Racal Instruments 9901 Maintenance Manual page 60

(5)
Apply
a
1
kHz
signal
at 10
mV
r.m.s.
(6)
Depress
the
PERIOD
'A'
and
n
=
10^
Range
buttons.
(7)
Verify a
display of approximately 1000.00.
(8)
Depress
the
FREQ.
'A' button.
Change
the signal generator
to
20
MHz
at
IV
r.m.s. approximately.
(9)
Turn the
SENSITIVITY
control clockwise and
verify that counting ceases
before the
control reaches
the fully clockwise
position.
(10)
Reset the
SENSITIVITY
to
the
10
mV
position
and
disconnect
the signal
generator.
Time
Interval Single Line
Check
5.9
Equipment
Required
Timing source such
as
a
pulse generator.
5.10
Procedure
(1)
Set the following
controls:-
(a)
HOLD/NORMAL
to
NORMAL.
(b)
Pulse/Contact
to
Pulse
.
(c)
B-B/B-A
switch
to
B-B.
(d)
Depress
the
Tl
button.
(2)
Set the pulse generator
to
1
kHz
p.r.f.
1
:1
mark/space
ratio
and
amplitude
1
.25V peak
to
peak. Connect
to the
'B'
input socket terminated
in
50Q.
2
(3)
Select the
n
=
10 Range
button. Set the START and STOP
slope switches
to
the positions
in
Table 9 and
verify the measurements
in
column
(x)
bearing
in
mind
the calibration accuracy
of the
pulse generator.
(4)
Set the pulse generator
to 4:1
mark/space
ratio
and
verify the measurements
in
Table 9 column
(y).
This
checks
for correct switch connections,
if
for
example,
the display board
has
been
replaced.
5-7
9901 VoJ.2