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)
Thank you for your detailed reply. You are so right! Everything can look rosey on the transmitter side of a tuner with what one may see as a "good match". But, what about the antenna side? lol
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!
Great suggestion Rafael. Here is what I measured from the low inductive carbon resistor load. 1 Mhz 433 ohms -j2.0 ending at 30 Mhz with 433 ohms -j18.6
Great video. I follow all of it, except I can't set up my nano to show the same info that you have. Can you direct me to where I might find the set-up procedure. 73 Thanks.
Hello Richard and welcome to the channel. I could not find any setup procedure on TH-cam or the internet. I just had to figure it out. Let’s take you through the process in two segments. Just make sure you calibrate your NanoVNA before beginning the tests. (there are many good TH-cam videos for this) The beginning of the video is straight forward showing how to measure the UNUN from the 450 ohm secondary side. Follow the video on how to change the "system" impedance to 450 ohms. If you get this far, let me know and we can go through testing the primary side of the UNUN. 73's
@@rfburns3472 Thanks for the response. Let me work on the calibrations using the components you have used during the testing. I think that after I get beyond that point, I will be able to figure out the rest.
Just found your channel. Great presentation. Question: I only have 1 watt resistors to make 450 ohms. Will they handle any power? I presume they will but am still curious.
Welcome to the channel! As demonstrated in the video, the two resistors can be whatever wattage you have on hand as long as they are noninductive. But, let's say instead of using the NanoVNA as the source, and you use your transmitter, you may easily burn up those resistors that only have a 1 watt rating. This would depend on how much power you apply to the UNUN's 50 ohm connection point.
What cable / test lead are you using for shorting the Nano-vna? I made one with RG58 but I get 90d full inductance. I even shorted one of the pig tails that came with my Nano but it too goes full inductance
@@rfburns3472 hunh ... not the first time: YT just evaporates my comment when my Edit fails. Anyhow: when I see stuff on having Arduino feeding digital readout my mind got into a whirl! cheers
All makes sense ... thank you for sharing! I understand how you measure SWR insertion as you demonstrated. But I want to measure insertion loss of my 4:1 unun, how do I measure insertion loss? I tried several configurations with my NanoVNA but none of the results make sense. I know how to do it with a 1:1 choke but when I use the same method with the 4:1 unun, the results are wonky 😀73 KJ6ER
Hi Greg. First of all, I have not tested the insertion loss of any of my UNUN's with the NanoVNA. That being said.......... Your 4:1 UNUN assumes a primary winding of 50 ohms. The secondary would be 200 ohms. If you connect from S11 to S21 on the VNA you will get a terrible mismatch on the 200 ohm side. The VNA wants to see 50 ohms. I only know of one way using the "back-to-back" method. This would require two of the same exact type of UNUN's. Both secondary windings would then be paralleled together. Then you would use the 50 ohm primary windings for the S11 and S21 ports on the VNA. The insertion loss would then be twice that of a single transformer. Just divide the result by 2. This assumes both transformers have identical characteristics. If anyone cares to opine on this, your invited to do so. I would like to hear from you.
@@rfburns3472 Yes, that makes sense! I've recently heard about the back-to-back method for x:1 ununs and baluns, so I will try that with duplicate devices. I just got my NanoVNA for Christmas and am still learning how to take full advantage of it, but your wonderful video helped me get started measuring SWR insertion, common mode attenuation and insertion loss on my 50 ohm chokes! Thanks so much and keep these NanoVNAs videos coming! Happy New Year, KJ6ER
@@gregmihran8616 Congratuations on the new NanoVNA and getting right into it! I had mine for about 2 years and still have a lot to learn. LOL Thanks for the kind remarks!
@@rfburns3472 LOL, yes it is a bit overwhelming at first (and still is)! And the repetitive calibration process is a bit cumbersome. I know u can store it for future use, but I'm a geek and want to calibrate it each time I use it because I haven't standardized my cables and adapters yet (but will eventually). And yes, there is so much more to learn ... I now want to learn how to test inductors and capacitors, too! The gift that keeps on giving I guess 😀73 KJ6ER
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.
Perhaps your right. I am planing on changing out the hardware using stainless steel. I then will see if there is any difference looking at the antenna with the VNA. Anyone else care to comment on this?
@@rfburns3472well, here you’re checking the transformation ratio of 49. It is obvious that when you connect the wire (the real antenna) you’ll have different results. The complex impedance of the real antenna on its own installation will be all over the place and the transformer will transform (lower) that value closer to 50ohm for the radio or an antenna matching unit. (This was for the guy who commented first). I have an antenna like this myself. 54 meters of wire starting from the roof, going up to a tree and then down to the end of the property. In my case on few bands I’m lucky to have already a good match, for the other bands where swr is little high I then use the “tuner”. Otherwise one could buy a remote antenna tuner, place it outside and start the random lenght of wire out of it. This way it’ll adapt the LC network to give you always the best matching transformer at the antenna point. 73 Diego
You see it right! Its nickle plated hardware that was exposed to the elements for 2 years. It's easy to change it out to stainless steel fasteners if I ever use it outdoors again.
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...
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!
It really does...glad you enjoyed it! And, thank you for subscribing.
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)
Thank you for your detailed reply. You are so right! Everything can look rosey on the transmitter side of a tuner with what one may see as a "good match". But, what about the antenna side? lol
Umm, how may RF paths are there between a radio and an antenner.?
Great demonstration. All mind blowing stuff. 73
For sure! What we have today, in the world of amateur radio, is far different than what I used to see 50 years ago.
@@rfburns3472 yeah technology doesn't hang about for anyone. has come a long way. 73
Excellent informative video. Many thanks. 73..John..G4EIJ
Appreciate the comment. Glad you liked it John.
Great video. I just got a Nanovna H4 and I’m learning. Or trying at least.
For less than $70 theres a lot to learn about this little gem! Thanks for watching.
Ape sent me. Just subscribed. Great demonstration of both sides of the transformer. 73 OM
I am glad you liked it. And....Ape's the man! Learned a lot from his channel.
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!
Great suggestion Rafael. Here is what I measured from the low inductive carbon resistor load. 1 Mhz 433 ohms -j2.0 ending at 30 Mhz with 433 ohms -j18.6
Thank you ! I will check my diy 49-1 and gives my nanoVNA some other uses .
Please do that Mike and let us know what you find out! 73's
How if needed to be adjust? Thanks!!!
Great video. I follow all of it, except I can't set up my nano to show the same info that you have. Can you direct me to where I might find the set-up procedure. 73 Thanks.
Hello Richard and welcome to the channel.
I could not find any setup procedure on TH-cam or the internet. I just had to figure it out.
Let’s take you through the process in two segments.
Just make sure you calibrate your NanoVNA before beginning the tests. (there are many good TH-cam videos for this)
The beginning of the video is straight forward showing how to measure the UNUN from the 450 ohm secondary side.
Follow the video on how to change the "system" impedance to 450 ohms.
If you get this far, let me know and we can go through testing the primary side of the UNUN.
73's
@@rfburns3472 Thanks for the response. Let me work on the calibrations using the components you have used during the testing. I think that after I get beyond that point, I will be able to figure out the rest.
@@RichardKilmer-b8m Your welcome Richard. Hope you can get it working.
Just found your channel. Great presentation. Question: I only have 1 watt resistors to make 450 ohms. Will they handle any power? I presume they will but am still curious.
Welcome to the channel!
As demonstrated in the video, the two resistors can be whatever wattage you have on hand as long as they are noninductive. But, let's say instead of using the NanoVNA as the source, and you use your transmitter, you may easily burn up those resistors that only have a 1 watt rating. This would depend on how much power you apply to the UNUN's 50 ohm connection point.
What cable / test lead are you using for shorting the Nano-vna? I made one with RG58 but I get 90d full inductance. I even shorted one of the pig tails that came with my Nano but it too goes full inductance
The cable/test leads are the ones in the video. Sorry, but I am not clear on how you explained your test setup.
Nice work 👍
Thank you sir. Your video's are truly apprecated and inspiring!
New Subscriber From Aberystwyth , Wales
Bless Up ❤
Thanks!
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.
I couldn't agree with you more. I will take your suggestion to heart and see if I can improve my video's.
Hi, what is the purpose of this device called unun? Thanks
www.nextpcb.com/blog/what-is-an-unun-rf-antenna-unun#:~:text=An%20Unun%2C%20short%20for%20Unbalanced,suited%20for%20the%20transmission%20lines.
_Nice analyzer!_ In my day a variable frequency (MFJ) antenna analyzer was a big deal! :-)
73
Same here Ben. Amazing stuff we now can get our hands on these days!
@@rfburns3472 hunh ... not the first time: YT just evaporates my comment when my Edit fails.
Anyhow: when I see stuff on having Arduino feeding digital readout my mind got into a whirl!
cheers
All makes sense ... thank you for sharing! I understand how you measure SWR insertion as you demonstrated. But I want to measure insertion loss of my 4:1 unun, how do I measure insertion loss? I tried several configurations with my NanoVNA but none of the results make sense. I know how to do it with a 1:1 choke but when I use the same method with the 4:1 unun, the results are wonky 😀73 KJ6ER
Hi Greg. First of all, I have not tested the insertion loss of any of my UNUN's with the NanoVNA. That being said..........
Your 4:1 UNUN assumes a primary winding of 50 ohms. The secondary would be 200 ohms. If you connect from S11 to S21 on the VNA you will get a terrible mismatch on the 200 ohm side. The VNA wants to see 50 ohms. I only know of one way using the "back-to-back" method.
This would require two of the same exact type of UNUN's. Both secondary windings would then be paralleled together. Then you would use the 50 ohm primary windings for the S11 and S21 ports on the VNA. The insertion loss would then be twice that of a single transformer. Just divide the result by 2. This assumes both transformers have identical characteristics.
If anyone cares to opine on this, your invited to do so. I would like to hear from you.
@@rfburns3472 Yes, that makes sense! I've recently heard about the back-to-back method for x:1 ununs and baluns, so I will try that with duplicate devices. I just got my NanoVNA for Christmas and am still learning how to take full advantage of it, but your wonderful video helped me get started measuring SWR insertion, common mode attenuation and insertion loss on my 50 ohm chokes! Thanks so much and keep these NanoVNAs videos coming! Happy New Year, KJ6ER
@@gregmihran8616 Congratuations on the new NanoVNA and getting right into it! I had mine for about 2 years and still have a lot to learn. LOL
Thanks for the kind remarks!
@@rfburns3472 LOL, yes it is a bit overwhelming at first (and still is)! And the repetitive calibration process is a bit cumbersome. I know u can store it for future use, but I'm a geek and want to calibrate it each time I use it because I haven't standardized my cables and adapters yet (but will eventually). And yes, there is so much more to learn ... I now want to learn how to test inductors and capacitors, too! The gift that keeps on giving I guess 😀73 KJ6ER
@@gregmihran8616 Your welcome Greg...73's
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.
Perhaps your right. I am planing on changing out the hardware using stainless steel. I then will see if there is any difference looking at the antenna with the VNA. Anyone else care to comment on this?
@@rfburns3472 Yes, I would suggest using brass hardware. 👍
@@rfburns3472well, here you’re checking the transformation ratio of 49. It is obvious that when you connect the wire (the real antenna) you’ll have different results. The complex impedance of the real antenna on its own installation will be all over the place and the transformer will transform (lower) that value closer to 50ohm for the radio or an antenna matching unit. (This was for the guy who commented first).
I have an antenna like this myself. 54 meters of wire starting from the roof, going up to a tree and then down to the end of the property. In my case on few bands I’m lucky to have already a good match, for the other bands where swr is little high I then use the “tuner”.
Otherwise one could buy a remote antenna tuner, place it outside and start the random lenght of wire out of it. This way it’ll adapt the LC network to give you always the best matching transformer at the antenna point.
73
Diego
Is it just me, or does this thing look all corroded ?
I think I even see rust ?
You see it right! Its nickle plated hardware that was exposed to the elements for 2 years. It's easy to change it out to stainless steel fasteners if I ever use it outdoors again.
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...
Thanks for opining Paolo!
@@rfburns3472 He has a point. You can use both ports of the NanoVNA to show bandwidth, insertion loss etc. It's easy and fascinating.