THE
8520A Digital multimeter
The John
Fluke Model
8520A Digital multimeter is designed
for use in an automated test system or as an independent
device. The 5~lA digit instrument can be operated locally
from the front panel or remotely via an IEEE-488 1978
interface. The
8520A can directly measure dc, ac, and ac+dc
voltage; resistance (both 2 and 4 wire); and conductance
(the reciprocal of resistance). While the range of
measurement can be manually selected, air functions except
conductance (nS) have full autoranging
capabilities (conductance only has one range). When
measurement function and range are selected, the 852ÖA
automatically programs the reading rate and
Filter for
optimum measurement accuracy. Other values for reading rate
and
Filter can be manually selected. The seven math programs
allow more sophisticated processing of measurement data
(such as computing the peak-to-peak value, percentage of
deviation, rise time, etc.) and additional measurement
functions. For example, the standard
8520A can make voltage
ratio measurements and an
8520A equipped with the -010
Option can make voltage ratio measurements, dB measurements,
and temperature measurements in addition to the direct
voltage and resistance measurements. The burst feature of
the
8520A allows the operator to capture up to 50 readings
(400 with the -010 Option) at various reading rates and to
display the readings at a different rate, to delay the time
after a trigger before the readings are taken, or to look at
what happened to the signal before the trigger occured. The
TRIGGER controls allow internal triggering, manual
triggering, triggering via the IEEE-488
Interface, and
triggering from an external source. All measurements can be
guarded.
DC voltage can be measured from a 1 juV up to 1000V in five
ranges: 100 mV, IV, 10V, 100V, and 1000V. Ac and ac+dc
voltage can be measured from 10 /xV ac rmsto650V ac rms in
four ranges - IV, 10V, 100V, and 650V ac rms — over the
frequency range of 10 Hz to 1 MHz.
Resistance can be measured in two ways. Either directly
using the 02 WIRE and 04 WIRE functions or inversely using
the conductance function. The 02 WIRE and 04 WIRE functions
provide measurement of resistance from 100 µohm to 20 Mohm
in seven ranges: 10 ohms, 100 ohms, 1000 ohms, 10 kohms, 100
kohm, 1 Mohm, and 10 Mohm. Conductance provides fast,
accurate, noise-free measurement of resistances from 10 MOhm
up to 10,000 Mohm in a single range - 100 nS. Conductance is
displayed in the international units,
Siemens which is equal
to the reciprocal of ohms (S = 1 / O).
The standard
8520A has seven math programs:
#1 TEST Four diagnostic self-test programs
#2 ZERO Automatic meter zeroing for dc voltage offsets and
resistance offsets (such as test lead resistance)
#3 XREF Ratio between the input voltage and an external
reference voltage
#4 OSR Subtracts an offset (OFST) from the input, multiplies
by a scale factor (SCAL), divides by a ratio factor (RATO),
and displays the result
#5 Delta PCT Displays the percentage deviation of the input
with respect to a stored nominal value
#6 PEAK Captures upper and lower peak values and computes
peak-to-peak value
#7 LIM Tests the reading against stored upper and lower
limits and displays the results of each reading, the number
HIGH, the number LOW, the number that PASS, and the TOTAL
number of readings
#8 STAT Statistics program that computes mean, standard
deviation, variance, number of reading, bias, sum of the
squares, sum of readings, difference, and the sum of the
differences
#9 LFAC Computes the ac rms value of inputs 10 Hz and below
#10 dB Computes dB, dBm, or dBV ratio
#11 RTD RTD
Thermometer measurements
#12 JV C Works with the John
Fluke 80T-150C to measure
temperature in °C
#13 JV F Works with the John
Fluke 80T-150F to measure
temperature in °F
#14 THMS Thermistor linearization
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