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OPERATING INSTRUCTIONS
MODEL
616
b.
Automatic Sensitivity
Operation.
In the
AUTO
mode, the
Model
616 automatically selects
the
pro-
per
sensitivity
in
accordance with
the
following
rules
1.
Upranging.
If
the
display reading
is
be-
tween
0-1-8-0
and 1-9-9-9
and the
input signal
is
increased beyond 1-9-9-9,
the
Model
616
auto-
matically up-ranges
to the
next higher
(less
sensitive) range.
The three least
significant
digits are
blanked
during range changing
so as
to
prohibit incorrect readings from being dis-
played.
If the
input;
signal exceeds +199.9
volts
the
display
will
continue
to
indicate
up to :+201.7
volts but the three least significant digits
will
flash on and off
to
indicate an over voltage
condition.
2.
Dcrton
ranging..
If the
display reading
is
at least
d-l~8-0
and the input signal is
decreased,
the
Model
616 automatically down ranges
to
the
next
lower (more aensitive) range.
To
interpret
a
reading on OHMS, COULOMB,
or
AMPERE
ranges both
the
digital display
(with
decimal location)
and
the
RANGE setting
(
powers of ten)should be consi-
dered.
For example,
given
a
digital reading
of
17.32
and
a
R^INGE
setting
of
10"^ AMPERE, the actual_meas-
ured value would be
interpreted
as
17.32
x
lO"'"
ampere.
Since
the
decimal point
is
moveable,
it is
important
to
notice
the
position
of the
dcraimal
point
to
deter-
mine
the
full range
of Che
instrument.
See
Table
3-3
for typical range
settings
in the
AMPERE function.
TABLE
3-3.
Typical
Current Range Settings*
Input
Range
Sensitivity
Digital
Current
Setting
Setting
Display
10_i^A
10
1
10_
-
A
10_.
A
10
^-^A
10
mV
.00010
10 mV
10 mV
.00100
.01000
100 mV
1
V
.1000
1.000
1
c.
Remote Sensitivity Selection.
When
the
Model
61.6
is
used
with
the
Model
6162 Isolated Output/
Control
,
the
616's voltage sensitivity may be re-
motely selected.
The output connector on
the
rear
panel
of the
6162 provides
four
isolated control
lines for the
purpose
of
remote sensitivity
pro-
gramming.
The lines are coded as shown in
Table
3-2.
The 616'® front
panel SENSITIVITY switch
must be
set
to
AUTO
position.
TABLE
3-2.
Remote Sensitivity Programming Logic
Sensitivity
^0
Control
"a
Lines
^2
.01000
V
0
0
0
0
,
1000
V
0
1
0
0
1.000
V
0
1
0
1
10.00
V
0
1
1
0
100.0
V
0
1
1
1
*The current reading
is
interpreted by multiplying
the
display reading times
the.
range setting.
Other
cur-
rents not shown can be
measured
by
selecting
the
appropriate RANGE switch setting
in
decade steps from
10"^^A
to
,10*^A.
3-b.
OP
E
RA TI ON AS A VOLTMETER.
The
Model
616 can be
used
to
measure voltages from ±10 microvolts
to +200
volts.
Although
the
Model
616
is
useable
as a
gener-
al
purpose digital voltmeter,
it
has
certain,
charac-
teristics which enable reliable measurements from
very high source resistances.
When used in
the
VOLT
mode,
the
Model
616 has
an input resistance greater
than
2
x
lO^'^ft.
As a
result, the loading
of
the
source circuitry
is
relatively insignificant when
compared
to typical
digital voltmeters having
10°
ohms input resistance.
The Model 616 has
20
pico-
farads
of
shunt capacitance (not including the input
cable capacitance)
.
Since
a
large amount
of
capaci-
tance causes a slowing of response, the Model 616
input capacity
is
kept
as
small
as
possible.
NOTE
The
remote enable
line Ry is used to
defeat
the
automatic sensitivity
feature.
WTien
Rq
is
open, the 616 returns
to
automatic opera-
tion.
Logic
L
=»
open.
3-5.
RANGE SELECTION.
The front panel RANGE
switch
(SlOl)
provides selection
of
four functions, VOLT,
OHMS, COULOMB, and AMPERE
as
described
in
paragraph
3-3.
For each function,
a
wide selection
of
ranges
is.
provided;
8
ranges on
OHMS,
4
ranges on COULOMB,
and
11
ranges on AMPERE.
Since
the
SENSITIVITY
switch
is
used in conjunction with
the RANGE
Switch,
the actual
number
of
useable spans
is 12
decades on
OHMS,
8
decades
on COULOMB, and 11 on AMPERE.
NOTE
On
the
10"^A
to
10"^A
ranges,
the
voltage de-
veloped must not exceed
2
volts, otherwise,
overheating
of a
range resistor could result.
As a
result,
the 10 volt and 100
volt sensi-
tivity settings are not recommended
for
10"^A
to 10"'^A
ranges.
a.
Measurements From Very High Source Resistance.
To
use
the
Model 616
as a
voltmeter, set
the front
panel controls
as
follcwsj
RANGE
—
VOLT
SENSITIVITY
—
AUTO
FAST /NORMAL
—
NORMAL
(A
complete explanation
of the use
of
the
FAST/NORMAL
switch
is
given in paragraph 3-7b)
Make connections
to the
Model
616
using
a
shielded
triaxiai cable.
Keep cable length
as
short
as
poss-
ible
to
reduce
the
slowing effects
of cable capaci-
tance.
The zero
control may need occasional adjust-
ment
to
reduce
any
voltage offset which may
occur
due
to
temperature variations.
To
rezero
the
Model
6.16,
set
the
ZERO
CHECK switch
to
CHECK position
and adjust
the
front panel ZERO control for
a
O-O-O-O
display.
(The
recommended warm-up
time for the Model
616 is
two
hours although it
is
useable Immediately
after power
is
turned on.)
The Model
616
provides a
direct reading voltage display with automatic decimal
point position
and
polarity.
6
0374
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