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Red wire mod / Volting? opinions.

In 1991-1993 before I went off to college for the first time I asked my mentor about this mod and why we did not do it at his shop. It was a trashy mod that did nothing positive except shifting the failure point from one part of the radio to another part of the radio. It was a solution looking for a problem. All of the problems it caused back then still have not been solved.

I guess I just do not understand how it is people can continue to be so ignorant about CB when all this time has passed! It is like 70% of the population that talk on CB are retarded with an IQ below 70 and they just are not able to learn, understand or move on. It just does not make sense that so many people would be this stupid about the history of the hobby and what has come before them!

The only thing worse than this is idiots that think ATF is loaded with "detergents" and will somehow clean an engine. No ATF is not loaded with additive it is the opposite ATF is almost devoid of additives compared to motor oil because it does not need them since there is no combustion gases and the seals in a transmission cannot take more than about 165F before they start to oxidize and harden up. No amount of facts stops these idiots from passing on bad info as if they are an authority on tribology! It is right up there with people that think there is a connection between mirrors and bad luck! At some point, you have call an idiot an idiot and you have to stand back and watched them mess even the simplest idea's

For the record adding ATF to your oil will generate more unwanted insoluble and crap you do not want. ATF's high paraffin content, low flash point and lack of additives mean it will dilute your already dirty oil and it will burn off it's light components at it heats up generating ash and combustion by-products and sludge.So the red wire mod is about like adding ATF to your crankcase in hopes it will solve a problem when in reality it can only make things worse!
 
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i feel like most of the posts in response to the OP are giving different perspectives on this mod, so what i post will have likely been said before in one way or another.

To me, this mod was originally conceived in order to wake up linear amplifiers with a higher PEP output. Yes, the ultimate goal was always to make a wattmeter look more impressive, as we all know that these increases aren't really seen or heard on the other end.

The biggest change that this mod makes is that the final transistor is no longer modulated by the AM power regulator.

So, of course it's going to run cooler as it is only modulating the driver transistor.

The problem with this idea is that if you don't modulate both the driver and final in a high level modulated radio, your modulation will never have the punch that a radio that does modulate both will.

To me it's not really about whether or not it's good for the radio, or whether or not it creates a splatterbox; it's about the fact that there is a trade off, and to me the trade off is not worth it.

If you really want to get a higher PEP out of the 148/2000 style radios that use an NPN AM reg. you mod it with a modulation transformer from a 29LTD to take advantage of the voltage gain.

this way, you are still modulating both transistors and have a higher PEP.
(no, i do not do this mod to radios anymore, but it was cool to play with back when it was popular. i was shown how to do it by someone. i didn't come up with any of it)

LC
 
I thought NPC/RC, RWOB was to allow the positive peaks to go over 100% modulation while keeping the negative peaks below 100%? Looking for the mod for the Texas Ranger 936 (Galaxy 939). The mod that removes a capacitor and replaced it with a resistor diode combination and then puts the capacitor on the foil side of board. The limiter is disabled because the negative peaks are compressed and the RWOB takes the heat off the am regulator.

Anyone still do this mod?
 
@Shadetree Mechanic - you can also research this thread...

https://www.worldwidedx.com/threads/old-school-president-grant-dx-pc-999-board.152505/

On the 3rd page, you'll see this...
upload_2021-4-9_21-51-6.png

Pay attention to the Left graphics, they show orientations of the Resistor, Capacitors and The Diode.

But notice too, they don't all use the Diode Resistor pair EXCLUSIVELY - this is important to know and to test your ideas for and with.

The 560 ohm resistor - sets a "mid-point" for Carrier and Audio - so the audio's own varying waveform can remain centered on the AM Carriers' "Bias" so the envelope is symmetrical if the Carrier and the Audio signal see a preset Bias - something it can work from.

When you use the Diode, you change the way this mid-point is sensed and regulated - it can show more POSITIVE shift in Audio signal - the negative peaks are compressed or even removed - you've heard this numerous times before - and rightfully so - you're affecting how the AM regulator can even regulate the Carrier and Signal together.

So it's why I caution you on the push the diode and resistor and neglect the 560 ohm resistor - that resistor plays an important role in the recovery of carrier bias - process.

So as you work this, get your screen shots - and see how this NPC mod can butcher the signal - pay close attention to the symmetry, for as you will see, you can LOSE audio signal "loudness" to obtain a forward power Swing in the meters. The others listening may or may not hear the loudness change, but will see the swing effect in their meters - to do the NPC RD (Resistor Diode) combination right, you will also need the 560 ohm resistor - in combination with the Diode/Resistor combo - in PARALLEL with.

See above.- note how the 560 ohm can be subbed with a 470 ohm along with the diodes 100 ohm - in the lower left box - the diode is straddled with the resistor - so the Diode still acts as the one way valve, but the way that resistor is placed across (parallel to) the diode the entire series resistance is closer to the singular 560 ohm resistor you're modifying - it allows you to recover the portion of the signal and power to restore bias as if both the sets were installed and working.

upload_2021-4-9_22-26-10.png
In the original discussions on CB Tricks about these concepts - the 560 ohm resistor was always kept in circuit - but somehow in time - this mod interpretations seemed to have forgotten a step or part or two - or a combination thereof and made a mess of it.

CAUTION: *** - if Used, Remove R266 - use it or 470 ohm or any combination of Resistor, Diode - Resistor parallel as long as 560 ohm "return" is satisfied
 
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How important is it to have a 1n4148 diode? All I have is a 1n4001 and it seems to work. I put a diode and trimmer together so I could play with it on the scope and it seems to work well. I put it in the c233 spot with the cap on the foil side. It will do 150% easily without looking or sounding bad. I have not removed the limiter yet, I will try that next but I really don't need more than 130%. Next I will try the way Andy showed. Thanks guys!

IMG_20210410_164036868.jpg
 
I refuse to comment on Billy's ghost, aka the NPC/RC.

But the 'power jump' is something we never did until MOSFET finals. They draw enough current to plaster the modulator transistor. Drivers with the radio in an overhead tray where it gets hot had a big problem that needed a fix. The RWOB took the load off of the modulator transistor. Dumps it onto the finals, sorta.

shifting the failure point from one part of the radio to another part of the radio

Like the man said.

73
 

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