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MODEL
616
OPERATING INSTRUCTIONS
% ERROR
=
IQQ
R
R
+
Rxn
Figure
6
.
Operation
As
a
Voltmeter in NORMAL
Mode..
b.
Measurements From Low Source Resistance.
To
use the
Model
616 for voltage measurements
from low
source resistances, set
the
RANGE switch
to
the
10"^^
AMPERE position.
In
this
mode,
the
Model
616
input
resistance
is
reduced
to
lOH
ohms;
as a
result
the
electrometer
will
be
less
sensitive
to
electrical
noise pickup and input cable vibration.
Voltage
measurements can be made
by following
the
same
procedure given in paragraph
3-6a.
The
Model
616
can be used
with
the
RANGE
set at
any position be-
tween 10^11
AMPERE
to
10-1 ampere.
The
Model
616
input resistance can be determined by taking the
reciprocal of
the
AMPERE setting.
Significant load-
ing error
may result
if the
input resistance
is
reduced
to
less than lOOx the source resistance.
c.
Measurements
Above 200 Volts.
The
Model
616
can be used with accessory divider probes
to
measure
voltages
up to 30
kilovolts. Range must
be set to
VOLT
1.
Model 6102A Divider Probe
(10:1).
This
accessory extends
the
voltage measuring capability
of
the
Model
616
to 1000 volts.
The input resis-
tance
is
10^*^
ohms.
The
divider accuracy
is
±4%
to
1000 volts.
(To use the
Model 6102A an access-
ory
Model 6012 Adapter
Is
needed
to
mate the triax-
ial
input with
the
UHF connector on
the
probe.)
2.
Model 6601A Divider
(100:1).
This
accessory
extends the voltage measuring capability
of
the
Model
616 to
5000 volts.
The input resistance
is
10^ ohms.
The divider accuracy
is
±0.01%.
3.
Model
6
10 3A
Divider Probe (1000:1).
This
accessory extends
the
voltage measuring capability
of
the
Model
616
to 30
kilovolts.
The
input re-
sistance
is 10^^ ohms.
The divider
accuracy
is
±57o
to 30
kilovolts.
(To
use
the
Model 6103A
an
accessory Model 6012 Adapter
is
needed
to
mate
the
triaxial input with
the
UHF connector on
the
probe.)
NOTE
The
Model
616
may exhibit
a
large amount
of
zero offset or
drift Immediately after an
overload
or a
long period
of
storage.
In
addition, the offset current may exceed
the
specification
for
a
short
time until the
Model
616 is
sufficiently stabilized.
Although
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 noticed
when
the
input
is
open.
Use
the ZERO
CHECK
switch
to
discharge
the
offset charge.
CAUTION
The
Model
616
.should
not
be operated with
cir-
cuit
Icrw
floating
by
greater than
1000 volts
with respect
to
chassis ground.
If the
Model
616
is to
be used with circuit
lc«
floating
make certain that no connection
is
made be-
tween
the
LOW and GROUND
terminals
on
the
rear panel.
Do not connect
a
grounded re-
corder or other instrument
to the
XI
or IV
outputs
when
the
Model
616
is
floated.
d.
Voltage Measureme
r
iits
in
FAST Mode
.
Whe;n
the
FAST/NORMAL Switch
is
set
to
FAST, the
Model
616 is
connected
in a
"FEEDBACK" amplifier configuration.
In
this configuration, the Model 616
requiress
special
connections.
To
measure voltage,
connect the source
between input HI and GUARD.
An easy way
to
accom-
plish this connection
is to
connect the link
(on
the
rear panel)
between "GUARD"
(blue terminal) and
"GROUND" (black terminal).
Then use
the
triaxial
cable for input connections with the input voltage
applied between the "red" clip lead
and the "green"
clip lead.
NOTE
In this
special voltage connection, the
LO
input (black clip lead)
is
not used since
the
voltage amplifier configuration has been
changed.
This "FAST" method significantly
0374
7
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