Conformity Magazine - June 2008 - (Page 59)

strength for a specific material as a function of frequency. It should be noted that, as frequency increases, the effect of biases diminishes. New Materials Since the compilation of this data, our company has introduced two new materials. Our 44 is a nickel zinc, medium permeability material, while 31 is a manganese zinc high permeability material. Figure 19 is a plot of impedance vs. frequency for the same size bead in 31, 73, 44 and 43 materials. 44 material is an improved 43 material with higher dc resistivity, 109 ohm cm, better thermal shock characteristics, temperature stability and higher curie temperature (Tc). When compared to our 43 material, 44 material has slightly higher impedance vs. frequency characteristics. Still, material 31 exhibits higher impedance than either 43 or 44 throughout the measured frequency range. Designed to alleviate the problem of dimensional resonance that affects low frequency suppression performance of the larger manganese-zinc cores, 31 has found successful applications as cable connector suppressor cores and large toroidal cores. Figures 20 is a curve of impedance vs frequency for 43, 31, and 73 material for a Fair-Rite core with an OD of .562”, ID of .250 and a HT of 1.125. When comparing Figure 19 to Figure 20, it should be noted that for the smaller core in Figure 19, for frequencies up to 25 Mhz, 73 material is the optimum suppression material. However, as the core cross section increases, the maximum frequency decreases, as can be shown by the data in Figure 20, where the highest frequency where 73 is optimum is 8 Mhz. Also noteworthy is that 31 material is superior from 8 MHz to 300 MHz. However, being a manganese zinc ferrite, 31 material has a much lower volume resisitivity of 102 ohmcm and exhibits greater changes in impedance with extreme temperature variation. Carole U. Parker is the president of Fair-Rite Products Corporation, and can be reached at parkerc@fair-rite.com. References Notes 1. In phase is when the maxima and minima of the magnetic field, H, and those of the induction B, coincide. Out of phase is when the maxima and minimum is displaced by 90°. Ferromagnetic Resonance is also called spin precession resonance. It should be noted that the impedance for each ferrite material is optimum over a specific frequency range. As a rule of thumb, the higher the permeability, the lower the frequency range. It should be noted that the impedance for each ferrite material is optimum over a specific frequency range. As a rule of thumb, the higher the permeability, the lower the frequency range. This remains true so long as the increase in height/length does not cause the core to be in dimensional resonance. 2. 3. 4. 5. FAST Link www.conformity.com/1870 Comprehensive EMI Solutions, On Time & On Budget From design, quick-turn protos, and worldwide ISO9001 manufacturing, we are the superlative EMI solutions provider. The cornerstones of our mission are simple: Quality. Integrity. Service. Value. It is this commitment to total solutions without compromise that has led to our established position as a premier designer, manufacturer & distributor of EMI ﬁlters and magnetic products. • Soft Ferrites, Properties and Applications, 2nd Edition 1988, Snelling E. C., Butterworth, Boston MA Crane, Russak and Company, New York, NY • Magnetic Materials and their Applications, 1974, Heck, C. • "Prayer Beads" Solve Many of Your EMI Problems, Parker C., Tolen, B., Parker, R., EMC Technology, Vol. 4, No. 2, 1985 Plug into our comprehensive solutions. Radius Power is a leader in the design & manufacture of power products used to condition, regulate and govern electronic performance. The company provides a broad line of EMI Filters, Power Entry Modules, Power Transformers & Inductors to meet front-end requirements for AC & DC power line applications. We offer free pre-compliance testing for conducted emissions at our labs or yours! Bring us your EMI challenge & we will provide an optimized solution usually within 48 hours. Call Radius today. 714-289-0055 PH 714-289-2149 FAX 1751 N. BATAVIA ST. ORANGE, CA 92865 • Fair-Rite Products Soft Ferrite Catalog, 15th Edition, 2007 www.radiuspower.com JUNE 2008 CoNformity 59 http://www.conformity.com/1870 http://www.radiuspower.com http://www.radiuspower.com

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Conformity - June 2008 Contents Editor's Note 700 MHz Auction Raises a Record $20 Billion FCC Modifies PCS and AWS Power Limit Rules for Broadband Wireless Commission Designates Spectrum Test Bed FCC Releases Report on Wireless Competition Commission Proposes $5 Million Fine for Slamming Using EDX for Non-Destructive Detection of Lead in Consumer Products ESD Open Forum Challenges in Testing - Improving Election Security and Accuracy Part 1 Challenges in Testing - Human Body Model: The Hidden Challenges High-Speed Signal Integrity Considerations for ESD Components Focus On...EMC Components Buyer's Guide FCC Levies $2.6 Million Fine for Junk Faxes FDA Updates Guidance on its Product Review Process EU Issues Updated Energy Star Regulations EU Repeals Directive on Veterinary Electro-Medical Equipment New Product Announcements Updated Standards List for the EU's PPE Directive CPSC Announces New Effort to Keep Out Hazardous Products CPSC Actions in the News IEC Standards Update UL Standards Update Product Reviews Telcordia Standards Update From Our "You Can't Make This Stuff Up" Department Looking Back: Items from Past Issues of Conformity Advertisers

Conformity - June 2008

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