Tektronix 7B70 Time Base Instruction Manual page 13

Operating Instructions-7B70 (SN B205000 and Up)
Sweep Controls
POSITION
tor. Select TRIGGERING SOURCE
and COUPLING.
Controls horizontal position of dis-
play.
VARIABLE
(amplifier)
Varies deflection factor by a factor
of 10.
Provides more precise control of
horizontal positions.
TEST SETUP CHART
TIMEIDIV
Selects the basic sweep rate of the
output sawtooth. The VARIABLE
control must be in calibrated posi-
tion and MAGNIFIED switch set to
X 1 for indicated sweep rate.
General
Fig. 2-3 shows the front panel of the 7B70. This chart
can be reproduced and used as a test-setup record for
special measurements, applications or procedures, or i t may
be used as a training aid for familiarization with this instru-
ment.
VARIABLE
(TIMEIDIV)
Two-position switch actuated by
the VARIABLE knob to select cali-
brated or uncalibrated sweep rates.
At the in position, the VARIABLE
GENERAL OPERATING INFORMATION
control is inoperative and the sweep
rate is calibrated. When pressed and
released, the knob moves out to
activate the VARIABLE control for
Sweep Calibration Check
Whenever the 7B70 is inserted into a plug-in compart-
ment other than the one in which it was calibrated, the
sweep calibration should be checked and readjusted if nec-
essary. Allow five minutes warmup before performing this
procedure.
NOTE
uncalibrated sweep rates. The
sweep rate in each TIME/DIV
switch position can be reduced to
at least the sweep rate of the next
adjacent position, to provide con-
tinuously variable sweep rates from
2 nanoseconds/division (X 1 O-MAG-
N l F l E R on) to about 12.5 seconds1
division. with MAGlU lFlER at X I .
For accurate sweep timing, apply a signal o f known
frequency or time period (time-mark signal, calibrator
square wave,
60
hertz line etc.) to the associated
vertical amplifier unit and adjust the TIME/DIV OR
DLY TIME switch and the SWP GAL control to
calibrate the signal to the oscilloscope graticule. Be
sure that the sweep timing signal is accurate within
0.5%. The following sweep calibration procedure uses
a Tektronix TimeMark Genera tor.
Push-button switches to select the
horizontal magnification. The
Selected magnification i s indicated
by a lighted button.
MAGNIFIED
X1 :Magnified sweep at the basic
sweep rate indicated by TIME1
DIV switch.
1. Connect
a
1 millisecond time-mark signal from the
Time-Mark Generator with a 50-ohm BNC coaxial cable and
50-ohm BNC termination to the Input of the associated
vertical unit.
X10: Magnified sweep at a sweep
rate 10 times faster than the
basic sweep rate indicated by the
TIMEIDIV switch. The portion
of the normal sweep within the
center division of the graticule is
the portion shown in magnified
form.
2. Set the TIMEIDIV switch to 1 ms and press the top
TRIGGERING and DISPLAY MODE pushbuttons.
3. Set the Vertical unit to display at least two divisions
of the signal vertically.
4. Check the CRT display for one complete cycle per
division.
Screwdriver adjustment to set am-
plitude of the output sawtooth.
SWP CAL
5. I f necessary, adjust the SWP CAL adjustment for one
complete cycle per division.
Display Mode
TIME BASE Selects sweep rates a s determined
by TIMEIDIV switch.
Simplified Operating Instructions
The following information i s provided to aid in quickly
obtaining the correct settings for the 7B70 to present a
AMPLIFIER
Displays signals applied to the EXT
TRIG IN or EXT VOLTS IN connec-
Scans by ArtekMedia O 2006