Introduction; Functional Block Description - Fluke 39 Service Manual

2-1. Introduction

Chapter 2 provides circuit descriptions for the Fluke 39 Power Meter and Fluke 41B
Power Harmonics Analyzer. First, the Tester is described in general terms with a
Functional Block Description. Then each block is detailed further with Detailed Circuit
descriptions. Schematic diagrams are provided in Chapter 7.
A signal name followed by an asterisk (*) is active (asserted) low. A signal name not
followed by an asterisk is active high.

2-2. Functional Block Description

The Tester is unlike most Fluke handheld meters. All waveforms and readings are based
on hundreds of measurements instead of a few integrate cycles used in most DMMs. The
128 points used to display waveforms are not directly sampled, but are synthesized using
several hundred measurements. This approach allows the instrument to be more flexible
and display a wider range of data; such as time and frequency domain data. Using
sampled data for watts and RMS values, instead of traditional analog measurement
techniques, reduces cost, size, and power consumption. The entire digital section
operates on 3.3 volts, which saves power and generates less Radio Frequency
Interference (RFI).
Refer to Figure 2-1 during the following functional block descriptions
Tester has seven basic sections:
•
Power Supplies
•
Input Conditioning
•
Analog to Digital (a/d) Conversion
•
Digital Kernel (Computer)
•
Keypad
•
Display
•
Optical Interface (Fluke 41B only)
Theory of Operation

Introduction

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2-3