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The Search for the Perfect Antenna . . .

Discussion in 'Amateur Radio Antennas' started by Riverman, Dec 5, 2018.

  1. Riverman

    Riverman Part-time Member

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    Can't believe I've had this antenna nearly a month and it's still in the box. o_O Christmas, birthdays, being sick twice and the winter weather have all conspired against me. :(

    Six half-wave dipoles, one feedline, and one mast in just a small area. Perfect for a homeowner with restrictions and limited options.



    Or so it seems.
    Will report back one of these days. (y)
     
    binrat and Slowmover like this.

  2. binrat

    binrat WDX Club Coordinator
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    Antennas never work if installed when the weather is nice.
     
  3. Slowmover

    Slowmover Sr. Member

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    Much too funny. True for more ventures.
     
  4. Riverman

    Riverman Part-time Member

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    No question about it. (y)
    I'd get out there and put it up right now, but the cold wind, fireplace and football game won't let me. :whistle:
     
  5. Riverman

    Riverman Part-time Member

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    Finally!
    A nice day for antenna work! (y)

    Got the cobweb 80% done. Just have to add wire for the 6 meter portion and go through the tuning process.

    Cobweb.JPG

    Everyone says these are a snap to assemble but it took me the better part of an afternoon and still not done. That said, it looks good and is actually smaller than what I had pictured in my mind. Am excited to get it put up.

    And wouldn't you know? Rain forecast for tomorrow followed by cold front. o_O
     
    #50 Riverman, Feb 5, 2019
    Last edited: Feb 6, 2019
    hillbilly101 and Slowmover like this.
  6. Riverman

    Riverman Part-time Member

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  7. Riverman

    Riverman Part-time Member

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    Well, what began as an encouraging undertaking on Day 1 changed course on Day 2 when I noticed that I was short some flat washers. Not a big deal. Just another reminder of MFJ's poor quality control. However, things quickly went downhill from there.

    1. The wire supplied is cheap and, upon closer inspection, frays easily at the hold-down points.
    2. The 6 meter portion is clearly a last minute add-on and hokey as all get-out.
    3. I could've lived with those shortcomings and would have, but the tuning phase was the nail in the coffin. Instructions say to tune the antenna at a height of at least 6'. I tuned at 12', raising and lowering the antenna on a painter's pole for each adjustment. Meticulously removing only small lengths of wire each time, the very best I could come up with was this:

    20 meters: 2.6 @ 14.150 1.4 @ 14.250 3.4 @ 14.350
    17 meters: 1.1 across the band!
    15 meters: 3.1 @ 21.250 2.6 @ 21.325 3.4 @ 21.450
    12 meters: 2.5 across the band
    10 meters: 2.3 @ 28.300 1.5 @ 28.400 2.7 @ 28.500
    6 meters: 4.3 @ 50.125

    Adjusting a single band affects the others making this a Rubik's Cube of tuning. o_O

    Hence the reference in my previous post to a picture of a hacksaw. And the cobweb's not-so-peaceful demise. :D

    But, all is not as dire as it seems. For anyone looking for a GREAT 17 meter antenna, I highly recommend the cobweb! (y)
     
    #52 Riverman, Feb 7, 2019
    Last edited: Feb 7, 2019
  8. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    Hopefully not a total loss yet Riv: Which band did you start on? Plus when removing or adding wire you did this on both sides of the feedpoint?
    Trying to help OM
    All the Best
    Gary
     
  9. BJ radionut

    BJ radionut Supporting Member and 6m addict

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  10. Riverman

    Riverman Part-time Member

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    Installed all wiring.
    Began tuning on 20 meters. Yes, kept equal lengths on both sides.

    Already have the PDF you attached. (y)

    There's a lot of interaction between the bands. Might strip this cheap wire off and start over with some insulated copper wire and maybe just set it up for 10, 15 and 20 meters. That will give more space between the wires.
     
  11. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    Maybe try putting a little solder where it connects the screws-ty points...Insulated wire will change tuning for sure...it will appear to make the antenna LONGER...I am thinking
     
  12. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    Here's a thought...Try adding a short "Tail" of wire on the 20m section near the spacer...just rap it around the end/ let it hang down...make it say 2 inches longer on either side of spacer...
    Just see what happens!
     
  13. Riverman

    Riverman Part-time Member

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    Tried adding tails to a few when it appeared they were too short. Would help a little but mess up adjacent bands. I think tuning one of these is akin to a monkey writing Gone With the Wind. Given a typewriter and enough time, he'll eventually peck it out.
    Quite frankly, I'm pooped and keep eyeing my hacksaw. :cautious:
     
  14. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    Yes they'er going to interact...just like fan dipoles will...try getting just 20m and forget checking other bands for now...once 20m acceptable...then move to next lowest band...
    Yes a little frustration involved...but got to just stay with it...one band at a time
     
  15. Riverman

    Riverman Part-time Member

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    Did that, Gary.
    Started at 20 and worked my way through. Then started again because the first ones had changed. And so on and so forth.
    And I understand when an antenna is long or short, when to shorten and when to add.
    The numbers I showed were the best I could get. Am thinking the matchbox has a problem. What's crazy is 17 meters never changed. (n)
     

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