This is a good and accurate test. It is also done under ideal conditions. Once the choke sees anything other than 50 ohms on either side, it will always have less attenuation to CM. Type 31 is a great absorber, but it has a shortcoming....it can not handle high heat. This means that a single core of type 31 would not be suffecient for a system where the operator wants to push QRO power. It would be fine as shown for about 200W or less. One needs to MEASURE the actual currents (both CM and DM) in the antenna "system" to accurately design a balun that will handle heat, current and voltage. 73 OM
Hi thanks for the great video. I followed your steps and tested my first self wound RF choke. However, I saw a lot of variabilty on my S12 gain plot as opposed to what you showed here. I did see your video on jenky test leads (very helpful). I was getting sub -40db measurements as well... so I am suspicious that something is off. My choke is a 240-43 wound with 11 turns of RG8x with 6 forward and 5 backward turns. I did hook my leads to the center then the shield, and got similar results. 73's!
Hi, I have been playing with common-mode chokes a lot over the last few years, chiefly using FT240-31 and FT240-43 cores. I have made them with coax but found them relatively narrow band, possibly due to the capacitance between turns. Consequently to achieve good common mode attenuation on 160m made 10m performance suffer. My most recent uses 2 twisted pairs from CAT6 cable (nominally 100ohm) but configured similarly to yours. (I have two cores stacked). The results from mine are very similar to yours but not quite as flat, better than -26dB from 160-10 but close to -40dB on 40m. As you can imagine I have no confidence in it handling high power but 100w of carrier has been fine. Insertion SWR is surprisingly good. I ran out of Teflon wire hence resorting to stripped down CAT cable..so a very cheap experiment. 73
I really appreciate this video. Sorry to hear about your eyes, but I can relate. I wear Rx lenses and had cataract surgery on both eyes 23 months ago. Best vision thing to happen to be since I first got my glasses and could see once again.
Nice. I had trouble with the upper end of HF using enameled wire as I didn't have the Teflon coated stuff at the time. Ended up making a coax choke instead. Would be cool to see a comparison between a few different types ;)
Thank you for the video. I too had impedance matching issues with the Teflon wire, or with the butterfly design using any wire, despite great attenuation characteristics. After reading about transmission line transformer impedance I wound up using a tight wound bifilar pattern with 18awg which ended up with great attenuation and a characteristic impedance of 50 ohms +/- 3 ohms from 1.5Mhz to over 30Mhz (and nearly to 60Mhz)
I really enjoyed the video, as I do with most of your videos. However, I was disappointed that you glossed over the calibration parts. In this case, you've added two cables that aren't present when one does a standard OSL calibration. You mention doing the thru part of the calibration using the two sets of clips connected to each other, which makes perfect sense. But is that the ONLY difference from a standard OSL calibration? What about the isolation part of the calibration? Needed, not needed? Were those cables present for the OSL part of the calibration as well (In other words, did you use the OSL standards at the port end of the S21 cable, or did you use them on port 1 without either cable in place)? Sorry if I'm missing something obvious.
Hi mister Ape, truly interesting videos..could you make a dIY video of this toroid with all the steps, windings etc? I tried by to copycat but i think i missed someting. 73!
Sweet but where is the Amidom Kmix core testing ☺️I’m still anxiously waiting maybe not so patiently 😉I ll try to vid my short of my 4core balun finally got it wound pretty enough that I can show it off sum how got 16 turns around it doing 8 then a cross over to opposing side & working my way back to start and using a center spacer so I can use nylon all thread to secure it in a uhmd cassis that will float it above ground. I used rg400. Next step is cut uhmd and drill a few hole to hide some hardware
I made a choke with ferrites and the coax running through them. What is the best way to test that choke with a nano vna? Looks like I use the mag log test, short the shields and run the test through the center pin. Does that make sense?
Hi, as always great video! Can you test in the future mix 77&75, I've heard that 75 is better than 77 specially for listening VLF&LW, I've had not bad results with 77, but 75 is almost impossible to get locally here in my country Poland, 73's
Conceptually I understand how a CMC works, I have the Halibut Electronics CMC test rig, which just puts the center pin signal on the sheild and measures return loss, which makes sense to me, its forcing current into common mode. I am struggling to understand how a through measurement like you have here (as i understand it, could be missing something) it looks like youre just measuring continuity. A schematic would have been helpful, perhaps with how it "would" have been connected in a coax feedline. Thanks Ape!!
Fair point, here is a video that shows how chokes "work": th-cam.com/video/pR3yciM45UY/w-d-xo.html Here is my playlist that show all kinds of toroid projects: th-cam.com/play/PLm8ROkpFeqoqkGQtBYfcT9Y-2GCKxBuuk.html
@@TheSmokinApe Thank you for taking the time to reply! I watched the linked video, and it cleared up my question. Thanks! I appreciate the patient education you give here.
Great video. It is a simple setup. You explained everything very well. I have seen other videos that want to inject signals using resistors and put a -10 db load on the s21 input. I don't see the point. Your video shows a much simpler way of measuring a common mode choke. Thank you very much. Some VNAs only have 101 fixed data points, not adjustable ones. I'm considering getting the NanoVNA-H4 V 4.3 which only has 101 fixed data points. Are 101 data points ok instead of 401? Thank you again for your video on explaining how to measure common mode chokes. I really appreciate it.
@@TheSmokinApe Ok, great thank you very much for that information. You did say in your video that you liked NanoVNA saver. I'll make sure that I have it installed on my computer and make sure my VNA is updated. Thank you again.
Got a 240 size toroid that arrived cracked cleanly across the width of the toroid on one side. It was replaced but I'm wondering if it could be used if I taped across the crack to keep that side from wiggling. The crack appears to mesh back together good enough that it is hard to see the crack.
Great video Ape! I will have to try that on my choke. I built mine with RG58 coax so I will have to see how that impacts the way you connect. Be curious to see if I can get that good of results.
HI - recent subscriber - love your videos and you convinced me to purchase an SV4401A - works really well. But.... I am soooo confused and I should know better about this stuff. I just wound 12 turns of RG-174 on an FT140-43. Did a calibrate on the 4401, hooked up a pair of SMA--> bare wire cables and connected the new choke. Well, I get a nice
Thank you, sir! How would you use this specific choke? On a noisy RF source in or near your shack? The findings are very specific to this hardware and architecture. Or is it a testing/learning/teaching tool? I expect a need to place 1 or more 240-31 chokes in series on the RG-8X feedline to an EFHW antenna (same that you built in earlier videos). It seems I could use this approach with a short length of RG-8X to measure the choke effect change with increasing # of windings, and then hook 2 or more in series and assess the sum of the decrease in CMC. Sound right? Or am I off base? Could you perform a similar assesment with a tiny SA? ATB! 73, John - KK7JBZ
Hey John, glad you liked the video. You should check out this playlist where I cover this stuff in detail: th-cam.com/play/PLm8ROkpFeqoqkGQtBYfcT9Y-2GCKxBuuk.html I put a choke / balun at both ends of my coax, at the antenna feed point and right before the tuner and it really helps. A counterpoise will help with the noise as well. This video was more about teaching the process of testing, which can be applied to any balun. You can make these with coax, I have a video on that too... Hope that helps!
Is it necessary to use an inline attenuator (something like 10dB) on the s21 port? Would it impact the safety of the test equipment when measuring baluns? My thoughts are that it would help with impedance mismatches. 73 de YU4BGN !
Hey bteixeira. The impedance is important as is the nature of the current. With the choke we are suppressing Common mode and not differential, check this video out: th-cam.com/video/pR3yciM45UY/w-d-xo.html
Good video and appreciate what you do for the hobby, question though, is the wire size critical or could you use a larger guage wire without any negative effects
@@TheSmokinApe The wire used for the winding will definitely have an impact on SWR especially at higher frequencies if the characteristic impedance of the wire isn't around 100 ohms. The core won't effect the SWR, but the wire will. Use a 50 ohm resistor to simulate an antenna and do a sweep with the VNA, Would suggest looking at TrxLabs 3 videos on common mode chokes and a 4:1 balun. You'll understand why your 4:1 balun (another video) has a high SWR above 14mhz. 73 de K3RDF
On the 4:1 the wire was a low grade hook up with and I am sure the cheap resistor added reactance with increased frequency. Additionally the windings were not paired correctly.
No isolator (choke) is perfect for all situations. A CMC may help, it may do nothing or it might make common mode worse. It depends on the entire system design..
Your test procedure just didn't show the fine differences between bands and your hookup just wasn't quite what I would expect. There is a video on which has this heading, you should be able to search this title. " Attenuation testing 1:1 common mode choke balun design from TRX Bench" which is a valid test aproach.
The video was to show how to test, not so much the actually results of that particular balun which is why there was no diatribe on a band by band base. What about the approach was invalid?
Great video. I took out my nanoVNA and spent last Sunday making measurements. I have a bunch #31 and #43 (2.4" OD) toroids. The #31 for chokes and the #43 for 49:1 ununs. I learned to mark them too, but one thing to note, these two mixes can easily be identified using an Ohm meter. I don't recall which, but one will measure a value of 100s kOhms whereas the other measure out of range. My question. have you tried different wrapping materials and configurations? My observations show that coax wrapped chokes stop choking near 25MHz and I also find that wrapping 8 then a cross thru with another 8 (8x8 =16 wraps including cross thru) performs with a flatter -35dB whereas a straight 16 wrap rises by 5dB over the same range. I also tested using silicon wire and enamel coated wire. Enamel coated wire worked much better -35-40dB to 30MHz then rising to -25dB to 50MHz. And while using coax is super easy to wrap, I observed that can overcome the lower performance by wrapping several in series. It actually gives great -40-50dB performance over a wider range. My understanding is that wrapping a core increases capacitance but as you know, adding capacitance in series reduces overall capacitance (1/C = 1/C1 + 1/C2 + ...). Thanks again, prior to this I only used my nanoVNA for measuring antenna VSWR.
Yes, always mark them or it can be a problem... lol. I have tried different configurations and materials, what I have found is the more wraps the less improvement you continue to see. Thanks for the comment dreupen 👍
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This is a good and accurate test. It is also done under ideal conditions. Once the choke sees anything other than 50 ohms on either side, it will always have less attenuation to CM. Type 31 is a great absorber, but it has a shortcoming....it can not handle high heat. This means that a single core of type 31 would not be suffecient for a system where the operator wants to push QRO power. It would be fine as shown for about 200W or less. One needs to MEASURE the actual currents (both CM and DM) in the antenna "system" to accurately design a balun that will handle heat, current and voltage. 73 OM
Great post Hollywood, thanks for checking out the video 👍
Hi thanks for the great video. I followed your steps and tested my first self wound RF choke. However, I saw a lot of variabilty on my S12 gain plot as opposed to what you showed here. I did see your video on jenky test leads (very helpful). I was getting sub -40db measurements as well... so I am suspicious that something is off. My choke is a 240-43 wound with 11 turns of RG8x with 6 forward and 5 backward turns. I did hook my leads to the center then the shield, and got similar results. 73's!
It’s fun to keep messing with these and testing. Thanks for watching Jim 👍
It's alarming how often I come back to this video.. you think I'd just remember
Lol, thanks for watching Andy!
Hi, I have been playing with common-mode chokes a lot over the last few years, chiefly using FT240-31 and FT240-43 cores. I have made them with coax but found them relatively narrow band, possibly due to the capacitance between turns. Consequently to achieve good common mode attenuation on 160m made 10m performance suffer. My most recent uses 2 twisted pairs from CAT6 cable (nominally 100ohm) but configured similarly to yours. (I have two cores stacked). The results from mine are very similar to yours but not quite as flat, better than -26dB from 160-10 but close to -40dB on 40m. As you can imagine I have no confidence in it handling high power but 100w of carrier has been fine. Insertion SWR is surprisingly good. I ran out of Teflon wire hence resorting to stripped down CAT cable..so a very cheap experiment. 73
Thanks for the informational post g0fvt 👍
I really appreciate this video. Sorry to hear about your eyes, but I can relate. I wear Rx lenses and had cataract surgery on both eyes 23 months ago. Best vision thing to happen to be since I first got my glasses and could see once again.
Thanks Alvin, glad you liked the video. And yes, it sucks when you have trouble seeing...
Nice. I had trouble with the upper end of HF using enameled wire as I didn't have the Teflon coated stuff at the time. Ended up making a coax choke instead. Would be cool to see a comparison between a few different types ;)
We're going to go in more depth on Saturday. Thanks for checking it out Derek...
Thank you for the video.
I too had impedance matching issues with the Teflon wire, or with the butterfly design using any wire, despite great attenuation characteristics. After reading about transmission line transformer impedance I wound up using a tight wound bifilar pattern with 18awg which ended up with great attenuation and a characteristic impedance of 50 ohms +/- 3 ohms from 1.5Mhz to over 30Mhz (and nearly to 60Mhz)
Thanks Ape...nice demonstration of how to measure the attenuation of a choke. Off to measure one of mine now. :)
Thanks man, let me know how it goes 👍
Appreciate the video Ape. Looks perfect, under -30db. Gonna download this one, So I remember how to test. Toroids are fun.
Thanks Andy, glad you liked it 👍
I got to buy a Nano VNA, you have me sold on them!
Awesome, let me know if you have questions 👍
@@TheSmokinApe thanks!
Where can I buy the BNC with the alligator clips so I can do the same experiment?
I really enjoyed the video, as I do with most of your videos. However, I was disappointed that you glossed over the calibration parts. In this case, you've added two cables that aren't present when one does a standard OSL calibration. You mention doing the thru part of the calibration using the two sets of clips connected to each other, which makes perfect sense. But is that the ONLY difference from a standard OSL calibration? What about the isolation part of the calibration? Needed, not needed? Were those cables present for the OSL part of the calibration as well (In other words, did you use the OSL standards at the port end of the S21 cable, or did you use them on port 1 without either cable in place)? Sorry if I'm missing something obvious.
Hear you go NorthTX Alligator Test Leads and the NanoVNA
th-cam.com/video/gzmrueSXteE/w-d-xo.html
@@TheSmokinApe Thanks! I'll check that out RFN!
Hi mister Ape, truly interesting videos..could you make a dIY video of this toroid with all the steps, windings etc? I tried by to copycat but i think i missed someting. 73!
Hey BAM, I might have done that video but can't rememeber. I will add it to the list... thank you!
How would you measure insertion loss in one of these? I read somewhere that they become noticable when you go above 28mhz.
Hey Vojislav, I will do a video 👍
Fantastic info Ape! News we can, and will, use.
Thanks Shooter, glad you liked it 👍
Sweet but where is the Amidom Kmix core testing ☺️I’m still anxiously waiting maybe not so patiently 😉I ll try to vid my short of my 4core balun finally got it wound pretty enough that I can show it off sum how got 16 turns around it doing 8 then a cross over to opposing side & working my way back to start and using a center spacer so I can use nylon all thread to secure it in a uhmd cassis that will float it above ground. I used rg400. Next step is cut uhmd and drill a few hole to hide some hardware
Hey Kevin, it will make an appearance on this Saturday's show 👍
I made a choke with ferrites and the coax running through them. What is the best way to test that choke with a nano vna? Looks like I use the mag log test, short the shields and run the test through the center pin. Does that make sense?
I did the test. The one with 6 ferrites is a-41 dB and the one with 5cis - 37db
That toroid... looking forward to any future videos about it!!!
Thanks DeWayne!
Thanks, Ape. This was helpful.
Thanks Mike, glad you liked it bro...
very informative video
Thanks Thump
Hi, as always great video! Can you test in the future mix 77&75, I've heard that 75 is better than 77 specially for listening VLF&LW, I've had not bad results with 77, but 75 is almost impossible to get locally here in my country Poland, 73's
Hey MrD, I think i have a 75 around here somewhere... I'll see what I can dig up.
Conceptually I understand how a CMC works, I have the Halibut Electronics CMC test rig, which just puts the center pin signal on the sheild and measures return loss, which makes sense to me, its forcing current into common mode. I am struggling to understand how a through measurement like you have here (as i understand it, could be missing something) it looks like youre just measuring continuity. A schematic would have been helpful, perhaps with how it "would" have been connected in a coax feedline. Thanks Ape!!
Fair point, here is a video that shows how chokes "work": th-cam.com/video/pR3yciM45UY/w-d-xo.html
Here is my playlist that show all kinds of toroid projects: th-cam.com/play/PLm8ROkpFeqoqkGQtBYfcT9Y-2GCKxBuuk.html
@@TheSmokinApe Thank you for taking the time to reply! I watched the linked video, and it cleared up my question. Thanks! I appreciate the patient education you give here.
@@danielwinn5707 glad you like them 👍
Great video. It is a simple setup. You explained everything very well. I have seen other videos that want to inject signals using resistors and put a -10 db load on the s21 input. I don't see the point. Your video shows a much simpler way of measuring a common mode choke. Thank you very much. Some VNAs only have 101 fixed data points, not adjustable ones. I'm considering getting the NanoVNA-H4 V 4.3 which only has 101 fixed data points. Are 101 data points ok instead of 401? Thank you again for your video on explaining how to measure common mode chokes. I really appreciate it.
Hey Matt, with the newer firmware most support 401 points. You can also use NanoVNA saver to create segments, 401 point x 10 segments is 4010 points 👍
@@TheSmokinApe Ok, great thank you very much for that information. You did say in your video that you liked NanoVNA saver. I'll make sure that I have it installed on my computer and make sure my VNA is updated. Thank you again.
Good luck with it Matt 👍
Got a 240 size toroid that arrived cracked cleanly across the width of the toroid on one side. It was replaced but I'm wondering if it could be used if I taped across the crack to keep that side from wiggling. The crack appears to mesh back together good enough that it is hard to see the crack.
it won't be as good as a new one but it will work like a clamp on ferrite, give it a try.
Solid work, son!
Thanks FEP 👍
Great video Ape! I will have to try that on my choke. I built mine with RG58 coax so I will have to see how that impacts the way you connect. Be curious to see if I can get that good of results.
I've done the same video with an RG58 cable and the results were good.
Great work Ape. All that's way above my pay grade 🥴 lol.
Fantastic content.
Motters M7TRS 73 👍🏻
Thanks for watching Motters, glad you liked it 👍
HI - recent subscriber - love your videos and you convinced me to purchase an SV4401A - works really well. But.... I am soooo confused and I should know better about this stuff. I just wound 12 turns of RG-174 on an FT140-43. Did a calibrate on the 4401, hooked up a pair of SMA--> bare wire cables and connected the new choke. Well, I get a nice
Check out this video and it should cover it for you: Balun Chokes - How do they work?
th-cam.com/video/pR3yciM45UY/w-d-xo.html
Thank you, sir!
How would you use this specific choke? On a noisy RF source in or near your shack? The findings are very specific to this hardware and architecture. Or is it a testing/learning/teaching tool?
I expect a need to place 1 or more 240-31 chokes in series on the RG-8X feedline to an EFHW antenna (same that you built in earlier videos).
It seems I could use this approach with a short length of RG-8X to measure the choke effect change with increasing # of windings, and then hook 2 or more in series and assess the sum of the decrease in CMC. Sound right? Or am I off base?
Could you perform a similar assesment with a tiny SA?
ATB!
73,
John - KK7JBZ
Hey John, glad you liked the video. You should check out this playlist where I cover this stuff in detail: th-cam.com/play/PLm8ROkpFeqoqkGQtBYfcT9Y-2GCKxBuuk.html
I put a choke / balun at both ends of my coax, at the antenna feed point and right before the tuner and it really helps. A counterpoise will help with the noise as well.
This video was more about teaching the process of testing, which can be applied to any balun. You can make these with coax, I have a video on that too...
Hope that helps!
Is it necessary to use an inline attenuator (something like 10dB) on the s21 port? Would it impact the safety of the test equipment when measuring baluns? My thoughts are that it would help with impedance mismatches. 73 de YU4BGN !
You typically use them when testing amplified signals, so you don’t overload and damage the input 👍
@@TheSmokinApe Thanks Ape! Keep doing amazing stuff for the hobby. Many thanks from Serbia, 73 de YU4BGN!
@@bogdanmaksimovic37 thanks man, stay warm 👍
Would you have a link from where to source that teflon cable? Any specifications, and if we need to use that at 1KW, what cable should be used?
Hey Jai. I use this in 18AWG: www.remingtonindustries.com/hook-up-wire/electronics/ptfe-600-volt/
Sorry, I am not sure about 1KW.
Hello again thank yiou for your reply, I have a question, does "Power SDR" work with the RTL-SDR ?
It looks like it will www.rtl-sdr.com/big-list-rtl-sdr-supported-software/
What about the impedance? Isn't it important that besides having a -30dB gain also have high impedance?
Hey bteixeira. The impedance is important as is the nature of the current. With the choke we are suppressing Common mode and not differential, check this video out: th-cam.com/video/pR3yciM45UY/w-d-xo.html
Good video and appreciate what you do for the hobby, question though, is the wire size critical or could you use a larger guage wire without any negative effects
Different gauge can have an impact. Give it a try and see how it works. Thanks for watching James 👍
Is this type of choke better than wrapping coax around the toroid?
I use both, it will depend on the type of core, coax and wire. It’s best to test whatever you make to make sure it will work for you 👍
Half way through the video, and the test hasn't started yet!
Glad you like it!
Now I know!
The more you know... 🌈
Can you show how the “normal RF”will pass or will it be 30db attenuated also?
It will have < 1db of insertion loss, I will do a video...
In theory "normal RF" is differential mode voltage/current (as opposed to common mode) and therefore not affected by the choke.
Where did you get your ptfe wire?
Hey @mblogler, it's made by Remington and I got it on Amazon.
How is the SWR from 3 to 30mhz?
This choke would have a minimal impact on SWR 👍
@@TheSmokinApe The wire used for the winding will definitely have an impact on SWR especially at higher frequencies if the characteristic impedance of the wire isn't around 100 ohms. The core won't effect the SWR, but the wire will.
Use a 50 ohm resistor to simulate an antenna and do a sweep with the VNA,
Would suggest looking at TrxLabs 3 videos on common mode chokes and a 4:1 balun. You'll understand why your 4:1 balun (another video) has a high SWR above 14mhz. 73 de K3RDF
On the 4:1 the wire was a low grade hook up with and I am sure the cheap resistor added reactance with increased frequency. Additionally the windings were not paired correctly.
No isolator (choke) is perfect for all situations. A CMC may help, it may do nothing or it might make common mode worse. It depends on the entire system design..
Thanks for the info 👍
Your test procedure just didn't show the fine differences between bands and your hookup just wasn't quite what I would expect. There is a video on which has this heading, you should be able to search this title. " Attenuation testing 1:1 common mode choke balun design from TRX Bench" which is a valid test aproach.
The video was to show how to test, not so much the actually results of that particular balun which is why there was no diatribe on a band by band base. What about the approach was invalid?
Great video. I took out my nanoVNA and spent last Sunday making measurements. I have a bunch #31 and #43 (2.4" OD) toroids. The #31 for chokes and the #43 for 49:1 ununs. I learned to mark them too, but one thing to note, these two mixes can easily be identified using an Ohm meter. I don't recall which, but one will measure a value of 100s kOhms whereas the other measure out of range.
My question. have you tried different wrapping materials and configurations? My observations show that coax wrapped chokes stop choking near 25MHz and I also find that wrapping 8 then a cross thru with another 8 (8x8 =16 wraps including cross thru) performs with a flatter -35dB whereas a straight 16 wrap rises by 5dB over the same range. I also tested using silicon wire and enamel coated wire. Enamel coated wire worked much better -35-40dB to 30MHz then rising to -25dB to 50MHz.
And while using coax is super easy to wrap, I observed that can overcome the lower performance by wrapping several in series. It actually gives great -40-50dB performance over a wider range. My understanding is that wrapping a core increases capacitance but as you know, adding capacitance in series reduces overall capacitance (1/C = 1/C1 + 1/C2 + ...).
Thanks again, prior to this I only used my nanoVNA for measuring antenna VSWR.
Yes, always mark them or it can be a problem... lol. I have tried different configurations and materials, what I have found is the more wraps the less improvement you continue to see. Thanks for the comment dreupen 👍
👍
Thanks DP!
🥰👍
Also, that wire chart in the audio article you linked to the other day was a fantastic read♡ hecka appreciate you.
Glad it was helpful, thanks for watching Aname 👍