NOTE
To
easily maintain
the
A SWP and B SWP
difference while
checking timing and cursor accu-
racy, use
the
following method:
1.
Set TRACK/INDEP off. Pull B SEC/DIV knob
out.
2.
Push and hold the TRACK/INDEP button while
pushing the
B SEC/DIV knob in. This will lock
the A and
B sweeps together with A sweep one
speed slower than
B sweep.
3. Press
~t
button
to
obtain
~t
cursors.
q.
CHECK-
The B sweep timing and cursor accuracy
as
in
parts b through
f,
making sure that the A SEC/DIV is
set slower than the
B SEC/DIV.
3. Check Delta Time Accuracy using the Delayed
Sweep.
a.
Set:
HORIZONTAL
A SEC/DIV
B SEC/DIV
X10 MAG
TRACK/INDEP
Delta
~t
TRIGGER
MODE
SOURCE
COUPLING
SLOPE
LEVEL
B TRIG MODE
20 ns
1 0 ns (knob out)
On
Off
Off (DL Y readout)
AUTO LVL
VERT
DC
+ (plus)
As required for
a stable display
RUN AFT DLV
Performance
Check-2445A/245SA
Service
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
ho/doff and sweep speed.
This
is normal behavior
with this type
of
signal and is not an Instrument
defect.
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.
For CTT instruments, use the following setup
of
the
CTT while performing the Delta Time performance check.
1. Push the upper TRIGGER MODE button for
MENU.
2. Adjust the
~
REF OR DL Y POS
or
~
control
to
underline COUNT in the CTT MENU.
3. Push the upper TRIGGER MODE button.
4. If the instrument contains Option 09, adjust the
~
REF
OR
DL Y POS control
to
underline MODE.
5. Adjust the
~
control
to
underline PERIOD.
6. If the instrument contains Option 09, adjust the
~
REF OR
DL
Y POS control
to
underline EVT.
7. If the instrument contains Option 09, adjust the
~
control
to
underline
A.
4-25
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