Table of Contents
Advertisement
OPERATING INSTRUCTIONS
MODEL 616
3-7.
OPERAT
I
ON
AS
m
AWTER.
The Model 616
can be
used
to
aeaKure currents from
110-25 ampere to 200
milliamperes
Although
the
Model
616 is
useable as
a
general purpose
pico--iEimeter,
it
hits
certain
charac-
teristics which enable reliable measurements
of
very
small currents with fast response.
a.
Korpsal
Mod
e Cu
rrent Meas urements
]!n
t..his
mode,
the
Model
616
measures
current over a wide range.
When
the
FAST/NORMAL
switch
Is
set
to
NORMAL, the
Model
616
operates
as a
shunt-type picoammeter in
which
a
resistor
is
connected directly across
the
input
teruiinals.
The
Model
616
measures
the
volt-
age drop across the shunt resistors where
Vj-jj
=
Ij^
X
Rg.
This
method
of
measurement
is
typical of
most
multimeter
current measuring techniques.
To
use
the
Model
616 as a
shunt-type picoammeter, set
the front
panel controls
as
follows:
range
—
10 ^
AMPERE
(or
appropriate range)
SENSITIVITY
—
AUTO
EAST /NORMAL
—
NORMAL
NOTE
Full range
is
determined by
the
sensitivity setting
and
the
AMPERE
range setting.
Make connections
to the
Model
616 using
a
shielded
triaxlal cable.
Keep cable length
as
short
as
pos-
sible
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
616, 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 immediat-
ely after
power
is turned on.)
NOTE
The Model 616
may exhibit
a large amount of
zero orfset or
drift immediately after
an
overload
or
a
long period
of
storage,
in
addition,
the
offset current
laay
exceed
the
specification
for
a
short
time,
until the
Model
616 is
sufficiently stabilized.
A.i-
though
the
offset current
of the
Model
616
is
well below offset found
in
conventional
voltmeters,
the
effects
of
the
offset current
charging
the
input capacitance may be nociced
when
the input Is open.
Use
the
ZERO CHECK
switch
to
discharge
the
offset charge.
CAUTION
Do not use the
10
volt and
100
volt sensi-
tivity settings for RANGE switch settings
of 10
,10
,
10"5, and 10"^ ampere.
If
the
voltage exceeds
2
volts on these ranges
overheating
of the
resistors could result
with subsequent degradation of accuracy
in
tlie
AMPERE mode.
1
1
I
!
__J\AAA
1
A
A
A
A
1
I
dr
"
ll_
n
i
i
vvv
1
T
{
1
Measuring
|
1
Points
1
1
}
I
1
1
rrveter
I
X
1
j
SOURCE
!
1
AMMETER
i
t
1
1
=
Imeter
R
%
error
in
reading
due
to
circuit
loading
=
—
lOO
if
Rin
«
R,
1
Imeter
and
%
error 3
^
0
Rin
R+Rin
FIGURE
9.
Loading Effects in Ammeter Function.
0374
Advertisement
Table of Contents
