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Base antenna elements

Discussion in 'CB Antennas' started by Arkieguide, Jul 17, 2018.

  1. Arkieguide

    Arkieguide New Member

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    Probably very basic to you folks. I am building a 3 element CB base antenna. QUESTION - do I bolt my aluminum elements directly to a metal boom - are separate them with insulating pads. Getting back in after 30 years absence.Forgot most of what I knew. Any way I have the aluminum for the elements but thought of using PVC pipe for the boom which would separate the elements from the boom.. are maybe steel tubing and insulate the elements from the boom. SUGGESTION please.



    Thanks
    arkieguide
     

  2. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Either way works but insulated elements may require a slight adjustment in length..........longer.
     
    357magnum likes this.
  3. Arkieguide

    Arkieguide New Member

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    I guess I will use aluminum elements connected to a 10' piece of EMT. That connected to a steel piece into my rotor, then to my steel mast, I will use a 1-1 balun. Then 50' from antenna a coax ground block. Thanks for your help
     
  4. sp5it

    sp5it Master of puppets

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    Insulated or not, depends on antenna design.
    MIke
     
  5. Arkieguide

    Arkieguide New Member

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    sp5it - simple 3 element beam - the DE positive and negative separated by 2 " with a fiberglass rod , it will not be connected to the boom. Antennas are nor as simple as some people say.
     
  6. sp5it

    sp5it Master of puppets

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    Driven element must be insulated, no doubt, but reflector and directors depends on design :)
    Mike
     
    Captain Kilowatt likes this.
  7. camaro1

    camaro1 Well-Known Member

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    driven element can also be attached directly to the metal boom if your feeding it with a gamma match,, have several antenna's up in the air that are designed this way
     
    Captain Kilowatt likes this.
  8. JAF0

    JAF0 New Member

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    I vote no on EMT. Poor conductor & dissimilar metals do funky things when you add water + RF + time.
     
  9. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Starting with the fact that there is no positive or negative parts of an antenna element. RF is AC and as such has no fixed polarity.
     
    JAF0 and sp5it like this.
  10. sp5it

    sp5it Master of puppets

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  11. Arkieguide

    Arkieguide New Member

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    First I refer to positive & negative - looking at the sine wave up and down is goes - down is negative up is positive. I did not want to get into advanced discussion . I do not know it all - unlimited master electrician ship & shore- Elec. Eng. - not a smart ass. you are correct sp5it.I get so many different answers to my antenna question. It gets confusing. The fed element is isolated from the boom, so I wonder why the other 3 could not be isolated.
    If all 3 are isolated then a steel boom is ok to get more strength. I chose the 3 element for space and weight. I started out with a 4 element but dropped to 3 to save space and boom length. Thanks for ant help you can give me.
     

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