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INSTRUCTION
MANUAL
Digita, M"ltim*,*r
Models 172A. 173A
MAINTENANCE
TABLE 6-2.
DC Voltage
Performance
Check.
RANGE
APPLIED
NOMINAL
ToLERANcE
(SPECIFIED
SOURCE
VOLTAGE
DISPLAY
ACCURACY) IN DIGITS;"
ERROK*
24 hr,
20 to
30°C
25 f
1°C
6 mo.
I year
300mV
+0.20000Vdc
"200.00mVdc
?3d
i4d
+4d
?2d
3V
?Z.OOOOVdc
12.0000Vdc
r3d
+4d
t4d
t0.4d
30 v
c20,OOOVdc
*20.000Vdc
+3d
+4d
+4d
?0.4d
300 v
r200.00Vdc
c200.00Vdc
+3d
+4d
+4d
?0.4d
1000 v
+IOOO.OVdc
tlOOO.OVdc
+2d
?2d
i3d
i0.2d
*
The Manufacturer's
specified
uncertainty
of
the
DC Calibrator
(A).
If
this
calibrator
is used,
add uncertainty
to the
172A/l73A
tolerance
to obtain
the
allowable
reading.
For example,
the
allowable
I year
20"
to 30°C
reading
on
the
300mV range
would
be 199.96
to 200.04
with
a zero
source
error.
Including
the
source
uncertainty,
the
reading
would
be 199.94
to 200.06.
**
Tolerances
above
one half
digit
have
been
rounded
off
to
the
next
higher
digit
because
of
the
approximate
0.5
digit
flash
point
of
the
least
significant
digit
of
the
display.
d.
AC Voltage
Accuracy
Check.
1)
Select
AC Volts
and AUTO.
2)
Connect
the
AC Calibrator
(B)
to
the
instrument.
Set
the
calibrator
frequency
to 20kH.z.
3)
Apply
200mVac
to
the
instrument.
The reading
must
be within
the
limits
specified
in Table
6-3.
4)
For
the
3 and 30 volt
ranges,
apply
the
required
voltages
stated
in Table
6-3
and verify
that
the
readings
are
within
specifications.
5)
To check
the
300 and
1000 volt
ranges,
connect
the
High
Voltage
Amplifier
(c)
to
the
output
of
the
AC Calibrator
per
the
manufacturer's
instructions.
connect
the
amplifier
output
to
the
Model
172A/173A
input
terminals.
Set
the
calibrator
to
supply
200.00
Vrms at
20kHz
for
checking
the
300V range,
and
1000.0
Vrms at
IOkHz
to check
the
IOOOV range.
Verify
that
the'readings
are
within
the
specified
limits
in Table
6-3.
6)
To check
accuracy
at
50 Hz,
apply
the
voltage
specified
in Table
6-3
for
the
30V range
and verify
that
the
reading
is within
the
specified
limits.
7)
To check
accuracy
at
IOOkHz,
apply
the
voltage
specified
in Table
6-3
for
the
200mV range
and verify
that
the
reading
is within
specified
limits.
6-3
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