Keithley 237 Service Manual

SECTION
2
Calibration
12. Ca1culate
the
actual current
(I+o)
using
the
follow-
21.
Send
the calculated
current
reading
(I-9o)
over
the
ing caiculation:
bus
with
the C41
command
as
follows:
v1o2
C41,L9oX
! Calibrate
gain;
4OOmA source
I+9OmA
=
=________________
mA
and
measure
range
R 1o
13.
Send
the
calculated
current
reading
(I+9o)
over the
Note:
Check
that
the CAL
LOCK
switch
is in the de
bus
with the
C37 command as
follows:
sired
position;
‘in for
permanent
calibration,
or
“out“
for
temporary
calibration.
C37,I÷9oX
!
Calibrate
gain;
+lOOmA
22.
Send
the following
command
over
the bus:
source
and
measure
range
C59X
! Exit
calibration
and store
cal
14.
Send
the following
command to
source
—OmA
on the
constants.
lOOmA
range:
If
the
switch
is in the
“out“
position,
the
message
C38X
! Source
-000.00mA
“TEMPORARY
CAL“
willbe
briefly
displayed
to in-
dicate
that
newly
entered
cal constants
will
be
lost
15. From the
display
of the Model
193A
DMM,
record
when
the
Model
236/237
is turned
off.
Permanent
the
voltage
drop
across
the
lO2 resistor
(Vio)
in
the
calibration
can stube
done
by
setting
the calibration
space
below.
switch
to
the “in“
position,
and
sending
COX
and
C59X
over
the
bus
in that
order.
vb0
=
_______________
v
After
sending
the C59X
command,
the
Model
236/237
wffl return
to
normal
Operation.
16.
Caiculate the actual
offset
current
(Lo)
using
the
23.
Place
the Model
236/237
in standby.
following caiculation:
v1o
2.6.4
Low
Current
Ranges
Calibration
LOmA
=
=______________________
mA
Rio
(1 nA
1
OmA)
17. Send the calculated
current
reading
(Lo)
over
the
Coect
the
characterized
Model
263
calibrator
to the
bus
with
the
C39 command
as follows:
Model236/237
as
shown
in
Figure
2-5.
The
characterized
I-source
values
(Io9A,
I9LA,
I9OIA,
Io9flA
and
Im)
of the
C39,I-oX
! Calibrate offset;
—lOOmA
Model
263
that
are
used
to
calibrate
the
liiA
source
and measure
range
throughlomA
ranges
were
determined
in the
equipment
characterization
procedure
(paragraph
2.6.1)
and
re
18.
Send
the following command
to
source
—9OmA:
corded
in Table 2-3.
C4OX
! Source
—90.00mA
Perform
the
following
steps
to
calibrate
the
inA
through
19.
From
the
display
of the
Model
193A DMM,
record
lOflIA
measurement
ranges:
the
voltage
drop
across
the 1O resistor
(V 1 o)
in
the
space
below.
NOTE
If
controffing
the
Model
263
from
the
front
panel,
always
select
the
lowest
possible
cur
vb0
=
_________________
v
rent
range.
Over
the bus,
AUTO
range
can
be
used.
20.
Caiculate
the actual
current
(I-9O)
using
the follow
ing
caiculation:
In standby,
set
the Model
263
to
O.9nA
and
enable
GUARD.
v1o2
2.
Place
the Model
236/237
in
OPERATE.
The
calibra
I—9OmA
=______________________
mA
Rio
tion
mode
cannotbe
entered
with
theModel236/237
in
standby.
2-11

Keithley 237 Specifications

General

Output Power	200 W
Voltage Resolution	1 μV
Current Resolution	10 fA
Type	Source Measure Unit
Interface	GPIB, RS-232
Accuracy	0.02%
Compliance Voltage	±1100V