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