45

Users Manual

modifier is selected, the relative base is shown in the secondary display. To turn off this feature, press Sand, while holding it down, press K.

dB (Decibels and Audio Power) Modifier

The decibels modifier takes a voltage measurement, converts it to dBm (measure of decibels relative to one milliwatt), and displays the result on the primary display.

Press Ito toggle in and out of the decibels modifier. When the decibels modifier is selected, "dB" is shown on the primary display.

Decibels can be selected only when a voltage function is selected on the primary display (volts ac, volts dc, or volts ac + dc). Decibels are always displayed in a single, fixed range with 0.01 dB resolution. However, the basic measurement itself (e.g. volts ac) autoranges.

A voltage measurement is converted to dBm using the following formula:

dBm = 10*log (1000*value2/reference impedance)

where "value" is the measurement value. The reference impedance can be set to any of 21 reference impedances listed in Table 3-8 by using the list editor as described in "Using the List Editor" later in Chapter 3.

Table 3-8. Reference Impedances in Ohms

8000

1200

1000*

900

800

600

500

* Voltage annunciator lit

† Audio power readings possible

300

250

150

135

125

124

110

93

75

50

16†

8†

4†

2†

To access the reference impedance list, press Sthen press I(REF e). The reference impedance currently selected is displayed, along with the db and eannunciators. Press

Uor Tto scroll to the desired value, then press Eto select a reference impedance and return the primary display to the measurement function. Press any function (white) or modifier (light grey) button to exit the reference impedance list without selecting a new value.

Setting the dB reference resistance to 16, 8, 4, or 2 ohms allows you to use the meter to calculate audio power. After the reference resistance has been set to 16, 8, 4, or 2 ohms, press Itwice to select the audio power modifier. "POWER" will be shown on the secondary display.

The following equation is used to make a power calculation:

Audio power = Volts /reference resistance

where volts is the measurement value.

3-12

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Fluke 45 user manual DB Decibels and Audio Power Modifier, Reference Impedances in Ohms
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45 specifications

The Fluke 45 is a versatile and high-precision Digital Multimeter that is designed for a wide range of applications in electrical testing, troubleshooting, and maintenance. Known for its reliability and advanced features, the Fluke 45 is an essential tool for engineers, technicians, and professionals who require accurate measurement capabilities.

One of the standout features of the Fluke 45 is its ability to measure both AC and DC voltage and current. With a maximum input voltage of 1000 volts and current ranges up to 10 amps, users can conduct a variety of electrical tests with confidence. The device is equipped with an intuitive dual display, allowing for simultaneous viewing of multiple measurements. This feature enhances usability during complex diagnostics.

The Fluke 45 also boasts an impressive resolution of 0.1 mV and a basic accuracy of 0.25%, which translates to highly reliable readings. The auto-ranging capability simplifies the measurement process, automatically selecting the appropriate range based on the input signal, thus saving time and reducing user error.

In addition to voltage and current measurements, the Fluke 45 features resistance measurement capabilities, with a range of up to 40 MΩ. This makes it an effective tool for testing circuits, identifying faults, and ensuring the integrity of electrical systems. The continuity test function, complete with a built-in beeper, assists in quickly diagnosing wiring issues.

Another remarkable characteristic of the Fluke 45 is its frequency measurement capabilities, which can measure frequencies up to 1 MHz. This is particularly useful in applications involving signal analysis and troubleshooting oscillators.

Moreover, the Fluke 45 is designed with user convenience in mind. It is lightweight and portable, making it easy to carry around, whether on a job site or in a workshop. The rugged construction, reinforced with high-quality materials, ensures it can withstand harsh conditions often encountered in the field.

To enhance functionality, the Fluke 45 features a data hold function that freezes the displayed measurement for easier reporting. Additionally, it can store data for later retrieval, making it convenient for users who need to compile test results over time.

In summary, the Fluke 45 Digital Multimeter is an advanced instrument that combines precision, versatility, and user-friendly design. Its wide measurement capabilities, high accuracy, and durable build make it an invaluable tool for professionals in diverse electrical and electronic applications. Whether for routine maintenance or complex troubleshooting, the Fluke 45 stands out as a reliable partner in achieving accurate and efficient results.
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