Sonel TDR-420

TDR-420 is a hand held Time Domain Reflectometer designed to identify and locate faults in power, telecommunications and teletechnical cables. TDR-420 reflectometer allows to measure the length of the cable and determine the distance to damage or impedance variation in the range of 4 m to 6000 m in conductors with metal wires. The shortest measuring range of 7 meters and a dead zone of 0.6 meters allows to locate damages at a very close distance from the place where the device is connected.

Two cursors allow to determine the place of two damages simultaneously and the distance between them.

Thanks to the colour 3,5” TFT display with a resolution of 320 x 240 pixels, the indication of the location of the damage is precise and the results easier to interpret.


Product features

• fault location in power and telecommunication cables
• two independent cursors to indicate two fault locations and the distance between them
• fault location in coaxial cables
• fault location in infrastructure cables
• detection of breaks, short-circuits, damage caused by moisture and other changes in cable impedance
• graphic presentation of cable faults with an indication of the distance to the fault on the display

Diagnose faults with the TDR reflectometer

• For measurement of coaxial cables
• For measurement of shielded cables
• For measurement of twisted pairs
• For measurement of multi-conductor cables
• For measurement of pre-insulated pipes
• Core identification mode (TONE)


TDR-420 time-domain reflectometer is designed to detect where faults in metal wires are. This product is designed for:

• Electrical Wholesalers and Cable Dealers,
• Electrical Installation Companies,
• Maintenance Personnel at Manufacturing Plants,
• Utility Cabling Engineers.

This device meets the expectations of all those who have to accurately locate a fault and wire end in either power or telecommunications cables.

Easy readout

The TDR-420 reflectometer is equipped with a readable colour display that, due to its 320 x 240 pixel resolution, allows the fault location to be indicated even more accurately.

Integrated Help

In the TDR-420 device a handy help function has been added to facilitate the interpretation of the result obtained during measurement. Thanks to this function, a user can quickly determine the type of anomaly that is present in the cable segment which is being examined, by comparing the displayed reflectogram with typical fault shapes.

Durable and practical casing

In response to the customers needs the TDR-420 has been designed to operate in difficult environmental conditions. A unique casing with the IP67 ingress protection rating ensures that the device is both waterproof and dustproof. An additional advantage is the elastomer coating of the casing that prevents the device from slipping out of the hands and provides protection if it should be accidentally dropped.

Device capabilities

The SONEL reflectometer is distinguished for its long operating range of up to 6,000 m, very low margin of error in measurement (in the order of 1%) and the ability to adjust both the velocity of propagation and the impedance of the cable which is under investigation. By using two cursors there should be no problem with determining both the distance to two faults and the distance between them.

Download Datasheet TDR-420