cb radio. no distance

Discussion in 'CB Radio Forum' started by leftlayne, Sep 13, 2018.

  1. craig_sez

    craig_sez Road Train Member

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    Go to youtube and look up MikesRadioRepair and then search for why not peak n tune,clip amc limiters.It only causes distortion........
    It will just show you the bs out there..
     
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  3. leftlayne

    leftlayne Bobtail Member

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    Apparently the guy at the cb shop told me he had to remove it because it restricts your wattage. I'll search it up
     
  4. craig_sez

    craig_sez Road Train Member

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    It doesn't take too long before a new CB'er begins to yearn for more. More power, louder modulation, stronger signal, greater distance. The reasons for this are as much psychological as they are technical. Practically speaking, more power allows you to work the more distant stations, which is an advantage if DX'ing is in your blood. Also, when playing in that proverbial sandbox that is the CB experience, like in many other competitions in life, people tend to look up to and respect those who excel at their vocations, and display traits which are head and shoulders above their peers. Likewise then, those same people feel that the stronger they become, the more they will be respected. Power as a sign of status as it were.
    Whatever the underlying reasons, one of the most sought after modifications that CB'ers look for, in their grand quest to be king of the block, is the "peak job". On the surface, this seems straightforward enough. Take a stock FCC legal 4 watt radio, and "boost" the power output to some higher value. After all, more power output translates to the transmission of a stronger signal and more range right? To a point this is true, but it doesn't happen without some tradeoffs. These ramifications of the peak job are not always fully understood by the technically challenged CB'er. Many of these people become confused and can be easily misled by the many inflated claims made by those unscrupulous "Screwdriver Technicians", who are looking only to make a fast buck, and who work hard to promote radio myths in order to separate the unsuspecting CB'er from his disposable income.
    In this article, I will attempt to explain why simply peaking a CB radio is not really a good value for the money.
    Let's first look at signal strength and how it relates to actual transmitter power.
    It would be prudent at this point, to mention a unit of relative measurement which relates to this subject. Many people have heard of the term "db". db is short for "decibel", which is a unit of power relative to a standard reference. Radio people refer to "db's" fairly regularly. The common "S" (for signal) meter, which is standard equipment on most radios, indicates numeric values which are comprised of 6 db increments until "S9", and then read in straight db afterward. The difference between any 2 "S" units is therefore a difference of 6 db, for any signal under "S9". A station giving you an "S8" reading on the S-meter is 6 db stronger than someone giving you an "S7". This, of course, assumes an accurate and linear "S" meter, which most CB's do not have. But for the sake of a discussion, lets assume that they do for now.
    So what does this all, mean? Not much yet until you understand the other side of the equation. That is, what it will take in transmit power to raise that all-important signal reading. On the transmitter side of the equation, every time that you double your power, you increase your output signal by 3 db, or 1/2 of an "S" unit more on another station's "S" meter. That means that if you want to go from say, an "S7" to an "S8", you would have to double your power twice. For someone running a 4 watt CB, that equates to raising the carrier power to 16 watts. And that's just to move one "S" unit. Expanding on this further, lets look at another example. Say that you want to go from an "S7" to an "S9". You would now have to increase 12db (6db per "S" unit), which is the equivalent of going from a stock 4 watt CB, and then turning on a 65 watt amplifier. The steps in wattage get even larger from there. If you are already running 100 watts, and you want to jump 2 "S" units, you'd have to jump up to over 1600 watts (average NOT peak) to achieve it. You're into serious power at this point.
    Ok, now you hopefully get an idea about what is required in the process of raising your signal level. So now let's look at what a typical FCC legal CB is capable of producing in both power and modulation. Power and modulation are in a balanced relationship in an AM radio. If you raise the carrier power, without a proportionate increase in modulator power, you lose modulation percentage, and vice versa.
    A stock, out of the box CB is normally set to run at around 4 watts of carrier power (per FCC rules). Experience has shown me that the most carrier power that a typical radio can be made to produce by alignment only, in most cases, is in the range of 6 to 10 watts. Since it takes an increase to at least 16 watts of power to jump the 6 db necessary to gain just 1 "S" unit increase, you can see that typical CB radios fall far short in "peaking" potential. Increasing the power from 4 to 6 watts will hardly be noticed on the other end
    The other (and very important) factor to consider is modulation. Modulation is what actually carries your voice. Modulation is rated in terms of percentage, and can also be be referred to as "peak" power. A 100% modulated AM signal will have a peak power of 4 times the carrier power in watts. This means that a stock CB running 100% modulation on a 4 watt carrier will have a peak power of 16 watts. CB transmitters are designed to be able to handle the extra peak power contained in the modulation. But when you "peak tune" a radio to put out more carrier power, there is often not enough extra "headroom" left to fully modulate the new power level to 100%. The result is a lower peak modulation level along with the accompanied clipping distortion. Many so-called "CB doctors" try to compensate for the lower modulation level by removing the modulation limiter. By doing this, you allow the modulator to increase its level of audio drive up to the point of modulator clipping and saturation. While this can make you sound louder to a point, this capacity is not infinite and when the modulator reaches the saturation point, the audio wave flat tops and produces audio harmonics and other distortion. This is what is commonly called "splatter", and is responsible for much of the bleed over that is heard on the channels.
    Also, for a high level modulation scheme, (Most AM-only radios) you need to produce an equivalent of 50% of your R.F. carrier power, in audio watts for the modulator to 100% modulate the R.F. carrier. This means that for a 4 watt R.F. carrier, you need 2 watts (1 watt per sideband) of clean audio power. Most CB radios employ an audio amp chip which produces no more than about 3 watts of audio before distortion starts to set in. So you can't properly 100% modulate an R.F. carrier over about 6 watts without incurring distortion.
    For a regulator modulated radio (Most newer AM/SSB radios), the peak power that the modulation can achieve has to be less than or equal to the maximum peak power that the transmitter strip can produce, at the full operating voltage, in order to maintain 100%. Most modern SSB radios can produce SSB and peak power levels in the 18 to 21 watt range. Remember that in order to 100% modulate a 4 watt carrier, you need to be able to reach 16 watts (4X4=16). For a 5 watt carrier, that means you need to peak at 20 watts (5X4=20). For 6 watts of carrier, you need to be able to reach 24 watts peak (6X4=24), and so on. Since most radios are limited to around 20 watts peak, you can not support more than about 5 watts of carrier, before you start losing peak modulation percentage.
    Another factor to consider is the future. When the result of the "peaking" job fails to produce the results which were originally anticipated (and it will!), the owner will then seek out additional power enhancements. This usually means springing for a power amplifier. Most modern transistorized amplifiers can be driven to their full rated carrier output (peak rated power divided by 4) with as little as 1.5 watts of drive power. Driving an amplifier like this with a "peaked" and "clipped" radio running a distorted 6 watts output is a recipe ripe for disaster. It will not sound good, and eventually the owner will have to get the radio "detuned" again, so that it will work properly with the amplifier.
    So you can see that there is very little benefit to be gained by peaking, and a lot to lose. Other than falling short of the high signal goal, peaking a radio can also place more strain on the transmit final transistor which can lead to premature failure. My advice; don't do it! Save the money and buy a better antenna system. A good quality antenna can achieve signal improvements which will be at least as effective as those from a "peak" job, and usually quite a bit better. A better antenna will also improve your receive performance as well as your transmit signal.

    http://home.ptd.net/~n3cvj/peaking.htm



    Antenna Problems

    Antenna Myths

    That site has tons of info for you to browse..

     
  5. x1Heavy

    x1Heavy Road Train Member

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    That to me smells funny.

    You have power to the radio. Provided everything is factory stock, your radio will broadcast whatever you say into it. It will put out a certain amount of power into the air via radio waves for other radios to hear you and speak to the human near it.

    You will be heard and sometimes you will hear. IF someone has 50,000 watts in Omaha, you will hear him. But he aint gonna hear your 4 watt radio in bonchance tahiti.

    This babbly BS from the Tech about restricting wattage? nuh uh. nope sorry. He's leading you down a pathway you do not wan to go.

    In electricity there is watts, Amps, Ohm and resistance. All of them have a relationship.

    You can always add wattage with a amp. But I don't know anything about American Law on limits to power allowed on radios and broadcasting etc.

    Did you ever stop to wonder how your tiny smartphone pushing maybe a watt can talk to a Cell tower 4 miles away? It needs a whole lot of power to convert very high energy frequency and carry the data across that.

    You are talking into a CB radio that has been around since essentially the late world war two years. The only difference between their vacumn tubes and today is the solid state chip that all modern computer based technology runs on today. Your radio has a certain amount.

    Your precious tech babbling about clipping wires and watt restrictions, Im sorry, bless his heart my precious. He needs some learning don'tcha know.
     
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  6. craig_sez

    craig_sez Road Train Member

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    Tks heavy..Finally 2 people understand and help me tell op..
    Some were sayin amp it will solve most of his issue...
    Good now maybe op will be a lil closer to understanding he has issues..Been sayin through the tjread that no amp yet..Figure out ant/radio issue 1st...
    Now we know that 99% of the issue is the tech(hahahaha) who got into it..
     
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  7. jessejamesdallas

    jessejamesdallas Road Train Member

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    Well...a Amp wont help you hear any better...They do have things called "pre-amps" which are suppose to bring distant signals in louder...but for the most part all they do is make the noise louder...pre-amps pretty much do the same thing as turning up your RF Gain knob on the front of the radio.
     
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  8. slim6596

    slim6596 Medium Load Member

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    So, to summarize:

    Fix what was done to the radio
    Upgrade antenna system

    Then see where you are
     
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  9. craig_sez

    craig_sez Road Train Member

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    Pretty much...I dont know anyone who is any good with basic radios..
     
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  10. Meteorgray

    Meteorgray Heavy Load Member

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    Telling a guy with a new 62-inch mag-mount Wilson on the top of his pickup truck to "upgrade his antenna system" is really poor advice here.

    I know that some folks have an aversion to magnet-mounted antennas for whatever reason, but it can't objectively be for poor performance. There have been tests during the past several decades, from Motorola on down, that show the signal loss for a magnet-mounted antenna on a metal roof to be 0.2 decibel or less as compared with a hole-in-the-roof equivalent. This level of loss can only be detected by sensitive equipment, which doesn't include the human ear.

    So unless the Wilson is defective, it will do as good a job on top of that truck as any 62-inch antenna out there. Talking 20 miles vehicle-to-vehicle as the OP has said demonstrates his is not likely to be defective.
     
  11. Ridgeline

    Ridgeline Road Train Member

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    But those at the bat company didn't take into account a problem with common mode current which I've seen in mag mounts. This will degrade preformance.
     
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