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Slim Jim for 11m

Discussion in 'CB Antennas' started by linearone, Feb 2, 2009.

  1. linearone

    linearone King of NY

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    Has anyone ever attempted to make a slim jim for 11m? I know at 26 ft its kinda big but has it ever been done?


     

  2. W5LZ

    W5LZ Crotchety Old Bastard

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    linearone,
    Probably not. Not that it couldn't be done, or that it wouldn't be worth the effort, but just becasue of the length, 26 feet. I'm not too sure I could find any PVC pipe that would stand up at that length. Or a 2 x 4 at that length?
    What typically works at one frequency can be 'scaled' to work at another frequency. The 'catch' is that the physical properties, as in supporting the thing, change too. If you can figure a way around that, why not?
    - 'Doc
     
  3. linearone

    linearone King of NY

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    would there really be any benefit over a dipole?

    would there be matching issues with this much metal up in the sky?

    Would I have to add a small capacitor to tune it?
     
  4. W5LZ

    W5LZ Crotchety Old Bastard

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    "would there really be any benefit over a dipole?"

    I don't know, but doubt it, both are 1/2 wave lengths.


    "would there be matching issues with this much metal up in the sky?"

    That's what that 'J' thingy at the bottom is for, it does that matching.


    "Would I have to add a small capacitor to tune it?"

    Not really. Adding capacitance is a means of shortening a radiator. So, just shorten the radiator. Or, make that matching thingy slightly larger/smaller, change the feed point.
    This 'Slim Jim' is very much the same as a 'J'-pole. Treat it as such and it should act just fine.
    - 'Doc
     
  5. bob85

    bob85 Supporting Member

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    greg i was talking about making one out of two cut down vector 4000 radiators a while back,
    the most difficult part imho would be mounting it and isolating it from the mast, the other dimensions ( length / spacing / insulator gap size ) could all be made adjustable for tuning,
    after looking around at conflicting ideas about how they work with some claiming they are no better than a regular jpole i decided against the idea,
    its the vector style for me, no pretenders to the crown will do;)
     
  6. DX-DIGGER

    DX-DIGGER Member

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    Not Sure if you have considered this but the lower 1/4 wave of the slim jim
    could actually be bent 90 degs to the vertical part and I dont think it would make any difference to the transmitted vertical signal, i saw a guy who had made one for 70MHz band and he had done this to fit it inside his loft space.
    just thought i would offer this info. HTH Mark 73 :D
     

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