Electrical Terminators

Electrical terminators are installed at the end of a bus or transmission line to prevent signals from reflecting back. Sometimes called electrical terminators, these electrical devices are used to prevent electrical interference. There are four basic types of electrical terminators: chip, coaxial, SCSI, and waveguide. Chip terminators have a form factor of an integrated circuit (IC) chip. They are manufactured using thin-film technology. Coaxial terminators that terminate coaxial ports. SCSI terminators are electrical circuits placed at each end of a small computer system interface (SCSI) cable for impedance matching. Waveguide terminators are devices that terminate waveguide ports. Other unlisted or proprietary electrical terminators are also available.  

Electrical terminators differ in terms of performance specifications and category or application. Power rating, voltage standing wave ratio (VSWR), return loss are the most important performance specifications to consider. VSWR, a unit-less ratio ranging from 1 to infinity, expresses the amount of reflected energy at the input of the device. A value of 1 indicates that all the energy passes through. Any other value indicates that a portion of the energy is reflected. In terms of category or application, there are four choices for electrical terminators: general-purpose terminator, RF terminator, telecommunications or telecom terminator, and audio / video cable terminator. 

RF connector type is an important parameter to consider when selecting electrical terminators. Choices include BMA, BMMA, BNC, Type C, Type F, FME, Type G, MCX, MHV, and MMCX. Electrical terminators also use connector types such as QMA, QWS, SC, SMA, SMB, SMC, SSMA, SSMA, SSMB, TNC, Triax, Twinax, UHF, Mini-UHF, and ZMA. Numbered connector types for electrical terminators include 1.6 / 5.6, 7-16, 1.0 / 2.3, 1.85 mm, 2.4 mm, 2.92 mm, 3.5 mm, and 7 mm. 

Standards and certifications are important to consider when selecting electrical terminators. Products that are destined for sale in Europe should comply with the following European Union (UE) directives: Restriction of Hazardous Substances (RoHS), End-of-Life Vehicles (ELV), and Waste Electrical and Electronics Equipment (WEEE). Electrical terminators that are sold in the United States should comply with requirements from the Federal Communications Commission (FCC), or bear marks from Underwriters Laboratory (UL). In Canada, electrical terminators that meet requirements from the Canadian Standards Association (CSA) bear the CSA Mark, alone or with indicators.

• SCSI Terminators
  SCSI terminators are an electrical circuit at the end of the SCSI cable designed for impedance matching. With the terminator in place, the electrical signals traversing the cable will not be reflected...
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