9:1 UNUN Testing : Interesting Discoveries Using a NanoVNA

RF Burns
RF Burns
8,100
4
Published 2024-04-03
In this video we will a test a 9:1 UNUN at both the 50 ohm coaxial feedline point and the 450 Ohm antenna termination point with a NanoVNA. We will discover the UNUN's impedance, SWR and Return Loss from 1.8 Mhz to 30 Mhz.
My apologies for the camera being a bit off target in some of the scenes.
All Comments (15)
  • @wkjagt
    I built my own 9:1 unun a little while ago and it felt like magic. This demonstrates really well what it does. Thanks for sharing!
  • @W1RMD
    Thanks, I was always wondering if this kind of test could be done. I'm always leary about hooking an antenna matching network (tun er) because a tuner will "hide" a bad antenna. You can tune up a wet piece of spaghetti, but that doesn't mean that it's a good antenna. With THIS test you KNOW that it does indeed tune a 450 ohm load to 50 ohms PERIOD! You CAN'T tell that with an MFJ-259. Thanks for showing with no BS and 73! (Liked and subscribed)
  • @WECB640
    Ape sent me. Just subscribed. Great demonstration of both sides of the transformer. 73 OM
  • @m7trsradio
    Great demonstration. All mind blowing stuff. 73
  • @rafaelgcpp
    Nice video! May I suggest measuring your load with the VNA? The inductance you are seeing on the 50 ohm port might be caused by the long leads and spiral structure of the resistors... If they are somewhat inductive, then your transformer is actually pretty fine!
  • @joohop
    New Subscriber From Aberystwyth , Wales Bless Up ❤
  • @BenTrem42
    Nice analyzer! In my day a variable frequency (MFJ) antenna analyzer was a big deal! :-) 73
  • @lawrencesherman8435
    Good stuff. I would suggest you invest in either a phone holder or small tripod. Doing RF measurements with one hand lets the video down.
  • @anlpereira
    Hi, what is the purpose of this device called unun? Thanks
  • @renaat9829
    I already see a (big mistake) never use magnetic hardware! Bolts and screws must be made of stainless steel or brass. With a 450 Ohm resistor you always get a nice picture, now place the effective antenna wire on it and then look again, you will be surprised what it looks like.
  • @IK8XOO--Paolo
    Testing ?!? This way you only demonstrated the transformation ratio, but this was already known: just count the turns! Now you also know that there is almost no reflected power but you do not know how much of the incident power is available at the output of the transformer, its insertion losses: the most important thing! Yet measuring them is not difficult...
  • @sleeve8651
    Is it just me, or does this thing look all corroded ? I think I even see rust ?