c.
Set the generator output level for
an
8-division
display
of
the reference signal on
CH
1.
d.
Adjust either the
CH
1 VAR control or the
CH
2 VAR
control for a minimum ADD display amplitude while leaving
the other control
in
the calibrated detent (whichever pro-
vides the best CMRR).
e. Set the generator frequency
to
50
MHz.
f. Set the A SEC/DIV
to
20
ns.
g.
CHECK-ADD
display amplitude is 0.4 division or
less (discount trace width).
h. Set ADD
and
INVERT Off and rotate the
CH
1 and
CH
2 VAR controls CW
to
their calibrated detent positions.
i.
Disconnect the test setup.
7.
Check Channel Isolation.
a. Set:
VERTICAL
MODE
CH
1,
CH
2,
CH
3, and
CH
4
CHOP/ALT
Input
Coupling
CH
1 and
CH
2
VOLTS/DIV
CH1andCH2
CH
3 and
CH
4
TRIGGER
SOURCE
Horizontal
A SEC/DIV
On
ALT
500
DC
100 mV
0.1
V
CH
1
20 ns (knob
in)
Performance
Check-2445A/2455A
Service
b. Connect the Primary Leveled Sine-Wave Generator
to
the
CH
1
OR
X input connector via a
50
n BNC cable.
c.
Set the generator frequency
to
100 MHz and adjust
the output level for
an
8-division display.
d.
CHECK-Amplitude
of
each trace other than
CH
1 is
0.08 division or less (discount trace width).
e.
Move the signal
to
the
CH
2 input connector and
change the TRIGGER SOURCE
to
CH
2.
f.
CHECK-Amplitude
of each trace other than
CH
2 is
0.08 division or less (discount trace width).
g. Add a
50
n BNC termination
to
the BNC cable and
move the signal
to
CH
3.
h. Set the TRIGGER SOURCE
to
CH
3 and adjust the
generator output for a signal display amplitude
of
8
divisions.
i.
CHECK-Amplitude
of
each trace other than
CH
3 is
0.16 division
or
less (discount trace width).
j. Move the signal
to
CH
4 Input connector and set
TRIGGER SOURCE
to
CH
4.
k.
CHECK-Amplitude
of
each trace other than
CH
4 is
0.16 division or less (discount trace width).
I.
Connect the generator to the
CH
1
OR
X input con-
nector. Remove the
50
n termination.
m.
Set the TRIGGER SOURCE
to
CH
1.
n.
Set the generator output frequency
to
150 MHz for
the 2445A or
to
250 MHz for the 2455A. Set the generator
output level for
an
8-division display.
o.
CHECK-Amplitude
of
each trace other than
CH
1 is
0.16 division
or
less (discount trace width).
p. Move the signal
to
the
CH
2 input connector and set
the TRIGGER SOURCE
to
CH
2.
4-13
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