Triplett Fox & Hound 3 – PN: 3397 - Manual (Page 18)

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Helpful Hint:
Almost any type of earphones whose plug will fit into the
Earphone Jack will work. Some types will work better than
others. An earphone with shielded wires is recommended.
Use of earphones with unshielded wires may cause a squeal-
ing sound to be heard.
7.6: How it works
The HOUND 3 works by capacitively sensing the electrostatic
field radiated by wires carrying a signal from the FOX. The
greater the radiated field, the better the HOUND 3’s ability to
locate a wire. Anything that reduces the intensity of the field
will impair the HOUND 3’s effectiveness in locating a wire.
In general, several things affect field intensity . . . shielding,
signal (tone) amplitude on the wire, and wire dress. In in-
stances where a system is shielded (shielded wires, metal
junction boxes, metal conduit, etc.), the effectiveness of the
HOUND 3 is impaired. In multi-wire cables, grounded wires,
or wires connected to low impedance circuits, adjacent to
the target wire can act as shields, reducing the HOUND 3’s
ability to sense properly. Spreading the wires apart will re-
duce the shielding effect and allow the HOUND 3 to work
better. Defects in a cable or wires, such as shorts or opens,
will reduce the signal amplitude and hence the HOUND 3’s
ability to locate the target wire. Terminating a wire or line in
a low impedance also reduces signal amplitude and the
HOUND 3’s locating ability. It is also possible for wire posi-
tion to cause nullification of the field.