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Loop fed 4 element 6 meter Yagi for VHF contest.

Discussion in 'Amateur Radio News' started by KJ4YZI, Jun 9, 2017.

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  1. KJ4YZI

    KJ4YZI Ham Member QRZ Page

    I got it up just in time. Should make 6 a lot better for me when the band opens. Loop fed 4 element array, this video i put it together and checked out the tune. This weekend i should be able to make a lot of contacts and some video.
     

    Attached Files:

    AK5B likes this.
  2. W0AAT

    W0AAT Ham Member QRZ Page

    5 element, reflector, driven element, 3 directors... that is your pic on the video... might want to correct that with the 4 element pic
     
  3. WA3UTC/SK2023

    WA3UTC/SK2023 XML Subscriber QRZ Page

    This is a 4 element LFA, the driven element is a closed loop and is considered to be 1 element. 1 reflector, 1 driven element, 2 directors
     
  4. W1YW

    W1YW Ham Member QRZ Page

    Huh??

    Guys, as shown, this is a 5 element Yagi-Uda . The driven element is commonly called a FOLDED DIPOLE. There are --3-- directors. The close-spaced director serves two functions: 1) some directivity; 2) impedance matching.

    The video actually shows the 4 element version: why the confusion introduced by the OP??

    The folded dipole driven is used to increase the bandwidth, which can be substantial: up to rougly 25%. However, the GAIN is optimized over just a few percent of bandwidth.

    People use these types of Yagi-Uda's on 6m because there is an exponentially growing trend to be able to use CW, SSB, and JT-65. While you only need a regular Yagi-Uda to do this, people like the overkill of a much wider bandwidth.

    73
    Chip W1YW
     
    Last edited: Jun 9, 2017
    NU4R, AD5KO, K1HC and 2 others like this.
  5. KT5OT

    KT5OT XML Subscriber QRZ Page

    excellent antenna.glad i bought mine before mfj got the line and the inflated price tag!
     
    NU4R likes this.
  6. F1TRN

    F1TRN Ham Member QRZ Page

    KJA4YZI,
    Very good.

    And what about impedance matching for this kind of dipole that is closed ?
     
  7. W1YW

    W1YW Ham Member QRZ Page

    I cant speak about this specific design, but other commercial offerings have no matching system, because the impedance is brought down to 50 ohms by the positioning of the clossst director, and to a lesser degree, the reflector.
     
  8. F1TRN

    F1TRN Ham Member QRZ Page

    Ok thanks for this information ...
     
  9. KJ4YZI

    KJ4YZI Ham Member QRZ Page

    I usd a generic pic. I will correct it if i can, please don't be alarmed, it is an error in picture on my part.. SORRY!!
     
  10. KJ4YZI

    KJ4YZI Ham Member QRZ Page

    Not sure how i can change the picture i posted on this post. But it is a 4 element, just added a wrong generic pic of the 5 element by mistake..
     
    AK5B and KA0HCP like this.
  11. K6MTS

    K6MTS XML Subscriber QRZ Page

    That was evident once one viewed the vid...lots of panties in a bunch, LOL.
    Thanks for posting!
     
    AK5B and WA7PRC like this.
  12. LU5WE

    LU5WE Ham Member QRZ Page

    GN, Eric. Nice antenna. IMHO, your current balun has too many turns, and also, they must not be scrambled. Also, use very short connections as possible between balun's output and the active element. I see they are somewhat long. I have a simple dipole, with a 4 turns current balun, same diameter (15 cm); I'll try to upload a photo or two.... Regards - Guillermo - LU5WE.
     

    Attached Files:

    AK5B likes this.
  13. KA2FIR

    KA2FIR Ham Member QRZ Page

    How much has MFJ inflated the price?
     
  14. W1YW

    W1YW Ham Member QRZ Page

    I see nothing from MFJ that is out of line with the going market, price wise.
     
  15. KJ4YZI

    KJ4YZI Ham Member QRZ Page

    Thanks for the advice. I went by the manual 12 turns at a 6 inch diameter. Should i use less? What will the advantage be of taking it down and redoing the balun?
     

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