Fluke 8600A Instruction Manual 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