What the heck is this: https://www.ebay.com/itm/New-DIY-Ga...471897?hash=item2a9a7c6c59:g:1PcAAOSwnONZD3o9
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DX 2547 Red Wire Mod?
- Thread starter kaos513
- Start date
The ghost of Reverend Billy.
As in Billy Dean Ward. He originated this trick, called it "NPC/RC", as in Negative Peak Compression/Reduced Carrier.
Like light beer. Some folks swear by it, others swear at it.
The snippet of black heat shrink tubing contains a diode and a resistor, usually 100 ohms in series. It alters the negative feedback in the radio's AM modulator circuit to over-emphasize positive peaks. Also tends to nearly remove the negative side of your audio waveform, below the carrier level. Never did see a point to losing half your audio waveform. You need all of it.
The "Red Wire On Bottom", or RWOB is used to jumper around the radio's modulator transistor, feeding a steady 13.8 Volts DC to power the finals. Now the AM modulator is only modulating the driver transistor. In all fairness, the modulator transistor does breathe easier in this setup. Finals may work harder, though.
Mostly a wattmeter worshipper's trick. I found that the carrier setting becomes critical with this mod installed. Too low and it sounds terrible. Too high and you lose your modulation level. Makes it sound as if you turned down the mike gain. Set the carrier at the 'sweet spot' and it sounds okay. Not my idea of a way to set up a radio with a carrier-power knob on it.
Billy championed his pet idea as if sliced bread was never really a big deal. Full disclosure: he was an ordained Church of God minister.
Yeah. But he died a few years ago, slumped over his bench if you can believe the rumors.
But that's the short version of NPC. Anyone who is curious is fully entitled to investigate it, try it on your radio and make up your own mind. But once you see what the radio's AM transmit is doing on a 'scope you will probably uhnook it and put the radio back like it was.
That's what I did. Decades ago.
73
As in Billy Dean Ward. He originated this trick, called it "NPC/RC", as in Negative Peak Compression/Reduced Carrier.
Like light beer. Some folks swear by it, others swear at it.
The snippet of black heat shrink tubing contains a diode and a resistor, usually 100 ohms in series. It alters the negative feedback in the radio's AM modulator circuit to over-emphasize positive peaks. Also tends to nearly remove the negative side of your audio waveform, below the carrier level. Never did see a point to losing half your audio waveform. You need all of it.
The "Red Wire On Bottom", or RWOB is used to jumper around the radio's modulator transistor, feeding a steady 13.8 Volts DC to power the finals. Now the AM modulator is only modulating the driver transistor. In all fairness, the modulator transistor does breathe easier in this setup. Finals may work harder, though.
Mostly a wattmeter worshipper's trick. I found that the carrier setting becomes critical with this mod installed. Too low and it sounds terrible. Too high and you lose your modulation level. Makes it sound as if you turned down the mike gain. Set the carrier at the 'sweet spot' and it sounds okay. Not my idea of a way to set up a radio with a carrier-power knob on it.
Billy championed his pet idea as if sliced bread was never really a big deal. Full disclosure: he was an ordained Church of God minister.
Yeah. But he died a few years ago, slumped over his bench if you can believe the rumors.
But that's the short version of NPC. Anyone who is curious is fully entitled to investigate it, try it on your radio and make up your own mind. But once you see what the radio's AM transmit is doing on a 'scope you will probably uhnook it and put the radio back like it was.
That's what I did. Decades ago.
73
I've done a few, always with scope and spectrum analyser. When done correct, works as it should.
It is nothing really new, first npc mod I did in early 90's on rci2950 I owned those days.
All those negative comments is the lack of understanding or just plain trolling?
Mike
It is nothing really new, first npc mod I did in early 90's on rci2950 I owned those days.
All those negative comments is the lack of understanding or just plain trolling?
Mike
I agree. But then again; how many actually take the time to do it right and use the proper equipment to see it through? Not enough. End result? Hacks that end up creating band pollution because they don't follow through.
It has been my observation that these NPC/RC radios also sound terrible when used on SSB. Invariably, these owners try to continue to use SSB function simply because they can't tell the difference - IMO. At least not until someone on SSB tells them how bad they sound - and even then they continue. If they were to use it for AM only and not SSB that would be OK - to a point.
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It is pure impossible because resistor+diode does nothing in SSB since it is located in AM circuit. On SSB finals are powered directly from power supply - 0.7V drop on CE junction of TR51 so red wire just gives 0.7V more on the finals on SSB because CE bypass.
Mike
Mike
Others that do this mod recommend that the AM Limiter needs to be removed. So did Billy dean Ward, and I quote (excerpt):
"....Locate and remove R-249 Note: This is the AM limiter and it MIUST BE REMOVED for the NPC/RC modification to function properly! IN THIS CASE, there is NOTHING wrong with removing the limiter because you are replacing it with something much better. Compression IS A FORM OF LIMITING superior to the original limiter."
Once again I agree with you. OK fine - you don't do it that way. But others do apparently. Just pointing this out - is all.
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AM limiter must be removed. Properly done npc-rc and you are unable to overdrive or produce flattops because of that circuit.
But: it needs to be done right way, not by butcher from interstate container.
Mike
But: it needs to be done right way, not by butcher from interstate container.
Mike
When done right the NPC mod is nothing at all like the "whack pak" or "super whack pak" crap that Radiohacktive Radio was doing.
The problem is that it is poorly implemented usually by white trash that has as much understanding of electronics as the average toddler has about advanced mathematics! That means we have 99% of NPC-RC modded radio's sounding like total garbage polluting the airwaves. To do NPC properly like what is done in professional broadcasting you need more than $.20 in parts and a scope! Not only that but you need additional filtering as well. I can count on 1 hand and have 4 fingers left over the number of times I have seen a cb'er do this!!
Some of us remember what it was like to talk on the cb before it was overrun with classless nit-wits that are so ignorant that a box of rocks looks like a Renaissance man and true intellectual by comparison. The internet has not made this better it has just allowed the ignorant a place to learn about all the half-baked things other nitwits have done before.
Instead of learning about electronics and why they doing what they are doing they look for the easy answer on a sight like this. They get a $8 soldering iron at Harbor Freight and $.20 in parts and start hacking, cranking and clipping parts. They proceed to pat themselves on the back while drinking terrible domestic beer and keying over other's and swearing and acting a fool on the radio.
You are almost always better off with EQ, phase shifting, compression and some rf clipping.
About 18 years ago I talked 90% AM. Had a local guy that was a very good radio tech do the non volted final version of the NPC mod to two of my radio's. He always used a scope, had a wall full of stuff and was anal about every radio he worked on. That Delta Force and 2950 were superb AM talkers. I'm on mostly SSB these days but I still wish he was around and working on radio's.
I'm a little concerned that you are not telling us what you really think about this subject? LOL..
I have a modified version of the NPC/RC mod for the MB8719 chassis radios that works very well. But then again, I suppose that's junk too.
~Cheers~
~Cheers~
I don't recall you removing the limiter for your version; did you?
Hey I really do not have a problem with this mod to begin with. With exceptions. Taught me a few things. However in the wrong hands; can it do damage?
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