Confusions about CB's...

[Soldaun]

I am extremely new to CB's and would like to have several things cleared up. I will admit though when I first came into this ,because of a whim to install a CB onto my truck, I did not realize how technical some of this gets, let along the sheer amount of things related to CB's.

Side note: I know almost nothing about CB's and would like to learn a few things but I don't even know where to start. I know so little it's actually hard for me to think of questions to ask.

1) SWR rating:
One thing I would like to know more about is SWR. Now a lot of people say to lower your SWR rating you cut off 1/8th increments off of the coax until an acceptable rating is acquired. Well I came across a site that says no matter the length of your coax, the ohm impedance between the coax and the antenna determine your SWR rating. Which one of these are true?, If the first part is true then achieving an acceptable SWR rating is quit simple but if the later is, how do you get an acceptable SWR rating? It's kinda hard to know the ohm impedance of both the antenna and the coax unless explicitly stated on the box.

2) Modulation:
First off what exactly does modulation do for me? I have heard that companies set it below 80% so they can stay within the FCC's regulations, so does turning it up make me run at above 4 watts?, and if I am running above these 4 watts does it make my CB more susceptible to burning up unless I tune/upgrade other parts to handle the new power output? Then there's over modulation, and from my understanding it's like turning the volume up on your radio to high, and since your radio can't safely push that much power the sound distorts, is that the same for over modulation?

3) Dead key:
I know nothing about this, so everything you can explain about this will help.

4) Amps:
How hard is it to setup an amp to your CB and how readily available are they? Do they still make amps or are they from a lost generation and you have to buy whats left of the ones that work? What kind of range can you get out of an amp, and I know people will answer the amp determines the range so please list what power outputs will do what range.

5) Swing:
I'll post a quote from another site, and it will be bold.

"To get out you need lots of swing in your AM signal.

Wrong. An AM signal is fully modulated when the "swing" doubles the carrier. That is to reach 100% modulation a 4 watt key should swing no more than 8 watts. Anything more than that is distortion to your voice. The AM carrier is necessary for the receiver to properly demodulate the audio from the signal. If you add excessive swing it will distort your audio. It will not help you get out better.

If you really want to see the needle swing when you talk purchase a sideband capable radio. Sideband is a much more efficient means of transmitting. You will be able to talk much further with alot less power. The signal to noise ratio on sideband is much better than AM which means you should be able to hear weak signals better on sideband than on AM."

What exactly is swing and how can you run at 8 watts if your set to 4 watts as stated in the above post?


6) Q rating:
How do you determine Q rating and what Q rating do you want? I heard the Q rating you want determines what your doing with your CB, so what exactly are the options of operation you have with a CB so I can then find out the rating I want my antenna to have?

7) SSB:
Is side band a completely different set of frequencies or what, I know nothing about this so anything you can post will help.

8) Stock mic vs Power mic:
Does going with a different mic help that much and if so do you have to re tune your CB to the mic? The reason I ask is it does say "power mic" which says to me it adds power to the signal, and if power is added will it hurt your CB unless properly setup since over modulation can happen with a power mic more easily?

9) Dual antenna:
Does running dual antenna help or is it useless?

So far those are the only questions I can think of, and I will ask more guaranteed. I realize I sound like an idiot asking all these questions and I bet I got half of them wrong but I would rather look dumb for a month instead of walking away from CB's because I'm to afraid to ask questions about them.

I want to be able to reach out at least 15-20 miles, what kind of work will have to be done to achieve that? I currently own an SBE Land Command mobile CB but expect to install an 06' Cobra 29 WX NW ST fairly soon that I got not to long ago from a friends dad, what would I have to do to reach this distance with either CB?

-Thank you

 

[W5LZ]

Soldaun,
I think you've hit on just about every area where there's misunderstandings, or 'myths' about radios, the different modes (means of applying intelligence to a signal), SWR, and so on. The problem is that to understand what you want to know, you really do have to do some 'learning' about the basis for all those thingys, which means you need to know some electronics. You are asking for a simplified electrical textbook. I wish it were that easy, it's not. Hows your math? Know what imaginary numbers are? That's just a 'taste' of understanding all this stuff. It's certainly not impossible, but it ain't easy sometimes.
I'm not a good teacher. I would suggest finding a few "Basic Electronics/Electricity" books and start reading. I'm sure you'll get a gob of explanations for all those things you asked about. Most, if not all, of them are going to be contradictory to some extent.
Good luck!
- 'Doc

 

[Soldaun]

Are there any basic electronic CB books because most electronic books probably wont have information necessary to use/tune/work on your own CB, or explain things like SWR or Q rating among other things.

 

[Robb]

All you need to do is ask one of these questions -one at a time- on this forum and I think you will get all of the answers you need and want.

Sometimes simple questions might have complicated answers. Or perhaps even go in directions one didn't know existed. SO be prepared for some money spent, reading a lot more than you might have thought you needed, and having to apply what you have learned. It is a fun experience that hurts no one. It might put a dent in your wallet - though. Just be glad you don't have a photography hobby - it's much worse!

Learning about radio is an ongoing experience. One might start out on a CB and in a couple of years -and with some effort- can become a Ham operator.

Keep asking questions here!
It keeps the members on their toes and challenges them to remember what they have also learned!

 

[Soldaun]

I'll start with SWR then considering I will get an antenna for the Cobra within the time frame of my next two pay days. How do you achieve a good, but legitimate, SWR rating without tricking the meter?

 

[Shockwave]

Hello Soldaun. Having worked in the field of radio for decades now I have a fairly easy time explaining how it all works in layman's terms. I'll attempt to answer your questions but keep in mind these answers are just the short versions to keep you on the right path. You'll need to learn more electronics theory to fully understand the concepts. Fortunately, you just need to follow good simple instructions to assemble a well talking CB station. The learning process will develop over time.

1) SWR rating is the match between the antenna system and the transmitter. The lower the SWR reading, the better the match. While adjusting the length of the coax can hide an SWR problem, it is not the way to correct the problem. The proper match must occur by adjusting the antenna itself so it provides a 50 ohm impedance at the operating frequency. Each antenna is adjusted differently but most mobile antennas are adjusted by the length of the whip. Base antennas often use tuning rings or gamma matches to adjust the SWR.

2) Modulation is the application of your voice to the radio frequency signal. Some radios will only produce 80% modulation stock from the factory. Adjusting the radios internal modulation limiter for 100% will make you sound louder. This will make the radio do a little more power but usually does not require upgrading other parts. Over modulation does cause distortion that makes you sound muffled and causes interference to adjacent CB channels.

3) Dead key is when you transmit on AM without any modulation. This is called the "carrier" since when you talk on AM, it carries your voice information over the air. When you transmit without talking or letting any sound into the microphone, some people call it a dead key rather then the technical term of carrier.

4) Amps are generally easy to setup unless you purchase a big amplifier. Then the installation can be complex. They still make CB amps and they be found on the internet. Predicting the range a certain power amplifier provides on CB is nearly impossible. Other things like solar storms, antenna used, and location can effect range from under 20 miles to over 2000 miles. The biggest easy to obtain increase in range with an amp is going from 4 watts to 100 watts. To get the same increase in range from 100 watts you would need to increase to 2,500 watts!

5) Swing is the difference in power between an unmodulated carrier or dead key and a 100% fully modulated carrier. The 4 watt carrier should actually increase four times to 16 watts PEP output when 100% modulated. If you look at this on a scope the "swing" should double the carrier but that's because the scope measures voltage. When RF voltage doubles going into an antenna, the power goes up by four times.

6) Q factor deals with a resonators bandwidth and is based on losses within the circuit. As it concerns antennas, we want a high enough Q that keeps losses down but the tradeoff here is that bandwidth is reduced simultaneously as Q is increased. Q is an engineering term not often given in the specifications of an antenna. Bandwidth however, is given on quality antennas and you'll find just about all of them can easily cover the CB channels. When talking about antennas, Q basically refers to how wide a frequency range the antenna can cover while still providing a good SWR.

7) SSB is actually slightly offset from the frequencies AM channels use but SSB is really a different mode of transmission rather then different frequencies. SSB is more efficient because the transmitter does not have to send a carrier to place the modulation on. The carrier is reinserted in the receiver and saves power at the transmitter end. Efficiency is further increased by filtering out one unwanted sideband but that takes a deeper understanding of radio to fully explain. This also makes it possible to have two SSB conversations on a single channel. One on USB and one on LSB.

8) Stock mics usually do not reproduce the same quality and volume of sound as a power mic can. The power mic contains an amplifier inside that boosts the gain of the microphone. You do have to pay closer attention to the microphone setting so that you don't over modulate with a power mic but this will not cause damage to your radio. The modulation limiter inside the stock radio should be adjusted to get the full potential out of a power mic.

9) Dual antennas are a waste of time in 99% of installations. Unless you can space the two antennas a minimum of 9 feet apart, the two patterns they develop completely overlap each other and do not increase signal. While it may look nice on a truck, the performance is lower then a single antenna mounted on the center of the cab roof. The maximum advantage of using two antennas occurs when they are spaced between 18 and 36 feet apart. I hope that helps!

 

[C2]

Swing - lets consider a 4W carrier that is then 100% Amplitide Modulated:

This carrier will "swing" to a PEAK power of 4 times the carrier (16W peak), or to an AVERAGE of 1.5 times the carrier (6W average).

The peak voltage of the carrier is what is doubled when 100% modulated, not the power!

SSB is much more efficient because all of the power is concentrated in a single component of the signal, the part carrying the information (your audio). A 100% modulated AM signal has two, almost identical sidebands, one of which is really a redundant mirror image of the other. In this case, you have power spread between the carrier and two sidebands, a big waste of power. Out of the 6W average, 2/3 of that power is in the carrier and 1/3 is in two sidebands, and really only 1/6 of all that is needed (the single, 1W sideband could accomplish the same thing).

 

[BOOTY MONSTER]

questions are great , we love questions around here . sometimes getting through some missinformation can be quite entertaining in the process of finding the truth . kepp on asking questions

1.
this link will explain wht vswr is .
SWR - what is it, and why is it so important?
this one will explain how to adjust your antennas length for setting that vswr .
SWR - what is it, and why is it so important?
dont get all wrapped up in having a perfect 1.1 vswr . if it happens , great , but being under 1.5 from channel 1 through 40 is perfectly acceptable .

2.
Modulation - what is it and how much is too much?

3.
cb radio uses two types or modes of transmitting our modulated signals . SSB is single side band and uses no deadkey . its all modulated power and its also the easiest to talk the farthest on . AM does require a deadkey and the signal is modulated from that point . there are other modes of communications used by hams but those arnt used for CB .

4.
amps are pretty popular and are easily had . they are however against the FCC rules/laws for the cb band . many things have to be considered when choosing an amp , and its more than i want to get into at the moment .

5.
swing is the increased power output necessary to modulate our signals . AM requires the radio/amp to put out 4 times as much power and it deadkeys for optium signal fidelity and effect . deadkey is also called carrier power . SSB doesnt need any deadkey , its a "swing" or modulated power .

6.
others that have a better understanding of Q will need to answer that one .

7.
ssb is the same frequencys , but a different mode or method of transmitting on them .

8.
some radios sound great with the stock mic that comes with them . some others sound better with an after market mic that may or may not be powered and some mics have built in echo . this is basically gonna come down to a preference thing of what you think sounds best , and if you cant hear your transmission youll have to rely on locals opinions . im a big fan of the 2018 xtreme power echo mic , and they're are others that feel echo is from the devil himself , hehehe .

9.
dual co-phased antennas usually arnt effective on vehicles due them not having enough spacing to get the effects claimed for them . a single quality antenna on the roof (and typically in the center of the roof) has a better dispersion pattern and is the better performing setup .

so those are my answers and opinions to your questions . i dont know much compared to some of the folks here and opinions are like butt holes , everybody has one .. so keep that in mind

your SBE radio with a wilson 5000 or predator 10k on the roof should have no problem talking 15-20 miles when there isnt a lot of noise or skip and if you area isnt filled with folks that have to use hundreds or even thousands of watts to talk local . im not a fan of the new front mic cobra radios , id stick with your SBE or get a uniden grant if you want another or better radio .

if you want to get a amp dont underestimate the effect a simple 2 pill has on your signal . those first coupla hundred watts make a LOT OF DIFFERENCE .

 

[Soldaun]

1) So if I purchase a Wilson 5000 antenna, are there tuning knobs of some sort built in or do I need to find a different way of getting a good SWR reading?

2) Thankyou, I understand this

3) So what applications does Dead keying have since it doesn't apply your voice to the signal?

4) How much would a 100watt amp cost to purchase/setup?

5) Still not sure about this.

6) Does a Wilson 5000 have a good enough Q rating without losing to much bandwidth?

7) Running on a sideband do you still pick people up on AM or is it completely different way to communicate? Also what is the purpose of side band?

8) I understand this

9) I understand this

My SBE is a side mic plug in, not sure if that makes a different and she works good so far but then antenna I have paired with here is extremely cheap. I forgot the brand but I have a really hard time hearing people because their voice is distorted. I do know that it is an older brand though.

My area from what I can tell doesn't have to many CB hobbyist, just the truckers running up and down I5 have radios for the most part.

 

[Robb]

Ahhh, now you have chosen a specific antenna.

Wilson magnetic-mount antennas -like the 1000 or 5000 series- are great antennas for a mobile application. I am quite satisfied with the 1000 model, as it receives and transmits very well in local and distant communications.

Moving the whip portion upwards/downwards after loosening the set screw that is in place will adjust the SWR - as you will need to get is as low as possible for best results. You will need an SWR meter to make this adjustment. Some Cobra radios have this feature built-in; so you can use that. Although not known for being terribly accurate, they will get you close enough.

I recommend placing the antenna on the center/top of your vehicle for best tuning and overall performance. Route the coax so that it doesn't get pinched or smashed flat when coming into the vehicle. Route the coax under the carpet and avoid looping/overlapping it before it makes to the radio.

Using a 100 watt linear amp in a vehicle should be done AFTER you set up the radio and antenna properly FIRST.
One thing at a time will ultimately yield the best final results.

 

[Soldaun]

I get paid this Friday and will try to purchase the antenna this paycheck or my next one. After that I'll come to you guys to help tune it. Would I experience better performance with my SBE Land Command mobile CB or the Cobra 29?

The SBE radio is an LCMS-4

 

[mackmobile43]

I get paid this Friday and will try to purchase the antenna this paycheck or my next one. After that I'll come to you guys to help tune it. Would I experience better performance with my SBE Land Command mobile CB or the Cobra 29?

The SBE radio is an LCMS-4

Either radio is well suited for the task but the cobra will give you 17 more channels to choose from.

ON edit I was looking at the wrong radio it does have 40 channels and ssb which is always better.

 

[BOOTY MONSTER]

if its a side mic 29 and has been tuned and aligned properly id stick with that if ssb isnt of intrest to you . im not familiar with the SBE radios .

 

[Soldaun]

if its a side mic 29 and has been tuned and aligned properly id stick with that if ssb isnt of intrest to you . im not familiar with the SBE radios .

The SBE is a 40 channel side mic with LSB, AM (obviously AM), and USB. I tried looking on the back to see date of manufacture but couldn't find it because of the position of the radio installed under my dash. I heard that side mic CB's aren't manufactured anymore and that a lot of the newer front mic CB's are of less quality. If that is true does that mean since my CB is a side mic, it being older would make it of higher quality?

EDIT: Is SSB different from LSB or USB?

Heres a picture of the CB prior to installation as well as the antenna. If anyone recognizes the antenna please let me know what it is and what kind of quality the company had.

 

[Robb]

SSB is used to include/designate both Upper Side Band ('USB') and Lower Side Band ('LSB').
SBE radios are GREAT in SSB usage.
You will like it - I think.