Datron 1061 Calibration And Servicing Handbook page 19

r.;1,,:i'':
:,-.-.
10
1.7
CALIBRATION
USING
'KEYBOARD'
1.7.1
General
The 'KEYBOARD' method of
calibration
is
useful
when
a calibratíon
source although
set
to
a
nominal value
has
known errors. ln this
situation
the known value of the
calibration
source
can be entered
into the
DVM before the
'AUTOCAL'
process is
executed. The process
is
functional
during any calibration
with
a source
of
magnitude between
20o/o
and
2OOo/o
of the
range selected,
but
it should be
noted
that for equal magnitude
source errors,
calibrating
at
the
lower percentage end
of
range produces
a
higher percentage
calibration error. The 'KEYBOARD'
method operates
for
both the 'Gain' and 'AcHf'
calibration operations.
An
example using
'KEYBOARD' to
calíbrate
directly
against
a
Standard Cell
is
shown in
the table below.
CAL¡
BBAT¡ON EXAMPLE USING'KEYBOARD'
1.7.2'KEYBOAR
D'
with
Negative tnputs
lf
the 'KEYBOARD, method
is
used
on
DC
Voltage
calibration
with
Negative
polarity
sources,
it
is
important
NOT
to
enter
a
negative sign
with the
keyed-in source
value,
The instrument
itself
can determine the
polarity
of
the
source
and update the
appropriate calibration memory
location.
1.7.3'KEYBOARD' Calibration
Example
The
example
shown
in
the table
below
uses
'KEY-
BOARD'
to
calibrate
the
1000V AC
LF
Range
Gain at
500V (step 15
of
the AC
Voltage Calibration
table for
Option
121.
o
-l
Remarks
Lethal voltage
present.
I
ncrease
Calibration
Source in
100V steps
if
possible
rl
DMM
Reading
After
Calibration
1.00v
+1
digit
0
then
+500.00
500.00v
+1
disit
,CALIBRATE'
Key
'Zero'
'Gain'
DMM
Settíng
AC,1000
,KEYBOARD'
then
5,0,0,-,0,0
Calibration
Source
1.00V
rms
500H2
500.00V
rms
500H2
As
above
Calibration
Operation
1000V
Range
Zero
Set
and Enter
Source
Value
lOOOV
AC
LF
Range
Gain
Calibration
r
Step
1
2
3
I
I