Circuit
Description—Type
P6042
under
test.
The
low-frequency
waveforms
at the
two
output
terminals
of
the
Hall
device
are equal
in
amplitude
an
d
op
posite
in
polarity.
The
peak-to-peak
difference
of
the
two
waveforms is
determined
by
the amount
of
current
passing
through
the
conductor,
and
the
polarity
is
determined
by
the
direction
of
current
flow.
See Fig.
3-1.
The
components
on
the
decoupling
board
(C5,
R5,
C6,
C9,
LRZ,
and
LR8),
located
at
the
input
of the
amplifier, form a
low-pass
filter
to
isolate
the
cable
from
the
amplifier
system.
R
10
and
R14,
in
series
with
the
inputs
of
the
Hall
device,
are
factory-selected
according
to
the
input
resistance
of
the
de
vice
to allow a
current
of
approximately
20
mA.
As
the
temperature
in
the
Hall
device
varies,
the
voltage
drop
across
the
input
terminals changes.
The
temperature
compensation
network
(R
11,
R12,
and
R13),
applies
a
portion
of
the
Hall
device
input
voltage
to
the
output,
reducing
the
drift
caused
by
temperature
change.
The
output
signals from
the
Hall
de
vice
are
applied
to
pins
2
and
10
of
M18,
a
differential
ampli
fier
circuit.
See Fig.
3-2.
Pins
1,
5,
and
11
of
the
integrated circuit
are connected
to
the
CURRENT/DIV
BALANCE
control
through
R16
and
R17.
This
balance
network is
adjusted
for zero
volts
at
connector
J59
with
no
signal
applied
to
the
probe.
The
Hall
Band
width
potentiometer, R18,
and
a
factory-selected
capacitor,
C
18,
connected
to
pins
3
and
9
of
the
integrated
circuit, pro
vide
the
bandwidth
adjustment
for
the
low
frequency
ampli
fier.
Q22
and
Q24
reduce
the
voltage level
at
the
output
of
the
integrated
circuit, which
is
near
one-half
the
supply
voltage
for
the
following
stage.
The
voltage gain
of
this
stage
is
adjusted
by
the
Loop
Gain
potentiometer,
R24.
Q42,
Q44,
Q45,
Q51,
Q53
and Q54
form
a
current
ampli
fier.
Q42
and
Q51
provide
constant
current for
Q44
and
Q53.
Q44
and
Q53
are
the
drivers
for
Q45 and
Q54,
respectively.
Q45
or
Q54,
depending
upon
the
polarity
of
the
signal
at
the
collector
of
Q29,
provide
the
current
path
through
the
50-
turn
secondary
winding
in
the
probe
and
through
the
attenu
ator.
When
the
signal
at
the
collector
of
Q29
is
negative,
Q44
increases
conduction which lowers
the
base
voltage
of
Q45
and
turns
it
off.
Q53
reduces
conduction,
causing
an
electron
flow
from
—16 V
through
Q54,
which
is
turned
on,
through
the
probe
secondary
and
the
attenuator
to
ground.
As
the
collector
of Q29 goes
positive,
current
through
Q53
increases,
causing
an
electron
flow
from
ground
through
the
attenuator,
through
the
50-turn
secondary,
and
through
Q45
to
+16
V.
Q44-Q45
and
Q53-Q54
are
thermally
cou
pled to hold
the
voltage
between
the
base
of
the
driver
and
the
output
of
the
stage
constant.
This prevents
thermal
run
away.
R49
and
C49
provide
stabilization
for
the
output
to
prevent
oscillation.
The
CURRENT/DIV
switch
provides
attenuation
of
the
signal
in
a
1,2 and
5
sequence
up
to 1000 times
attenuation
in
the
1
A
position.
In
all
positions
of
the
CURRENT/DIV
switch,
the
attenuator
and
R81
provide
50
ohms
input
to
the
high-frequency
amplifier.
In
the
1
mA
and
2
mA
posi
tions
of
the
CURRENT/DIV
switch
the
collector
of
Q29
is
limited
to
+
or
—
0.5
volts
by
D39
or
D37,
respectively.
The
current
from
the
DC
amplifier
through
the
coil
of
the
probe
transformer
causes
a
flux
in
the
core equal
and
op
posite
to
the
flux
generated
by
the
signal being
measured.
This
gives
a
resultant
zero
flux in
the
core.
This
feedback
system
permits
the
Hall
element
and
ferrite
core
to
operate
at
very
low
flux densities, providing excellent
sensitivity
and
linearity.
High Frequency Amplifier
The
Attenuator
Balance,
R84,
is
adjusted
for
zero
volts
at
the
base
of
Q87
with
J80
disconnected. Q87,
an
emitter
fol
lower
therm
ally
coupled
to
Q96,
stabilizes
the
current
flowing
through
Q96
at various
temperatures.
Q96,
Q
113,
and
Q
1
21
make
up
a
complementary
feedback
amplifier.
The gain
of
the
amplifier is
set
by
the
ratio
of
R96
to
R107
and
R108.
High-frequency
waveform
compensation is provided by the
peaking
network
paralleled
with the
gain-setting
resistors.
The
DC
level
at
the
output
of
the
amplifier is set
internally
by
the
Output
DC
Level
Range
control,
R93,
and
by
the
front-panel OUTPUT
DC
LEVEL,
R91.
Q1
13
is
biased
at
its
maximum
power
point
for
a
minimum
temperature
coefficient.
When
the
probe
is
unlocked
(SW3
grounded)
D1
28
con
ducts,
bringing
the
base
of
Q1
23
up
and
turning
the
transis
tor
on.
This
latches up
the
output
of
the
high-frequency
amplifier
and
prevents
any
display.
Fig.
3-3.
P6042
amplifier operation.
3-3
Содержание P6042 PROBE
Страница 3: ......
Страница 4: ...Characteristics Type P6042 Fig 1 1 P6042 Current Probe and accessories...
Страница 7: ...Characteristics Type P6042 1 3...
Страница 8: ...Characteristics Type P6042 1 4...
Страница 10: ...Operating Instructions Type P6042 Fig 2 2 Function of front panel controls and connectors 2 2...
Страница 28: ...NOTES...
Страница 30: ...Calibration Type P6042 Fig 6 1 Test equipment recommended 6 2...
Страница 46: ...NOTES...
Страница 64: ...HE RMAL COUPLER SEE PARTS LIST FOR SEMICONDUCTOR TYPES AMPLIFIER MRH S...
Страница 65: ...P 6 042 CURRENT PROBE DC TO 50MHz...
Страница 66: ...FIG 1 P6042 PROBE PACKAGE STANDARD ACCESSORIES P6042 PROBE...
Страница 67: ...FIG 2 P6042 PROBE MECHANICAL PARTS...
Страница 68: ...FIG 3 AMPLIFIER PO...
Страница 69: ...3 AMPLIFIER POWER SUPPLY P6042 PROBE...
Страница 70: ...FIG 4 CABINET...
Страница 71: ...FIG 4 CABINET P6042 PROBE...
