Tektronix 3B5, Instruction Manual

Page: 109 / 187

Calibration —Type 3B5
Fig. 6-2. Initial equipment setup for steps 1—5.
Control Settings
Type 3B5
Mode MAN
POSITION Midrange
DLY'D SWP MAG OFF
DELAY 1.00
MANUAL TIME/DIV .5 ms
VARIABLE CAL
Trigger Function EXT-AC
LEVEL Midrange
SLOPE
+
Amplifier Unit
Position Midrange
Input Coupling
DC
Volts/Division 10 Volts
Mode
Manual
Indicator Oscilloscope
Focus Adjust for correct
display
Intensity Visible display
Calibrator
10 Volts
Power
On
1. Adjust Trigger Level Centering O
a. Test equipment setup is shown in Fig. 6-2.
b. Connect the low-frequency sine-wave generator to the
amplifier unit input connector through the BNC cable and the
BNC T connector (use the BNC to alligator clips adapter
to connect the generator output to the BNC cable). Connect
the output of the BNC T connector to the Type 3B5 EXT TRIG
INPUT connector with a BNC cable.
c. Set the low-frequency sine-wave generator for a four-
division CRT display (40 volts peak to peak) at one kilohertz.
d. Turn the LEVEL control fully counterclockwise.
e. ADJUST — TRIG LEVEL CENTERING adjustment, R15,
(see Fig. 6-3), to setting where unit does not trigger (no trace
and NOT TRIG'D
readout
on) for both 4- and — slope.
f. Turn
the
LEVEL control fully clockwise.
g. ADJUST —TRIG LEVEL CENTERING adjustment, R15, to
setting where unit does not trigger for both 4- and — slope
triggering. Then, set the adjustment midway between the
setting obtained in step e and this setting.
h. Recheck steps d through g and readjust if necessary.
The display must not be triggered (no trace) at either end of
rotation for both 4- and — slope triggering when correctly
adjusted. (This step also checks EXT-AC trigger LEVEL range
for at least
4-
and — 20 volts.)
6-5