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I wanted to show everyone what an NPC/RC (diode/resistor) mod looks like on a scope, and the distortion that it causes. So I went over to F.G. Best, where we took a Galaxy off the shelf, and applied the mod to it. We then ran a test tone through it (so the signal pattern shows the easy to see sine wave) before and after.



This first pic is of a properly modulated AM signal with no NPC/RC mod. Note the nice symmetrical pattern.







Now this is with the NPC/RC mod applied. I took a pic of the radio so you can see that the mod is there. This is also an "extreme" NPC mod so it's easy to see in the tiny picture on the internet. We did a more typical one as well, and the results were the same, just not quite as dramatic.



Shot of the mod:





What it looks like on the scope:



Notice how the negative peaks (the part of the signal closest to the X axis. It's at the center, not the bottom of the sine wave) are totally trashed. This gets represented as distortion under normal voice operation.



Here's one last video clip of the mod being applied then disconnected while a steady tone is running. If you turn up your speakers, you can even here the tone change frequency as it distorts when the mod is applied and then disconnected.



Click here for video clip



Hope everyone finds this educational and revealing.



Moleculo


</p>Edited by: <A HREF=http://p067.ezboard.com/bworldwidecbradioclub.showUserPublicProfile?gid=mo leculocdx363>MoleculoCDX363</A> at: 12/20/04 9:20 pm

I wanted to show everyone what an NPC/RC (diode/resistor) mod looks like on a scope, and the distortion that it causes. So I went over to F.G. Best, where we took a Galaxy off the shelf, and applied the mod to it. We then ran a test tone through it (so the signal pattern shows the easy to see sine wave) before and after.



This first pic is of a properly modulated AM signal with no NPC/RC mod. Note the nice symmetrical pattern.







Now this is with the NPC/RC mod applied. I took a pic of the radio so you can see that the mod is there. This is also an "extreme" NPC mod so it's easy to see in the tiny picture on the internet. We did a more typical one as well, and the results were the same, just not quite as dramatic.



Shot of the mod:





What it looks like on the scope:



Notice how the negative peaks (the part of the signal closest to the X axis. It's at the center, not the bottom of the sine wave) are totally trashed. This gets represented as distortion under normal voice operation.



Here's one last video clip of the mod being applied then disconnected while a steady tone is running. If you turn up your speakers, you can even here the tone change frequency as it distorts when the mod is applied and then disconnected.



Click here for video clip



Hope everyone finds this educational and revealing.



Moleculo


</p>Edited by: <A HREF=http://p067.ezboard.com/bworldwidecbradioclub.showUserPublicProfile?gid=mo leculocdx363>MoleculoCDX363</A> at: 12/20/04 9:20 pm

No offense but I would like SS8541 to look at this because he seems to have good luck with a mod similar to the NPC and I have been happy with his work so I wonder if something is missing.



I sent Richard an email about this post


</p>

No offense but I would like SS8541 to look at this because he seems to have good luck with a mod similar to the NPC and I have been happy with his work so I wonder if something is missing.



I sent Richard an email about this post


</p>

Well, there's a couple of ways to do it, but they all end up with the same result, that is, if done correctly, and that's negative peak compression. Everyone thinks that the top of the scope pattern is the positive peaks, and the bottom is the negative.... not so...where the lobes meet in the middle is negative, and the otp and bottom lobes are the positive, in English, it's because the scope only has the capability to display it this way.


Click Here To Go To FG Best Communications



</p>

Well, there's a couple of ways to do it, but they all end up with the same result, that is, if done correctly, and that's negative peak compression. Everyone thinks that the top of the scope pattern is the positive peaks, and the bottom is the negative.... not so...where the lobes meet in the middle is negative, and the otp and bottom lobes are the positive, in English, it's because the scope only has the capability to display it this way.


Click Here To Go To FG Best Communications



</p>

No offense, but how come when I here a guy ask for a radio check, and he sounds distored, over modulated and at best like crap, but the guy tells him he sounds good? Most CBers do this (not all) over and over. If you do this mod It IS over modulating and distorting your radio period. Now if thats the sound your lookig for than that's what you will get. Bill Good would rip that mod out of every radio so fast it would make your head spin.



Frank.






Click Here For FG Best Communications Web Site</p>

No offense, but how come when I here a guy ask for a radio check, and he sounds distored, over modulated and at best like crap, but the guy tells him he sounds good? Most CBers do this (not all) over and over. If you do this mod It IS over modulating and distorting your radio period. Now if thats the sound your lookig for than that's what you will get. Bill Good would rip that mod out of every radio so fast it would make your head spin.



Frank.






Click Here For FG Best Communications Web Site</p>

I tell the local guys all the time they sound good when they sound like crap. I do it because it's funny to keep them talking like that for a while and make my station sound better! <img src=http://home.comcast.net/~shockwav/medium-smiley-002.gif ALT=":lfh"> ok, ok...after a while I clue 'em in that I was messing with 'em.... <img src=http://users.joplin.com/dutch64804/posticon24.gif ALT=":lmao">


</p>

I tell the local guys all the time they sound good when they sound like crap. I do it because it's funny to keep them talking like that for a while and make my station sound better! <img src=http://home.comcast.net/~shockwav/medium-smiley-002.gif ALT=":lfh"> ok, ok...after a while I clue 'em in that I was messing with 'em.... <img src=http://users.joplin.com/dutch64804/posticon24.gif ALT=":lmao">


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