* Small size-to-power ratio. * Stackable * Integral mounting bracket conducts heat to mounting surface. * Low profile for use in equipment where space is limited. * All-welded construction. * RoHS compliant product available Jan. 2006 Add "E" suffix to part number to specify. `Thin' Stackohm(R) Vitreous Enamel Power Resistors Diam. 0.125" 3.175 mm 0.110": 2.776 mm 0.125" 3.175 mm 10W & 20W L A 0.125" * 3.175 mm 0.375" 9.525 mm 0.250" 6.350 mm Diam. 0.109" 2.776 mm 0.125" 3.175 mm Diam. 0.196" 4.979 mm 0.250" 6.350 mm 0.188" 4.763 mm 30W, 40W & 55W L A 0.250" * 6.350 mm 0.125" 3.175 mm Note: When resistors are stacked, use 0.625" 15.875 mm 0.375" 9.525 mm Diam. 0.063" 1.588 mm 0.031" 0.794 mm 0.375" 9.525 mm Material Coating: Lead free vitreous enamel. Core: Ceramic. Terminals: Tinned lug with hole. Derating: Linearly from 100% @ +25C to 0% @ +350C. Electrical Tolerance: 5% (J) Power rating: Based on mounting a single resistor on a metal surface measuring 10" (254mm) square by .04" (1.016mm) thick. Reduce rating by 15% when mounting on non-metallic surface. Overload: 5 times rated wattage for 5 seconds. Temperature coefficient: 1 to 20: 400 ppm/C. Over 20: 260 ppm/C Dielectric withstanding voltage: 500 VAC: 10 and 20 watt rating. 1000 VAC: 30, 40 and 55 watt rating (measured from lug to mounting bracket) To calculate max. amps: use the formula P/R 1.000" 25.400 mm FEATURES 250 Series SPECIFICATIONS 0.938" 23.813 mm When limited space is a consideration, choose Ohmite's "thin" stackable 250 Type resistors. These oval-shaped ceramic-core resistors feature a low profile to permit installation in spaces with minimal height. They are also equipped with integral mounting brackets so they can be fastened to a chassis and stacked in locations with limited surface area. When properly fastened, the mounting brackets add a heat sinking benefit resulting in a smaller size per watt. Durable 250 Type resistors are fully welded and coated with lead free vitreous enamel. 0.438" 11.113 mm *Reference dimension only; varies according to resistance value washers or spacers as required to insure clearance and improve power dissipation. Dimensions (in. /mm) Length L Length A Voltage 0.750 / 19.050 1.000 / 25.400 187 2.000 / 50.800 2.313 / 58.750 815 1.250 / 31.750 2.000 / 50.800 281 2.000 / 50.800 2.750 / 69.850 655 3.500 / 88.900 4.250 / 107.950 1405 Series Wattage Ohms F10 10 1.0-15K F20 20 1.0-50K F30 30 1.0-10K F40 40 1.0-25K F55 55 1.0-30K Adjustable versions available. Consult factory. Other sizes available. Consult factory. Also available in low cost Centohm coating. Consult Factory. S T O C K PA RT N U M B E R S F O R S TA N D A R D R E S I S TA N C E VA L U E S 3,000 3,500 4,000 5,000 6,000 7,500 10,000 12,500 15,000 20,000 25,000 30,000 35,000 40,000 50,000 ---3K0 ---3K5 ---4K0 ---5K0 ---6K0 ---7K5 ---10K ---12K5 ---15K ---20K ---25K ---30K ---35K ---40K ---50K F55J--- 55 F40J--- 40 F30J--- 30 F10J--- 10 ---125 ---150 ---200 ---250 ---300 ---400 ---500 ---600 ---750 ---800 ---1K0 ---1K25 ---1K5 ---1K75 ---2K0 ---2K5 Part No. Prefix Suffix F20J--- 20 125 150 200 250 300 400 500 600 750 800 1,000 1,250 1,500 1,750 2,000 2,500 Ohmic value Ohmic value F55J--- 55 F55J--- 55 F40J--- 40 F40J--- 40 F30J--- 30 F30J--- 30 F20J--- 20 F20J--- 20 F10J--- 10 F10J--- 10 ---1R0 ---1R5 ---2R0 ---3R0 ---4R0 ---5R0 ---7R5 ---10R ---15R ---20R ---25R ---30R ---40R ---50R ---75R ---100 Part No. Prefix Suffix Wattage 1 1.5 2 3 4 5 7.5 10 15 20 25 30 40 50 75 100 Wattage Part No. Prefix Suffix Ohmic value Wattage = Most popular stock values = Stock values = Non-stock values subject to minimum handling charge per item Shaded values involve very fine resistance wire and should not be used in critical applications without burn-in and/or thermal cycling. Ohmite Mfg. Co. 1600 Golf Rd., Suite 850, Rolling Meadows, IL 60008 * Tel. 1-866-9-OHMITE * Fax 1-847-574-7522 * www.ohmite.com * info@ohmite.com 31