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Thread: Best CB Antenna

  1. #61
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    Default Re: Best CB Antenna

    Quote Originally Posted by Bbasso View Post
    Yup, mine has constant power, so for camping and such I can have it on and not leave the key in also keeps the last station in memory.
    I have no clue how the coax cable's condition is, it's been around a while and not removable from the antenna.
    Is there a way to check the SWR without a meter? ( I doubt it) I don't know of any local CB shops near me... Everything is big box stores with no knowledge or care.
    As for the placement of my antenna, While it's far back it is on the roof (good) but with not willing to drill holes this was the best place for running the short 15ft wire.
    I don't seem to be one taken seriously in this thread but because I know things learned in college I will throw this out there for the wolves to attack.

    In the old days before there was equipment that checked SWR readings, light bulbs were used. The old timers pit them at the end of the antennas and keyed up and the bulb would light up. These are not magnetic waves. They are Nikola Tesla's standing waves. If I remember right the bulb does not have to be connected TO the antenna. Just near it. The bulb brightness and dimness explained what your power readings were doing which helped "tune" your antenna.

    Google it to see how it was done because If I explain it, I might be told I don't know what I am talking about so I'll let you do the research.
    Good luck!

  2. #62
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    Default Re: Best CB Antenna

    Quote Originally Posted by Chickasaw View Post
    I don't seem to be one taken seriously in this thread but because I know things learned in college I will throw this out there for the wolves to attack.

    In the old days before there was equipment that checked SWR readings, light bulbs were used. The old timers pit them at the end of the antennas and keyed up and the bulb would light up. These are not magnetic waves. They are Nikola Tesla's standing waves. If I remember right the bulb does not have to be connected TO the antenna. Just near it. The bulb brightness and dimness explained what your power readings were doing which helped "tune" your antenna.

    Google it to see how it was done because If I explain it, I might be told I don't know what I am talking about so I'll let you do the research.
    Good luck!
    No attack just providing alternative information along with some posts supporting the information I was giving.

  3. #63
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    Default Re: Best CB Antenna

    Quote Originally Posted by Mudderoy View Post
    No attack just providing alternative information along with some posts supporting the information I was giving.
    Now I had a long explanation as a reply but the forum kicked me out I guess because I took too long.

    I'm not going to bother retyping all of that.You have been kind since I have been a member so I will just go back to the shadows and enjoy good reads.
    Let it be known that I DO have an Associates in Electrical Engineering and understand radio propagation well, along with a million other things necessary to graduate, such as process control. PLC programming, robotics, sensors and troubleshooting, C+ programming, Digital/Analog, Physics, Ohm's, and everyone else's laws, Mosfets, through hole and surface mount circuitry, AC/DC, logic controllers, hydraulics and pneumatics, and a list too large to mention.

    I have mentioned this only to show I have not just had my head filled full of mush but instead I experimented on these things myself and the coax is part of the length of the antenna. No one has to believe me. Just like you, I only came to help but no one will "get it" until they tune an antenna then hook up a different length coax.

    If your antenna is not tuned, eventually that final transistor is gonna fry whether you like it or not. Can't tune a whip unless you add to it or cut it off. The only other way is to adjust the length of your coax. Been there.

    I will just leave it alone now and keep what is in my head, in my head. It's late and I need to post this before the ether eats it.

    Happy muddin' everybody!

  4. #64
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    Default Re: Best CB Antenna

    Quote Originally Posted by Mudderoy View Post
    No attack just providing alternative information along with some posts supporting the information I was giving.
    I put links to everything I was trying to say on Firestiks website. They explain it ALL and in laymans terms. If you want facts installing an antenna go check out their FAQ's. They do a FINE job of explaining do's, dont's, why's and why nots. Don't take my word. Go see what the pro's say. It's to the point.
    PEACE!

  5. #65
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    Default Re: Best CB Antenna

    You know I bet we're both saying the same thing.

    If the antenna impedance ISN'T 50 ohms (or not the same as the transmitter and feed line) then changing the coax length will change the SWR, although it's not doing anything for you but fooling the transmitter, like a tuner does.

    Found this on http://www.k0bg.com/

    Coaxial Myths

    Coaxial myth one: Several antenna manufacturers suggest using a specific length coax cable between the transceiver, and the antenna. Or, they suggest using an open stub cut to some length. Both of these schemes are SWR patches, not fixes. Shunt matching is the only correct way to match a remotely tuned HF mobile antenna to 50 ohms. If you read the article, you'll know why.

    Coaxial myth two: Using the best grade of coax money can buy, will be worth the expense. Not! There are two aspects of this myth. First, the the length of coax used in the average mobile installation, seldom exceeds 10 feet. Thus the difference between say RG213, and RG8X, is less than .25 dB! Ah, but there is a hidden facet as well! As mentioned above, it is very important to properly choke off common mode currents from coaxial feed lines, especially mobile ones. In order to duplicate the common mode choke shown at right (7 turns, 3/4 inch ID, mix 31 split bead, ≈2.2 kΩ @ 10Mhz) on RG213, would require 49 similar split beads. That's about 250 worth, instead of just 5! By the way, serial bead chokes tend to be mostly inductive, rather than mostly resistive over their bandwidths, which reduces their common mode effectiveness.

    The Article
    Matching a mobile antenna to the requisite 50 ohms is a requirement for several reasons. For example, modern solid state radios are designed to reduce their output power when the input SWR reaches ≈2:1. Some will handle a little more, some a little less. Once matched, the SWR doesn't have to be flat, so anything below 1.6:1 is close enough. Remember too, if the unmatched input impedance of your antenna, is less than 1.6:1 at resonance, you need a better antenna and/or mounting scenario.

    One very important point needs to be mentioned before proceeding. If you're using a remotely controlled HF mobile antenna like a Scorpion, the motor leads (and reed switch leads if used), and the coaxial feed must be properly choked. If they're not, you'll have terminal problems, and that's no pun! If you don't understand why choking is so important, read these articles: Antenna Controllers and Common Mode.

    Further, improper choking of the motor leads will also affect the input impedance of your antenna. Therefore, the motor leads should be disconnected at the antenna before attempting to adjust any matching method. Once matched, if reconnecting the motor leads changes the matching point and/or SWR (no matter how small the change is!), it is a good indication that the motor lead choke impedance is too low.

    Antenna manufacturers often tell their customers to cut their coax feed lines to a specific length in order to get a good match. All this does is mask the problem, by moving the SWR node to a different position along the feed line. While this may appear to fix the problem, it doesn't fool most automatic controllers. The truth is, if the antenna is properly matched, it doesn't make any difference how long (or short) the feed line is.

    In the following sections, it is necessary to know the exact resonant point (X=) of the antenna we're trying to match. This fact alone, should not infer that exact resonance is a requirement; it isn't! Rather, in this case, it is only a means of arriving at the end point (wide-band match). Once the matching is complete, whatever the SWR is (assuming it is under ≈1.6:1) is irrelevant.

    It should be noted that solid state transceivers can generate excessive IMD levels (the FCC mandated ones) when the SWR is over 1.8:1 or so—yet another reason to properly impedance match antennas. While most mobile operators seemingly don't care about IMD, they should! Especially so when using an amplifier which amplifies the IMD along with everything else. In other words, garbage in, garbage out!

    Hang in there, nothing like a good argument as long as respect is maintained!

  6. #66
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    Default Re: Best CB Antenna

    Quote Originally Posted by bluedragon436 View Post
    Going a bit higher on the new Firestik antenna I'm ordering, as well as a new coax, just in case the current coax on my setup is the issue... I cannot however go with a 102" whip, as they are illegal in DE apparently, cause I have a friend who has one on his XJ, and he got a ticket for it... and it was tied down to the front of his rig, but still got a ticket... so going with a 5' Firestik instead of the 4' Radio Shack special I had.. since I was having a SWR tuning issue with my setup... Tried to grind the mounting points to give it a better ground connection, but for some reason the SWR got worse... so going to try and replace the ant, with a better one, and a new coax, in case that was the issue for some reason...
    Wow that sounds about as dumb as the cutting barbed wire law we have (had?) in Texas. Wait! Are you sure about this? I mean HAMs can and do have MUCH longer antennas. I wonder if it's a law for a specific antenna. HAMs would come unglued in DE if it was an antenna length thing.

  7. #67
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    Default Re: Best CB Antenna

    Quote Originally Posted by Mudderoy View Post
    Wow that sounds about as dumb as the cutting barbed wire law we have (had?) in Texas. Wait! Are you sure about this? I mean HAMs can and do have MUCH longer antennas. I wonder if it's a law for a specific antenna. HAMs would come unglued in DE if it was an antenna length thing.
    Yeah I don't get it... Apparently hams are allowed to have whatever ant. setup works for the rig... but CB's can't??!! I don't know, doesn't make any kind of sense to me.. I just know that he got a few tickets on different occasions for his ant, being too long and a danger to bystanders... which is kind of funny, since he always has the end tied down to the front of his Jeep, not up in the air and whipping around where it'd be dangerous... Kind of confusing to me...
    FORMER GREEN XJ CLUB MEMBER
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  8. #68
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    Default Re: Best CB Antenna

    Quote Originally Posted by bluedragon436 View Post
    Yeah I don't get it... Apparently hams are allowed to have whatever ant. setup works for the rig... but CB's can't??!! I don't know, doesn't make any kind of sense to me.. I just know that he got a few tickets on different occasions for his ant, being too long and a danger to bystanders... which is kind of funny, since he always has the end tied down to the front of his Jeep, not up in the air and whipping around where it'd be dangerous... Kind of confusing to me...
    I've found there are usually several HAMs in the legislature.

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