Attenuation testing 1:1 common mode choke balun design from TRX Bench
HTML-код
- Опубликовано: 10 фев 2025
- This is a follow up on a previous video I made testing the SWR on a balun design explained by Peter TRX Bench (now TRX Labs). Hit "PLUS" below to see more information and related links ↓↓↓
This time it will be to test the attenuation using a nanovna. Of course this is no precision measuring device and my testing procedure might not be adequate but this is to give a rough idea of the attenuation performance of a balun.
You can watch the previous video testing the SWR response here : • SWR testing 1:1 common...
I am using a nanovna-h : nanovna.com/
Firmware and NanoVNA-App by OneOfEleven : github.com/One...
NanoVNA-App by DiSlord forked from OneOfEleven : github.com/DiS...
Firmware by DiSlord that now support OneOfEleven NanoVNA-App github.com/DiS...
Test leads are RG-58 with BNC connectors, the center conductor has a foil over it so it is "shielded" up to the yellow aligator clip. The black aligator clip is the coax shield.
Measuring technique and balun design of Peter TRX Labs is taken from Wolfgang Wippermann DG0SA (SK) can be found here : www.wolfgang-w...
Please visit TRX Bench videos about the BalUn subject.
Video 101 Balun PART 2: Balun's magic and how to wind an effective working Balun (that is the particular video where I took the information to build mine)
• #101 Balun PART 2: Bal...
Video 100 Balun PART 1: Broadcast Interference, Common Mode Current and Balun's magic
• #100 Balun PART 1: Bro...
Video 105 Balun PART 3: How to build an effective working 4:1 Balun for 800 watt HF power
• #105 Balun PART 3: How...
Thanks for watching ! 
Наука
Than You for this video. From Peter's video I wasn't able to get clearly how the test setup is constructed. In his video Peter poited out how important is to check SWR value of a common mode choke. I've tried to make one on the FT140-43 core, based on his instructions and it took me quite a while to find proper cable to get the SWR part right. 73!
thank you for your appreciation I'm glad you found the information helpful !
Hello, do you think you could help me sort this out? In OKX, I’ve stored USDT TRX20 and kept the recovery phrase [ clean party soccer advance audit clean evil finish tonight involve whip action ] How can I move it to EXMO or Bybit?
Hi - just wanted to clarify that this design is not Peters of TRX bench. It came from Wolfgang Wippermann DG0SA. Peter mentions this numerous times during his video series. The same applies for the 4:1 and 9:1.
Yes I know and I took care of specify it in the video description from the begining, not many people read that information though. I also shared the german information from Woflgang website url even though he is SK, his family left the website up so information can still be share around the world.
Hey, sorry to impose, but could you give me a hand? USDT TRX20 is in my OKX wallet and I know the recovery phrase [ clean party soccer advance audit clean evil finish tonight involve whip action ] How do I transfer it to EXMO or Bybit?
Great video. Very interesting results. It seems the two paralleled 100 ohm transmission lines in parallel, used to make the balun, is going to be better than one run of 50 ohm coax to make a balun on the same core. You did not test the coax balun but I did and the results of the balun you tested performs much better and has a better band coverage.
Thanks for posting the great video. de Barry, KU3X
Hello Barry, thanks for your comment. Indeed, it seems an excellent method to build a balun, on top of all, you can make a 4:1 with the same method just by having two of the secondary coils in series with each other instead of parrallel. You can find the information on the measurement technique originally posted by Wolfgang DG0SA (SK) in the description box below the video. Even with random PTFE cable (unknown characteristics) it did work nicely. It is currently in use on a small compact 2el beam that covers 40/20/17/15/10 and 6m and it works really well. 73 de Claude VA2CST !
Hey, sorry for asking, but could you lend me a hand? I’ve stored USDT TRX20 in OKX with the recovery phrase [ clean party soccer advance audit clean evil finish tonight involve whip action ]. How do I move it to EXMO or Bybit?
Very helpful, thank you.
you're welcome and thanks for your appreciation !
Beau boulot, Claude, très stimulant.
merci pour votre commentaire positif !
Hey, I don’t mean to disturb you, but could you help me with this? USDT TRX20 is stored in OKX and I have the recovery phrase [ clean party soccer advance audit clean evil finish tonight involve whip action ] How can I send it to EXMO or Bybit?
Excellent video and just about the stage i am at now :) Is there any chance of a video to show how the VNA was calibrated/nulled at the beginning please?
thanks for your appreciation ! I did the calibration from 3.5 to 29.7MHz using the aligator clip you see in the video, did the open, short and connected the 50 ohm dummy load on to the aligator clip.
It is not super precise but I think it is giving a good idea of the performance of the balun and specially I could compare both the original balun and the one I did build (which works way better than the original one).
I would not use aligator clips on higher frequencies, even at 29MHz I could see the reading started to derail a little bit, maybe half of a dB error but for what I wanted to test, i'd say it is not a big deal and it will give you a rough idea on the performane of your balun.
Have fun testing !
Cheers for sharing! Looking for help: My TRX Wallet has some USDT TRX20, and I have the recovery phrase: -clean- -party- -soccer- -advance- -audit- -clean- -evil- -finish -tonight- -involve- -whip- -action-. Could you suggest how to proceed with transferring them to Coinbase Exchange?
Hi, can you advise if the calibration is done with the resistors or without. Sorry if this has been asked before.
Thanks.
I did calibrate my nanovna with the usual OSL method and this is what I got in the video as per the instructions.
What's the purpose of the resistors? What would happen without them?
so the resistors are there to load the balun choke to the proper impedence and have the proper measurements. Since it is a 1:1 balun choke, it requires 50ohm load. If you look at the description, the link explain what value resisitor is needed depending on the radio of the balun and how to correct the gain of measurements.
S11 is ess one one, not ess eleven. Same for S21, which is ess two one.
Hi. Could you tell me why a 1:1 Balun requires a +2dB offset adjustment please? I'm sure it's logical but I really would like to understand it. 73, John.
hi John, I won't pretend I undestand everything, I got those instructions from where Peter TRX Labs got the information, from Wolfgang DG0SA (SK) www.wolfgang-wippermann.de/messbal2.htm. Peter did the exact same measurements technique.
By what I understand, it is because there is 2X 50ohms loads on each side of the balun to measure attenuation on both shield and center of coax thus this is inducing more loss in the reading that would be why you need to add 2dB to the total attenuation to get "real" values. I might be wrong but this is what I understand.
Thanks for your comment and question... sorry if this is not a solid answer... I am still learning too !
@@Aleziss Hi Aleziss. Thank you very much for the excellent video and the explanation. I have downloaded the pages after using Google Translate so now I see what you mean. A very clear explanation in your video. 73, John.
@@johntyler4222 you're welcome !! thanks for your appreciation and positive comment !
@@Aleziss The 2dB increase is from the delta between a 50 ohm load on an output with a 50 ohm impedance and this arrangement with the 2 parallel 25 ohm resistors on each bifilar leg. That arrangement yields a gain of 0.4 and the former yields a gain of 0.5. If you convert each of these and subtract, you'll get close to 2dB. To be precise, 0.5 gain results in a -6.02dB voltage gain. 0.4 gain results in -7.9588 dB. This number is nearly 2dB lower (1.93dB) than the 'model' 50 ohm loading.
Bifilar windings have an impedance of about 100 ohms. Tough to have a good match with 50 ohm coax.
it works excellent under 50 ohm load, my previous video shows no SWR under 50 ohm load prior being able to test the attenuation on this video.
modex20, the Bifilar common mode choke that you can see wound on the toroid core using white insulated wire is actually two 100 ohm transmission lines (approximately) connected in parallel and therefore the equivalent input and output characteristic impedance for this common mode choke is 50 ohms (approximately). Just FYI, Don (wd8dsb)
@@wd8dsb thanks Don for the precisions. That is also why you can do a 4:1 with that balun type while having both secondary coil in series. Makes sense. By the way it works pretty nicely my new antenna, no RFI comes back to the shack and it works beautifully up to 50MHz ! Thanks for the info.
@@wd8dsb by the way are you saying the windings end up to be 100ohm because of the PTFE insulation ?
@@Aleziss typically speaker wire type spacing of two parallel conductors produces a transmission line with an approximate impedance of 100 ohms, so looking at the spacing of your two parallel conductors most folks would say it produces an approximate characteristic impedance of 100 ohms. You would actually have to measure the center to center spacing between the two parallel wires and the diameter of each wire to determine the exact characteristic impedance, but 100 ohms is probably close. 73, Don (wd8dsb)
P.S. Most small insulated wire in parallel or a twisted pair produces a characteristic impedance of approximately 100 ohms. As an example cat 5 twisted wire has a characteristic impedance of approximately 100 ohms.
Did you just put 2 25 Ohm resistors in parallel and say that is 50? Maybe 2x 100 Ohms will give 50 Ohm. Regarding presentation for BalUn and VNA it is excellent.
Hello Milan, by what I understand, it is to load 50 ohms on each side of the balun because the attenuation is measured on both shield and center of coax. 25 at the input of the shield and another 25 ohms at the output shield side of the balun = 50 ohms load on this side of the balun. You then replicate the same thing on the center pin for the other side of the balun.
Peter TRX Labs got his design from Wolfgang DG0SA (SK) and you can see here it is his measuring method that Peter also used on his link : www.wolfgang-wippermann.de/messbal2.htm
That is what I have tried to reply based on their measurements method.
@@Aleziss Thanks for update.
@@MilanDjordjevicBG you're welcome !
@KG2RG the measuring method of Peter is the one that Wolfgang used, you can find the information here : www.wolfgang-wippermann.de/messbal2.htm (in german). This is what I have replicated and it is why we need to have a 2dB response correction in the measurements for a 1:1 balun. I am having 25ohm resistors at each end of each coils thus loading 50 ohms on each coils (since it is a 1:1).