Video: Oscilloscope Balanced Antenna System Tuner Performance Test

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

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  1. KA0KA

    KA0KA Ham Member QRZ Page

    Hello Friends:
    This video was made for anyone who wanted to see what is really happening at the carrier wave level when RF is leaving your station! I made two short videos, woven together showing you how to use a simple oscilloscope to measure the balance of your antenna tuner and antenna system. I will post additional videos regarding SDR technology, amplifiers, audio processing and more on my new channel.
    Hope you enjoy! Tyler, KA0KA




     
    N4ZOP, WA6Q, LU5WE and 15 others like this.
  2. KM1H

    KM1H Ham Member QRZ Page

    I wonder what it would look like with various levels of real TX RF up to the top of the tuner specs?
    And also the effect of near objects on the transmission line?

    Lab exercises are great to show the concepts and basics but often do not translate to the real world.

    Carl
     
    K4AHO likes this.
  3. KA2RRK

    KA2RRK Platinum Subscriber Platinum Subscriber QRZ Page

    Looks darn real world to me!

    KA2RRK
     
    N7TH and KA0KA like this.
  4. KA0KA

    KA0KA Ham Member QRZ Page

    Yes the antenna system test part of the video was with my 280 foot vertical loop feed with the 600 Ohm line into the shack. This is a zoomed out photo of the shack that was shown the at end of the video, ladder line can be seen in back area!
    [​IMG]
     
    Last edited: Sep 2, 2018
    N2EY, ON3FPG, KC2DHU and 3 others like this.
  5. WN1MB

    WN1MB Ham Member QRZ Page

    Very informative and well done, 'cept for the au courant use of a background music track (a personal bugaboo of mine). I particularly liked the attention to the phase shift and use of the add mode feature of the scope. Three thumbs up.
     
    K9FV and G4HBY like this.
  6. KM1H

    KM1H Ham Member QRZ Page

    Im not criticizing the procedure or equipment used and had worked in RF labs most of my working years plus have a nice lab at home that covers from audio to well into the microwaves.

    OTOH I'll start off by asking what RF power levels were used?

    Im sure you, maybe not others, will understand that the RF fields in the OWL expand with increasing power and what may be minor at low power becomes very important as power increases. That may cause feedline radiation which is not desirable in a balanced system.

    On receive even a small imbalance can cause common mode pickup.

    I also find the backround "noise" very annoying.

    Carl
     
    K9FV and KC2DHU like this.
  7. KD0CAC

    KD0CAC Ham Member QRZ Page

    Liked also , but also do not like music in this type of video .
    At least for me , I would like to see things not working correctly - then demonstrate finding fault & correcting , rather than showing all working good / kinda telling us the butler did it and no storyline ;)

    Thanks John
     
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  8. K0UO

    K0UO Ham Member QRZ Page

    nice job and I enjoyed talking to you on 40 meters this morning
     
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  9. WA1ZMS

    WA1ZMS Ham Member QRZ Page

    Comments:
    1) Ditch the music track. You're trying to give a technical presentation and we're not at a dance club.
    2) The video seemed more about setting up a dual-trace o'scope than anything else.
    3) To Carl's fine point....so the system is almost ballanced at low power levels. That's the easy part. What about real-world practical impacts from say a real dipole?
    4) Unless the tuner is link coupled, the output V & I in each leg is a function of the balun type and the load ballance.
    5) Finally...ditch the o'scope. Use an RF ammeter in each leg to see if the CURRENTS are equal. That is what really matters if your concern is feedline radiation.
     
    N1SZ and KR3DX like this.
  10. WB0OEW

    WB0OEW XML Subscriber QRZ Page

    Nice work as far as you went, thank you.

    But I agree the music is not helpful.
     
    KG9D likes this.

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