Keithley 237

Connect
the
test
fixture
~
screw
to
safety
earth
ground
using
#18
AWG
wire
mini-
mum
before
use.
Turn
off
all
power
before
connecting
or
disconnecting
wires
or
cables.
Also,
keep
in
mind
that
GUARD
is
always
enabled.
Thus,
a
lethal
voltage
on
OUTPUT
HI
is
also
present
on
the
two
GUARD
termi-
nals
of
the
Model236/237.
Table
F-2. Specifications For Alternate
Equipment
Instrument
Type
Required
Specifications
DMM
Same
as
Keithley 193A
(see Table 1-1)
Source
de
Current
0.9nA, 9nA, 90nA, Same
as
Keithley 263 (see Table 1-1)
0.9JlA; ±180ppm
9J.LA,
90J.LA,
900JlA,
9mA;
±170ppm
Measure
de
Current
250ppm
rdg
±500nA
F.5.1
Equipment
Characterization
In
order
to verify
the
lJlA, lOJlA,
lOOJlA
and
lmA
source
and
measure ranges
of
the
Model236/237,
the
0.9JlA,
9J.LA,
90JlA, 0.9mA
and
9mA
outputs
of
the
Model263
are
characterized. For
the
lOrnA
source
and
measure range, a
100
resistor is characterized.
Perform
the
following steps
for characterization:
1.
Connect the
Model
263 source, Model 193A
DMM
and
Model8006 test fixture
as
shown
in
Figure F-1.
Install
the
lOOk.Q
resistor (in Table F-1)
in
the AXIAL
KELVIN
CLIPS
test socket
of
the
test fixture.
2.
Configure the source
and
DMM
as
follows:
Model 263 -
Amps
function,
+0.90000JlA
on
2J.LA
range,
GUARD
enabled
and
output
in
standby.
Model193A-
Ohms
function
on
the
200k.Q
range.
3. Zero the Model193A as follows:
+
+
APPENDIXF
236/237
Performance
Verification
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
Model193A
at
the
test socket.
C.
On
the
Model193A, 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
are
correct as
shown
in
Figure F-1.
4.
In
the
space
provided
below,
use
a pencil to record
the
actual value
of
the
lOOk.Q
resistor from
the
dis-
play
of
the
Model193A.
R10oldl
=
-------
k.Q
5. Set
the
Model 193A
to
the
DCV
function
and
the
200m V
range,
and
disable
ZERO.
6.
To cancel
any
offset, zero
the
Model193A
by
short-
ing
its
input
(VOLTS
HI
to
LO)
and
enabling ZERO.
7.
Remove the
short
from
the
input
of the Model193A
and
place the Model 263
in
operate
to
source
+0.90000J.LA
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
Model193A.
Vtooldl=
_______
mV
9. Calculate (to
5-1/2
digits)
the
current
through
the
lOOk.Q
resistor
as
follows:
Vtooldl
Io.9JJ.A
=
--
--------
JlA
Rtooldl
Io.9JJ.A
is
the
characterized
current
for
the
2JlA
range
of
the
Model263.
It
is
used
to check
the
lJlA
measure-
ment
range
of
the
Model
236/237. Using
a pencil, re-
cord the calculated
value
of
Io.9JJ.A
in
Entry 1 of
TableF-3.
10. Place
the
Model263
in
standby.
11.
Set
the
Model193A
to
the
2V
range.
12.
Set
the
Model263
to
source
9.0000J.LA
on
the
20JlA
range
and
enable
OPERATE.
F-3