Heathkit T-2 - Scan 4

nection in the instrument and mark if on the circuit diagram with a colored pencil. In this manner,
any connections overlooked or incorrect will be disclosed. If wiring is in order, insert tubes
and connect to llOV 60 cycle AC. After warm up period, advance the gain control and touch prod
tip. If loud hum is heard in the speaker (providing switches are set in correct position), the
tracer is in proper operating order.
USE OF SIGN AL TRAC ER
The gain control determines the sensitivity of the instrument and allows the signal being followed
to be adjusted to a suitable volume .
The slide switch 094 should be in the internal position. The selector switches should be in posi-
tions 4 and 5 to properly match the 6K6 tube in this instrument.
To trace a receiver, set the dial of receiver under test to known local station or preferably a
signal from a test oscillator. Turn gain control full on, connect ground clip of tracer prod to B-.
(On AC-DC radios, a small potential may exist which may be eliminated by reversing either the
plug on radio or tracer or both.) Note: B- and chassis may not be at the same potential in some
AC-DC receivers. Hum and distortion may be minimized by placing a condenser of afew MMF
in series with the test prod. A reduction in signal strength due to detuning is to be expected when
checking receivers having relatively large inductances and small capacities in the tuned circuits.
Start at the antenna coil and touch the prod tip to fir st the secondary , continuing through the RF,
and IF coils (always to the high or plate and grid sides of the coils) continuing through the audio
section by connecting progressively to the grid and plate of each section at tube socket. When
the signal stops, the difficulty lies in the stage just prec~ding. To illustrate--if the signal appears
at the plate or primary connection of a coil but not at the secondary or grid of the coil, the fault
is between the plate and grid. The gain of each stage is indicated by the amount the gain control
of the tracer must be reduced to maintain equal volume. Power supply filters may be checked
by touching the prod to each section and noting the reducU on in hum (no re duction indicates de-
fective filter condenser). Distortion, noise or hum may be followed through a radio in the same
manner and isolated. The Hea thkit Signal Tracer may be used for many other trouble shooting
purposes which appear desirable to the user. The crystal diode in the probe is in effect a crystal
detector which will respond to any frequency up to 200 megacycles.
The selector switches make 30 different impedance ratios available which make the instrument
a valuable test speaker. To use as a test speaker for receivers or amplifiers with output trans-
formers, connect to jacks C (common or grounded side) and VC (voice coil) with slide switch
to "external." To use as a test speaker for receivers or amplifiers without an output transformer,
c6nnect to jacks "P" and "B+" (for single ended output) or "P" "B+" and "P" (for push pull
output) with
slide switch in internal position, and adjust the selector switches for proper matching
to the tubes using the chart on the panel. A mismatch of 30 percent will not adversely affect
operation. When used as a test speaker, be sure the power is turned off turning the gain control
all the way counter clockwise till the switch clicks.
The transformer can be used as a matching tran s former only, by connecting the amplifier or
receiver as above and "C" and "SEC" terminals to an external speaker . The sHde switch should
then be in the external position .
To
use the tracer as an audio amplifier or small public address system, connect either a phono-
graph pickup or high impedance crystal microphone to the input terminals and use either the in-
ternal speaker or a remote external speaker. For visual signal trac ing, insert the AC test prod
from a vacuum tube voltmeter into the "P" connection. Connect the GND connection of the tracer
to the common or GND connection of the VTVM. The VTVM should be set on the correct AC
scale. Signal levels and gain per stage may be read directly in volts or db. In checking inter-
mittents, the tracer and VTVM may be left at a known setting and will indicate any change in-
stantly. The "P" co nne ctio n may also be connected to an oscilloscope for visual tracing.
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