Tektronix 7834

Vertical Trace Separation
When one of the dual-sweep horizontal
modes is selected,
the
VERT TRACE SEPARATION (B) control allows the
trace produced by the B HO RIZ sweep to be positioned
above or below the trace produced by the A HORIZ sweep .
To use
the control, first position the trace produced by the
A HORIZ plug-in unit . Then adjust the VERT TRACE
SEPARATION (B) control to move the trace produced by
the B HORIZ plug-in unit away from the A HORIZ display .
If both waveforms are larger than four divisions in ampli-
tude, the displays can only be positioned so they do not
directly
overlap since each waveform cannot be positioned
to a unique area of the crt .
Trigger Source
The
A and B TRIGGER SOURCE switches select the
internal trigger signals for the A HORIZ and B HORIZ
time-base units . For most applications, these switches can
be left in the VERT MODE position . This position is the
most convenient since the internal trigger signal is automat-
ically switched as the VERTICAL MODE switch is changed
or as the display is electronically switched between the
LEFT VERT and RIGHT VERT plug-ins, in the ALT
position of the VERTICAL MODE switch . It also provides
a usable trigger signal in the ADD or CHOP positions of
the
VERTICAL MODE
switch,
since
the internal trigger signal
in these modes
is
the algebraic sum of the signals applied
to the vertical plug-in units . Therefore, the VERT MODE
position ensures that the time-base units receive a trigger
signal regardless of the VERTICAL MODE switch setting
without the need to change the trigger source selection .
If correct triggering
for the desired display is not obtained
in the VERT MODE position, the trigger source for either
the A HORIZ or B
HORIZ time-base unit can be changed
to obtain
the
trigger
signal from either the LEFT VERT or
RIGHT VERT plug-in . The internal triggersignal is obtained
from the selected vertical compartment whether the plug-in
in that compartment is selected for display on the crt or
not . If the internal trigger signal is obtained from one of the
vertical units but the other vertical unit is selected for
display, the internal trigger signal must be time-related to
the displayed signal in order to obtain a triggered (stable)
display .
Calibrator Output
The CALIBRATOR provides a convenient signal for
checking basicvertical gain and sweep timing . The calibrator
signal is also very useful for adjusting probe compensation
as described in probe instruction manuals . In addition, the
calibrator can be used as a convenient signal source for
application to external equipment .
VOLTAGE
.
The
CALIBRATOR provides accurate output
voltages of 40 millivolts, 0 .4 volt, and
4
volts
into high
Operating Instructions--7834
impedance loads . In addition, it provides 4 millivolts,
40 millivolts, and 0 .4 volt into 50-ohm loads .
CURRENT . The optional current loop accessory provides
a 40-milliampere output current (the CALIBRATOR must
be set for
4
volt
output), which can be used to check and
calibrate current-measuring probe systems . The current
signal is obtained by clipping the probe around the current
loop .
REPETITION RATE . The repatition rate of the CALI-
BRATOR is 1 kilohertz . The calibrator circuit uses
frequency-stable components to maintain
accurate fre-
quency and a constant duty factor . Thus,
the CALIBRATOR
can be used for checking the basic sweep timing
of time-
base units (1-kilohertz rate only) .
WAVE SHAPE .
The square-wave output signal of the
CALIBRATOR can be used as a reference wave shape when
checking or adjusting the compensation of passive, high-
resistance
probes . The square-wave output from
the
CALIBRATOR has a flat top ; any distortion
in the
displayed waveform is due to the probe
compensation .
Signal Outputs
+ SAWTOOTH OUT . The
+
SAWTOOTH OUT connector
provides a positive-going sawtooth signal derived from the
time-base unit installed in the A HORIZ compartment or
from the time-base unit installed in the B HORIZ
compartment .
+
GATE OUT .
Electric-shock hazard present . Only qualified
service personnel should internally modify the
operation of the instrument .
It is possible to select either the A HORIZ or the B HORIZ
compartment as the source of the + SAWTOOTH output
signal . Refer such selection to qualified service personnel
only . The unit of time for the sawtooth output is deter-
mined by the setting of the time-base-unit
Time/Division
switch . Refer to Table 1-4, in the
General Information
section, for signal parameters .
Electric shock hazard present . Only qualified
service personnel should internally modify the
operation of the instrument .
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