Tektronix Option 10 Service Manual page 143

EXTERNAL FREQUENCY REFERENCE
CHECK
CTT and WR Options-Performance Check and Adjustment Procedure
24X5B12467B Options
Service
NOTE
The Oscilloscope under test, the Oscillator, and the
Time Mark Generator must have at least 20 minutes
warm-up prior to performing the verification
procedure.
Initial Control Settings
1. Verify External Reference Operation
a. Connect the time-mark generator to CH 1 via a
50-a cable.
b. Set the generator to 0.2 p s time markers.
c. ADJUST-A Trigger Level Control for a 1.00 V Trigger
Level Readout.
d. VERIFY-Displayed time markers are triggered
and stable.
Control settings not listed do not affect the procedure.
e. Press the measure button to enter the MENU mode.
NOTE
Select channels to set VOLTSIDIV
VERTICAL
CH 1
CH 2, CH 3, CH 4, ADD,
and INVERT
BW LIMIT
CH 1 VOLTSIDIV
CH
1
INPUT COUPLING
CH 1 POSITION
HORIZONTAL
A SECIDIV
XI0 MAG
AV AND At
TRIGGER
TRIGGER MODE
TRIGGER SOURCE
TRIGGER COUPLING
TRIGGER SLOPE
TRIGGER HOLDOFF
READOUT INTENSITY
l
NTENSITY
MENU Functions
ON
OFF
OFF
500 mV
50 DC
MID RANGE
200 ns (Knobs locked)
OFF
OFF (Press and release
until associated readout
is off)
AUTO
VERT
DC
+
MINIMUM
SCALE FACTORS ON
COMFORTABLE
DISPLAY
OFF
f. Select COUNTER from menu.
g. Select FREQ from menu.
h. CHECK-The top right READOUT now displays a count of
the input time markers using 7 digits.
i. VERIFY-The count reading is within 4.999995 to
5.00005 MHz.
2. Verify External Reference Count Stability
NOTE
External Reference Count starts approximately 100
counter updates after the Reference Signal is
connected to the EX1 REF input at the rear of the
oscilloscope under test.
a. Connect output jack J20 of the oscillator to the oscillo-
scope EXT REF input via a 7542 cable and 7 5 4 termination.
b. CHECK- After approximately 100 counter updates
(about 1 minute 30 seconds) the readout count frequency is
displayed with 8 digits.
c. Note the value of the 8 digit display.
d. VERIFY
-
For approximately 100 more counter updates
that the frequency count does not vary by more than ~ k 0 . 8 Hz
from the initial reading noted in Step c above.
e. Disconnect the test set-up.