VACUTRACE Vacuum Tube Curve Tracer
6
Power
Sets the maximum peak power dissipated by the tube’s plate
during a sweep.
Rate/Offset
This is a dual function control. While sweeping it acts as sort
of a sweep rate adjustment. It offers a compromise between
accuracy and visual flicker. In Hold mode this becomes an
offset adjustment for the grid bias voltage.
Sweep/Hold
Sets the operating mode between sweeping curves and taking
measurements. In Hold mode the 3½ digit LED display is
turned on and reads the value of the measurement selected by
the Output control.
Output
Selects the measurement to be read in the display. Normally,
tube curves are swept in the gp mode, but the gm mode can
also provide useful information.
Triode/Pentode
Operates the tube as either a triode or pentode. The screen is
tied directly to the plate in triode mode.
Screen
Adjusts the screen voltage when in pentode mode.
Status
LED indicates the present operating mode or condition. When
in standby it is red. During normal operation it is green. If
flashing yellow, then VacuTrace is experiencing an overload
condition.
Caution
LED lights up yellow when a voltage greater than 70V is
present on the output connector.
Rear Panel
The rear panel holds the ac mains input/fuse holder connector, on/off power switch,
and three output signal BNC connectors. The outputs are labeled X, Y and Z and
connect to your oscilloscope by the BNC cables provided. See Chapter 1 for correct
wiring.
Socket Adapter Cards
Some of the socket adapter cards contain switches. These are for heater voltage
selection or, in the case of a diode, to choose which plate is operating (pin 4 or pin
6). The heaters of a 12AX7 type tube are run in parallel at 6.3V (set switch to
12.6V). All heaters are ac. The wing nuts are connected to chassis ground. There
are two tube circuits, A and B, which allows for tube matching. The output connector
has the following pinout:
