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homebrew astroplane build

Discussion in 'CB Antennas' started by loosecannon, Jul 10, 2009.

  1. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    Hey Oscar, I'm always open for dimensions for the A/P.


     

  2. Oscar Goldman

    Oscar Goldman Active Member

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    When I get to the shop I will measure it and post them.
    I have my custom built sigma 4 up right now, so the astro plane is hanging up.
     
  3. Oscar Goldman

    Oscar Goldman Active Member

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    Hoop diameter 29.75
    Lower elements from top of bracket to ring 92.5
    Straight top section, from top of bracket to tip 88 inches.
    Element separation at feed bracket 6 inches center to center.
    Element separation 48 inches below feed bracket 11 inches center to center.
     
  4. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    Thanks Oscar. Considering some differences in tubing diameters, our dimensions are very close. I also have a model that has a full 0.25w radiator instead of the top hat version.

    Thanks
     
    Redbeard U812 likes this.
  5. Riverman

    Riverman Intermittent Member

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    #50 Riverman, Feb 24, 2020
    Last edited: Feb 24, 2020
    wavrider and HomerBB like this.
  6. Redbeard U812

    Redbeard U812 WDX-1030 / U812 South Texas

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    So.....you gonna drill that hole after awl.
    gettyimages-940502128-612x612.jpg
     
  7. Riverman

    Riverman Intermittent Member

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    Won’t be necessary. :)
     
  8. Dmans

    Dmans Sr. Member

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  9. Riverman

    Riverman Intermittent Member

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    Oh, man! No wonder it was so cheap. :(
    Guess I can use it as a coaster.
    And who the heck is BKS? (n) I thought he was a serial killer from Kansas. o_O
     
  10. Dmans

    Dmans Sr. Member

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    The same seller has a CD of the "Tail Gators". The bass player (Keith Ferguson) is the original bass player of the "Fabulous Thunderbirds" and is excellent (though dead now). Thought about snagging it up-but then I realized I don't have a CD player!!

    73
    David
     
  11. Riverman

    Riverman Intermittent Member

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    I was just funnin' about the Astroplane and seeing if I could fool fool anyone. :D

    I still have a CD player and a ton of CD's. Bought one of the small Bose Music Machines when they first came out. Still works great.

    Thanks for the heads-up about Keith. Didn't know. (y)
     
  12. loosecannon

    loosecannon Sr. Member

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    Hey Marconi or anyone else who uses EZnec.

    does that program allow you to play with different types of capacity hats?

    like if you wanted to try changing the "four horizontal element" cap hat on the astroplane to a clover style cap hat, would the program help you get the dimensions that would be involved?

    thanks in advance.
    LC
     
  13. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    LC, I use straight wires, mostly 4 as in a cross. I can make simple arcs, but they are not easy to model or edit when necessary.

    So, is it possible? Yes, but IMO it is not practicable for me as long as I can basically do the same with straight wires. I'm not sure there is a functional benefit difference either.

    There maybe software out there that provides some geometric shapes however.
     
    #58 Marconi, Feb 26, 2020
    Last edited: Feb 26, 2020
  14. loosecannon

    loosecannon Sr. Member

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    thanks for the reply Marconi.

    the idea popped into my head while reading about lightning protection, and i was thinking that the clover leaf design would be less attractive to lightning than the four pointed radials.
    how much is it attractive to lightning right now?
    no idea.

    how much would it benefit from the change in this regard?
    no idea.

    now im wondering if connecting the ends of all four horizontal radials together at the tips might accomplish the same thing.

    is there an easy way to model that change?
    not trying to give you work, but if it's easy it might be neat to see how this would affect the patterns if at all.

    what can i say im a curious guy.

    i am finally about ready to order the fiberglass tubing i will need for my non-conductive mast, and i already have the ferrite kit from Palomar Engineers to put on 1/4 wave down from the hoop.

    i do wonder how much using the .240" coax shield as the only metal conductor going down the center will affect the K factor/ bandwidth, and whether it would be worthwhile to go with .405" coax.

    don't really have any data from previous experience to use for comparison, so i guess i'll just see what happens when i finally get this up in the air.

    final height for the top of the antenna (horizontal radials) will be right about 46 feet above ground. i have abandoned the idea of using a straight vertical radiator on the top for now, as i don't need any more variables involved.
    LC
     
  15. Marconi

    Marconi Usually if I can hear em' I can talk to em'.

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    LC, I don't know the science here, but I've always heard making the tip of a conductor larger helps deter lightning better than a small sharp pointed tip. Not sure what would work best between a clover leaf design vs. 4 pointed radials, bur the straight radials are much easier to model.

    I have a GR45 mobile antenna with two SS orbital top hat elements. They are touchy to tune and maintain, even though I used them as static 1/4 wave antennas over a good groundplane as a base setup. I don't know if it was birds or poor design, but they tended to get bent down a bit and that changed the tune. The same could happen with straight radials, but they are easier to secure to the top of the radiator without adding weight.

    I'm like you. No idea.

    I'm curious too, so I'll take my A/P with the 4 wires and get a base line. Then connect the wires together and report the effects on match and performance. Then I can re-tune it and see how much the length changes.
     
    #60 Marconi, Feb 28, 2020
    Last edited: Feb 28, 2020
    loosecannon likes this.

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