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c.
Attach
all
covers.,
and
allow instrument
to
operate
for
at least
1
hour.
4-73.
REFERENCE VOLTAGE ADJUSTMENT
a.
Unfasten
the
top cover
and
slide
back
just far
enough
to
expose
REF
ADJUST
control
R26
and
test
point
TP2.
b.
Connect
the
895
A
differential
voltmeter
to
TP2,
using
+
SENSE
as
common.
c.
Adjust
R26
for
an
895
A
indications
of
15
±0.0001
volts dc.
d.
Disconnect
the
895A, and
position the
top cover
so
that
only
the beta
string
calibration controls are
exposed.
4-74.
ZERO OUTPUT ADJUSTMENTS
a.
Set
Model 343
A
voltage
dials to
zero,
and
connect
the negative
OUTPUT
terminal
to chassis
ground.
b.
Zero
the
895A
on
the
1
volt range,
with
null
sensi-
tivity set
to
100
microvolts,
then
connect
the
895
to the
Model
343A
OUTPUT
terminals using low-
thermal copper
leads.
c.
Set
RANGE
switch
to 10,
and
adjust the
10V
ZERO
ADJUST
control
for
zero
(±4
microvolts) indication
on
the
895A.
WARNING*
Use
only
an
insulated tool for
all
adjustments
within the beta
string
compartment.
d.
Set
RANGE
switch
to
100,
and
adjust the
100V
ZERO
ADJUST
control for zero
(±10
microvolts)
indication
on
the
895
A.
e.
Set
RANGE
switch to
1000,
and
adjust the
1000V
ZERO
ADJUST
control for zero
(±10
microvolts)
indication
on
the
895A.
4-75.
BETA
STRING LINEARITY
ADJUSTMENTS
a.
Set
RANGE
switch
to
1000, and connect
the
895
to the
Model
3
43
A OUTPUT
terminals,
with
the
Model
343A
negative
OUTPUT
terminal
connected
to
chassis
ground.
b.
Set the
Model
343A
controls
as
shown
in
Figure 4-12,
and perform
the indicated
operations.
STEP
RANGE
VOLTAGE
DIAL
POSITION
OPERATION
Go
1000
00
X.
0000
Record
voltage
indication within
10
uv.
d.
1000
010.0000
Adjust
DECK
B
1
to within
10 uv
of
step
c.
e.
1000
OIX.OOOO
Record
voltage
indication
within
30
uv.
f.
1000
020.0000
Adjust
DECK
B
2
to within
30
uv
of
step
e.
9-
1000
03
X.
0000
Record
voltage
indication within
30
uv.
h.
1000
040.0000
Adjust
DECK
B 4
to
within
30
uv
of
step
g.
i.
1000
OBX.OOOO
Record
voltage
indication
within
30
uv.
J-
1000
060.0000
Adjust
DECK
B 6
to within
40
uv
of
step
i.
k.
1000
07
X.
0000
Record
voltage
indication
within
40
uv.
1 .
1000
080.0000
Adjust
DECK
B
8
to within
40
uv
of
step
k.
m.
1000
09X.0000
Record
voltage
indication
within
60
uv.
n.
1000
0X0.0000
Adjust
DECK
B
X
to within
60 uv
of
step
m.
0
.
100
ox.ooooo
Record
voltage
indication within
10
uv.
p.
100
10.00000
Adjust
DECK
A
1
to within
10 uv
of
step
o.
q.
100
1
X.
00000
Record
voltage
indication
within
30
uv.
r.
100
20.00000
Adjust
DECK A
2
to
within
30
uv
of
step q.
1
100
3X.
00000
Record
voltage
indication
within
30
uv.
Figure 4-12.
MODEL
343A
PRELIMINARY
LINEARITY
ADJUSTMENTS
(Sheet
1
of
2}
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