Keithley 237 Service Manual

SECTION
2
Calibration
(paragraph
2.6.3)
and bw current
ranges
calibration
(paragraph
2.6.4).
Calibration is
performed
using the “C“
command
over
the IEEE-488 bus.
Details concerning
the
use of the “C“
command and other commands
are
contained
in
Section
3 of
the Model
236/237
Operator‘s
Manual.
WARNING
Lethal
voltage (up
to 1000V
for
the Model
237)
will
be connected to
the
Model 8006
test
fixture.
To
avoid a possible
shock
hazard,
the
safety
interlock circuit
must be
con
nected to the
Model
236/237.
3.
Zero
the Model
193A as follows:
A. At
the SENSE
1
(HI)
terminal
of
the
test
socket,
disconnect
the
jumper
whose
other
end
is
con
nected
to
BINDING POST
2 on
the Signal Panel.
B. Connect
that
jumper to
the
SENSE 2
(LO)
termi
nal
of the
the test
socket.
This shorts
the Ohms
Sense input
of
the Model
193A
at the
test
socket.
c.
On
the
Model
193A,
enable
ZERO
to
cancel
test
lead
resistance.
D.
Relocate
the jumper
back
to the
SENSE 1 termi
nal of
the
test
socket.
Make
sure
the
connections
at the
Component
Test
Module
arc
correct
as
shown
in Figure 2-2.
4.
In the
space
provided
below,
use
a
pencil
to record
the
actual
value of
the lOOk2
resistor
from the dis
play
of the
Model
193A.
RlookO
=
________________________
k2
Connect
the
test
fixture screw to safety
earth ground using
#18 AWG wire
mmi
mum before use. Turn off all
power
before
connecting
or
disconnecting wires
or
cables.
Also,
keep
in
mmd
that
GUARD is always
enabled. Thus, a
lethal
voltage
on
OUTPUT
HI is also present
on
the two
GUARD
termi
nals of the
Model
236/237.
5.
Set the Model
193A to
the
DCV
function and the
200mV
range,
and disable
ZERO.
6.
To cancel
any
offset, zero
the
Model 193A by
short
ing
its
input (VOLTS
HI to
LO)
and enabling
ZERO.
7,
Remove
the
short
from
the input of
the
Model
193A
and
place
the
Model
263
in
operate to
source
+O.9OOOOiA
to
the
lOOk.Q
resistor.
8.
In
the space
below,
use
a
pencil
to
record
the
voltage
drop
across
the resistor
from
the display of the
Model
W3A.
2.61 Equipment Characterization
VlOOkQ
=
mV
In order to calibrate the
ljiA,
1OiA,
1OOiA,
imA
and
lOmA
source
and measure
ranges
of
the Model 236/237,
the
O.9iiA,
9i.tA,
9OjiA, O.9mA
and
9mA
outputs
of
the
Model
263
must
be characterized.
For the WmA
source
and measure
range, a 1O2
resistor
is
characterized.
Per-
form the following
steps
for
characterization:
1. Connect the
Model 263
source, Model
193A
DMM
and Model
8006
test fixture as
shown
in
Figure 2-2.
Install the lOOk.Q
resistor
(Table
2-1)
in
the AXIAL
KELVIN CLIPS test socket of the
test
fixture.
2.
Configure the source and
DMM
as
follows:
Model 263
AMPS function,
+O.90000iiA
on
2iiA
range,
GUARD enabled
and output
in
standby.
Model W3A
—
Ohms
function on the
200k2
range.
9.
Calculate
(to
5-1
/2d)
the current
through
the
lOOkQ
resistor as
follows:
VloDkO
Io9,
=_______________________
L1OOk2
Io9
IS the
characterized
current
for the
2iA range
of
the
Model
263. lt
is used
to
calibrate
the
1
iA
range
of
the
Model 236/237.
Using
a
pencil,
record the calcu
lated value
of
Io.9A
in Entry
1 of
Table
2-3.
10.
Place
the Model
263
in
standby.
11.
Set the
Model
193A to the 2V
range.
12.
Set
the Model 263 to
source
9.OOOOiA on the
2OpA
range
and enable
OPERATE.
2-3

Keithley 237 Specifications

General

Brand	Keithley
Model	237
Category	Measuring Instruments
Language	English