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Mobile Base Station setup help.

Discussion in 'General CB Services Discussion' started by Capt Crunch, Mar 2, 2021.

  1. Recon

    Recon NY 881

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    Hey guys, don't laugh but I had the same issue all of a sudden. Believe or not, one of my neighbor's LED lighting pods for his pepper plants in his cellar was the culprit. He said it was a bad / cheap ballast. By process of elimination, he turned off one pod at a time until the noise went away. Is this a candidate for Myth Busters? lol...lol...lol!


     

  2. Recon

    Recon NY 881

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    Are you interested in a Carl Built 100 Amp Power Supply?
     
    Capt Crunch likes this.
  3. loosecannon

    loosecannon Sr. Member

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    Hi Capt. Crunch.

    Is that aluminum siding on the house next to your antenna?
    if so, that is going to distort your signal pattern and block you from getting out in that direction. may even affect SWR.

    if you can get the base of your antenna up to the same level as the top of the siding, you will get out much better.

    also, chain link fencing is a terrible counterpoise, which means other half of your antenna.
    this "other half" can consist of another 1/4 wave radiator pointing straight down from your mount, or it can be a ground plane, like radials, or in your case, the chain link fence.
    the electrical connections in a chain link fence are iffy at best for RF, and can create a lot of noise in your receive.

    if you get an 8 foot long 4x4, and strap it to that fence post; you can mount your antenna up on the top of the 4x4 and run the four radials down from the mount as others have suggested.
    even two will work quite well for you. not ideal but a much smaller difference than you would think.

    remember that using ground rods is for safety from lightning, not for RF counterpoise like is needed for your antenna.
    LC
     
    Capt Crunch likes this.
  4. Capt Crunch

    Capt Crunch Captain Crunch NJ Mobile

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    No thank you. Bought a 30 amp Jetstream, dual meter. Didn't even think of Carl's PSs, and I have one of his amps LOL.
     
  5. Capt Crunch

    Capt Crunch Captain Crunch NJ Mobile

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    First, thank you. Well one of my questions is should I shield the fence from the mast I am going to do. My SWR is flat across the 40 channels. Was a little off in the beginning(1.2 on1 1.5 on 40) before tune at antenna. I can put heavy duty rubber gasket material on the pole to pole mounts to separate th mast from the fence. I will be doing my set up as in the video. Only difference is I am using 103 inch lengths, same as antenna. The video is what I am doing on the fence post if you haven't seen the previous reply...
     
    #65 Capt Crunch, Mar 12, 2021
    Last edited: Mar 12, 2021
    Shadetree Mechanic likes this.
  6. M0GVZ

    M0GVZ Sr. Member

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    Good old antenna theory and testing shows that in any direction there are no radials there is a -6dB difference to the direction there are. So if you only had radials north and south you'd find signals to the east and west being about 6dB or 2 S points weaker.

    For DXing the proximity of the house will make little difference. I once remember demonstrating to a friend of mine this by parking right next to a metal roller shutter door in my car about 6ft away and making contacts with the USA despite the roller shutter door being directly in the way.
     
  7. Capt Crunch

    Capt Crunch Captain Crunch NJ Mobile

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    Good to know, thank you. Well the two radials will be pointing where I need them to be as per your reply and people I talk to. I would like at least one more out in the open yard but I don't want to interfere with my landlords yard. I was reading about radials and the amount as per the length and a chart on how good so many radials will do. They said between 16 and 32 radials is the sweet spot. It says how to do the math on the length of the radials as they said its gets shorter the more you use, but I couldn't figure it out. I was wondering if anyone knew the length and how many I would need for my 103 in set up here, if that is all correct, would it be better to make a multiple shorter radial GP? I have about 2ft of open space all around the mount.
     
    #67 Capt Crunch, Mar 12, 2021
    Last edited: Mar 12, 2021
  8. freecell

    freecell Member

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    Capt Crunch,

    your vertical radiator @ 103" is not resonant anywhere at any frequency in the 11 meter (citizens) band. it is resonant near 28.65 mhz, in the ssb phone segment of the 10 meter amateur band. that "whip" with the added heavy duty ball and spring is approximately 108.5" long as it is used in the 11 meter band. at its current length it's about 5.5" too short. fyi.

    reference:

    http://www.csgnetwork.com/freqwavelengthcalc.html
    when the page loads it defaults to 27.185 mhz.. just click
    on the "1/4 wave" button and read the information below.

    enter 28.650 mhz. and repeat the process to confirm the
    information provided above.
     
    #68 freecell, Mar 14, 2021
    Last edited: Mar 14, 2021
  9. Capt Crunch

    Capt Crunch Captain Crunch NJ Mobile

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    Ok read that before. I use 27.205. This one says 103 in whip with radials the same length? http://www.csgnetwork.com/antennagpcalc.html I understand its two things but it's for the same frequency. That's what's confusing me as when I saw 108 I only saw one other and then I found like 4 of the GP calculators and they say 103.
     
  10. freecell

    freecell Member

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    246 divided by 27.205 = 9.042 feet, 108.504 inches.

    the gp calculators are wrong every time and will
    leave the antenna resonant at frequencies well
    above your target frequency, easily confirmed
    with any decent network analyzer. just fyi,
    27.185 mhz. is the exact center of the assigned
    citizens band from 26.965 - 27.405.
     
    #70 freecell, Mar 14, 2021
    Last edited: Mar 14, 2021
  11. Riverman

    Riverman Premium VIP Member

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    In my experience, books and calculators are good for starting points but the actual figures depend on other factors such as height above ground and nearby objects. Have made 1/4 wave GP’s in the past and usually ended up at about 103” all around. Mine were never mounted very high though. Usually only about 10-15’.
     
  12. Capt Crunch

    Capt Crunch Captain Crunch NJ Mobile

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    Ok cool, thank you. Been reading about that all week LOL.I myself was going with 108 for years until I started reading the other ones when starting this and changed recently as per all the GP calculators saying 103.. Glad to be clarified on that. That being said I gather my radials should be the same length at the 108. Also, maybe you would know I recently read that you can divide the radials and have multiple shorter ones, and between 16 and 32 radials is the sweet spot. Have you read this or have knowledge in this as I would rather have a bunch of short radials around my mount than the fewer(2) longer ones hanging down. I have at least a 2ft open space around the mount.
     
  13. Capt Crunch

    Capt Crunch Captain Crunch NJ Mobile

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    Yes I read about the factors also. And the guy in the video I found was at 102 which is the one I am going by as per his build but at 108 to start. Mine is probably going to be about 16ft high to the top. I think I will start with 108 and go from there just in case, and the experience. I would like to figure out what I read if true about making multiple radials shorter(elevated), but then again its saying its not the same as long radials as these are elevated. I wish my brain would read and compute what I want to learn faster LOL. Plus all the difference in opinions and wording. They say how to figure it out but I don't know about dividing wavelengths well at all. https://ham.stackexchange.com/quest...nt-number-of-radials-with-ground-plane-antenn
    http://www.astrosurf.com/luxorion/qsl-radials.htm
     
  14. freecell

    freecell Member

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    Riverman,

    "In my experience, books and calculators are good for starting points but the actual figures depend on other factors such as height above ground and nearby objects. Have made 1/4 wave GP’s in the past and usually ended up at about 103” all around."

    exactly what did you measure that led you to determine that 103" was a proper resonant length for the frequencies in question?
     
    Capt Crunch likes this.
  15. Riverman

    Riverman Premium VIP Member

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    Didn’t say they were resonant. Those were made in the days before I purchased my RigExpert AA-54 so had no way of measuring reactance. Like many, the only thing I had to go by was SWR. Adjusted lengths for lowest on CH 20. (y)
     

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