Fluke 8600A - Page 73

8600A
e.
Connect
the
probe’s
ground
lead
to
a suitable
ground
when
using
the
straight
or
hooked
probe
tip.
The
ground
clip is
not
required
when
using
the
high
frequency
adapter
with
an
appropriate
50
ohm
termination.
f.
Touch
the
probe
tip to
the
circuit
point
to
be
measured.
g.
Observe
the
voltage
reading
displayed
in
volts rms
on
the
8600A
readoug.
as
a dc
blocking
capacitor,
diode
CR1
is used as a
detector,
and
resistors
Rl,
R2,
R3
and
Rj
n
form
a divider
network.
During
the
negative
half
cycle
of the
ac input
voltage,
Cl
charges
through
CR1
to
the
negative
peak value
of
the
input signal.
This
negative
charge
path
provides the
zero
reference
for
the
dc
output
signal.
During
the
positive
half
cycle
of
the input
signal
the
charge
on Cl
is added
to
the
peak
value
of the
positive
input
to
produce a
positive
peak-peak
voltage
at the
junction
of
Cl
and CR1.
The
divider
network
scales
this
voltage
to
provide
a dc
output
voltage
which
is
equal
to
the
rms
value
of the
input
signal.
6-38.
Theory
of
Operation
6-39.
A schematic
diagram
of
the
80RF-1
High
Fre-
quency
probe is
given
in
Figure
6-10.
Capacitor
Cl is used
640.
Diode
CR2
compensates
for
the non-linearity
of
the
detector,
and
R3
is a
selected
part
having
a value
of
50 kQ
to 100
k£2.
6-41.
Maintenance
642.
PERFORMANCE
TEST
643.
The low
and
high
frequency
tests
given
below
are
used to
verify
the
ac-to-dc
transfer
accuracy
of the
80RF-1
High
Frequency
Probe.
644
. LOW
FREQUENCY
RESPONSE
645.
Connect
equipment
as shown
in
Figure
6-1
1 ,
and
perform the
following
steps.
AC SIGNAL
SOURCE
DVM
50
OHM
FEED THRU
v
«EC3»~~
<
-CO-
CONNECTION
"A"
PROBE
80
RF-1
CONNECTION
"B'
1
BNC
ADAPTER
Figure
6-1
1
.
LOW
FREQUENCY
RESPONSE
CHECK
6-7