ETS-Lindgren's Series N24X and N29X series of RFI/EMI telephone filters are specifically designed to meet the stringent requirements for telephone circuits. The high electrical symmetry between lines means they are suitable for modern applications and similar digital data links.
As each line is closely matched electrically to all other lines, the need for matched pairs is eliminated - thus easing considerably the complexity of installation in multi-line systems.
All of these filters meet the technical requirements of British Telecom, Deutsche Bundepost, PTT Nederlandse and similar organizations. 

Our telephone filters are designed to operate in harmony with both Class 'A', and Class 'B' (standard) telephone systems. For filters to function on Class 'A' systems, a complex impedance match is provided by a specifically designed range. 

These filter series offer two levels of insertion loss performance, thus providing the flexibility to meet your requirements. A series of filters specifically designed for 64 kbit ISDN lines is also available.
For maximum versatility these filters are available in 2-line units and modular 10-line packages. The 2-line filters are available in either a flat-pack or tubular design. The tubular designs are manufactured from brass; with nuts, washers and plastic end covers supplied.

This 10-line package provides filtering of 50, 100 and 200 lines and beyond in multiples of ten. Further to this, the data and control modules are directly interchangeable with this series, enabling the user to mix and match filters in the same housing.

This modular system is ideal for installations where future expansion of the communications network is envisaged. The system is enclosed in high quality corrosion-proof electroplated steel cases for low impedance grounding.

Key Product Information


Specifications Select a tab below for more information



Current Rating: 0.3 Amps 
Voltage Frequency Maximum: 150V-DC 

Key Features


  • Suitable for EMI, EMP and Tempest Protection
  • Tubular, Flat-pack or Modular Design
  • 100 dB Insertion Loss
  • ISDN Filters Available
  • Matched to Balanced 600 Ω Lines

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