Heathkit IT-12 Signal Tracer
This is a Heathkit Model IT-12 Visual and Aural Signal Tracer. This instrument
is used to trace both audio and RF signals through a circuit to determine
where a fault is. The silver probe has a switch that selects either audio
or RF. When RF is selected, a diode detector and filter is placed in the circuit.
The audio or detected signal is passed to a 2-stage vacuum tube amplifier with a gain
control mounted on the center left of the front panel (labeled Level). The
amplified signal is then passed to a vacuum tube driver stage that drives the
A green "eye tube" in the lower left of the front panel gives a visual indication
of the audio level. Stronger signals make the green eye segments come closer
The speaker and its audio output transformer can be used independent of the
signal tracer to diagnose vacuum tube audio amplifiers by replacing the
unit under test transformer and speaker. When the signal tracer is turned off,
you can use the three binding posts in the lower right of the front panel to
connect the internal output transformer to the circuit under test. The internal speaker
is always connected to the transformer.
I purchased mine at a hamfest for a low price. The only thing wrong with mine
is that the paint is flaking off the case. Otherwise it works perfectly. Even the
eye tube is bright.