Chapter VII Performance feature test
92
Frequency of Audio Source 1: 1000Hz
Amplitude of Audio Source 1: 20mVrms
ON/OFF status of Audio Source 1: ON
3) Set the input impedance of the audio analyzer as high impedance.
4) Read the amplitude value in the amplitude measurement window of the audio analyzer, and
record it in Table A.10.
10. Harmonic distortion of audio source
a) Test items
The audio analyzer is applied in the following steps to measure the harmonic distortion of the
output signal of the audio source. The harmonic distortion of the audio signal output of this
instrument is less than 3% (1kHz, 1Vrms).
b) Test block diagram and meters
The same as the test of the audio output frequency range and accuracy.
Instrument / equipment:
Audio analyzer (recommended model: VA-2230A)
One BNC cable (100cm)
c) Test steps
1) Connect the device as shown in the figure, start it, and warm it up for 30min.
2) Open the audio source window by pressing the [Audio] hard key or pressing the [Measurement]
hard key and setting the instrument menu. Set it as follows.
Output port: audio output
Output source: internal audio
Frequency of Audio Source 1: 1kHz
Amplitude of Audio Source 1: 1Vrms
ON/OFF status of Audio Source 1: ON
3) Set the input impedance of the audio analyzer VA-2230A as high impedance, and the
measurement mode as THD.
4) Observe the test result of harmonic distortion of the audio analyzer, and record it in Table A.11.
11. Dual-tone signal
a) Test items
Two audio signals can be outputted at the same time by the audio source of this instrument. The
spectrum analyzer can be applied to measure the capability of the audio source to output the
dual-tone signal.
b) Test block diagram and meters
Audio output port
Spectrum analyzer
4992A Rradio Test Set
RF input
Fig. 7-4 Block Diagram of Dual-tone Output Capability of
Audio Source
Summary of Contents for 4992A
Page 1: ...I 4992A Radio Test Set User Manual China Electronics Technology Instruments Co Ltd...
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Page 23: ...Article I Handling Instructions 11 Article I Handling Instructions...
Page 93: ...81 Article II Technical Specifications...
Page 132: ...Article III Maintenance Instructions 120 Article III Maintenance Instructions...
