A question of BALUN

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by BA7LFI, Aug 14, 2021.

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  1. BA7LFI

    BA7LFI Ham Member QRZ Page

    Recently I want to make a half-wave end-feed antenna.So I want to make a 9 to 1 BALUN,which magnetic permeability is about 850.How much turn should I wind?
  2. WA7ARK

    WA7ARK Ham Member QRZ Page

    If you want to feed a resonant half-wave antenna designed (for example) 40m, and hope to use that antenna on harmonic bands, like 20m, 15m and 10m, the required transformer ratio is 1:49 (50:2450 Ohms), not 1:9 (50:450 Ohms)!

    Please read my recent QRZ posts here:

    You might also learn from reading a .pdf of a slideshow I did about EFHW antennas, linked to from the bottom of this page:

    EFHW antennas can benefit from a "balun" (also known as a "coax choke"), placed to define where the feeding coax ends, and where the antenna begins. Covered here:
    Last edited: Aug 14, 2021
    BA7LFI and N6MTT like this.
  3. W9IQ

    W9IQ Ham Member QRZ Page

    To properly design a matching transformer, you need to specify the ferrite mix that will be used (or its ui and then u' and u'' for each band) along with the dimensions of the toroid or its Al specification. Without this information, any guidance is simply a guess.

    - Glenn W9IQ

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