HP 8924E, Assembly

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Chapter 4, Periodic Adjustments
Introduction
N:\mkt\MANUALS\HP8924C\ALR\per_adj.fb
1. The internal paths that run from Audio Frequency Generators 1 and 2 (individually)
through the Modulation Distribution assembly, to the monitor select output, then onto
Audio Analyzer 1 to the DVM
2. The paths that run from Audio Frequency Generators 1 and 2 (individually) through the
Modulation Distribution assembly to the AUDIO OUT connector, externally to the
rear-panel MODULATION IN connector, then again through the Modulation
Distribution assembly to the monitor select output and to the DVM
The above-measured levels are used to adjust the output level of the audio
generators so that they produce a calibrated level to the modulation inputs of the
RF Generator. These measurements are made at DC. Both positive and negative
levels are measured to produce an optimum calibration factor.
External Modulation Path Gain
The Audio Frequency Generator Gain program should be run first.
The path in this program runs from the external MODULATION IN connector
through the Modulation Distribution assembly, through the Monitor Select
Switch, then through Audio Analyzer 1 to the Test Set’s internal DVM. The DC
source is Audio Frequency Generator 1 through the AUDIO IN connector and an
external cable.
The goal of this procedure is to set the External Level Amplifier gain DAC (on the
Modulation Distribution assembly) to produce a gain of exactly 4 between the
MODULATION IN connector and output of the Monitor Select Switch. This
requires measuring the input and output levels, calculating the gain, changing the
DAC setting, and then repeating the process until the calculated gain equals 4.