Video: Oscilloscope Balanced Antenna System Tuner Performance Test

Discussion in 'Amateur Radio News' started by KA0KA, Sep 1, 2018.

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  1. NX5T

    NX5T Subscriber QRZ Page

    Nice vid Ty. Very informative with much to be gained from. More people should try sharing their knowledge, if they have any, rather than picking apart the efforts of hams that do. Keep 'em coming.
    KA0HCP, WG8Z, KA0KA and 2 others like this.
  2. KA2RRK

    KA2RRK Platinum Subscriber Platinum Subscriber QRZ Page

    I think thee tuner had current meters.

  3. K5AX

    K5AX Subscriber QRZ Page

    I hoping you would adjust the tuner, and show the effect.
  4. WA6AM

    WA6AM Ham Member QRZ Page

    Well, I liked the whole thing. And I learned a thing or two, isn't THAT why he made this?
    Get us thinking a bit? Very nice thank you.
    N7TH and KA0KA like this.
  5. NK4K

    NK4K Ham Member QRZ Page

    Thank you for the nice effort. Such videos are fun and elevate the hobby to something more than just CB. You can tell it worked well, because in the 44 years as a ham op/engineer, I've known in the back of my head this would work, but never tried it. To me, the words: "What's the next step" popped into my head almost immediately, i.e. what else can be done along these lines (no pun intended)?
    I listened to it through headphones, and the only comment is the music may be a VU or so hot. But, the video would have been dramatically worse without the music.
    If you listen to your flat ATV through tiny speakers you won't notice that program music on shows like Discovery's (now defunct) "MegaBuilders" et al is similar. PBS's "Nova" uses it, too. It provides just enough tension to keep the viewer from dozing off if he becomes bored.
    Don't be mislead by the previous music comments. They are based on a misunderstanding of music in general, e.g. it's techno-jazz but NOT dance hall music. Without apology, some folk just hate jazz in general, no matter the kind.
    Further, you really can't use country music for these videos. Maybe you could use Chet Atkins, but no singing.
    If you wanna try their patience, use the Rippington's "Welcome to the Saint James Club" next time, appropriate if you work DX, or any older recordings from Pat Metheny Group such as "The Girls Next Door" or "Red Sky" (We Live Here) or "Are You Going with Me?" (Travels). Go-head -- listen on Amazon. Dare ya.
    Might be old enough to escape copyrights...
    Before you poo-poo Metheny, consider he has the same number of Grammies as Springsteen.
    Looking forward to more...
    Last edited: Sep 3, 2018
    KD4AYU and KA0KA like this.
  6. KB3ONZ

    KB3ONZ Premium Subscriber QRZ Page

    Nice job. I like the video. Don’t worry about the nit pickers. I am trying to learn this type of testing and your video,caught my eye. I thought it was interesting and hope you can explain more, some of the basics: for example when you say you applied a carrier, what did you do? CW signal. How much power? When you connected the scope probes, did you go direct or did you have a buffer or something to prevent to much power from going tot the scope?


    KA0KA likes this.
  7. AB9VJ

    AB9VJ Premium Subscriber QRZ Page

    I don't know, I kinda liked the music. He isn't operating, helps bridge the camera switches. Besides, I learned something.
    N7TH and KA0KA like this.
  8. KA0KA

    KA0KA Ham Member QRZ Page

    Thank you guys for your kind words, this is the first video I have ever made and thought it was well edited on a subject that has been missing in demonstration! The carrier was only 5w, the tuner selected for the demo as seen by the back of the tuner was a commercial Palstar AT5K because it is a widely used product and would be more relatable to all HAMs, not the 80LB tuner in the opening shot reel as it is perfect and no one else has it because it was a one-off unit, therefor, I felt it would devalue the video if I used it.
    Thank you all for your kind words, I will be continuing my post on my ty-fi KA0KA youtube channel as well.
    N4QNT and KD7FQI like this.
  9. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    Okay I tried the experiment, I have over a half a mile of 600 ohm feed line feeding various antennas. I had been using a current meter before and that provided me some initial relative information. I was able to make a few adjustments using oscilloscope technique, very helpful for the rhombic antenna setup and the matching networks that I have here thank you
    KA0KA likes this.
  10. WA1ZMS

    WA1ZMS Ham Member QRZ Page


    All music and such aside...

    I think you missed an important "teaching moment" in your video. I don’t recall you saying that voltage balance implies no feedline radiation, and it never does. For that, I thank you.

    But what you could or should have emphasized was that any feedline radiation from open-wire line is actually caused by CURRENT imbalance. Showing what the VOLTAGES are on an open-wire feedline, even if interesting and educational, tends to overlook one of the most important facts about open-wire, that being: unless the CURRENTS are equal the line will radiate transmitted signal. That's a sure way to let RF into the shack and not where we want it.

    Any coaxial-based antenna tuner feeding open-wire should have a current balun as the last item before transitioning to open-wire. For those who may doubt, try it in any NEC-based simulation and use two but unequal current sources. Excellent references have been written, one is titled “Reflections” by W2DU. Another is an article in March 1983 QST. Hams should give both a good read.

    Voltage baluns came into popular fashion for coax-feed dipoles ages ago, are cheap, easy to build, and still sold as part of low-cost antenna tuners. Current baluns can be harder to build but are worth every penny. I believe your Palstar tuner uses a current balun.

    Perhaps in future videos you can point some of these things out. It will make for a more complete understanding.

    N1SZ, K8AI, N2EY and 1 other person like this.

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