#766

Episode 766
I measure the frequency response of various ferrites and a couple iron core toroids. The sweep on the oscilloscope is a plot of frequency vs transmission. The horizontal was 1 to 15 MHz in a linear sweep.
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[@peterklein3632]

There's a way to do this without a synch pulse. I triggered on channel 2 of my function generator outputting a square wave at the reciprocal of the scan frequency (example: 0.5 seconds scan, 2 Hz). The scan will appear, but will "march" across the screen. Tweak the function generator's sweep time in small fractions of a second until you slow the "march" down to a crawl. When you can see the entire sweep on the screen, press Run/Stop or Single trigger to freeze it. (FY6800 function generator, Siglent 1202X scope). This was a very useful video, thank you! I'm really enjoying your channel!

[@electronicengineer]

Thanks so much for performing this demonstration for us IMSAIGuy! I've installed much more ferrite beads, over the course of my professional career, than I care to recall, however in so doing, I've imagined, almost exactly, the very type of response you obtained on your scope screen during this experiment. I never thought of actually measuring the high frequency "soaking" effect like you just showed us myself... I don't know why I am lacking in imagination, but you actually do the types of experiments that I find entirely fascinating. This is one of the main draws for me, to check your great KZbin content daily. I could have done this very experiment myself decades ago, but I honestly just never had the idea to do what you just did. Being a mostly "visual learner", this is the best way for me to learn new (or in this case old) things. You honestly have a great imagination sir. Thank you again for showing this! I really love this channel. Fred

[@mostlypostie1]

here here! Well said :)

[@gsansoucie]

Glad this video popped up, I have a box of those cheap no name snap on ferrite beads that haven’t appeared to have any affect on my rig. Now I know why. I have an O-Scope and a signal generator, but no means to inject a sweep. But you gave me an idea to use my Oscope to test my wires for suppression. Thanks.

[@k5rmj]

Another great video. Thanks for all your efforts. I'm going to try that with my VNA

[@briandonaldson612stringgui8]

I know, 2 years later, but gee I wish you had a cleaner desk so we could see how you connected your test leads. But it did give me an idea on how to use my NanoVNA and TinySA with my Oscope to test some snap on beads. Thanks

[@MrYogibehr]

I really like your style of teaching.

[@subramanianr7206]

I feel very sorry to make my comments here. On seeing the title of the video I thought that you have read/learned something about the ferrite and the iron powder cores; because I had made some clarification when you posted a video on your attempt to make "a low pass filter" for 7 MHz using the "yellow-grey" type 33 or 08 mix iron powder cores. I had told you that it was a low frequency mix suitable for less than 1 MHz switching power supplies. It has very high saturation point, volume resistivity and Curie temperature. It's good for using to suppress EMI on lines carrying high current DC or low frequency AC. You can find them in the SMPS of all kinds. You answered to one of the comments that there is no standards available; not anymore. The "Fair-rite" and the "Micrometals" of the USA are the largest manufacturers and they have the colour code standard for the iron powder cores and of course there is no way to discriminate between the ferrite mixes just by looking at them. Again one has confusion with the "yellow-clear" (mix 6, with initial permeability of 8, a material good for narrow band, high Q inductor as in a filter from 14-70 MHz) and the one bulky (and few smaller) core "yellow-white"( mix 26, again good for the SMPS EMI suppression, ie, less than 1MHz. The ferrite cylinders (or sleeves) are made of mix 43, 31,33,61,75 or 77. Mix #43(HF) and #61(VHF and UHF) are used to suppress RFI in the amateur radio use. They're made of Ni-Zn. Initial permeability is less than 1000, like 850 for #43 and 125 for #61. You Ni-Mn mix with high permeability like 31,31,75, and 77. Type #31 is a new Ni-Mn mix that can be used for RFI for the HF, VHF and UHF bands. W2DU BalUn consisted of sleeving several Ni-Mn, #77 torroids over the coax cable at the feed point to avert the CMC (common mode current) that tends to flow down the cable towards the radio. Then there are #52 and "K" materials (Ni-Zn) for the recently popular "EFHWA", end fed half wave antenna apart from the #43. Please study about the mixes, saturation, coercivity, magnetic flux lines, volume resistivity, Curie temperature, inductive, capacitive and resistive components of the reactance in a torroid coil etc. Every inductor (whether air cored or ferrite/iron cored) would have a reactance proportional to the frequency of the AC (RF) and it is used widely meticulously chosen for the particular application. People think that it's a subject of conundrum but not anymore. The "Fair-rite and the Micrometals" offer a very elaborate products catalog and datasheet that's a kind of Bible for every RF enthusiast. I think you are coming across the name Fair-rite for the first time. The late G3TXQ, was one among many whose works should not be ignored in the addictive hobby of "HAM RADIO" Good luck to you. I have been a fan of your channel for more than 2years since you started making videos on the "Nano VNA". I suggest you make great videos with correct scientific content. De VU2RZA

[@electronicengineer]

Great information sir. Thank you! Fred

[@bobkozlarekwa2sqq59]

If you increase your test frequencies I think you’ll see they are much more effective. Most of the snap on tape chokes where designed to minimize higher frequency noise such as that for me switching power supply. For lower frequency work I’d start out using cores that are made from a mix 75 material. I have found that multiple turns of wire through one individual core tightly wound works much better than slipping multiple cores over one wire. Regarding the yellow core it’s very large for the skinny wire that you’re passing through it you need much tighter coupling between the wire and the inductor

[@K1ZEK]

A fun video. Thanks 73 Leo.

[@samuellourenco1050]

Some of the rings are ferrite, while others are made of sintered iron powder. They have completely different characteristics and applications.

[@zeno2712]

You showed that the straight wire on its own made a difference (because it had some inductance) but what would have been interesting would have been to compare a ferrite core that you wound a couple of turns through with just the turns without the core. This would have shown what the core added to the inductance of the air-cored coil.

[@MidlifeRenaissanceMan]

It’s a square effect 2 turns 4x 3 turns 9x Like a transformer AFAIK

[@K6TJO]

Great video. I want some of that equipment now

[@W4BIN]

He doesn't say if the input of the 'scope is terminated or not. (like transmissions lines are) Ferrite cores absorbs the energy and add inductance and the iron cores mostly add inductive, that is why ferrites are not painted. I think sweeping to 30 MHz would have been appropriate. (HF bands) Ferrite beads are called "VHF beads," they prevent VHF oscillations in some circuits. (usually in high impedance inputs) Ron W4BIN

[@perryjones5500]

A lot of ferrites are aimed at radiated emission from leads, that is to say, above 30MHz where they become lossy (by design) turning emi in to heat. They often hit their sweet spot around 100MHz, so with these, might not be much attenuation at all 15MHz and below.

[@jdmccorful]

As is in everything else. Thanks for the look.

[@georgesmith2431]

This was an interesting video, thank you for putting it out for us. I know the returns where small after 3, but it would have been nice to see what 4 or 6 or 8 would do, and you already had them. or even a mix of the long and short ones. I bought the cheap snap ones as I’m trying to fix the static noise in my radio from my LED light bars. But after watching your video I ordered some of the ferrite toroids.

[@Greg_Chase]

Ferrite has a skinny ('narrow') hysteresis curve, which in laymans terms, means that a AC/RF alternating signal can more easily flip the electron spins (the magnetic field) in the material, compared to iron. Ferrite is made partly with iron but mixed with other elements. The benefit of the ease of flipping electron spins (aka reversing the magnetic field in the material as forced to do so by the alternating current, the AC or RF) - is that less energy is spent torquing the electron spins in a new direction during the flip in each of the two half-cycles in each period of the supplied frequency. So ferrite is used in transformer cores because (1) it still increases the magnetic field compared to free space, since it contains iron, but (2) without the loss of energy of a 'thick' hysteresis curve like iron has. RF chokes benefit from the same "let's not waste too much power torquing these electron spins back and forth" motive. The technical term for 'running roughshod' over electron spins in this regard is coercivity. "Low" coercivity means the electron spins (the magnetic field) are like the subjugated minions of a powerful totalitarian dictator: "do it now, with no resistance!" type of deal. .

[@glasslinger]

Impedance matters. The impedance you are feeding with the choke will have quite an effect on the attenuation. The reactance of a clip lead is quite high which may be the reason for the poor attenuation. Try a .001 mf capacitor on the output side.

[@jameswest7945]

More turns more affective as you probably already know

[@dapperdave4952]

I've been going to Amidon Corp for my ferrite needs for many years. Great resource to determine which mix will work best for the results your looking for...Mix 43 is my fav. ExtraOld Ham with a GROL/w Radar here. Enjoy your videos very much OM

[@natevirtual]

Which is the best type /brand ferrite bead for an audio interface usb c cable?

[@dapperdave4952]

@@natevirtual Split core mix 43 is usually the best general purpose from Amidon Corp

[@natevirtual]

@@dapperdave4952 thank you! Also, which would I need for the 3 prong power cords? And I'd have to put it closer to the male end? I had to search what GROL W/RADAR meant. You're the guy!

[@dapperdave4952]

@@natevirtual 3 Prong power 120 Volts AC cords don't usually require anything additional since the 60 hertz is low enough that it won't interfere with USB data even at harmonics of 60 hetrz

[@natevirtual]

@@dapperdave4952 wow you're the best! I'm so glad to have come across a professional like you! Thanks for sharing your knowledge with me!

[@rossbrawley]

I have had one of those tnc's since right after the 2 model came out.... It's great.... I set it up once with my android tablet and Ft-891 and did some sstv... But I remember it was tricky. Works great for aprs..... Now I wonder if I can use it as a wireless tnc with ft-8 and winlink on the laptop..... Oooooo test time!

[@flemming2jacobsen911]

Cool video. Thanks! Did I miss a video showing how you set up this kind of measurement?

[@Bobo-ox7fj]

That "Absolutely!" is the benefit of dealing mostly with technically inclined people, you don't typically need to walk them through a flowchart to make sure the product is actually turned on before sending out new parts...

[@andrewverran3498]

Great video, any chance you could do a follow up video regarding RF chokes/ferrites on some USB cables? ie why some have them but most don't, ? Cheers..

[@johnrees44..G4EIJ]

Thank you for this informative video.. I have a problem in my shack with 7mHz ‘feedback’ making my CW keyer unstable.. From your experience, it would appear that ‘ferrite suppression’ on the cables is not very effective at 7mHz.. Do you know of a suitable alternative please?.. Thank you.

[@peterwu831]

The amount of RF suppression is also shown in the inductance of these cores as inductors. The iron core is inefficient to make inductance, while the ferrite core is very efficient.

[@richardlinn5512]

Seeking filter for external LED POD LIGHTS ON JEEPS to eliminate radio interference !

[@ThinklikeTesla]

The free Fair-Rite catalog is GREAT. I have a junk box full of assorted surplus-shop ferrites, and I'd like to categorize them somehow (maybe by nearest Fair-Rite material number?). Curious how other folks handle this...

[@SkyhawkSteve]

I've spent time getting my designs to pass EMC standards, and Fair-Rite offered a variety of useful ferrites. Their catalog helps explain the way that different materials do best in certain frequency ranges. I've used a lot of their SMD ferrites too. I've even used one of their SMD common mode chokes on a home project when a switcher interfered with my nearby FM radio. 🙂

[@gordslater]

2 years have passed since you asked, but ... Measure the inductance of a single turn (which for a toroid, is a straight wire through! - you count the wires passing through the core, so 3 copper wires through the centre is a 3 turn core (even though your brain says "that's just two turns") This single turn can then be matched to the "n-squared" or "t-squared" inductance value in product catalogs to give a clue to the product. Personally, I then confirm it by then winding 10 turns (producing 10-squared the inductance) and do the math/check the chart too. However... People are usually surprised to find that different cores are targetted for different frequencies, as well as different temperature characteristics. For stable tuned circuits, you chose stable low-loss core material (and the also are designed to give a high Q-factor). For supression, however, you need a high-loss material (and temperature stability is not an issue and Q is better kept low to avoid unwanted peaks in the response) So for categorising odd/loose/junk cores, you can easily end up with 3 or 4 different cores of different types (high power/high saturation, high stability tuned-RF, supression (low temp stability) or $whatever types that all give the same n-squared (some manufacturers call this the t-squared) figure. But hey, not everything is easy in life :) A swept response in as in this vid can be a clue, a broader atteuation over a wider upper region of frequencies usually signifies a higher-loss suppression core, at least for low numbers of turns and say 1-to-20MHz test sweeps. For smaller cores, or those designed for VHF/UHF supression, you may need to sweep much higher to see differences (say 30-100MHz) If you only have simple test equipment that can't measure a single turn, you can add a standard RF-stable capacitor in parallel and do the math from a HF RF tuned circuit. Tune the sig-gen to find the peak resonance then do the match 1/twoPiRootLC, where your C is known) If you use a RF voltmeter you don't even need a scope to do this (you can make one from a small-signal diode - look up "RF diode probe" - and a millivoltmeter - an analogue needle one is best, digital ones can be twitchy as you sweep the sig-gen frequency and befuddle yor brain. If you use a FET voltmeter, (high input impedance) then with a quality moving-coil meter you can sometimes even see the difference between high-Q core materials (for use in medium-precision tuned RF circuits) and low-Q high-loss core materials (designed for supression or general-purpose use) The higher Q circuit will be more "peaky" as you tune the sig-gen across resonance. The low-Q one will be less peaky and a more broad resonance.

[@eddydogleg]

LOL black arts. What learn from working w/ geologist is that geology is a black art. It drove me nuts when they'd ask me to change vertical depth of the well a quarter metre. Always fun to ask them which side of the 158.8mm bit they want on that 250mm change in vertical depth.

[@bildmateria]

Fantastic overview. If you do too many windings don't you end up with an inductor? (Can't tell if this is a stupid question or a clever one).

[@TheRetiredtech]

Wonder if the Nano VNA could do this.i loved the demo.

[@IMSAIGuy]

yes, you can do an S21 measurement

[@MidlifeRenaissanceMan]

@@IMSAIGuy so you just hook up the centre conductor from S1 to S2 and sweep the piece of wire with whatever clips / cores you want to test That should help you determine the type Am I right ?

[@IMSAIGuy]

@@MidlifeRenaissanceMan kzbin.info/www/bejne/qWmVgWiYqamZm7c

[@khimbittle7705]

interesting! ... but I assume you scope has a linear response so I'm assuming you are not attenuating many db? might be better with the spectrum analyzer and tracking generator?

[@AndrewMurphy8383]

try testing them aging wraping about three or 4 turns of the wire

Thank you very much for the video. Could you please explain us on how to find the ferrite material of an unknown ferrite? With avaliable tools like nanovna, DVM? Cheers!

[@IMSAIGuy]

kzbin.info/www/bejne/h2qYh6qhaNCNpc0

@@IMSAIGuy Hi! Thank you for the video link. I don't think nanovna is good enough at 10Hz to measure inductance, thus my question if I can replace the LCR meter with the VNA... Frequency where R=X (MHz) and µi might give a clue, but its too much for me... Maybe someone with knowledge could explain it better? :) ;) º.º For reference: owenduffy.net/blog/?p=6842

[@jifangzhang2832]

thanks a lot for the demo. but if I want to cut the signal by many orders like 50db, would ferrites be able to do that?

[@IMSAIGuy]

maybe, maybe not, depends on frequencies and the ferrite. you might consider a filter such as: kzbin.info/www/bejne/a2TGk6t4eqh9fLs

[@pixelpatter01]

Does a good ferrite toroid that was made to resonate with no loss make a good RFI choke? I would think lossy ferrite would be what you want. Your setup seems to be testing for inductance where the higher the inductance the more fall off at the higher end. I admit I don't have any answers, only questions.

[@LouiseBrooksBob]

The colour coding confuses me - I bought a toroid in type 6 material which is yellow and supposedly suitable for winding transformers for HF, but there are smaller toroids made for switch mode power supplies that are also yellow. Would they be type 6 material too? Is there a consistent colour coding?

[@IMSAIGuy]

there is no standard. each company had it's own colors.

[@LouiseBrooksBob]

@@IMSAIGuy Thanks! That makes sense. I saw an amateur radio video somewhere that was warning against using red toroids and that got me thinking about a red type 2 toroid I had just bought. Good to hear that colour isn't an issue.

[@wm0davis]

Is the scope showing a linear or log scale. A log scale might be better since it would allow you to see a dB improvement and it would be easier to see quantitative improvement.

[@IMSAIGuy]

linear horizontal 1 to 15 MHz , linear vertical

[@PinakBERT]

@@IMSAIGuy how is that setup on the 1054z?

[@IMSAIGuy]

@@PinakBERT kzbin.info/www/bejne/qIOmqmqgqrZjsM0

[@g-tech9349]

Hi what is the magnetic permeability of the yellow white core? I want to use it as lc filter for sinewave inverter.

[@IMSAIGuy]

color codes are not standard, you need to get the datasheet from the vendor. these were from the junk store so I don't know for sure what that part number they are

[@johnwest7993]

If I recall correctly, the Yellow/White are not ferrite, but iron powder, a 'mix 6', and you are basically correct about what they are good for and what ferrites are good for and why. And certain core types are good at certain frequencies for noise suppression and good at other frequencies for wide-band transformers. Or are you looking for a high Q coupling transformer for a particular frequency? In fact, most core materials aren't good for 'a frequency' per se, but good at various different things at various frequencies. So you need to know your application for different materials. The ham's friend, ferrite mix 43 is actually pretty poor at handling high power. That's why hams running a KW and a half use huge ones for their antennas. They can be easily and permanently cooked. Powdered iron typically can't be permanently cooked and thus is better for high power. And of course different manufacturers have their own ways of describing the characteristics of their products. Nothing is standardized. I've been reading about this stuff for the last month and I'm only now figuring out what to use in what size for what application. Even then, I still don't know if what I've selected is the very best choice for the application, or just 'good enough'.

[@IMSAIGuy]

and no standards for color. what a mess

[@gordslater]

@@IMSAIGuy there are plenty of standards - each new manufacturer just invents their own :) The only rule-of-thumb I use for junk/Aliexpress cores is the totally green ones are more often than not usually high inductance and low-medium loss and suitable for use for suppression in the low tens of khz-20MHz region. For other colors, it's anyone's guess and seems to change with the wind. You can make no assumptions at all about black cores, in particular.

[@8Ugri8]

Question from beginner: what settings did you use for oscilloscope and is that black box on ch3 cable 50 onm terminator?

[@IMSAIGuy]

settings: kzbin.info/www/bejne/b6CUhmyEq7usgsUsi=-phLR9INvzk9-jk2 yes, a 50 ohm terminator

[@alklapaxida850]

yea ferrite will crack once 1.5kw is going through it "when triodes are glowing electrons are flowing"

[@Musicalpa]

Can you use a ferrite bead over the shielding of a power cord with three conductors, or is it required to use a ferrite bead on each individual conductor? My intention is to reduce any chance of RFI noise that may possibly occur on the power strip for my guitar effects pedalboard.

[@IMSAIGuy]

not familiar with a shielded power cable. If true, then put beads on each conductor.

[@Musicalpa]

@@IMSAIGuy No, no, no. The power cable isn't shielded. It only contains the three conductors for power supply to my pedalboard effects.

[@IMSAIGuy]

@@Musicalpa one big ferrite is ok, better is to get: a.co/d/7nqc9js

[@williamdenbeste9703]

Now show a coax cable to prove that you are not attenuating the shielded signal

[@IMSAIGuy]

that would be an interesting demonstration. many people would be confused. It is a very uphill battle with the general public on the understanding of transmission lines.

[@williamdenbeste9703]

@@IMSAIGuy I hope you don't limit your topics to things that "the general public" can understand!

[@IMSAIGuy]

@@williamdenbeste9703 OK but you will have to answer all the questions about dipoles don't work without a balun and you can't measure SWR with a coax between the antenna.

[@IMSAIGuy]

oh and my favorite. you can't use your HT with the antenna horizontal 😊

[@TheRetiredtech]

Have you any idea of the linearity of the Nano VNA

[@IMSAIGuy]

linear in what way?

[@pbaemedan]

Why did you decide on using an oscilloscope, frequency response is a better way to evaluate the cores, but you could use a transient with the oscilloscope.

[@IMSAIGuy]

there are many ways. I thought this would photograph well

[@Ahmedsayedzorro]

👌👌👌👍👏👏👏

[@user-do2gw8my2c]

Bu ferit kömürü tam anlamıyla ne işe yarıyor lütfen biri bana yardımcı olsun

[@pbaemedan]

Just watch the saturation of the material.

[@mj2801]

Messy Work Bench. Your presentation would look better if you clean up a bit.