Because I was told, but never understood why?

Discussion in 'CB Radio Forum' started by TheDude1969, Mar 21, 2016.

  1. Mar 21, 2016 #1
    TheDude1969

    TheDude1969 Heavy Load Member

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    Handlebar's post on coiling your coax is a perfect example, and got me thinking about some things I've always just done (or didn't do) because I read it somewhere, and never knew the purpose.

    Grounding:
    1. I fully understand the purpose of a good ground/counterpoise (at least I think I do), "to reflect the signal" in simplest terms. But if the coax outer braiding is already grounded and has 0 ohms to body, frame, and battery, what is the purpose of grounding (example a bird perch mount) to frame?
    2. Which begs the next question, why isn't the outer braiding used as the counterpoise... or is it? Thus making it a dipole, connected to a sea of grounded frame work, of chassis, body, and all kinds of hunks of metal within a vehicle.
    I've got many more questions, but don't want to muddy any response with other topics. Feel free to answer like I was in kindergarten, or draw a picture in crayon. <--- I find those most helpful!
     
    TheDude1969, Mar 21, 2016
    TheDude1969, Mar 21, 2016
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  3. Mar 21, 2016 #2
    Ridgeline

    Ridgeline Road Train Member

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    Ridgeline, Mar 21, 2016
    Ridgeline, Mar 21, 2016
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    handlebar and TheDude1969 Thank this.
  4. Mar 21, 2016 #3
    TheDude1969

    TheDude1969 Heavy Load Member

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    CRAP ! I was wanting a one line post. J/K
    Thank you Ridgeline
     
    TheDude1969, Mar 21, 2016
    TheDude1969, Mar 21, 2016
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    Blaskowitz Thanks this.
  5. Mar 21, 2016 #4
    Ridgeline

    Ridgeline Road Train Member

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    Sorry next time I will just put up on line.
     
    Ridgeline, Mar 21, 2016
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  7. Mar 25, 2016 #5
    TheDude1969

    TheDude1969 Heavy Load Member

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    Antenna:
    I've been told, the thicker the antenna the more power/performance/distance and more broadband is a result. And I've read all the articles about top loading vs bottom, (I get it) but what I don't get is how the small guage conductor inside the coax can be improved by a thicker mass after its already been limited in size within the coax. <---thus a wattage limit within the coax?
     
    TheDude1969, Mar 25, 2016
    TheDude1969, Mar 25, 2016
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  8. Mar 25, 2016 #6
    Ridgeline

    Ridgeline Road Train Member

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    Not true.

    The distance/performance and so on are dependent on a lot of factors but it isn't the thickness of the antenna. The reason you see antennas being heavy is because they are put into a mobile application and need the strength to survive. The same goes for base antennas, they are made to survive wind.

    On top of that, there are a few uniquely designed antennas (like EH and CFA) that out preform any standard CB antenna that you can buy. These antenna are small, thin and in many cases fragile.

    I've used 24 gauge multi-strand wire before to talk to Europe with a couple watts, did a bunch of contacts to the Caribbean on 10 meters with a simple dipole and 100 watts. I just was reading this morning about a guy who uses digital modes and 100mws with a simple dipole on 40 meters by the way.

    Wattage is limited first by the transmission line - Coax - then by the antenna mechanical features. I've seen mounts melted by the heat with 5k but they were running hardline to the antenna. I don't think anyone should be running 5K in a mobile because of the amount of RF exposure, beside it really pisses people off for miles.

    I have three antennas setup at my radio location, the first is a dipole made of aluminium electric fence wire, the other is a vertical (like a big Stepper IR) and for now I have a 80 meter EH - all of these have had 1.5Kw through them at one or another time and survived, the EH got really hot but survived.

    Hope that answers some of your concerns.
     
    Ridgeline, Mar 25, 2016
    Ridgeline, Mar 25, 2016
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  9. Mar 29, 2016 #7
    rabbiporkchop

    rabbiporkchop Road Train Member

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    A thicker Antenna add capacitance which requires a shorter coil for example a friend of mine used a piece of copper pipe on his F350 and it was only about 7 feet long but it was much thicker then a 9-foot whip
     
    rabbiporkchop, Mar 29, 2016
    rabbiporkchop, Mar 29, 2016
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    TheDude1969 Thanks this.
  10. Mar 30, 2016 #8
    Ridgeline

    Ridgeline Road Train Member

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    But in many cases the diameter has to be increased a bit more than a 1/4 inch to actually see a gain. There is also a difference in using steel opposed to aluminium opposed to copper.
     
    Ridgeline, Mar 30, 2016
    Ridgeline, Mar 30, 2016
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