Re: [Elecraft] HELP! Permeability of Ferrite Cores...
If the two are the same size, the inductance will be approximately the sum of the inductances of the separate toroids wound with the same number of turns. So for two identical cores the inductance will be about double for the same number of turns. You can see this by calculating the H field from Ampere's law making the usual assumption that the windings are equivalent to a uniform current. The magnetic field is the same as in the separate toroids. The magnetic energies then just add so the inductances add. 73 Kevin w9cf Dave G. wrote: Next dumb question What is the effect on inductance of stacki two toroids together?? -- Dave G. KK7SS '65 MK III Sprite in Richland, WA If life begins at 50, why am I falling apart ?! ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com -- View this message in context: http://n2.nabble.com/HELP%21-Permeability-of-Ferrite-Cores...-tp1086003p1091331.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] HELP! Permeability of Ferrite Cores...
On Mon, 15 Sep 2008 14:14:50 -0700 (PDT), w9cf wrote: If the two are the same size, the inductance will be approximately the sum of the inductances of the separate toroids wound with the same number of turns. So for two identical cores the inductance will be about double for the same number of turns. You can see this by calculating the H field from Ampere's law making the usual assumption that the windings are equivalent to a uniform current. The magnetic field is the same as in the separate toroids. The magnetic energies then just add so the inductances add. So does the loss component (resistance) inductively coupled from the core. There is also capacitance between turns, and from one end of the inductor to the other through the ferrite core (the ferrite core is a dielectric). It is a HUGE mistake to think of an inductor wound on a ferrite core as ONLY an inductor. Most cores contribute significant resistance and capacitance at HF. The approximate equivalent circuit of a ferrite inductor at HF and VHF is a parallel resonant circuit of fairly low Q. For #43 and #31 materials, a Q around 0.5 is common. For #61 material, a Q on the order of 10 is common below 10 MHz, but that Q drops with increasing frequency. For some ferrite mixes, the equivalent circuit is TWO parallel resonant circuits in series. See http://audiosystemsgroup.com/RFI-Ham.pdf Well below resonance, the equivalent circuit is a series R and L, and C drops out (because Xc is much much greater than XL). 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] HELP! Permeability of Ferrite Cores...
This site is the manufacturer of the Ferrite materials They are responsible for a major percentage of the material used by the ferrite core manufacturers and retailers. There are several tutorials on a variety of lists that break down the relation-ship between Fair-Rite and the 2nd party suppliers. These usually describe the disparity in prices and availability - basic wholesale/retail and quantity handling issues. The part numbers you show are the result of the retailers part numbering. If you know the retailers part number-to-material type (i.e. I believe the FT37-43) is a toroid size - material type id) the you can go to the following web pages and see the material specs for all of Fair-Rites sizes in the various materials. _www.fair-rite.com/_ (http://www.fair-rite.com/) _http://www.fair-rite.com/cgibin/catalog.pgm#select:freq3_ (http://www.fair-rite.com/cgibin/catalog.pgm#select:freq3) Amidon is a retailer or value added supplier. This is their page for the FT-37-43 _https://www.amidoncorp.com/items/13_ (https://www.amidoncorp.com/items/13) which indicates the type 43 material in a FT37 size. Also, the ISO standards list will give you other mfg names which may add to your list. BTW, I used Google for all this. Having been in the business for many years (Computer magnetic components and materials), I knew of Fair-Rite by name. I searched using the terms FAIRRITE first and then FT37 TOROID. The word TOROID is key to yielding results. Good luck, Al WA6VNN In a message dated 9/12/2008 11:16:12 A.M. Pacific Daylight Time, [EMAIL PROTECTED] writes: Can nyone provide me with the permeability number for the T37-2 and the FT37-43 cores??? Using Google hasn't got me the data I need ;-(( -- Dave G. KK7SS '65 MK III Sprite in Richland, WA If life begins at 50, why am I falling apart ?! ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com **Pt...Have you heard the news? There's a new fashion blog, plus the latest fall trends and hair styles at StyleList.com. (http://www.stylelist.com/trends?ncid=aolsty000514) ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] HELP! Permeability of Ferrite Cores...
Can nyone provide me with the permeability number for the T37-2 and the FT37-43 cores??? Using Google hasn't got me the data I need ;-(( -- Dave G. KK7SS '65 MK III Sprite in Richland, WA If life begins at 50, why am I falling apart ?! ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] HELP! Permeability of Ferrite Cores...
Dave G. wrote: Can nyone provide me with the permeability number for the T37-2 and the FT37-43 cores??? Try www.palomar-engineers.com (no association. 73 Paul -- View this message in context: http://n2.nabble.com/HELP%21-Permeability-of-Ferrite-Cores...-tp1086003p1086032.html Sent from the Elecraft mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] HELP! Permeability of Ferrite Cores...
Dave, Amidon has that information, and it is printed in th ARRL Handbook. OR - you can download mini-Ring Core calculator (free compliments of DL5SWB) from http://www.dl5swb.de/html/mini_ring_core_calculator.htm and it will not only give you that information, but do many other calculation for inductors, resonance, and tuned circuits. 73, Don W3FPR Dave G. wrote: Can nyone provide me with the permeability number for the T37-2 and the FT37-43 cores??? Using Google hasn't got me the data I need ;-(( -- Dave G. KK7SS '65 MK III Sprite in Richland, WA ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] HELP! Permeability of Ferrite Cores...
On Fri, 12 Sep 2008 11:15:22 -0700, Dave G. wrote: Can nyone provide me with the permeability number for the T37-2 and the FT37-43 cores??? I also suggest that you study the material on ferrites in http://audiosystemsgroup.com/RFI-Ham.pdf The discussion of ferrites in this tutorial is considerably more advanced than what's on the Amidon site or in ARRL publications, and should give you a much better understanding of ferrites, how they work, and how to use them. Tne most important thing to understand is that permeability of ferrites is not a single number -- it varies (a LOT) with frequency. The commonly published number is the LOW FREQUENCY permeability. The second most important thing to realize is that ferrites are pure inductors ONLY at low frequencies. As frequency increases, resistance and capacitance become increasingly important, and at high frequencies R and C dominate (to the extent that there's no L!). When we use ferrites to wind coils for transceivers, we mostly care about L. When we use ferrites to suppress RFI, we only want R. Most (all?) ferrite cores sold to hams by Amidon and others are actually made by Fair-Rite, a very good US company based in NY State. They publish an excellent catalog that includes extensive data on all of their products. http://www.fair-rite.com/newfair/index.htm 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] HELP! Permeability of Ferrite Cores...
From the Amidon flyer: Iron powder mix 2: permeability = 10 T-37-2 toroid: AL = 40 uH/100 turns Ferrite mix 43: permeability = 850 FT-37-43 toroid: AL = 420 mH/1000 turns Al N1AL On Fri, 2008-09-12 at 11:15, Dave G. wrote: Can nyone provide me with the permeability number for the T37-2 and the FT37-43 cores??? Using Google hasn't got me the data I need ;-(( -- Dave G. KK7SS '65 MK III Sprite in Richland, WA If life begins at 50, why am I falling apart ?! ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] HELP! Permeability of Ferrite Cores...
Next dumb question What is the effect on inductance of stacki two toroids together?? -- Dave G. KK7SS '65 MK III Sprite in Richland, WA If life begins at 50, why am I falling apart ?! ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] HELP! Permeability of Ferrite Cores...
One small addition to Jim's observations. Fair-Rite changed the chemistry of its Type 43 material a couple years ago. The new Type 43 material has much better Q (lower loss) compared with the old version, by a factor of more than 10:1 at some frequencies. There was also a very small change in the quoted permeability at low frequency, from 850 in the old to 800 in the new, if I recall correctly. Z remains relatively unchanged from old to new, but the R+jX components of Z are different, with more jX and less R at lower frequencies. This chemistry change is important if (a) you have an old core in the junkbox and (b) you are planning on using it in a tuned application or a filter. Otherwise, no. I'm working on an article for QEX on ferrite cored inductors and transformers but it's still some distance from being ready for submission. Jack K8ZOA www.cliftonlaboratories.com Jim Brown wrote: On Fri, 12 Sep 2008 11:15:22 -0700, Dave G. wrote: Can nyone provide me with the permeability number for the T37-2 and the FT37-43 cores??? I also suggest that you study the material on ferrites in http://audiosystemsgroup.com/RFI-Ham.pdf The discussion of ferrites in this tutorial is considerably more advanced than what's on the Amidon site or in ARRL publications, and should give you a much better understanding of ferrites, how they work, and how to use them. Tne most important thing to understand is that permeability of ferrites is not a single number -- it varies (a LOT) with frequency. The commonly published number is the LOW FREQUENCY permeability. The second most important thing to realize is that ferrites are pure inductors ONLY at low frequencies. As frequency increases, resistance and capacitance become increasingly important, and at high frequencies R and C dominate (to the extent that there's no L!). When we use ferrites to wind coils for transceivers, we mostly care about L. When we use ferrites to suppress RFI, we only want R. Most (all?) ferrite cores sold to hams by Amidon and others are actually made by Fair-Rite, a very good US company based in NY State. They publish an excellent catalog that includes extensive data on all of their products. http://www.fair-rite.com/newfair/index.htm 73, Jim Brown K9YC ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
