Performance Checkā2465B/2467B Service
q.
CHECKāThe B sweep timing accuracy as in parts b
through f, making sure that the A SEC/DIV is set slower
than the B SEC/DIV.
2.
Select COUNTER ("4") from menu.
3. Select PERIOD ("2") from menu.
3. Check Delta Time Accuracy using the Delayed
Sweep.
a. Set:
A SEC/DIV
B SEC/DIV
X10 MAG
At
TRIGGER MODE
TRIGGER SOURCE
TRIGGER COUPLING
TRIGGER SLOPE
TRIGGER LEVEL
BTRIG MODE
10 ns
5 ns (knob out)
On
Off (DLY readout)
AUTO LVL
VERT
DC
+ (plus)
As required for a
stable display
RUN AFT DLY
NOTE
Certain time marks from the TG 501 (and other
Time-Mark Generators) will vary in width and may
be displaced in time. This will happen in a repeat-
able sequence and is caused by the loading and
interaction of the 2, 5, and 10 dividers. This is
most noticeable with 10 ns, 20 ns, and 50 ns
markers. The following procedure will use the
above markers to set up the proper references
but the 5 ns markers will be used to make the
actual measurement. Close inspection of apparent
jitter or mistrigger of the time marks will show the
trigger point to be stable with the apparent jitter
to be variable with unique combinations of trigger
holdoff and sweep speed. This is normal behavior
with this type of signal and is not an instrument
defect.
The CTT period readout will appear on the left side of
the upper line of readout. The word "SET" will appear next
to the readout delay value. This denotes the indirect mea-
surement mode of Delta Time, simulating a non-CTT
scope.
b. Set the Time-Mark Generator for 10 ns markers.
Adjust the Vertical VOLTS/DIV as required for a display of
3 to 6 divisions.
c. Adjust the A REF OR DLY POS control for a readout
display of DLY 10.64 ns.
d.
Adjust the Horizontal POSITION control CW until the
trace stops moving, then CCW to display the leading edge
of the 2nd time marker near the graticule center. This
becomes the reference point for the following procedure.
Set the Time-Mark Generator to 5 ns and adjust the Verti-
cal VOLTS/DIV and Trigger LEVEL as required.
It is not necessary to count the number of marks given
in the tables. Switching to 10 ns, 20 ns, or 50 ns markers
as required and then to 5 ns will show the proper 5 ns
mark to be used.
e. Press and release the At button to obtain the At
display. Push in the SEC/DIV knob for B SWP only.
Rotate the A control for a readout display of At
-10.64 ns. If the time marks are not superimposed, adjust
the A control to do so.
For CTT instruments, use the following setup of the
CTT while performing the Delta Time performance check.
1.
Push the MEASURE button to enter MENU
mode.
f. CHECKāAt readout is within the limits listed in Table
4-9 for the 1st 5 ns time marker; then check that the 3rd
through 19th time markers are within the given limits as
the A control is rotated CW to superimpose every second
time marker on the reference time marker.
4-24
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