MT91A Test Set (Amplifier, Probe, and Headset)


The MT91A Test Set includes an amplifier, inductive probe, and headset to facilitate testing and fault locating where an amplifier is required.


The MT91A Test Set contains three major components housed in a portable plastic carrying case; the MT 147D Amplifier, the MT 723A Receiver, and the MT 513A Probe.  The MT 147D is a solid state amplifier intended to facilitate testing and fault locating work with exploring coils and other testing apparatus where an amplifier is required.  The amplifier with the MT 513A Probe is intended for identifying wires in toll or exchange cables without making metallic contact with conductors at a splice or sheath opening.

The MT 147D solid state amplifier features:

  • Incorporates a center frequency of 540 Hz for use with both old and new detection frequencies (500 or 577Hz)

  • Improved bandwidth response for elimination of outside interference.

  • Increased sensitivity for better fault detection

  • Lower current consumption through the use of integrated circuits.

  • 60Hz filter provides high AC inductance rejection with at least 34dB of isolation to AC harmonics at 540 hz.

Components (included in kit):

MT-723 Headset

  • Rugged craft headset used to monitor output of MT 147DMT-147D Amplifier. Coiled 4′ cord with 310 plug.

MT-513A Inductive Probe

  • Amplifier for inductive pick-up of tone signal. Has 6-ft cord with 347B plug and ground clip. Measures 7″ x .5″ and weighs 4 oz.

Additional information

Weight 5.6 lbs
Dimensions 15.5 × 13.5 × 4 in