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Loop-On-Ground Antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by AI5DH, Aug 1, 2018.

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  1. K0OKS

    K0OKS Premium Subscriber QRZ Page

    That was the plan. You could even power it with DC over the coax with some caps and chokes.

    Thanks so much for sharing that latest link, KF5LJW.
     
  2. WE4E

    WE4E Premium Subscriber QRZ Page

     
    WB5YUZ likes this.
  3. AI5DH

    AI5DH Ham Member QRZ Page

    You are welcome. Hit the Bullseye huh? Wished I had found that earlier would have saved me a few hours. Glad I found it though to share but mostly validated my research 75 mix, number of turns, and the core size I used were spot on. To be honest first time I wound a core since I was a kid with a Crystal Set. Always used Mini-Circuits or those miniature 9:1 transformers for $5. This time was different because of the LF application I was looking for does not exist commercially. Anyway what I am rambling on about now is that I looked at the document, and realized I needed to rewind the transformer. No big deal took 2 minutes and dang it matters how you wind them. So take not on what the author calls OL or Over Lap Wind technique. I picked up a good 2 to 3 dbm strength after rewiring. First time around I used what they call SS. Did not know any better.
     
  4. K0OKS

    K0OKS Premium Subscriber QRZ Page

    Yeah, the empirical data on the winding methods is precisely what I was most curious about, as you had answered most of the other questions with your post and the previous link.

    I was doing some further reading of the 23rd ed to the ARRL Antenna Book and found they suggested using a trifilar winding for a similar matching transformer for a Beverage. This made me want to give that a try vs. my winding, which was indeed side by side like you did. I do have a hefty 2.4” OD core, even though mix 31.

    I do wish I had a real VNA with which to test these.

    On a side note, the LOG was again working great last night. It was very noisy here with lightning noise, and I barely even noticed when using then LOG.
     
  5. AI5DH

    AI5DH Ham Member QRZ Page

    I did not go that route either the first or second time. I just do not like the look of Quadrafilar with all the spliced connections. Second time around I used Overlapped. Wrapped 12 windings spaced evenly so as to use 3/4 of the doughnut, then 4 turns over the top of the 12 so that took 3/4 of the doughnut. Used Black and White insulated wire so makes it super simple to see when wiring up. No guessing or mistakes. Nice. clean, and neat.
     
  6. K0OKS

    K0OKS Premium Subscriber QRZ Page

    I was using two colors of wires as well. Just makes it easier. I may try the tri-filar. Putting together an order for some mix 75 torroids, among other things.
     
  7. AI5DH

    AI5DH Ham Member QRZ Page

    Interesting, I am curious how that is going to work. When it comes to winding doughnut transformer my business card would read something like Mr Doeknow Chit bout Doughnuts. For the loop I built for now is a turn ratio of 1:3 which makes 1:9 Impedance ratio. After reading a second document with a lot more info from the same group, for a Loop a turn ratio of 4:1 might be a better match assuming 900 Ohm antenna impedance. Easy change to see what happens.

    OK back to the Tri-filar wind to make the transformer is throwing me off. Would that not make a 1:2 Turn Ratio? I think, please correct me if I am wrong, is you would use a quadra-filar winding to get 1:3 turn ratio? What am I missing?
     
  8. AI5DH

    AI5DH Ham Member QRZ Page

    KOOKS did I share this document with you? Basically the same as the last document, but the full design details, test, and results. You, me, or anyone should come away with a grasp and confidence rolling their own. Here in TX we would call it "The whole enchilada."
     
    N0TZU likes this.
  9. W4KJG

    W4KJG Subscriber QRZ Page

    I just want to thank everyone who has contributed so much good information and experience to this thread.

    Several months ago we moved from the edge of the US National Radio Quiet Zone. My closest neighbors were at least a half mile away.

    We only moved about 15 miles -- into an urban area where the noise is incredible.

    I'm in good shape for transmitting antennas.

    I can't wait to try an on-ground loop. I was planning on an untuned shielded loop, made with coax and a low noise amplifier, for receiving.

    Thanks again,
    Ken
    W4KJG
     
  10. AI5DH

    AI5DH Ham Member QRZ Page

    Let us know how it works out.
     

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