SNC QUIET-TEL® Noise Mitigation Equipment… Quietly Leading The Industry With Proven Electrical Interference Solutions.

Reduce Phone Equipment Or Electrical Interference Problems. Rely On Noise Mitigation Equipment From SNC.

Noise Chokes - Common Mode Transformers

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"The Voice or Radio Frequency Interference Solution"

Increasing power line harmonic and radio frequency interference (RFI) on ADSL circuits means more noise in your communication system. These induced noise frequencies can also lead to signaling problems and equipment malfunctions.

Equipment damages often occur from induced longitudinal currents associated with power surges or lightning.

Noise Chokes effectively suppress these problems, especially when they are caused by equipment unbalances resulting from age, deterioration, or a highly susceptible electronic design.

Noise Chokes are single circuit devices which are generally placed at the equipment end of a circuit- either the central office, PBX, or where special service equipment is located. When used effectively, Noise Chokes can improve circuit balance and suppress currents acting on sensitive equipment.

Each choke has a copper flux band formed around the coil to prevent cross talk when mounted close to each other, as in a central office. By grounding the flux band, the choke also becomes an effective Radio Interference Filter. The 70 series choke is the equivalent of a Transcom NSC 2 choke. Chokes are installed in the same manner as "load coils".

(i.e. Tip and Ring in and Tip and Ring out. Either side may be used as the "in" or "out.")

Noise Chokes are an economical solution to noise frequency interference and contribute to quieter, more reliable operation of your communication system.


  • Subscriber Lines/PBX Trunks/OPXs
  • Duplex (DX), Simplex (SX) Signaling Circuits
  • Voice Frequency Interoffice Trunks
  • Dial Long Line Circuits
  • Four Wire FXs
  • Data Modems/Answering Machines
  • Alarm/Telemetering Circuits
  • Data Circuits/Radio Pickups
  • Key Equipment Line

Individual Chokes

Part No Description

with wire wrap pins

P15047 with 30" (76.2 cm) long unshielded leads
P15069 with 30" (76.2 cm) long shielded leads

in plastic enclosure with 36" (76.2 cm) long jacketed leads

  • DC loop resistance @ 25 degrees Celsius 45 ohms +/- 10%
  • Resistance unbalanced @ 25 degrees Celsius 0.8 ohm Max.
  • Insertion loss @ 1.0 KHz. 0.5dB Max.
  • DC loop current 240 mA Max.
  • Longitudinal voltage @ 60 Hz* 70 VRMS per side
  • Approximately 10% less voltage at 50 Hz

Relay Rack Chokes

19" (48.3 cm) Rack Panels

Lead "L" models are prewired to two (2) (RJ21) 50 pin connectors- (1) male, (1) female

Part No Description

(12) 70L on a 3.5" (8.9 cm) panel

Main Frame Chokes

Prewired to 8" (20.3 cm) wire wrap terminal block

Part No. Description
P15063 (12) 70L on a 8" (20.3 cm) deep plate

(24) 70L on a 15" (38.1 cm) deep plate


(12) 70L metal encased "dense pak"