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Performance Verification: Analog Section
WFM90D and WFM91D Service Manual
4-13
8. Increase the frequency on the leveled sine wave generator until the edge of
the circle display expands out to the compass rose and again reduces to the
--3 dB (70%) point gaps on the vertical graticule axis. See Figure 4--1.
9. Check that the frequency readout on the leveled sine wave generator is
between 3. 98 and 4. 18 MHz (4.83 and 5.03 MHz PAL).
10. Adjust the frequency on the leveled sine wave generator until the edge of the
circle display reaches the --3 dB (70%) point gaps on the horizontal graticule
axis.
11. Check that the frequency readout on the leveled sine wave generator is
between 3. 98 and 4. 18 MHz (4.83 and 5.03 MHz PAL).
12. Remove all signals from the WFM90D or WFM91D monitor.
Audio Gain and Frequency Response
This procedure verifies the following requirement:
Measurement Accuracy: 0.5 dB at 1 kHz. Frequency Response: 0.5 dB from
50 Hz to 20 kHz.
1. Connect the output from the audio generator to the AUDIO IN connector on
the WFM90D or WFM91D monitor.
2. Set the audio generator for a 1 kHz tone output, with an amplitude of
+8.0 dBu. Select Signal On.
3. Select AUDIO display mode on the WFM90D or WFM91D monitor.
4. Enter the Operating menu and select 8dBu.
5. Check that the display amplitude is within 0.5 dB of the reference level
graticule lines.
6. Set the audio generator for a +4.0 dBu output amplitude.
7. Select 4dBufrom the Operating menu.
8. Check that the display amplitude is within 0.5 dB of the reference level
graticule lines.
9. Set the audio generator for a 0.0 dBu output amplitude.
10. Select 0dBufrom the Operating menu.
11. Check that the display amplitude is within 0.5 dB of the reference level
graticule lines.
12. Set the audio generator for a --10.0 dBu output amplitude.