what NPC/RC mod looks like on a scope

[speedracer6g]

Oh Boy CB vs Ham agian. Wow why is there so much friction between you guys anyway??? No realy dont tell me we would have to start another tread. I agree with the post that said it is a worthwhile mod when done corectly. Distortion is minimal if noticeable. I see some distorion on the negative peak but it is neglegable. Better than just letting it run wild anyway. I am doing some camparison on the top gun modulator verses the npc mod. So far the tgm seems to make your voice sound a little different. I think this is due to the fact the tgm doesnt respond fast enough on the power setting. if you talk you will see the deadkey drop slowly after you quit talking and hold the key. That could be a whole other discussion though. I think there is alot of confusion on what people are seeing on a meter. Meters are deceiving sometimes unless you know what you have going on in the radio. That takes a scope they are cheap on ebay and worth the investment. You can get away with disrotion to a certian degree but i have heard some radios that were loud but very hard to understand due to heavy distortion. If you are building a radio for everyday use maybe not a good idea but for compitition thats another story all together. I will post some results when i get some time. :headbang

Murdock

 

[SR385]

I use an industry standard broadcast microphone channel, Symetrix 528E, followed by BBE processing for speech intelligibility followed by a broadcast limiting circuit before the microphone input. The result is loud, clear audio without distortion. Think of Wolfman Jack!

A bit more than a couple of diodes but well worth it.

I L O V E my Symetrix 528e, it's a voice in a box. All stages are just perfect for voice.

I was a sound man for about 5yrs or so, in clubs and on the road touring. I'm well familiar with many many pieces of rack gear and particularly for radio use, the Symetrix is fantastic. 1U and it's just plain _done_.

Would I buy a new one for ham use? Probably not, but I got it for a lot less than half the cost of a new one and paired with a budget CAD M177 mic I also found for about half the street price, the results have been fantastic.

I'm not on AM, none of my rigs has the wide filters, but for 3k of SSB, the setup makes it sound as good as it gets.

 

[jazzsinger]

quote:

If that 'PPE' is what I think it is, Positive Peak Enhancement, it's just the other side of that NPC 'coin', it's still worthless.


ok,if this is a useless mod then why did my general lee go from doing squat on the bird(would key 5 and barely tickle 8-9 average )to doing 18 average from a 3 watt key?
this is on a bird 43 non peak mode into a 50 ohm dummy load ,radio on 13.8

now like i stated befor i can turn the variable power vr up to a 20 watt key and it still went forward to 25 bird.thats alot........

i of course do not run it that way .i am either keying 3 or 5 and swinging 18 average on a bird now .

thats hardly a useless mod ,wouldnt you say??

for comparison i hooked our non modded mirage 88 to the bird in the same fashion.9 watts average again ..10 at best with a whistle into the mic .
i am sure if a modded this in the same way i would see much more on the bird.

this is basically just a resistor/diode mod on the voltage regulator.no volted finals though.

more watts isn't the be all and end all of radio,your bird meter can't tell which frequency those watts are on either,it just measures the total watts including those found in harmonics.


despite what others say about an oscilloscope being the only way to see distortion,that isn't the case,an oscilloscope will only indicate its there but won't give an accurate view of it,the only thing that will do that is a spectrum analyser and they ain't cheap.the spectrum analyser will not only show where those extra watts your measuring are frequency wise but also how strong they are.your bird no matter how good can do neither of those things.


the best solution you will get without distortion is 100% modulation,as soon as you go above that any loudness you achieve will be at the cost of signal/audio purity.


you may sound bigger/louder but you definately won't sound better irrespective of what any cb'ers tell you,because as its already been mentioned some people's ears are very poor at judging audio quality,not to mention the fact that scopes and spectrum analysers don't tell lies,people do whether it be to flatter your ego or just to wind you up and have you sound rubbish on air.



a small bit of compression in difficult conditions can be a worthwhile trade off and help readability of a signal,but listening to it all the time causes fatigue for the listener.



p.s. i'm a cb'er not a ham,that doesn't even come into it,facts are facts irrespective of what band the person giving them uses.


do yourself a favour,don't waste your money or your radios getting mods done that devalue it and make it sound rough,buy a decent rf speech compressor with decent filtering built in and use it only when you need it,people doing these mods are making a hell of a lot of money out of people's ignorance.none of them improve your radio,if they did for the few cents the parts cost i'm sure the manufacturers would include them and use them as a selling point to hike the price.when you get these mods done your not paying for the parts,your not paying for the techs knowledge (many don't have any of that),your paying some halfwit to F@CK up your radio you spent hard earned dollars on,its that simple.

 

[cbdoctor]

Bill Good Was a personal friend of mine. He once told me that I was the only person that he knew of that he sent customers to. I am the one that sold him the Viper Antennas after he quit buying them from MJ products. I am the one that made them.

And BTW, Bill was the only one I would send people too also!

I am also the one that introduced the NPC-RC mod to the CB Forums,

Of course, Bill Good would tear that mod that you have pictured out of a radio he worked on. It is NOT THE NPC-RC MOD. Yes, it will compress the negative peak but as you can see, the two diode, two resistor mod compresses it to the point that it is only being modulated to about 45%.

I don't know who posted the scope pictures but he did so to show how it looked with NPC. NPC-RC does NOT look like that.

However the text on this thread said something like, SEE How the pattern is assemetrical and the negative peaks don't come together! How unbelievable!

That is the meaning of NPC! Compressed NEGATIVE PEAK. And that means that the negative peaks will not come together at the bottom. Whether or not you know it, with the original limiter, the negative peaks DO NOT come together!

They meet at about the same point as a well done NPC-RC mod--about 98% modulation. However, the positive peak is allowed to go as close to the saturation point--just beyound clipping as it can get for a very loud very assemytrical BEAUTIFULLY CURVED SINE SHAPE. NO more distortion than
a stock radio.

The NPC-RC mod uses ONE diode and ONE resistor and the value of the resistor is about 100 ohms for almost all Rangeer-Built radios and their copioes.

NPC-RC Negative Peak Compression-Reduced Carrier

This link shows scope patterns which are antimated but if your not getting the scope to look like the 2nd pic from the bottom, you are not doing the mod and tuning the radio correctly!

Two or three gave their credentials. I have been the Senior Design Engineer for two different CB equipment companies. I have built a 50 thousand watt FM station from the ground up. I manufactured in excess of 140, 000 amplifiers that were clean enough to pass FCC specs for ham radio--All harmonics down to about -62 dB. 119,000 were under my own brand name and the rest custom built for other companies.

And I was an Amateur Extra for 40+ years.

I'm not going to get into any debate here as I was asked to come oveer to this forum and say my piece on the subject!

BILLY DEAN WARD

 

[cbdoctor]

I have to address one more thing!

The idea that "if the mod were a good thing, it would come built that way from the manufacture".

That is such a lame idea that it almost does not deserve being addressed.

You have been in the cb world long enough to know that the FCC does not allow the amount of power that we ALL run! The limiter is placed in the radio to cause the negative and positive peaks to not go over 100% modulation.

There is ABSOLOUTELY NO PROBLEM with the positive peak going over 100% modulation as long as it does not flattop!

Compressing the negative peak keeps the negative peak from flattoping. If you want to talk about distortion, measured on a HP distortion analyzer there is distortion before the NPC-RC mod is done.

There is NO MORE distortion after it is done--appx the same--about 15% distortion of the audio signal--the microphone out put being compared to the audio received on another CB radio. And that icludes the distortion in the
2nd radio's receiver.

ANY variance of a signal other than amplification of the signal is distortion. The signal transmitted by the guy with the expensive mic on this thread is distorted because what comes out of his mouth into the mic is NOT the same as listened to on a speaker coming out of another radio receiver. It is not harmonic distortion--but then neither is the NPC-RC when done properly.

I am leaving within the next few days for San Diego to get some special cb products off the ground so I will NOT be on the forums until I can buy a new bench computer.

BTW, BF, That remark was uncalled for! But, enjoy my absence!

BILLY DEAN WARD

 

[cbdoctor]

'ok doc ,this being said why are we concerned what a machine says our audio sounds like?we should be concerned what our ears tell us ,not some machine.we hear with our ears ,not machines .

this could get beat down to death but you ham guys just cant get over it .i dont see any cb`ers jumping on this bandwagon?

if the bird meter is the industry standard and considered the best there is (to a degree)then upping my output power on such a meter is not a bad thing.

ps-everyone says the radio sounds great.i have heard it myself too and i agree.

cb/ham....2 different animals .dont confuse the 2."
.............................................................................................

I just want to make sure that everyone understands, I am on the Ham side of this type argument. What the "MACHINES" tell us is the Truth, no matter what our "EARS" TRY to tell us. Just because the Bird is the standand of the Land Mobile industry does not mean that it can tell us the definitive power reading because it cannot. An oscilloscope and a Spectrum Analyzer is very necessary equipment. In fact they are absolutely mandatory in knowing about the signal wave and the harmonic structure of the wave.

I am NOT defending the NPC-RC mod to the point of saying, "If it sounds good go for it."

It is a simple little thing-ONE diode--ONE resistor, and removing the limiter and placing "the red wire on the bottom".

Everyone that keeps complaining about removing the limiter is simply regurgating what he has heard from others that have no knowledge of why the limiter is there to start with and no idea of how the NPC-RC works.

When the NPC has been done, the limiter, if left in, only controls the positive peak! If tuned right, the positive peak will not flattop and the negative peak is controlled in a better way---compression!

If it does not sound good and loook GREAT on the equipment, redo it!
You didn't do it right the first time!

BILLY DEAN WARD

 

[fnkycoldmedina]

finally some correct info

more watts isn't the be all and end all of radio,your bird meter can't tell which frequency those watts are on either,it just measures the total watts including those found in harmonics


not true....the bird slug cannot read outside of 30 mhz..so it only reads output power within this tolerance.any harmonics created would be outside of the 30mhz and not read on the meter.
thats my understanding.......but i am new to bird meters.

am i correct in this assumption?

 

[speedracer6g]

Yes Good Info!!

 

[jazzsinger]

finally some correct info

more watts isn't the be all and end all of radio,your bird meter can't tell which frequency those watts are on either,it just measures the total watts including those found in harmonics


not true....the bird slug cannot read outside of 30 mhz..so it only reads output power within this tolerance.any harmonics created would be outside of the 30mhz and not read on the meter.
thats my understanding.......but i am new to bird meters.

am i correct in this assumption?

not all products of mixing are even order products,the odd order products will be well within the bird passband.there are other things which can make the bird meter read innacurately too,like not using a dummy load.

if manufacturers including the NPC-RC mod is such a lame idea,which you may well be right on with 40ch legal US sets due to regulations,it still begs the question why not fit it in export sets which will never fall within regulations anyway.

incidentaly my comment wasn't aimed at that mod in particular but more a general comment aimed at ALL the mods the cb chop shops perform that detract from radios performance,like you yourself say it may well be ok if done properly but how many of these mods are done properly? i suspect very very few of them,so its better to be safe than sorry and end up with a hacked up radio.

 

[W5LZ]

fnkycoldmedina,
I'm sorry, but your assumption is not correct.
- 'Doc

 

[V8Vega]

'ok doc ,this being said why are we concerned what a machine says our audio sounds like?we should be concerned what our ears tell us ,not some machine.we hear with our ears ,not machines .

this could get beat down to death but you ham guys just cant get over it .i dont see any cb`ers jumping on this bandwagon?

if the bird meter is the industry standard and considered the best there is (to a degree)then upping my output power on such a meter is not a bad thing.

ps-everyone says the radio sounds great.i have heard it myself too and i agree.

cb/ham....2 different animals .dont confuse the 2."
.............................................................................................

I just want to make sure that everyone understands, I am on the Ham side of this type argument. What the "MACHINES" tell us is the Truth, no matter what our "EARS" TRY to tell us. Just because the Bird is the standand of the Land Mobile industry does not mean that it can tell us the definitive power reading because it cannot. An oscilloscope and a Spectrum Analyzer is very necessary equipment. In fact they are absolutely mandatory in knowing about the signal wave and the harmonic structure of the wave.

I am NOT defending the NPC-RC mod to the point of saying, "If it sounds good go for it."

It is a simple little thing-ONE diode--ONE resistor, and removing the limiter and placing "the red wire on the bottom".

Everyone that keeps complaining about removing the limiter is simply regurgating what he has heard from others that have no knowledge of why the limiter is there to start with and no idea of how the NPC-RC works.

When the NPC has been done, the limiter, if left in, only controls the positive peak! If tuned right, the positive peak will not flattop and the negative peak is controlled in a better way---compression!

If it does not sound good and loook GREAT on the equipment, redo it!
You didn't do it right the first time!

BILLY DEAN WARD

WOW! It's great to see you around here.
Where is my Varmint XL-350 I sent you about 8 years ago???

 

[cbdoctor]

Thanks for your cheer for me being here! I don't know about YOUR varmint. I do remember that I received 3 amplifiers that I still owe for to someone. I know what the other 2 are and would recognize their handle if it were still the same. What was your handle then.

You have to realize that I am living quite a different lifestyle now than I was back then. I have been through absolute HELL--which is exactly where I should have been living the lifestyle that I was living.

A year and a half ago I took a fall and woke up from a four day coma and was larthargic for a couple of months--didn't hardly know who I was or where for over a month.

I spent 11-1/2 months on my back or in a wheel-chair in 5 different hospitals and 2 convelesant homes.

I have a new hip (OCT 8-2008), a still broken knee on the same leg and two severely torn shoulder rotator cuffs. I am NOT making very much money at this time but I am heading for San Diego in the next few days to go to work with a will known amplifier company. Let me know the particulars on the Varmint. Most of my memory has returned but once in a while I find myself remembering things that I didn't know that I knew<---that does make sense--if your me! LOL!

Now, to address the Bird meter situation. I have to agree 100% with the author that mentioned the pass-band of the meter. You see, the pass-band cannot be cut off on either edge at a precise spot.

The pass-band as seen on a graph would be an incline to a point that may or may not be flat and then a decline back down to the starting point. It will usually look like a mountain that has one half of it as the mirror-image of the other half.

If the meter is to be accurate within the pass-band the plateau must be as flat as possible and the "usable" pass-band of the instrument must start and finish as close to the beginning and the end of that plateau as possible.

Even if it meets that criteria there will still be power located outside of the instrument pass-band that will be seen by the meter but not at the correct level. In other words if you have a signal power at 32 Mhz and use a 30 Mhz slug, you will still get a reading on the meter caused by the 32 Mhz signal--it just won't be accurate! So, as W5LZ states above, the statement that the slug cannot read above 30 Mhz is incorrect!

It would be wonderful if we could design a pass-band that would look exactly like one positive peak or one negative peak of a square wave, but so far, I know of no instrument that has one--for any use.

BILLY DEAN WARD

 

[Moleculo]

but I am heading for San Diego in the next few days to go to work with a will known amplifier company.

Can you get them to put out something better than they have been? I mean really, how much extra would it cost to regulate the bias to the transistors and put in some output filtering. It's not asking for much.

 

[Robb]

Can you get them to put out something better than they have been? I mean really, how much extra would it cost to regulate the bias to the transistors and put in some output filtering. It's not asking for much.

I'll second that.
If the FCC continues to trash on the use of dirty amps -which means trashing all of us- it would be a step forward to make an amp that wasn't the center of the 'Hams vs CBers' controversy.

A few extra parts in the right place would make a difference.
To be the first company that would do that and keep it affordable - isn't so far fetched nor impossible.

Build a better mouse trap - and the world will beat a path to your doorstep...

 

[dudmuck]

A bird slug is basically just a pickup wire with a resistor on one side and a detector diode on the other. There are no frequency limiting components other than the pickup wire itself.

When you operate a bird slug outside the frequency range printed on the front, the only thing you lose is it accuracy. Although the error varies up & down, as a general rule at higher frequencies it'll read more power than there really is, and at lower frequencies there is less coupling so it reads falsely low.

It means that harmonics power can be coupled by the bird slug more than the fundamental carrier. And all the harmonics add together in the slug.