaking the limiters are detecting
  • - the trimming effect is restoring the symmetry of the Audio envelope

Hey - don't like to read that? Then Don't DO The Mod - save the radio by lowering the carrier power to more closely match the power draw, and let the Envelope, with all your audio - come through - it will take care of the rest.

Hell, you run an amp - so you turn down that radio to match in the thing anyway - why add more to the mess than you've already got? You got it working - don't keep fixing it!​

• Do we have to go into the fact that you radio runs cooler and would also last longer lowering the power demands?

I'm not here to start arguments - I'm here to help dispel the myths of "why" there are the issues around the NPC-RC mess to begin with.

I’ve learned more by researching NPC-RC re tech terms than I knew before (unable to ignore or slide past if I wanted “some” understanding), so the effort wasn’t wasted. Not a goose chase, IOW; I’ve been trapped by circumstance for several days in one location; this was anodyne.

I recognize the form of admonishment you’ve used (argumentation; and have real appreciation of the effort), great choice for the ease in seeing the tableau on display.

Ya lit ‘er up real purty!

To wit: Whether or not strength of the argument rests on factory choices, there’s no free lunch. Things already optimized in an arrangement. Why start over?

I don’t see advantage, is the end of it.
Not for my circumstances.

Thank you for laying out the puzzle pieces in this manner.

.

 

[Slowmover]

In my understanding, the NPC is used to prevent the negative peaks from flat toping. This will allow the positive peaks to exceed 100% while keeping the negative below 100%. So with the positive peaks at 150%, it will be louder than a radio that can only do 100%. Right?

Contributor Loose Cannon posted details of his approach on the thread, DX2547 Red Wire Mod, that you might use as basis for discussion; as a suggestion.

Contributor Exit Thirteen also has mod specifics.

Someone has an approach worth trying to your satisfaction.

Had I the leisure of a different life lived — a shack & a bench to play with stuff — it might be fun to try. Only bad part is that I’d have to learn to solder.

So, I’ll volunteer two of your new Ranger TRE-936s as test subjects. Sound good?

Not: is the mod worth doing, but, here’s the Ward original and here are more modern interpretations.

1). Control Subject: the original Buffalo Hot Wings Recipe from Frank’s (B.D.Ward circa 2012 on the TRE-936)



2). Test Subject: and now for either the 2021 garlicky Romano or the chunky Bleu Cheese recipes!!

3). Ya gonna bake ‘em or fry ‘em? (amplifier design).

4). Etc,

— so forth; with bending everything towards one outcome of a very specific set of gear and operational boundaries.

.

 

[Shadetree Mechanic]

I already did a 936 with great results.

https://www.worldwidedx.com/threads/red-wire-mod-volting-opinions.230640/

 

[Shockwave]

“. . Checking the microphone phasing on AM. Flipping two wires can sometimes make a huge difference (voice-dependent).”

New to me (as are pretty much all tech issues).

Anyone?

.

The idea of NPC is to provide an AM waveform that has a stronger positive peak in comparison to its negative peak. In other words, the goal is to make the waveform asymmetrical, favoring the positive peak. What many people do not realize is, few of us have a symmetrical voice to begin with. With that in mind proper phasing on the microphone element can make a big difference in this area.

For example, if your voice favors the negative peak, you would definitely want to reverse the phasing in your microphone, assuming that some stage in the audio chain has not already inverted the phase. You can connect your microphone directly to an oscilloscope and determine if your voice favors one peak or the other. Then you can use the oscilloscope with your radio to determine if those wires need to be flipped on the microphone in order to provide a stronger positive peak.

Unfortunately not every microphone can have its wires reversed. Some microphones like electric condensers are polarized. In cases like these there are other alternatives which include using an isolation transformer someplace in the line to reverse the phase or adding a one-stage transistor amplifier that provides unity gain with phase inversion.

 

[Shockwave]

I first found a use for a phase inversion switch when I shared a station with a friend years ago. When I would talk on the microphone the bird 43p would sit in the corner at full deflection whenever modulated. When my friend would speak into the microphone and run the station, there was considerably less peak power regardless of where the mic gain was set.

While looking at the scope you could clearly see his voice produced lots more RF cut off in the carrier. We soon modified the on-off switch that was on the side of the studio microphone, to become a phase inversion switch that was forward for my voice and reverse when he was using the station.

 

[Slowmover]

The idea of NPC is to provide an AM waveform that has a stronger positive peak in comparison to its negative peak. In other words, the goal is to make the waveform asymmetrical, favoring the positive peak. What many people do not realize is, few of us have a symmetrical voice to begin with. With that in mind proper phasing on the microphone element can make a big difference in this area.

For example, if your voice favors the negative peak, you would definitely want to reverse the phasing in your microphone, assuming that some stage in the audio chain has not already inverted the phase. You can connect your microphone directly to an oscilloscope and determine if your voice favors one peak or the other. Then you can use the oscilloscope with your radio to determine if those wires need to be flipped on the microphone in order to provide a stronger positive peak.

Unfortunately not every microphone can have its wires reversed. Some microphones like electric condensers are polarized. In cases like these there are other alternatives which include using an isolation transformer someplace in the line to reverse the phase or adding a one-stage transistor amplifier that provides unity gain with phase inversion.

Thank you for the detail.

 

[dave457]