Video: Oscilloscope Balanced Antenna System Tuner Performance Test

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

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  1. K0EVN

    K0EVN Ham Member QRZ Page

    Fantastic video and editing caller. Don't know what's the deal with all the soundtrack bitching coming from the crustations.
    N7TH likes this.
  2. KA0KA

    KA0KA Ham Member QRZ Page

    Hi Brian and to my 14 year old neighbor Evan!
    Actually, the AT5K used a really smart idea of putting a current 1:1 unun on the input of the tuner network. I removed the original one and put in a custom made 4 core 1:1 unun for better performance. I made a separate video on that mod and comparing it to other tuners, such as the Millen 92200 unbalanced tuner. I wanted to keep this as simple as possible for the demo. The large tuner uses current transformers feeding a demodulator that feeds the DC to the actual current meters, but no one owns that so I choose to use my AT5K for the test to give more value to the video more relatable !
    Modification to my AT5K custom 4 core 1:1 UNUN on the input of AT5K network
    Last edited: Sep 4, 2018
    N7TH and N2EY like this.
  3. KM1H

    KM1H Ham Member QRZ Page

    Please explain why that is a smart idea
  4. WN1MB

    WN1MB XML Subscriber QRZ Page


    Did you mean crustation or crustacean? They're quite different, lad.

    Perhaps in time you'll understand why some of us prefer listening to content without the distraction of a background track - regardless of the musical genre.

    I don't listen to music with a background track of someone explaining electronic theory...
    KM1H and K8AI like this.
  5. WA1ZMS

    WA1ZMS Ham Member QRZ Page


    Please tell us why the balun on the *input* of that asymetrical T-match Palstar is a good idea?
    KM1H likes this.
  6. K3GAU

    K3GAU Ham Member QRZ Page

    You went through a big long procedure to 'prove' the voltage to 'ground' on both sides of the line was equal.

    Once you calibrated both channels to the same source, when checking for equality why didn't you just use the INVERT switch on one of the channels of the scope and lay one channel signal on top of the other. Most scopes have the ability to invert the signal from at least one of the channels. Laying the two channels on top of each other is quick and very easily shows up any imbalance in level or phase difference. Just a thought.

    Some have suggested using two ammeters to measure the currents and that is one way of doing it but who has two RF ammeters. (Have you priced them lately?) Also, using two ammeters gives you absolutely no information on phase imbalance.

    Dave K3GAU
  7. AJ4XM

    AJ4XM Ham Member QRZ Page

    Nice video. Agree on the music. Very nice and clean looking shack. What are you using as the controller between the radios on the desktop. I like how it seems to match well with the keyboard.
    Tom AJ4XM
  8. KA0KA

    KA0KA Ham Member QRZ Page

    Hi Dave, yes this was a demo only and as such it had to be illustrated for as many people as possible. Some scopes, I have had questions on from clients of my CleanRF Systems work have shown not to have this option thus I filmed this just like I wrote the Applications page on my CleanRF site, as universally correct as possible. Also, my two current meters you see there were custom built by Simpson, they are $130 each just for the meter since you asked!
    As you also indicated, my current transformers and meters will never show you the phase difference as demo in the film as you also picked up on! I have done a summing amplifier to one meter as well, so if if the phases and magnitudes are equal the meter stays in the center, but now we are getting too far into the weeds! Good questions!
    Last edited: Sep 4, 2018
    KA0HCP likes this.
  9. K0EVN

    K0EVN Ham Member QRZ Page

    Now listen here sunny boy, I was referring to you as CRUSTY. Obviously you don’t understand my complex wordplay.
  10. KA0KA

    KA0KA Ham Member QRZ Page

    Tom thanks for your comments! I have a separate video that goes into each component of the shack, some of the things happening are really cool such as the Adaptive Pre-Distortion system giving me a system wide linearity correction in phase and magnitude to improve your over-all IMD 1000X leaving the shack, it is wonderful.
    Some of the info in on my QRZ page some not, it will all be posted on my youtube channel in the near future, you can always get the direct notifications if you subscribe the current name of the channel is Ty-Fi KA0KA (Ty-Fi was a nick name I was given years back with my audio friends hihi)
    Last edited: Sep 5, 2018

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