Keithley 2001 Operator's Manual page 73

PREV
DISPLAY
NEXT
POWER
A. AC Voltage Input
PREV
DISPLAY
NEXT
POWER
B. AC Current Input
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Frequency measurements
Trigger level
The frequency function has an adjustable trigger level. An
appropriate trigger level is needed for the frequency counter
to operate properly. The instrument only counts cycles with
peak amplitudes that reach the trigger level. For example, if
the trigger level is set for 5V, cycles with peak amplitudes
less than 5V are not counted.
If using AC+DC coupling, make sure the trigger level
accounts for the DC bias level. For example, if a 1V peak-to-
peak input signal is riding on a 5V DC bias level, a trigger
level of 5.5V is appropriate.
While the display is showing frequency measurements, the
RANGE  and  keys can be used to change the trigger
level of the measurement.
Each press of a RANGE  or  key adjusts the trigger level
by 0.5% of the presently selected maximum signal level to a
maximum of 60% of the range. The AUTO RANGE key
returns the trigger level to 0V or 0mA. After pressing one of
the range keys, the present trigger level is momentarily
displayed. The trigger level is also available as a multiple
display.
2001-900-01 Rev. K/ August 2010
Model 2001
+000.00 mHz
Terminals: VOLT Coupling: AC
2001 MULTIMETER
Ω2 Ω4
DCV ACV DCI ACI FREQ TEMP
REL TRIG STORE RECALL FILTER MATH
INFO LOCAL CHAN SCAN CONFIG MENU EXIT ENTER
Caution : Maximum Input = 1100V peak, 2 x 10
Model 2001
+000.00 mHz
Terminals: CURR Coupling: AC
2001 MULTIMETER
Ω2 Ω4
DCV ACV DCI ACI FREQ TEMP
REL TRIG STORE RECALL FILTER MATH
INFO LOCAL CHAN SCAN CONFIG MENU EXIT ENTER
Caution : Maximum Input = 1A peak
SENSE
INPUT
Ω 4 WIRE
HI
350V 1100V
PEAK
PEAK
LO
500V
INPUTS PEAK
F R
RANGE
AUTO
FRONT/REAR
2A 250V
AMPS
RANGE
CAL
7
V•Hz
SENSE
INPUT
Ω 4 WIRE
HI
350V 1100V
PEAK
PEAK
LO
500V
PEAK
INPUTS
F R
RANGE
AUTO FRONT/REAR
2A 250V
AMPS
RANGE
CAL
See Table 3-21
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Trigger level range and increments
Maximum
signal level
1V
10V
100V
1000V
1mA
10mA
100mA
1A
Note: The trigger level for TTL triggering defaults to +0.80V.
Frequency configuration
The following paragraphs detail how to change the Model
2001 from its bench reset conditions for frequency
measurements. The configuration menu is summarized in
Table 3-22. Note that a function does not have to be selected
in order to be configured. When the function is selected, it
will assume the programmed status.
Front Panel Operation
AC Voltage
Source
AC Current
Source
for the trigger level ranges and increments.
Trigger level
Range
-0.600 to +0.600V
-6.00 to +6.00V
-60.0 to +60.0V
-600 to +600V
-0.600mA to +0.600mA
-6.00mA to +6.00mA
-60.0mA to +60.0mA
-600mA to +600mA
Increment
0.005V
0.05V
0.5V
5V
0.005mA
0.05mA
0.5mA
5mA
3-41