Is this a Current Balun or a Voltage Balun?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by 2E0CIT, Feb 28, 2019.

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  1. 2E0CIT

    2E0CIT Ham Member QRZ Page

    I have a Palstar balun, a B4000 1/1, s/number 16482 and have emailed Palstar (with no success) to find out whether it's a current or voltage type. It behaves as a 1 to 1.

    Checking continuity with a meter I find the centre terminal of the SO239 connects with the right antenna binding post and the shield of the SO239 to the left binding post. There is no continuity between centre and shield terminals of the SO239 or between the antenna binding posts. Checking diagrams of balun construction I assume from this continuity test that it's a current type (good!) but as there are so many weird and wonderful balun designs around am I correct???
    Are there any other tests one can perform with a meter, antenna analyser, dummy load, etc?
    73 Jeff
  2. AA5CT

    AA5CT Ham Member QRZ Page

    Watts the difference? I mean, why would you choose one over the other? In a purely resistive 50+j0 would there be any difference? (Other than one gets 'bad' press and the other doesn't)
  3. 2E0CIT

    2E0CIT Ham Member QRZ Page

    Thanks for the reply. Well, I've read loads of articles about baluns /chokes and they all seem to state current baluns will alleviate common mode current problems a whole lot better than a voltage type, and my doublet half over the house and half over the back yard isn't going to be a purely resistive balanced load. So the 'bad press' about voltage baluns is all fake news is it?

    73 Jeff
    p.s. some great links on your QRZ page!
    Last edited: Mar 1, 2019
  4. AA7EJ

    AA7EJ Ham Member QRZ Page

    Here is somewhat biased view.

    I gather "they" used frequency as one parameter to evaluate current versus voltage balun. .
    Not sure their view is correct , but from reading Sewick's book few years back and from unfortunate experience running OCF dipole as "mutiband" antenna - frequency response of "wide frequency " balun would concern me more than type.

    73 Shirley
  5. N5SMO

    N5SMO Premium Subscriber QRZ Page

    Voltage baluns are mainly for impedance transformations, and many times they are actually Ununs (Unblanced to Unbalanced). The Unun case is where you see a 9:1 coax fed inverted L or long wire, or a 50:1 coax end fed halfwave resonant antenna. Current Baluns are for common mode elimination and equalization of current flow in the elements of a balanced antenna fed with an unbalanced source (Coax feeding a dipole). When you look at the schematic, it is pretty easy to see which is which if you trace how current and volatege will flow through the balun schematic.
    N8ZL, AC7NP and KU3X like this.
  6. 2E0CIT

    2E0CIT Ham Member QRZ Page

    Thanks for the interesting input but I'm still hoping for an answer to my question!
    Steve, G3TXQ illustrated the need for a 'hybrid' double-core transformer / current balun for OCFDs and there's loads of literature stating the need to use current baluns/chokes to force the current on dipole / doublet elements to be equal . The schematic kind of indicates it's a current balun (thanks) so I'll go with that assumption but it would be good to know if this particular Palstar balun is definitely a voltage type or a current type and also to find it out if anyone has a simple way to test baluns for definitive type before I brave the terrible rain and cold to put it in line with my doublet.
    73 Jeff
    ps OK, I could make a rf meter to measure common mode with and without the mystery balun but I'm too darn lazy to do that........
    Last edited: Mar 1, 2019
  7. NL7W

    NL7W Premium Subscriber QRZ Page

    Here you go:


    I cannot imagine it being anything other than a current balun.
  8. AA5CT

    AA5CT Ham Member QRZ Page

  9. 2E0CIT

    2E0CIT Ham Member QRZ Page

    Thanks for that, I did check the web for info on Palstar baluns and they all seem to be called B4000 but none of them look like the one I have!
    Yes, I'll assume it's a current balun and stop worrying!
    73 Jeff
  10. 2E0CIT

    2E0CIT Ham Member QRZ Page

    Thanks for the link to the rf transformer info!
    73 Jeff

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