More NanoVNA videos ⬇ Using a NanoVNA to Fix Our Repeater Coverage: ruclips.net/video/0mRKMwVNPXc/видео.html How Long Is Your Coax? Testing with NanoVNA: ruclips.net/video/cQkBMDZ5AhQ/видео.html
You are on the right track with the resonance theory about your "3 turn" coil. This is evidenced by the fact that you are showing +6 dB on 2m, so you definitely have some E/I phase games going on. All coils have a self-resonant point, due to the L of the coil, and the (parasitic) C vetween the turns of the coil. I would expect a MUCH different result if you spread the turns around the ferrite. The Smith chart should explain what's going on. I might dig out my NanoVNA and do some experimenting. (Edit: I'm an EE, though it's been a few decades since I studied this.)
Thanks for the video. I've had a NanoVNA for a while collecting dust as I have a bunch of professional antenna analysers but I am finding these videos fasinanting as to what you can do with these tiny units and it's spuring me to get mine out and play. I look forward to the next installment :)
I was amazed when I was able to troubleshoot a coax switch on 1296 with a NanoVNA. The alpha delta switch I am using is rated to 1300Mhz but not all ports act the same, just had to move my antennas to the better ports.
I think the reason the small mix 31 ferrite beads were better than the snap-ons was the smaller inside diameter of the beads. There was more of the ferrite material surrounding the wire on all sides vs, on one side for those big ones. I bet two or three snap-ons with just large enough of an inside diameter to allow two passes of cable through and still be able to snap closed would solve the real-life RFI issue.
Dude you just solved a problem for me! Testing this was on my To Do list for the northern winter. Now I'm just going to implement your solution and be done with it.
Thanks Carlos. I've ordered one of the testing rigs from Halibut Electronics. That will be good for testing chokes around coax too. Do you have some RFI issues?
Very interesting video Hayden. I will have to make up some test leads, I have a box of ferrites of many sizes and mixes, some are a known mix, other are unknown. This is a simple method to show if they will work on a particular frequency, even if the mix is supposed to be for different frequencies. It would be nice to see a side by side of say, 43, 52, 62 and 74 mixes as they pertain to the HF end of the spectrum. These seem to be the most commonly used and recommended mixes for CMC and RFI choking. It would also be interesting to see the side by side of ferrite against iron core, as A LOT of guys seem to find 52 mix iron core toroids are the best for 20m antenna's, but I haven't seen any iron cores used for suppression chokes as yet. Problem of course is having the toroid's to test, as they can be VERY expensive items for some types. I only have one iron core toroid, I bought for a particular antenna build that Alex VK2PRC designed and has had GREAT success with, using an Iron core 52 mix toroid and some wire., he gets 40m and 20m from the same feedpoint. I know this bit is off topic, but I added it anyway.
Great video Hayden. I've been contemplating attacking my home Ethernet cabling with ferrite clamps to help reduce noise/birdies/whistles it creates on HF. This is something I've lived with for a while now (I've done a RUclips video about it years ago). Since upgrading to Cat6 (over Cat5E) cables through the house it is better.
I did forget to mention in the video I bought a common mode choke test rig from Halibut Electronics in the US on Friday… so looking forward to getting that to use - electronics.halibut.com/product/common-mode-current-choke-test-rig/ I put some clamps on my (new) router and WiFi AP after I suspected they were causing some noise on HF. Coincidentally the noise level has dropped - but time will tell if it has made a permanent improvement, even 6m is quieter! Thanks Michael 👍
thiis something ive been wanting to see, thanks. I have a pile of random unknown ferrites that i'd like to profile. I had similar result watching noise supression of multiple turns of an ethernet cable, turns were better than multiple ferrites, and more turns had diminishing returns, usually two or three turns did the most work and any more than that had minimal or no benefit. Also thanks for explaining why you do the crossover when winding, i've seen everyone do it but never heard an explanation.
Very useful, thanks! The question about "too many" turns on one core and less attenuation on higher frequencies, or even +dB's. Maybe you have too much capacity between the turns?
A timely vid Hayden! Thank you. I just got a Common Mode Current Choke Test rig (kit) from Halibut Electronics, and will be starting to play around with some "toe-roids" and un-un's and bal-un transformers. Thanks for the vid!
Thanks for the demo - and it may explain an issue I'm having with RFI. I use the clamp ons on the DC lines and Data lines of my HF radio, and they work well. That being said, I was continuing with having issues when I run my FT2800 2m mobile run at 70W using the same clamp-on ferrites on the 2800 DC lines. I suspect I will need to do your measurement on their DC lines. Thanks again.
OK if you are working on a spot frequency but if you are looking at say working across 3-30MHz then your half wave is anything between 50m & 5m so unless you have stretchy cable you wont be able to use a half wave across all the freq band you are interested in
Sooo would it have anything to do with the plastic on the square one? For example on the round one it touches inside and outside . The square only touches the inside. Trying to learn
Fascinating video. How many turns have you been able to do on coax cables? considering they're quite 'thick', I wouldn't have thought you'd be able to get many turns into a ferrite core.
Good ideas, but I have a few things to point out. Your setup measures a single inductor as a 2 port device, but you left the GND unconnected, thus you have a very big loop of return current, and I highly doubth that the calibration can compensate for that. I suggest connecting the shields of the 2 probes together, and repeating the experiments to check if anything chantges. At around 12:00 you say and show it measures +6dB transmission, that is clearly wrong, as it would suggest you getting more power out than goes in, and thus indicative of a bad measurement setup. I'm not 100% sure, but maybe it goes away if you fix the probing. At around 19:30, you have unconneccted cables, but the VNA shows nonzero and not flat transmission - also signs of bad probing. You do not measure the ferrites nonlinearity, but that is also a very important effect. The effect of it decreases as power increases, that can cause very strange effects. This might or might not be the reason why increasing the turns does not always help - I would suggest setting the VNA on CW, and checking using a scope how the voltages look.
For multiple turns through clamps, I try not to cross the wires. Sometimes not possible. Regardless, there is capactive coupling between the looped wires inside the clamp to create a resonance. How much? 🤷♂️
Doesn't attenuating RF on the network cables interfere with the data flow? Unless you use shielded cable. Or better yet, use fiber! YES! Ferrites attenuate signals on unshielded cable. There is a whole post about this in r/networking: "Ferrite choke on cat5/network cables"....
It will likely reduce the max distance of the cable, Ethernet uses a balanced transmission method via twisted pair so it shouldn't cause an issue beyond just some attenuation.
@@cthoadmin7458 Turns out yes, ferrites attenuate signals on unshielded cable. There is a whole post about this in r/networking: "Ferrite choke on cat5/network cables"....
What you call 1 turn iq actually half a turn. Two turns is 1.5 turn. etc. If you don't complete the turn on the ferrite with the two ends meeting at the same point, it's not a complete turn.
The overall circuit completes all loops to integers. With that said, the exact geometry of the loops come into play, so the effective “n” may be slightly off from being an integer. If you have a current clamp meter you can see that a single wire through reads almost exactly half of the reading with an additional “full” turn. If it was .5 compared to 1.5 you’d see a 3 x difference.
sorry lambda brian is right. The first wire through IS "one turn" (even though it may look like just a half) as the rest of the circuitry external to it completes the turn. To count the number of turns you ALWAYS just count the number of wires through the centre (& NOT the number of "tight wraps" on the outside as this misses the first turn).
More NanoVNA videos ⬇
Using a NanoVNA to Fix Our Repeater Coverage: ruclips.net/video/0mRKMwVNPXc/видео.html
How Long Is Your Coax? Testing with NanoVNA: ruclips.net/video/cQkBMDZ5AhQ/видео.html
You are on the right track with the resonance theory about your "3 turn" coil. This is evidenced by the fact that you are showing +6 dB on 2m, so you definitely have some E/I phase games going on. All coils have a self-resonant point, due to the L of the coil, and the (parasitic) C vetween the turns of the coil. I would expect a MUCH different result if you spread the turns around the ferrite.
The Smith chart should explain what's going on. I might dig out my NanoVNA and do some experimenting.
(Edit: I'm an EE, though it's been a few decades since I studied this.)
My NanoVNA arrives next week! Another rabbit hole to explore.. Can’t wait now to experiment. Thanks Hayden.
Hope you enjoy it! Have fun experimenting mate
Thanks for the video. I've had a NanoVNA for a while collecting dust as I have a bunch of professional antenna analysers but I am finding these videos fasinanting as to what you can do with these tiny units and it's spuring me to get mine out and play. I look forward to the next installment :)
I was amazed when I was able to troubleshoot a coax switch on 1296 with a NanoVNA. The alpha delta switch I am using is rated to 1300Mhz but not all ports act the same, just had to move my antennas to the better ports.
I think the reason the small mix 31 ferrite beads were better than the snap-ons was the smaller inside diameter of the beads. There was more of the ferrite material surrounding the wire on all sides vs, on one side for those big ones. I bet two or three snap-ons with just large enough of an inside diameter to allow two passes of cable through and still be able to snap closed would solve the real-life RFI issue.
Also the extra passes through the big one had a similar benefit
Dude you just solved a problem for me! Testing this was on my To Do list for the northern winter. Now I'm just going to implement your solution and be done with it.
Thanks Carlos. I've ordered one of the testing rigs from Halibut Electronics. That will be good for testing chokes around coax too. Do you have some RFI issues?
Awsome demonstration , very thorough.
Thank you!
Very interesting video Hayden. I will have to make up some test leads, I have a box of ferrites of many sizes and mixes, some are a known mix, other are unknown. This is a simple method to show if they will work on a particular frequency, even if the mix is supposed to be for different frequencies. It would be nice to see a side by side of say, 43, 52, 62 and 74 mixes as they pertain to the HF end of the spectrum. These seem to be the most commonly used and recommended mixes for CMC and RFI choking. It would also be interesting to see the side by side of ferrite against iron core, as A LOT of guys seem to find 52 mix iron core toroids are the best for 20m antenna's, but I haven't seen any iron cores used for suppression chokes as yet.
Problem of course is having the toroid's to test, as they can be VERY expensive items for some types. I only have one iron core toroid, I bought for a particular antenna build that Alex VK2PRC designed and has had GREAT success with, using an Iron core 52 mix toroid and some wire., he gets 40m and 20m from the same feedpoint. I know this bit is off topic, but I added it anyway.
Nice vid! Maybe need a test, 1,2,3 turns without ferrite.
Great video Hayden!
Thanks Hank 👍
Great video Hayden. I've been contemplating attacking my home Ethernet cabling with ferrite clamps to help reduce noise/birdies/whistles it creates on HF. This is something I've lived with for a while now (I've done a RUclips video about it years ago). Since upgrading to Cat6 (over Cat5E) cables through the house it is better.
I did forget to mention in the video I bought a common mode choke test rig from Halibut Electronics in the US on Friday… so looking forward to getting that to use - electronics.halibut.com/product/common-mode-current-choke-test-rig/
I put some clamps on my (new) router and WiFi AP after I suspected they were causing some noise on HF. Coincidentally the noise level has dropped - but time will tell if it has made a permanent improvement, even 6m is quieter! Thanks Michael 👍
great video, can you do a video on how to measure the suppression on air wound choke and also using a toroid??
thiis something ive been wanting to see, thanks. I have a pile of random unknown ferrites that i'd like to profile. I had similar result watching noise supression of multiple turns of an ethernet cable, turns were better than multiple ferrites, and more turns had diminishing returns, usually two or three turns did the most work and any more than that had minimal or no benefit. Also thanks for explaining why you do the crossover when winding, i've seen everyone do it but never heard an explanation.
Glad it was helpful! Thanks 👍
Very useful, thanks! The question about "too many" turns on one core and less attenuation on higher frequencies, or even +dB's. Maybe you have too much capacity between the turns?
Good point!
@@HamRadioDX But you can test that hypothesis by increasing or reducing the distance between the turns, I suppose.
A timely vid Hayden! Thank you. I just got a Common Mode Current Choke Test rig (kit) from Halibut Electronics, and will be starting to play around with some "toe-roids" and un-un's and bal-un transformers. Thanks for the vid!
Thanks Arnold, I literally just bought the same test rig! I’m looking forward to getting it and playing some more 👍
Great video Hayden! Thanks for that! 73
Thank you too!
Eggcellent video young fella😅
Thanks!
Thanks for the demo - and it may explain an issue I'm having with RFI. I use the clamp ons on the DC lines and Data lines of my HF radio, and they work well. That being said, I was continuing with having issues when I run my FT2800 2m mobile run at 70W using the same clamp-on ferrites on the 2800 DC lines. I suspect I will need to do your measurement on their DC lines. Thanks again.
Cheers! Yeah see what happens when you test at 2m, might be a bit different perhaps
You should use an half wavelength of wire and move it along the cable to see the effect.
OK if you are working on a spot frequency but if you are looking at say working across 3-30MHz then your half wave is anything between 50m & 5m so unless you have stretchy cable you wont be able to use a half wave across all the freq band you are interested in
Nice job! Thanks. ❤
Excellent! Thank you
I am so glad you did the video on this thank you kk4ekk
Thanks!
Great video, Hayden. Just wondering, what firmware version do you have loaded on your SAA-2N?
Hey mate, I have version v1.3.31
Sooo would it have anything to do with the plastic on the square one? For example on the round one it touches inside and outside . The square only touches the inside. Trying to learn
Perhaps 🤔 I do wonder about the distance between coils in the clamp, so do bigger coils make a difference or smaller etc
Fascinating video. How many turns have you been able to do on coax cables? considering they're quite 'thick', I wouldn't have thought you'd be able to get many turns into a ferrite core.
RG-58 fits through a couple of times (I think maybe 3) in a 13mm clamp. The ring ferrites are much better suited for making common mode chokes :)
I will make loops with a larger radius through the ferrite, and not pull them tight.
You should identify the ferrites and provide links.
Which mix did you end up using on your Ethernet cable?
I ended up ordering a combination of Mix 43 and 31 clamps - still waiting on them arriving
Good ideas, but I have a few things to point out.
Your setup measures a single inductor as a 2 port device, but you left the GND unconnected, thus you have a very big loop of return current, and I highly doubth that the calibration can compensate for that. I suggest connecting the shields of the 2 probes together, and repeating the experiments to check if anything chantges.
At around 12:00 you say and show it measures +6dB transmission, that is clearly wrong, as it would suggest you getting more power out than goes in, and thus indicative of a bad measurement setup. I'm not 100% sure, but maybe it goes away if you fix the probing.
At around 19:30, you have unconneccted cables, but the VNA shows nonzero and not flat transmission - also signs of bad probing.
You do not measure the ferrites nonlinearity, but that is also a very important effect. The effect of it decreases as power increases, that can cause very strange effects. This might or might not be the reason why increasing the turns does not always help - I would suggest setting the VNA on CW, and checking using a scope how the voltages look.
For multiple turns through clamps, I try not to cross the wires. Sometimes not possible.
Regardless, there is capactive coupling between the looped wires inside the clamp to create a resonance. How much? 🤷♂️
Yeah especially Ethernet which is maybe 2 turns before you have to cross over the top?
@@HamRadioDX Yes? Although Ethernet is twisted pairs which helps.
I am not sure if measuring S21 along a 30cm wire on anything higher in frequency than 50Mhz will be correct.
Why are you unsure?
Doesn't attenuating RF on the network cables interfere with the data flow?
Unless you use shielded cable. Or better yet, use fiber!
YES! Ferrites attenuate signals on unshielded cable. There is a whole post about this in r/networking: "Ferrite choke on cat5/network cables"....
It will likely reduce the max distance of the cable, Ethernet uses a balanced transmission method via twisted pair so it shouldn't cause an issue beyond just some attenuation.
Hayden's done an entire video on just this subject.
@@cthoadmin7458 nice, how do I find it?
@@cthoadmin7458 Turns out yes, ferrites attenuate signals on unshielded cable. There is a whole post about this in r/networking: "Ferrite choke on cat5/network cables"....
What you call 1 turn iq actually half a turn. Two turns is 1.5 turn. etc. If you don't complete the turn on the ferrite with the two ends meeting at the same point, it's not a complete turn.
The overall circuit completes all loops to integers. With that said, the exact geometry of the loops come into play, so the effective “n” may be slightly off from being an integer. If you have a current clamp meter you can see that a single wire through reads almost exactly half of the reading with an additional “full” turn. If it was .5 compared to 1.5 you’d see a 3 x difference.
sorry lambda brian is right. The first wire through IS "one turn" (even though it may look like just a half) as the rest of the circuitry external to it completes the turn. To count the number of turns you ALWAYS just count the number of wires through the centre (& NOT the number of "tight wraps" on the outside as this misses the first turn).