PATERSON, NJ - MMG-North America (MMG-NA), a leading manufacturer of soft ferrite cores, wound devices and magnetic materials, has developed a hum modulation sample kit that can help cable-TV engineers in their efforts to reduce hum modulation. Believed to be the first tool of its kind, this kit uses power-passing chokes to help engineers minimize the effects of hum modulation.

      MMG-NA has been working with leading cable-TV distribution equipment manufacturers in developing a new material, which displays exceptional properties, and subsequently eliminates the need for resistors in hum mod choke design.

      "The hum mod kit will help engineers accomplish their design goals and is a tool for them to use to meet new cable specifications," said MMG-NA Applications Engineer Douglas Toth, PE. "Consumers want to receive information faster and without distortions or glitches. The new hum mod specifications help create designs which will ultimately increase transmission speed while keeping the integrity of the data between the transmitted and received locations."

      The kit contains parts to design a choke to withstand 15 continuous amps and a peak current of up to 25 amps for two hours (in accordance with the most recent hum mod specifications being implemented). Several windings are provided for engineers who may want to try the balanced 10-10 turn type or the 10-12 turn version. A dampening resistor connected between the center tap of the winding and either outer leg can be used (a variation can be made by placing a dampening resistor across the other sections of the windings). One version has a 470-ohm dampening resistor across 12 turns on the 10-12 coil. The type of circuitry will ultimately determine which type of choke will be more effective.

      Although MMG placed a 470-ohm resistor on the lower potential winding, an engineer can experiment with various resistor values and placements on the windings to obtain the desired results. The need for insulation on the core has been eliminated because the core material is a nickel-zinc ferrite, which has a high electrical resistivity (no electrical shorts should occur to the core). However, the kit does contain some cores with insulation as an additional option for the engineer.

      Some cores come with shrink tubing to help engineers adjust the pitch of the winding. Once the configuration is determined, a small epoxy bead will hold the coil in place.

      For more information, contact MMG-North America at 1-800-664-7712; by fax at 973-345-1172; e-mail: sales@mmga.com by mail at 126 Pennsylvania Avenue, Paterson, NJ 07503-2512; or visit the MMG-North America web site: www.mmgna.com.

      MMG-North America, a manufacturing subsidiary of the TT Group PLC, manufactures soft ferrite, iron powder, MPP and permanent magnet components for the automotive, consumer and industrial electronics, communications, cable TV systems, computer, aerospace and EMI/RFI suppression markets.

      TT Group PLC, a publicly traded corporation in the United Kingdom, is a world-class supplier of electronic components in North America and throughout the world. The company has manufacturing facilities in the United States, Germany, Austria, the United Kingdom, Barbados and Mexico.