Fluke 8010A User Manual page 31

10 Hz, the update
rate
slows and
follows the input
signal.
For
frequencies
between
0.5
Hz and
0.3
Hz, the display
may
not
be
stable.
For frequencies
below
0.3 Hz,
the display
shows
0.000 Hz.
For
most frequency measurements,
turn the
rotary
switch
to
theVsetting,
co nnect
t
he meterto
the signal
being measured,
and
then press
C~*~) button.
Connecting the meter
to
the
signal
before pressing
Hz
will
normally allow the
meter
to
autorange
to
an appropriate range, but the
minimum
input
signal
required
to trigger
the
frequency counter
varies,
depending on the range
and
frequency
(see Specifications).
If
the input signal
is
below
the
trigger
level,
frequency
measurements
will
not
be
taken.
If
your readings are
unstable,
the
input signal
may be
near the
trigger level for
that range.
You
can usually correct
this
by selecting a
lower
range.
In
the
Frequency Counter mode,
the
range
(displayed
in
the lower-ri ght
co
rner of the
LCD)
will
only
change when
you press the (/mngF) button.
If
your readings
seem
to
be a
multiple of
what you
expected,
your input signal
may
have
distortion or ringing. (For
example,
electronic
motor
controls
distort
both voltage
and
current
waveforms.)
Select
a higher
input
range
if
you
suspect multiple
triggering.
An
alternative
is
to turn the
rotary
switch
to the'v
or
m"v
setting,
which
will shift
the
trigger level
from
0V
to a positive voltage
that
changes
with
each
range.
In
general,
the lowest frequency
displayed
is
the correct one.
APPLICATIONS
Measuring Frequency
In
the
Frequency Counter mode,
the input
range
acts
like
an
attenuator, the
V
function
ac-couples
the input
signal,
and
the
V
and
m'v
functions dc-couple
the input signal.
The
V
function
is
optimized
for triggering
on
logic
and
switching
signals.
The 4V
dc range
is
optimized
to trigger
on
all
common
5V
logic families (triggers at 1.7V
±
0.1V).
High
frequency
logic signals
may
require the
use
of the
400
mV
ac
range.
The 40V
dc range
is
optimized
to trigger
on automotive
switching signals
(triggers at
4V
±1V).
All
ranges
in
the
V
function
trigger at
approximately
10%
of range,
exceptforthe
4V
range.
Frequency measurements can be
made
on
current inputs.
The
inputs
are always dc-coupled.
The
triggering characteristics
are
shown
in
Table
5.
Table
5.
Frequency Counter
Operation With Current
Inputs
INPUT
RANGE
APPROXIMATE
SENSITIVITY
(0.5
Hz-20 kHz)
APPROXIMATE
TRIGGER
LEVEL
AC
CURRENT
DC
CURRENT
fiA
300
//A
0/iA 400
fjA
mA
30
mA
mA
40
mA
A 3A OA
4A
25