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Trying to find out what Ferrite material this is.
I came across two ferrite toroids with the measurements of 35mm
diameter, the hole in the middle is 21mm and it is 13mm thick. On the packet it says that the ferrite material is L15. Does anybody know if L15 is equivalent to 43 or 61 ferrite material? I have searched the net but have been unable to find any information. Any information would be appreciated. Cheers. |
Trying to find out what Ferrite material this is.
wrote:
I came across two ferrite toroids with the measurements of 35mm diameter, the hole in the middle is 21mm and it is 13mm thick. On the packet it says that the ferrite material is L15. Does anybody know if L15 is equivalent to 43 or 61 ferrite material? I have searched the net but have been unable to find any information. Any information would be appreciated. Cheers. Here's how to check them: http://www.w8pgw.org/node/303 Charlie. -- M0WYM www.radiowymsey.org |
Trying to find out what Ferrite material this is.
I haven't got an antenna analyser to do the above checks. The toroids
came in a box of stuff from a hamfest. They are in a packet which has the brand name "Duratech" printed on it. |
Trying to find out what Ferrite material this is.
wrote:
I haven't got an antenna analyser to do the above checks. The toroids came in a box of stuff from a hamfest. They are in a packet which has the brand name "Duratech" printed on it. If you have any means at all of mesuring inductance, you can go he http://en.wikipedia.org/wiki/Inductor Inductor - Wikipedia, the free encyclopedia Find the formula (#6) for the inductance of a toroidal ring. Enter the appropriate values and solve for u (permeability of the core). Then look at ferrites and iron power core properties with the calculated permeability at the test frequency. You'll probably find several core materials that fit. I think that's about all that can be done. Chuck ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Trying to find out what Ferrite material this is.
On Fri, 01 Jun 2007 11:03:30 -0700, wrote:
I haven't got an antenna analyser to do the above checks. Do you have a SWR meter? 73's Richard Clark, KB7QHC |
Trying to find out what Ferrite material this is.
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Trying to find out what Ferrite material this is.
Owen Duffy wrote in
: .... Search Jaycar's site for a LO1238. If that is what you have, you could ask them for data. I should have added that I think it is similar to the L8 material described in their data sheets. I have a vague recollection of measuring the inductance of a winding on the material, and I think the ui was around 1500 which suggests it is low loss up to a few hundred kHz, perhaps to 1MHz or so. Owen |
Trying to find out what Ferrite material this is.
Hello Owen,
I have tracked the product down to Jaycar but they don't know anything about the material. The person I contacted was very vague and couldn't steer me towards anybody that would know what material it was. All I want to know is if the toroids would be any good for HF 1:1 baluns. I have just made a balun using a FT-140-61 which is very close to the same dimensions as the 2 toroids in the Duratech packet. If they can be used they are a fair bit cheaper than sourcing FT-140-61 toroids. In reply to Richard Clark, yes I do have a SWR meter. Cheers Max |
Trying to find out what Ferrite material this is.
wrote:
All I want to know is if the toroids would be any good for HF 1:1 baluns. An antenna analyzer, like the MFJ-259B, is a very useful piece of test equipment for all types of measurements of this kind. Using the MFJ-259B, I discovered that the Amidon brochure, "showing typical 'Z' in ohms for one turn at 25 MHz", is misleading. Their "one turn" goes through the core twice which I consider as being two turns. That's bad news for w2du baluns. If you could gain access to an MFJ-259B, you could run the same kind of measurement on your toroids. Heck, if you send one to me, I will run the experiment and send it back to you. -- 73, Cecil http://www.w5dxp.com |
Trying to find out what Ferrite material this is.
On Sat, 02 Jun 2007 09:46:31 -0500, Cecil Moore
wrote: wrote: All I want to know is if the toroids would be any good for HF 1:1 baluns. An antenna analyzer, like the MFJ-259B, is a very useful piece of test equipment for all types of measurements of this kind. Using the MFJ-259B, I discovered that the Amidon brochure, "showing typical 'Z' in ohms for one turn at 25 MHz", is misleading. Their "one turn" goes through the core twice which I consider as being two turns. That's bad news for w2du baluns. If you could gain access to an MFJ-259B, you could run the same kind of measurement on your toroids. Heck, if you send one to me, I will run the experiment and send it back to you. Hi Cecil, You need to move up a notch. Check out http://w5big.com/ I've had one for several months now and won't want to be without it. Danny, K6MHE |
Trying to find out what Ferrite material this is.
Danny Richardson wrote:
You need to move up a notch. Check out http://w5big.com/ I've had one for several months now and won't want to be without it. Thanks for the URL, Danny - didn't know about it. -- 73, Cecil http://www.w5dxp.com |
Trying to find out what Ferrite material this is.
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Trying to find out what Ferrite material this is.
Cecil Moore wrote in news:9pf8i.10153$4Y.6557
@newssvr19.news.prodigy.net: wrote: All I want to know is if the toroids would be any good for HF 1:1 baluns. An antenna analyzer, like the MFJ-259B, is a very useful piece of test equipment for all types of measurements of this kind. Using the MFJ-259B, I .... The '259B is no doubt a handy device, but very limited for measuring components. Have you tried to measure at an inductance that has more than 250 ohms of reactance at some frequency of interest? Have you tried to explore self resonance of a coil..., invariably it runs into the same problem of inductive reactance going off scale way below the point at which self resonance bites in. When talking about ferrite or powdered iron cored inductors of reactance over 200 ohms, where mu is frequency dependent and flux dependent, I find the '259B nearly useless. Owen |
Trying to find out what Ferrite material this is.
Owen Duffy wrote:
The '259B is no doubt a handy device, but very limited for measuring components. Have you tried to measure at an inductance that has more than 250 ohms of reactance at some frequency of interest? Have you tried to explore self resonance of a coil..., invariably it runs into the same problem of inductive reactance going off scale way below the point at which self resonance bites in. When talking about ferrite or powdered iron cored inductors of reactance over 200 ohms, where mu is frequency dependent and flux dependent, I find the '259B nearly useless. I've had just the opposite experience. I find the 259B to be extremely useful in determining ferrite types and the impedances of inductors. Generally a single "turn" (pass through the hole) is adequate for measurement. For most toroidal inductors the impedance is closely proportional to the square of the number of turns, so the value of multi-turn inductors can be extrapolated with reasonable accuracy. Of course, two or three turns can be used for measurement if the unit can't resolve the impedance of a single turn. The frequency dependence of the mu and loss is just why the 259B is so useful -- I can find the impedance at the frequency or range of frequencies it'll be used at. I very seldom design magnetic components for applications where flux density noticeably alters the impedance. If the signal is so large as to permit this to happen, you'll be generating serious harmonics and, if multiple signals are present, intermod. If the saturation is being caused by DC, it's often possible to bias the core with the same current while making measurements. And I've never hit a powdered iron core with enough signal or DC to get anywhere near saturation. They tolerate much higher flux density than ferrites. I'd really feel handicapped in designing baluns and wideband transformers, in particular, without my 259B or something similar. Roy Lewallen, W7EL |
Trying to find out what Ferrite material this is.
On Jun 2, 5:28 pm, Owen Duffy wrote:
The '259B is no doubt a handy device, but very limited for measuring components. Have you tried to measure at an inductance that has more than 250 ohms of reactance at some frequency of interest? Have you tried to explore self resonance of a coil..., invariably it runs into the same problem of inductive reactance going off scale way below the point at which self resonance bites in. Like anything else, there is a limit to the usefulness of an MFJ-259B but it is far from useless. Toroids can be characterized by using one or two windings to keep the impedance within the 259's range. And self- resonance in a coil is super easy. Set the coil up as a base loaded mobile antenna without a stinger. Find the first lowest impedance. That's self- resonance when the coil is 90 degrees long and the reflected wave is interferring with the forward wave at the test point. Some of the things that limits the usefullness of the MFJ-259B are the concepts of the user. If one doesn't believe in (or ignores) the separate existence of the forward and reflected waves, then the 259 becomes a lot less useful. -- 73, Cecil, w5dxp.com |
Trying to find out what Ferrite material this is.
Cecil Moore wrote:
On Jun 2, 5:28 pm, Owen Duffy wrote: The '259B is no doubt a handy device, but very limited for measuring components. Have you tried to measure at an inductance that has more than 250 ohms of reactance at some frequency of interest? Have you tried to explore self resonance of a coil..., invariably it runs into the same problem of inductive reactance going off scale way below the point at which self resonance bites in. Like anything else, there is a limit to the usefulness of an MFJ-259B but it is far from useless. Toroids can be characterized by using one or two windings to keep the impedance within the 259's range. And self- resonance in a coil is super easy. Set the coil up as a base loaded mobile antenna without a stinger. Find the first lowest impedance. That's self- resonance when the coil is 90 degrees long and the reflected wave is interferring with the forward wave at the test point. Some of the things that limits the usefullness of the MFJ-259B are the concepts of the user. If one doesn't believe in (or ignores) the separate existence of the forward and reflected waves, then the 259 becomes a lot less useful. -- 73, Cecil, w5dxp.com Whaddaya mean, "believe in"? If I pray to the waves, will they bring good luck? 73, Tom Donaly, KA6RUH |
Trying to find out what Ferrite material this is.
i do would that help me with my mess of ferrites?
On Jun 1, 1:08 pm, Richard Clark wrote: On Fri, 01 Jun 2007 11:03:30 -0700, wrote: I haven't got an antenna analyser to do the above checks. Do you have a SWR meter? 73's Richard Clark, KB7QHC |
Trying to find out what Ferrite material this is.
Tom Donaly wrote:
... Whaddaya mean, "believe in"? If I pray to the waves, will they bring good luck? 73, Tom Donaly, KA6RUH Who knows? Maybe? At the present time, it is unknown if RF energy is photons, waves or a combination of the two. It is known that rf exhibits qualities ... So yes, a belief akin to what one must hold for his creator is in order here! But then, you already knew that ... JS |
Trying to find out what Ferrite material this is.
Roy Lewallen wrote in
: Owen Duffy wrote: The '259B is no doubt a handy device, but very limited for measuring components. Have you tried to measure at an inductance that has more than 250 ohms of reactance at some frequency of interest? Have you tried to explore self resonance of a coil..., invariably it runs into the same problem of inductive reactance going off scale way below the point at which self resonance bites in. When talking about ferrite or powdered iron cored inductors of reactance over 200 ohms, where mu is frequency dependent and flux dependent, I find the '259B nearly useless. I've had just the opposite experience. I find the 259B to be extremely useful in determining ferrite types and the impedances of inductors. Generally a single "turn" (pass through the hole) is adequate for measurement. For most toroidal inductors the impedance is closely proportional to the square of the number of turns, so the value of multi-turn inductors can be extrapolated with reasonable accuracy. Of course, two or three turns can be used for measurement if the unit can't resolve the impedance of a single turn. The frequency dependence of the mu and loss is just why the 259B is so useful -- I can find the impedance at the frequency or range of frequencies it'll be used at. Roy, with respect, you are describing work-arounds for the inability of the '259B to make useful measurements on inductors over about 200 ohms reactance. Sure, the instrument can be used to characterise a core, and that information extrapolated to design an inductor with higher reactance, but you cannot measure the larger inductance directly, or discover reliably, the properties of the larger inductor like self resonance effects, or loss. I won't address defensive posts by others who seem to have chosen to ignore my qualification "When talking about ferrite or powdered iron cored inductors of reactance over 200 ohms". An example of the traps: a chap recently confirmed to me that indeed mu is frequency sensitive as demonstrated by the '259B measurement of the inductance of an inductor over HF which showed inductance was highly frequency dependent. The problem was that the inductive reactance was over 250 ohms at most frequencies of measurement, and the '259B calculates inductance without warning that the value is unreliable because of the magnitude of reactance on which the inductance is calculated. Try measuring a 30uH coil's inductance over 2-30MHz using a '259B and you will see what I mean. Owen |
Trying to find out what Ferrite material this is.
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Trying to find out what Ferrite material this is.
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Trying to find out what Ferrite material this is.
On Sun, 03 Jun 2007 23:10:10 GMT, Owen Duffy wrote:
I won't address defensive posts by others who seem to have chosen to ignore my qualification "When talking about ferrite or powdered iron cored inductors of reactance over 200 ohms". Owen, are you trying to pull a Cecil or Art by changing the subject of the thread? If you recall, this thread was about identifying an unknown ferrite core. For that purpose *any instrument* capable of measuring Zmag less than 200 ohms will work fine - even one that is restricted to less than 100 ohms. I 'm not defending the 259 as I use something else here that can measure impedances greater that 20K, but that high range servers no purpose if I am looking a impedances less than 100 ohms. Danny, K6MHE |
Trying to find out what Ferrite material this is.
I agree that a 259B does not make a good general purpose instrument for
measuring inductor values over the HF range. In fact, there are very few instruments which are. One of the few I know of is the HP 4191A vector impedance meter, but it's not likely to be found in many amateur workshops. Making good impedance measurements at HF is often very much more difficult than most people realize. The 259B is, I maintain, a very good instrument for identifying core materials and for use in the design of inductors, transformers, and other magnetic components. I've used mine many times for the purpose and gotten the results I expected. That was, I thought, the subject of this thread, but it appears to have drifted elsewhere. Roy Lewallen, W7EL Owen Duffy wrote: Roy, with respect, you are describing work-arounds for the inability of the '259B to make useful measurements on inductors over about 200 ohms reactance. Sure, the instrument can be used to characterise a core, and that information extrapolated to design an inductor with higher reactance, but you cannot measure the larger inductance directly, or discover reliably, the properties of the larger inductor like self resonance effects, or loss. I won't address defensive posts by others who seem to have chosen to ignore my qualification "When talking about ferrite or powdered iron cored inductors of reactance over 200 ohms". An example of the traps: a chap recently confirmed to me that indeed mu is frequency sensitive as demonstrated by the '259B measurement of the inductance of an inductor over HF which showed inductance was highly frequency dependent. The problem was that the inductive reactance was over 250 ohms at most frequencies of measurement, and the '259B calculates inductance without warning that the value is unreliable because of the magnitude of reactance on which the inductance is calculated. Try measuring a 30uH coil's inductance over 2-30MHz using a '259B and you will see what I mean. Owen |
Trying to find out what Ferrite material this is.
Richard Clark wrote:
Hi Herbert, Pass a wrap of wire around the material if it is a bar, or through it if it is a toroid. Connect this to the output of the SWR meter. Hit it with a short blip of power and note the SWR. You have the multiple/divisor of 50 Ohms. . . Sorry, that's simply not true. You're almost certain to have reactance -- possibly, a lot of it -- in which case the SWR can be vastly different than the impedance divided by 50 ohms or its inverse. Roy Lewallen, W7EL |
Trying to find out what Ferrite material this is.
Danny Richardson wrote in
: On Sun, 03 Jun 2007 23:10:10 GMT, Owen Duffy wrote: I won't address defensive posts by others who seem to have chosen to ignore my qualification "When talking about ferrite or powdered iron cored inductors of reactance over 200 ohms". Owen, are you trying to pull a Cecil or Art by changing the subject of the thread? If you recall, this thread was about identifying an unknown ferrite core. For that purpose *any instrument* capable of measuring Zmag less than 200 ohms will work fine - even one that is restricted to less than 100 ohms. A fair point Danny. I did provide some specific information on the core if you read back through the posts, probably more than any others! But I still stand by my statement about the limitations of the '259B in assessing inductors as qualified. I 'm not defending the 259 as I use something else here that can measure impedances greater that 20K, but that high range servers no purpose if I am looking a impedances less than 100 ohms. I envy you, seems we always need (want?) to measure something that is beyond the range of the instrument conveniently to hand. Owen |
Trying to find out what Ferrite material this is.
Roy Lewallen wrote:
I agree that a 259B does not make a good general purpose instrument for measuring inductor values over the HF range. In fact, there are very few instruments which are. One of the few I know of is the HP 4191A vector impedance meter, but it's not likely to be found in many amateur workshops. Making good impedance measurements at HF is often very much more difficult than most people realize. Look at the L/C meter from AADE (Almost All Digital Electronics) www.aade.com which a 1 hour kit for $99. It is quite accurate and uses a variable frequency oscillator so that smaller values of inductance and capacitance are measures at higher frequencies. I own an 8753 HP Network Analyzer and still use the L/C meter most of the time since it is so convenient. It easily can tell the differences between 73/43/31/61 materials. I usually wrap 2 turns thru the torroid to do the measurement. 73, Larry, W0QE |
Trying to find out what Ferrite material this is.
Larry Benko wrote:
Look at the L/C meter from AADE (Almost All Digital Electronics) www.aade.com which a 1 hour kit for $99. It is quite accurate and uses a variable frequency oscillator so that smaller values of inductance and capacitance are measures at higher frequencies. I own an 8753 HP Network Analyzer and still use the L/C meter most of the time since it is so convenient. It easily can tell the differences between 73/43/31/61 materials. I usually wrap 2 turns thru the torroid to do the measurement. 73, Larry, W0QE That looks like a handy gadget. It wouldn't be very good for working with the kinds of ferrites often used for baluns, wideband transformers, or EMI suppression because of the very low Q encountered. Many of the ferrites I use have a Q of one or less over at least part of the frequency range of operation. And of course the L/C meter wouldn't be useful in assessing the loss or Q of inductors at all. One of the unique things about the HP unit is that it's able to resolve very small R in the presence of large X or vice-versa, which is very difficult to do. But then it costs a couple of orders of magnitude more. A network analyzer is poorly suited for making measurements of impedances which are a great deal higher or lower than 50 ohms. The problem with any of these instruments is that they'll all happily give you an answer, often to several decimal digits. But as Owen pointed out for the 259B, the answer can be anywhere from good to total garbage. The only way to know which is to understand the limitations of your test equipment and something about the nature of the component you're trying to measure. There just isn't any instrument which will do the thinking for you. Roy Lewallen, W7EL |
Trying to find out what Ferrite material this is.
On Sun, 03 Jun 2007 18:48:00 -0700, Roy Lewallen
wrote: Richard Clark wrote: Hi Herbert, Pass a wrap of wire around the material if it is a bar, or through it if it is a toroid. Connect this to the output of the SWR meter. Hit it with a short blip of power and note the SWR. You have the multiple/divisor of 50 Ohms. . . Sorry, that's simply not true. You're almost certain to have reactance -- possibly, a lot of it -- in which case the SWR can be vastly different than the impedance divided by 50 ohms or its inverse. Simplicity is not to be dismissed that easily (no one needs to spend $500 to figure out ferrite). A moment's worth of very little power will suitably allow for heat to discriminate reactance from resistance. 73's Richard Clark, KB7QHC |
Trying to find out what Ferrite material this is.
Roy Lewallen wrote:
That looks like a handy gadget. It wouldn't be very good for working with the kinds of ferrites often used for baluns, wideband transformers, or EMI suppression because of the very low Q encountered. Many of the ferrites I use have a Q of one or less over at least part of the frequency range of operation. And of course the L/C meter wouldn't be useful in assessing the loss or Q of inductors at all. One of the unique things about the HP unit is that it's able to resolve very small R in the presence of large X or vice-versa, which is very difficult to do. But then it costs a couple of orders of magnitude more. A network analyzer is poorly suited for making measurements of impedances which are a great deal higher or lower than 50 ohms. The problem with any of these instruments is that they'll all happily give you an answer, often to several decimal digits. But as Owen pointed out for the 259B, the answer can be anywhere from good to total garbage. The only way to know which is to understand the limitations of your test equipment and something about the nature of the component you're trying to measure. There just isn't any instrument which will do the thinking for you. Roy Lewallen, W7EL That is what I thought also Roy but the little L/C meter seems to work pretty well with low Q inductors. It is not measuring impedance but measuring a frequency of an inductor and known capacitor in an oscillator. The Q does change the oscillating frequency but not that much. As I said before it is super easy to tell the difference between 77/31/43/61 type ferrites. Of course the permeability difference between those types is a factor of 2 or more so ultra accuracy is not important. The original question was how to determine what type an unknown core was and not what impedance it represented at a certain frequency. I just grabbed 3 FairRite 59XX003801 torroids (2.4" OD x 1.4" ID x .5") in 3 materials and measured a single turn with the L/C meter. Material 61 (u=125) calc. inductance = .173uH, measured = .177uH Material 43 (u=800) calc. inductance = 1.07uH, measured = .930uH Material 75 (u=5000) calc. inductance = 6.85uH, measured = 7.39uH The calculated inductances came from the FairRite catalog. I would say the "low Q" inductors measured pretty well and the materilas were very easy to distinguish. 73, Larry, W0QE |
Trying to find out what Ferrite material this is.
John Smith I wrote:
... I should have mentioned, in case it escaped your attention, a SW receiver will serve as freq counter (watch out for harmonics), if you have patience to hunt the signal ... you can "rough guess" the freq by the expectations of the expected inductance (type 43, 61, etc. and no. of turns) and the capacitance used. JS |
Trying to find out what Ferrite material this is.
Larry Benko wrote:
That is what I thought also Roy but the little L/C meter seems to work pretty well with low Q inductors. It is not measuring impedance but measuring a frequency of an inductor and known capacitor in an oscillator. The Q does change the oscillating frequency but not that much. As I said before it is super easy to tell the difference between 77/31/43/61 type ferrites. Of course the permeability difference between those types is a factor of 2 or more so ultra accuracy is not important. The original question was how to determine what type an unknown core was and not what impedance it represented at a certain frequency. I just grabbed 3 FairRite 59XX003801 torroids (2.4" OD x 1.4" ID x .5") in 3 materials and measured a single turn with the L/C meter. Material 61 (u=125) calc. inductance = .173uH, measured = .177uH Material 43 (u=800) calc. inductance = 1.07uH, measured = .930uH Material 75 (u=5000) calc. inductance = 6.85uH, measured = 7.39uH The calculated inductances came from the FairRite catalog. I would say the "low Q" inductors measured pretty well and the materilas were very easy to distinguish. Yep, that's perfectly adequate to distinguish the types. You must have made the measurements at a pretty low frequency. Type 75 has a Q of 1 at about a MHz, and 43 at a few MHz, and they drop at higher frequencies. Will the circuit oscillate with Q that low? Roy Lewallen, W7EL |
Trying to find out what Ferrite material this is.
Roy Lewallen wrote:
Yep, that's perfectly adequate to distinguish the types. You must have made the measurements at a pretty low frequency. Type 75 has a Q of 1 at about a MHz, and 43 at a few MHz, and they drop at higher frequencies. Will the circuit oscillate with Q that low? Roy Lewallen, W7EL Referring to http://www.aade.com/lcm2binst/HP.html the measurement freq. was about 750KHz for the type 61 and 43 materials and about 70KHz for the 75 material based on the inductances that were displayed. 73, Larry W0QE |
Trying to find out what Ferrite material this is.
Larry Benko wrote:
Roy Lewallen wrote: Yep, that's perfectly adequate to distinguish the types. You must have made the measurements at a pretty low frequency. Type 75 has a Q of 1 at about a MHz, and 43 at a few MHz, and they drop at higher frequencies. Will the circuit oscillate with Q that low? Roy Lewallen, W7EL Referring to http://www.aade.com/lcm2binst/HP.html the measurement freq. was about 750KHz for the type 61 and 43 materials and about 70KHz for the 75 material based on the inductances that were displayed. 73, Larry W0QE Darn typo. That should be 750KHz for the type 61 and 43 and 700KHz for the type 75. Sorry. 73,Larry W0QE |
Trying to find out what Ferrite material this is.
Roy Lewallen wrote:
The 259B is, I maintain, a very good instrument for identifying core materials and for use in the design of inductors, transformers, and other magnetic components. I've used mine many times for the purpose and gotten the results I expected. That was, I thought, the subject of this thread, but it appears to have drifted elsewhere. It has certainly drifted away from Australia, and towards the USA. In the USA, it's a good bet that an unknown ferrite core will be made by Fair-Rite, and probably one of the more common materials; or else it's probably a dust-iron core from Micrometals. With help from the catalogs, and a few known cores for reference, even quite limited test equipment will have a good chance of identifying the specific product. But that may not be true in the rest of the world. You may have a core that is marketed in your home country but imported from another, but having been manufactured in a third country using a process licensed from... well, who knows any more? There are no world-standard sizes, and no direct equivalents between magnetic materials from different manufacturers. The best you can hope for is to identify the material as being "somewhat like" a known Fair-Rite mix. With such uncertainties about the material itself, you can afford far fewer uncertainties about the measurement. If you don't have advanced test equipment (or an advanced understanding of the limitations of simpler equipment) then it may be better to forget about characterizing the magnetic material. If you want to know if it will work in an HF balun, it may be much easier to *make* a balun. On the other hand, if you really want to chase down the problem of identifying and characterizing unknown cores from anywhere around the world, the following links may help. http://users.catchnet.com.au/~rjandusimports/ No coincidence that this site is .au - they know about this problem in Australia. There are very useful international cross-reference pages at: http://users.catchnet.com.au/~rjandu.../xref_mat.html http://users.catchnet.com.au/~rjandu...ze_toroid.html Do remember that these are not exact equivalents, only the closest available. Also note the huge gaps in the tables, where nothing even comes close. Another very useful resource is DL5SWB's Mini Ring Core Calculator: http://www.dl5swb.de/html/mini_ring_core_calculator.htm This software contains extensive libraries of cores from international manufacturers, including dimensions and paint colours as well as magnetic properties. If you know the identity of the core, it will calculate the inductance from the number of turns. If you have an unknown core, and can make some meaningful measurements, there are separate functions to help identify it. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Trying to find out what Ferrite material this is.
On Jun 3, 2:13 pm, "Tom Donaly" wrote:
Whaddaya mean, "believe in"? If I pray to the waves, will they bring good luck? Many of the posters here believe that reflected EM waves don't actually exist in reality. Their belief systems are interferring with their understanding of physics. And yes, it might as well be a religion to which one prays. I know a number of posters who pray that reflected waves don't exist because their entire house- of-cards will come tumblinging down if reflected EM waves actually exist in reality - while obeying all the boundary conditions that Mother Nature dictates for EM waves. Hopefully, you are not one of those individuals. -- 73, Cecil, w5dxp.com |
Trying to find out what Ferrite material this is.
Cecil Moore wrote:
On Jun 3, 2:13 pm, "Tom Donaly" wrote: Whaddaya mean, "believe in"? If I pray to the waves, will they bring good luck? Many of the posters here believe that reflected EM waves don't actually exist in reality. Their belief systems are interferring with their understanding of physics. And yes, it might as well be a religion to which one prays. I know a number of posters who pray that reflected waves don't exist because their entire house- of-cards will come tumblinging down if reflected EM waves actually exist in reality - while obeying all the boundary conditions that Mother Nature dictates for EM waves. Hopefully, you are not one of those individuals. -- 73, Cecil, w5dxp.com Maybe you'll tell me who you think thinks waves of any sort can't be reflected. I haven't run into anyone who thinks EM waves can't be reflected, refracted, etc. Maybe there's a misunderstanding somewhere. 73, Tom Donaly, KA6RUH |
Trying to find out what Ferrite material this is.
Tom Donaly wrote:
... Maybe you'll tell me who you think thinks waves of any sort can't be reflected. I haven't run into anyone who thinks EM waves can't be reflected, refracted, etc. Maybe there's a misunderstanding somewhere. 73, Tom Donaly, KA6RUH Very good, and oh so relevant! Krist, even the force on a tennis ball is "reflected" back off a wall! Better question would be, "What can't be reflected?" (well, ok, high radiation is NOT easy to reflect!) JS |
Trying to find out what Ferrite material this is.
On Jun 4, 5:39 pm, "Tom Donaly" wrote:
Maybe you'll tell me who you think thinks waves of any sort can't be reflected. I haven't run into anyone who thinks EM waves can't be reflected, refracted, etc. Maybe there's a misunderstanding somewhere. I don't want to get personal but if you have followed the reflected wave arguments, you know who they are. Some simple true/false questions will highlight the argument. 1. Do reflected EM waves actually exist in reality? 2. Is the reflected EM wave a traveling wave? 3. Does a reflected EM wave obey the rules for traveling waves? 4. Do reflected EM waves contain ExB joules/second? 5. Do reflected EM waves have any effect on forward waves in a constant Z0 environment? 6. Do standing EM waves superceed and obsolete the component traveling waves? 7. Does reflected EM energy violate the laws of physics by standing still within the standing wave? 8. Does reflected EM energy violate the laws of physics by just "sloshing" around? 9. Does reflected EM energy travel in the reverse direction at VF(c) until it encounters an impedance discontinuity? 10. Is it valid to consider the forward EM traveling wave and the reflected EM traveling wave separately and then superpose the resulting fields (voltages, currents)? 11. Are the decades-old EM wave intensity equations from the field of optics valid for an RF EM wave analysis? 12. Can standing wave current be used to determine the delay through a 75m mobile loading coil? 13. Is the current "drop" through that loading coil just an illusion caused by superposition of forward and reflected currents? 14. Would the delay be different if only a forward traveling wave was used for measurement purposes? -- 73, Cecil, w5dxp.com |
Trying to find out what Ferrite material this is.
Cecil Moore wrote: On Jun 4, 5:39 pm, "Tom Donaly" wrote: Maybe you'll tell me who you think thinks waves of any sort can't be reflected. I haven't run into anyone who thinks EM waves can't be reflected, refracted, etc. Maybe there's a misunderstanding somewhere. I don't want to get personal but if you have followed the reflected wave arguments, you know who they are. Some simple true/false questions will highlight the argument. 1. Do reflected EM waves actually exist in reality? 2. Is the reflected EM wave a traveling wave? 3. Does a reflected EM wave obey the rules for traveling waves? 4. Do reflected EM waves contain ExB joules/second? 5. Do reflected EM waves have any effect on forward waves in a constant Z0 environment? 6. Do standing EM waves superceed and obsolete the component traveling waves? 7. Does reflected EM energy violate the laws of physics by standing still within the standing wave? 8. Does reflected EM energy violate the laws of physics by just "sloshing" around? 9. Does reflected EM energy travel in the reverse direction at VF(c) until it encounters an impedance discontinuity? 10. Is it valid to consider the forward EM traveling wave and the reflected EM traveling wave separately and then superpose the resulting fields (voltages, currents)? 11. Are the decades-old EM wave intensity equations from the field of optics valid for an RF EM wave analysis? 12. Can standing wave current be used to determine the delay through a 75m mobile loading coil? 13. Is the current "drop" through that loading coil just an illusion caused by superposition of forward and reflected currents? 14. Would the delay be different if only a forward traveling wave was used for measurement purposes? It's ridiculous to assert that someone "thinks EM waves can't be reflected" based on the fact that they might happen to take issue with one or more of your speculations on the laundry list shown above. ac6xg |
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