Manufacturer: Schonstedt
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The MAC-51Bx consists of a receiver and a transmitter that simultaneously transmits on two frequencies - 571 Hz (LF) and 82.5 KHz (HF). The receiver has a three position switch that lets you change modes, "on-the-fly", between LO, HI, and MAG, for cable and line tracing with break locating, pinpointing a ferrous metal target, or identifying and pinpointing an energized 50/60 Hz power line.

In the LO and HI modes, the receiver's audio signal provides a sharp null when its tip is directly over the target. In the MAG mode (no transmitter required) the audio signal peaks when the receiver's tip is over the target. You can trace the 571 Hz LF signal conductively applied to any continuous metal conductor up to 4000 feet.

The receiver's on-the-fly mode-changing feature lets you locate a complete break using the LO mode, and then continue on to trace beyond the break in the HI mode, or trace a metal pipe joined with non-conductive gaskets.

The MAC-51Bx by simultaneously transmitting 82.5 kHz (HF) and 571 Hz (LF) signals, lets you select and compare received audio signals from both frequencies along with magnetic information without having to return to the transmitter.


  • Operating Voltage: 12 volts (eight C-cell batteries)
  • Battery Life: 50 hours intermittent operation at 70o F
  • Output Frequency: 82.5 kHz modulated at 382 Hz. pulsed at 4,8 Hz (inductive or conductive)
  • Audio Indicator: 2.58 kHz pulsed at 4.8 Hz
  • Weight: Approximately 5.5 lb.(2.5 kg.)
  • Operating Temperature: 0o F to 120o F (-18to 49o C)
  • Overall Size: 43.5 in. x 7 in. x 5 in. (110.5 cm. x l7.B cm. x 12.7 cm.)
  • Waterproof Length: 34.5 in. (87.6 cm.)
  • Nominal Sensor Spacing: 20 in. (50.8 cm.)


  • Operating Voltage: 6 volts (4 C-cell batteries)
  • Battery Life: 50 hours intermittent operation at 70o F
  • Output Frequency: Approximately 40 Hz idling tone from speaker; frequency of pulsing tone increases (ot decreases) with signal intensity
  • Weight: Approximately 3 lb. (1,36 kg.)
  • Operating Temperature: 0o to 120o F (-18o to 49C)
  • Overall Length: 42.3 in. (107.4 cm.)
Specifications subject to change without notice