Fine Tune CB shop

[Martian]

I was trying to keep it simple.

The person that pointed me to this thread and forum warned me that I had to keep it simple and keep it as non-technical as possible because Mr. Rabbi will turn anything around against you to try to prove his point.

If we started going into what the spurs were and where they were generated and what generated them it would turn into "NIST calibrated" equipment that cant possibly have such artifacts in them.

Yeah. I saw the "calibration certificate". I got a chuckle.

 

[rabbiporkchop]

I know what spurs are. And I know what Harmonics are.

I want to know what YOU think they are because far too many of these people doing radios call harmonics "spurs".

So, I am not enlightened, but thank you for answering my question.

IMD created by mismatched final transistors. It's pretty basic stuff.
I prefer to call a spade a spade instead of lumping Spurs and harmonics in the same category. Until Eric Lewis started beta matching his mosfets recently I don't recall any retailer doing the same thing or offering the same services to customers.
It was up to the technician to do the best he could with the mismatched transistors and make it as clean as possible which was never perfect.

 

[rabbiporkchop]

Let me help with this they are "HARMONIC SPURS" and they are as much a process of the non linear response of the ADC than being anything terrible but it matters not because they exist mostly as integral multiples of the input freq with some harmonic distortions added to the mix, another words there are many unimportant spurs in life as well as in spectrum analyzers, etc That's about all I have to say about that! hope that was not as generic and boring as it sounds it's a result of lost memories of being a calibration tech.

All of those artifacts disappear once you rip out the final stage of the RF chain and replace it with beta-matched components, so no they don't exist mostly as integral multiples of the input freq with some harmonic distortions added to the mix because when the final stage of the RF chain is replaced with beta-matched components they are no longer there.

 

[OldTech03]

All of those artifacts disappear once you rip out the final stage of the RF chain and replace it with beta-matched components, so no they don't exist mostly as integral multiples of the input freq with some harmonic distortions added to the mix because when the final stage of the RF chain is replaced with beta-matched components they are no longer there.

Shure, whatever you most likely are convinced of the incorrectness of a position that only someone smarter than everyone else could comprehend but then again maybe not and maybe I'm just yanking chains to see who can break them or maybe not. I'm going to go immediately to my mediocre bench and see if I can become one with beta matched finals just remember you can drag MOSFETs to the final section it doesn't necessarily mean they will get along, I will report on my findings if I don't get tangled up in outta phase relationship with an unwilling semiconductor that won't conform to my ways. LOLLOL! Sorry, I thought some mindless ranting might clear the air?

 

[rabbiporkchop]

Shure, whatever you most likely are convinced of the incorrectness of a position that only someone smarter than everyone else could comprehend but then again maybe not and maybe I'm just yanking chains to see who can break them or maybe not. I'm going to go immediately to my mediocre bench and see if I can become one with beta matched finals just remember you can drag MOSFETs to the final section it doesn't necessarily mean they will get along, I will report on my findings if I don't get tangled up in outta phase relationship with an unwilling semiconductor that won't conform to my ways. LOLLOL! Sorry, I thought some mindless ranting might clear the air?

Contrary to your opinion, the laws of physics do apply to CB radios. As much as you would like to deny the causes of intermodulation distortion, it's pretty much cut and dry.

Intermodulation (IM) orintermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities in a system. ... Intermodulation is caused by non-linear behaviour of the signal processing (physical equipment or even algorithms) being used.


As you can see, removing those nonlinearities helps us eliminate intermodulation distortion. There's really nothing to argue about.

 

[Martian]

Contrary to your opinion, the laws of physics do apply to CB radios. As much as you would like to deny the causes of intermodulation distortion, it's pretty much cut and dry.

Intermodulation (IM) orintermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities in a system. ... Intermodulation is caused by non-linear behaviour of the signal processing (physical equipment or even algorithms) being used.


As you can see, removing those nonlinearities helps us eliminate intermodulation distortion. There's really nothing to argue about.

Wait. Your a truck driver?
You just quote things off the internet for the most part.
You even plagiarised an article written by someone else in a comment I saw last night.

THAT SAID... do you realise just how insanely insignificant these products are?
Do you realise that the two signals in a CB radio that will create these IMD products will likely fall outside of the bandpass in the filters in these radios?

Do you understand that the reason they pick something like 35Mhz and 7.8Mhz to get 27.2 is for this reason? (But also for the IF)

So where is IMD a problem?
How about you do the math on these two frequencies THEN do the math on the filter network after the mixer in the TX chain and report back to me about how much IMD you will see and how much of the two original signals might actually make it to the amplifier.

 

[Martian]

Until Eric Lewis started beta matching his mosfets recently I don't recall any retailer doing the same thing or offering the same services to customers.

That's actually quite amusing because you can buy matched semiconductors from reputable suppliers and manufacturers for decades.

The reason they are not used in a CB radio is because it's not needed in that use case.
You think you need it because someone told you that you need it.

If it was needed then it would be on the BOM and installed on the line when the radios were manufactured.

He didn't invent anything new or novel. It's marketing fluff.

 

[w9cll]

OMG

 

[Captain Kilowatt]

FWIW harmonics and spurs are NOT the same thing.

 

[rabbiporkchop]

Wait. Your a truck driver?
You just quote things off the internet for the most part.
You even plagiarised an article written by someone else in a comment I saw last night.

THAT SAID... do you realise just how insanely insignificant these products are?
Do you realise that the two signals in a CB radio that will create these IMD products will likely fall outside of the bandpass in the filters in these radios?

Do you understand that the reason they pick something like 35Mhz and 7.8Mhz to get 27.2 is for this reason? (But also for the IF)

So where is IMD a problem?
How about you do the math on these two frequencies THEN do the math on the filter network after the mixer in the TX chain and report back to me about how much IMD you will see and how much of the two original signals might actually make it to the amplifier.

Using the radio barefoot it isn't a problem at all. You are correct that it isn't a problem. It becomes a problem when some brainless idiot plugs an amplifier into the back of the radio. Then it becomes a huge problem due to amplification.
Every little bit of efficiency that we can gain is a step in the right direction.
Pointing out that I'm no longer a sonar technician in the Navy and that I'm currently a truck driver has no relevance to any argument that you're trying to make.

 

[OldTech03]

FWIW harmonics and spurs are NOT the same thing.

Mr. Kilowat you are essentially correct!

First Spurious emissions are generally arbitrary signals created by the same oscillator stages that cause the harmonics especially if not well designed hence Broadbanded export radios.
This is correct the reason I referred to them as Harmonic spurs are because anyone with enough money to put a spectrum analyzer on the bench should probably spend at least as much on their education of how spurious emissions come to be. The problem I see isn't about are harmonics being generated or spurious emissions being generated it's the idea that final stage of the transmitter is the culprit because it's amplifying what is being fed to it and WOW! it shows up on spectrum analyzer set to it's most sensitive settings. Can a final section cause problems if has issues that cause it to go into self-oscillation? Of course the key here is "Self-Oscillation", it can but is that a prominent issue "NO" Start here in your journey to understand where harmonics and spurs come from "OSCILLATORS" and take it from there to understand how the harmonics in poorly designed radio can pass those harmonics on to the final section. Another thing to keep in mind is they are more prominent in broadly-banded radios hence "GALAXY" is about as broadband as you can find. To think that you would stand a chance in hell of using the finals in a matched configuration to stop harmonics is like pissing in the wind. There are many things in a mass-produced CB that can add to this problem and I will say that knowing what those issues can be isn't always straightforward and requires some technical knowledge that clearly isn't being exercised by those that claim they are the only ones that know how to fix it.

I reserve the right to revise and extend my remarks! especially if some points out my attempt to cause real debate by the words I have planted that should cause a debate? We will see.

 

[OldTech03]

There you go SEE! I have stuff too. I also have a bicycle would you like to see it.

Contrary to your opinion, the laws of physics do apply to CB radios. As much as you would like to deny the causes of intermodulation distortion, it's pretty much cut and dry.

Intermodulation (IM) orintermodulation distortion (IMD) is the amplitude modulation of signals containing two or more different frequencies, caused by nonlinearities in a system. ... Intermodulation is caused by non-linear behaviour of the signal processing (physical equipment or even algorithms) being used.


As you can see, removing those nonlinearities helps us eliminate intermodulation distortion. There's really nothing to argue about.

Mr. Kilowat you are essentially correct!

First Spurious emissions are generally arbitrary signals created by the same oscillator stages that cause the harmonics especially if not well designed hence Broadbanded export radios.
This is correct the reason I referred to them as Harmonic spurs are because anyone with enough money to put a spectrum analyzer on the bench should probably spend at least as much on their education of how spurious emissions come to be. The problem I see isn't about are harmonics being generated or spurious emissions being generated it's the idea that final stage of the transmitter is the culprit because it's amplifying what is being fed to it and WOW! it shows up on spectrum analyzer set to it's most sensitive settings. Can a final section cause problems if has issues that cause it to go into self-oscillation? Of course the key here is "Self-Oscillation", it can but is that a prominent issue "NO" Start here in your journey to understand where harmonics and spurs come from "OSCILLATORS" and take it from there to understand how the harmonics in poorly designed radio can pass those harmonics on to the final section. Another thing to keep in mind is they are more prominent in broadly-banded radios hence "GALAXY" is about as broadband as you can find. To think that you would stand a chance in hell of using the finals in a matched configuration to stop harmonics is like pissing in the wind. There are many things in a mass-produced CB that can add to this problem and I will say that knowing what those issues can be isn't always straightforward and requires some technical knowledge that clearly isn't being exercised by those that claim they are the only ones that know how to fix it.

I reserve the right to revise and extend my remarks! especially if some points out my attempt to cause real debate by the words I have planted that should cause a debate? We will see.

 

[rabbiporkchop]

Mr. Kilowat you are essentially correct!

First Spurious emissions are generally arbitrary signals created by the same oscillator stages that cause the harmonics especially if not well designed hence Broadbanded export radios.
This is correct the reason I referred to them as Harmonic spurs are because anyone with enough money to put a spectrum analyzer on the bench should probably spend at least as much on their education of how spurious emissions come to be. The problem I see isn't about are harmonics being generated or spurious emissions being generated it's the idea that final stage of the transmitter is the culprit because it's amplifying what is being fed to it and WOW! it shows up on spectrum analyzer set to it's most sensitive settings. Can a final section cause problems if has issues that cause it to go into self-oscillation? Of course the key here is "Self-Oscillation", it can but is that a prominent issue "NO" Start here in your journey to understand where harmonics and spurs come from "OSCILLATORS" and take it from there to understand how the harmonics in poorly designed radio can pass those harmonics on to the final section. Another thing to keep in mind is they are more prominent in broadly-banded radios hence "GALAXY" is about as broadband as you can find. To think that you would stand a chance in hell of using the finals in a matched configuration to stop harmonics is like pissing in the wind. There are many things in a mass-produced CB that can add to this problem and I will say that knowing what those issues can be isn't always straightforward and requires some technical knowledge that clearly isn't being exercised by those that claim they are the only ones that know how to fix it.

I reserve the right to revise and extend my remarks! especially if some points out my attempt to cause real debate by the words I have planted that should cause a debate? We will see.

If the Spurs were generated by the input signal then you're correct that by using beta-matched components in the final stage of the RF chain it won't prevent them from passing but when they are generated by mismatched components eliminating the nonlinearities will fix the problem. The trick is figuring out where the problem lies and rectifying that problem instead of making assumptions about where the problem lies when the radio is not on your bench if you even have one which we have yet to see.

 

[Martian]

Using the radio barefoot it isn't a problem at all. You are correct that it isn't a problem. It becomes a problem when some brainless idiot plugs an amplifier into the back of the radio. Then it becomes a huge problem due to amplification.
Every little bit of efficiency that we can gain is a step in the right direction.
Pointing out that I'm no longer a sonar technician in the Navy and that I'm currently a truck driver has no relevance to any argument that you're trying to make.

How much of a problem do you think this becomes?
Does it matter?
Should it matter?
Where is the actual problem?
Is it in the amplifier to start with?

"Every little bit of efficiency" is not a step in the right direction if the effort it takes to get there far exceeds the benefit.

Pointing out that I'm no longer a sonar technician in the Navy and that I'm currently a truck driver has no relevance to any argument that you're trying to make.

I never pointed this out because I did not know it until you just mentioned it.
Why do I get the impression that you are trying to slip this in to make a point?

 

[OldTech03]

If the Spurs were generated by the input signal then you're correct that by using beta-matched components in the final stage of the RF chain it won't prevent them from passing but when they are generated by mismatched components eliminating the nonlinearities will fix the problem. The trick is figuring out where the problem lies and rectifying that problem instead of making assumptions about where the problem lies when the radio is not on your bench if you even have one which we have yet to see.

Here is my stuff just wanted to make sure you have seen it. I'll upload the bicycle when I get time.