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Antenna Project

Discussion in 'Home Brew' started by JDemoret, Apr 27, 2009.

  1. RickC.

    RickC. Hopeless antenna junkie

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    Hey John,

    I'm coming to the party late on this one (you snuck this by me while I was tied up at Talladega), but good stuff! I was wondering what you were going to do with this that you needed an LC circuit at the base... But right, you shouldn't need a capacitor across this one. And your coil looks better than the one I made with the runny epoxy!

    I look forward to seeing more pics and hearing how this performs when you have it up in the air.


    Rick

     

  2. JDemoret

    JDemoret Member

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    Thanks Rick. So far the antenna has performed alot better than expected and I'm really excited about getting it up in the air.

    Homer, I picked up 40 ft. of 1 1/4 inch EMT and I'm going to try to use it all, will let you know how it goes once I get a full day to work on it and some good weather.

    John (y)
     
  3. JDemoret

    JDemoret Member

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    Finally got the antenna up in the air. Had to settle for 32ft. at the feed point but that's alot better than 6ft. where's it's been for the last two weeks. Had to replace the bottom section as it snapped in the first attempt to get it up but was able to fix it and eventually got it all in place.

    Final SWR:
    Channel 1: 1.4:1
    Channel 20: 1.2:1
    Channel 40: 1.1:1

    The antenna is reading "short" and I haven't messed with the tap point on the coil yet and am not sure if it would change anything and I need to double check the angles of the ground radials to make sure their at 45 deg. and again not sure if it would change anything but those are the only options I have unless I take it completly down and add more to the radiator. Oh well, it's all good.

    John
     

    Attached Files:

  4. W5LZ

    W5LZ Crotchety Old Bastard

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    About the antenna reading 'short'/shorted(?).
    Depending on how that coil is connected, it should read as being shorted at DC. That doesn't mean it will be a 'short' at the frequency of use. I can't tell from the picture (and am too lazy to go back through the thread), but if the bottom of the coil is connected to ground on the SO-239, then it is a DC short, and is still not a problem at the frequency of use. If the bottom of that coil is connected to the SO-239's center pin, then it isn't a 'matching' coil, it's a 'loading' coil. If it shows a short this way, then there is a problem somewhere.
    - 'Doc
     
  5. HomerBB

    HomerBB Sr. Member

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    Perhaps he's referring to the SWR being higher on 1 than forty which by some is said to be short and can be fixed by lengthening the vertical whip on an antenna. . .

    BTW, it looks good.
     
  6. JDemoret

    JDemoret Member

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    Doc,
    I'm sorry I was not clear. The antenna is showing physically short according to my SWR readings. I know that adding to the radiator would tune the antenna but I'm going to try messing with the tap point on the coil and the ground radial angles. Thanks for the come back. :D

    John
     
  7. W5LZ

    W5LZ Crotchety Old Bastard

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    Hmm. Guess I might pay a little more attention, you think?
    - 'Doc
     
  8. JDemoret

    JDemoret Member

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    It's all good Doc! (y)

    John
     
  9. JDemoret

    JDemoret Member

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    Homer,
    For some reason I missed your reply :unsure:. Thanks for the compliment and yes that is what I meant. As of right now haven't been able to work with it any further but will fool around with things and let you know.

    John
     
  10. HomerBB

    HomerBB Sr. Member

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    Cool
     

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