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Performance
Check
procedure
-
4g4Ll4g4Ap
Service
Vol.
1
Figure
-4-2.
Typical
display
of
catibrator
signat
In
Max
Span/Div.
i
Calibrate
Position,
Center
Frequency,
Reference
Level,
and
Dynamic
Range
This
calibration
should
be
done
at
regular
intervals
so
the
instrument
can
meet
its
eenter
frequency
and
reference
level
accu_
racy performance
specifi,cations.
lt
should
also
be
done each
time
the
ambient
tem-
perature
of
the instrument
is
changed.
To
observe
the results
after
the microcom-
puter
has
cornpleted
a calibration
routine,
press
the <Blue-SHIFT>
LIN
seguence.
A
message
will
appear
on
the
screen
that
shows
the correction
factor
used
by
the
microcomputer
to center
the
resolution
bandwidth
filters
to
produce
a
calibrated
center
frequency.
lt
also
shows
the
correc-
tion
that was required
to
bring
the
ampli_
tude
level
within
0.4
dB of
the
3 MHz
filter.
Press
the <Blue-SHIFT>
CAL sequence
to
start
the calibration
routine.
A prompt
message
on
the
screen
will guide
you
through
setting
the four
front-
panel
adjustments
of
vertical
and
horizontal
pOSlTlON,
and
AMPL
and
LOG
CAL.
This
sets
thE absolut€
refer_
ence
level
for
the 3 MHz
resolution
bandwidth
filter.
An
automatic
calibration
is
then
done,
which
measures
and
corrects
for
absolute
frequency
and
amplitudo
(r€lative
to
3 MHz)
errors
of
the filters.
tnis
takes approximately
60
seconds.
lf a
message
appears
on
the screen,
rsfer
to Error
Message
Readout
earlier
in
this section.
The
correction
factors
are
held
in
memory.
press
FINE
to
continue
calibration
as
instructed
or <Blue_SHIFT>
to
exit
the
routine.
lf
any
amplitude
correction
factor
for
a
fitter
is
greater
than
1 dB.
at
roorn
temperature,
the tilter
in
the
VR
assembly
should
be readjusted.
Refer
to Section
S.
Adjustment
Procedure.
When
the <Blue-SHIFT>
CAL
sequence
is
pressed,
the
microcomputer
pe*orms
a
center
frequency
and
reference
level
cali-
bration.
Prompts
app€ar
on
the
screen
to
guide
.the
user
step-by_step
through
the
procedure.
4-5