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Performance Verification: Analog Section
WFM90D and WFM91D Service Manual
4-9
Input and DC Restorer Frequency Response
This procedure verifies the following requirement:
X1 Gain Response (Flat filter selected): 50 kHz to 6 MHz within 2% of response
at 50 kHz. X5 Gain Response (Flat filter selected): 50 kHz to 6 MHz within 5%
of response at 50 kHz. Attenuation of 60 Hz (50 Hz PAL) on Input Signal:
SLOW mode: ≤20%. FAST mode: ≥90%.
1. Select EXT REF from the Configuration menu.
2. Connect the 50 Ω precision cable from the output of the leveled sine wave
generator to the dual-input coupler using a 50 Ω-to-75 Ω minimum loss
attenuator.
3. Connect one side of the dual-input coupler to the VIDEO IN connector.
4. Connect the Tektronix part number 015-0413-00 Peak-to-Peak Detector
Head to the other end of the dual-input coupler, using the female-to-female
BNC connector. Connect the other end of the Peak-to-Peak Detector Head to
the Tektronix part number 015-0408-00 Peak-to-Peak Detector + Input.
5. Connect the peak-to-peak detector Output to the digital multimeter or
oscilloscope.
6. Set the leveled sine wave generator frequency to 50 kHz and adjust the
generator amplitude for exactly 100 IRE (700 mV PAL) of display.
7. Adjust the peak-to-peak detector Plus amplifier and input control until the
green LED is on.
8. Note the digital multimeter readout level or the oscilloscope DC level.
9. Set the sine wave generator frequency to 3.58 MHz (4.43 MHz PAL).
10. Adjust the sine wave generator amplitude for exactly 100 IRE (700 mV
PAL) of display.
11. Check that the digital multimeter readout level, or the oscilloscope DC level
is within ᐔ14 mV of the reading noted in step 8.
12. Set the sine wave generator frequency to 6 MHz.
13. Adjust the sine wave generator amplitude for exactly 100 IRE (700 mV
PAL) of display.
14. Check that the digital multimeter readout level or the oscilloscope DC level,
is within ᐔ14 mV of the reading noted in step 8.
15. Set the sine wave generator frequency to 50 kHz.
16. Select X5 GAIN from the Operating menu.