Performance Verification: AnalogS ection
WFM90D and WFM91D ServiceManual 4-9
Input and DC Restorer Frequency Response
This procedureverifies the following requirement:
X1 Gain Response (Flat filter selected):50 kHz to 6 MHz within 2% of response
at 50 kHz. X5 Gain Response (Flatfilter 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 Ωprecision cablefrom the output of the leveled sine wave
generatorto the dual-input coupler using a 50 Ω-to-75 Ωminimum loss
attenuator.
3. Connect one side of the dual-input couplerto the VIDEO IN connector.
4. Connect the Tektronixpart 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 Tektronixpart number 015-0408-00 Peak-to-Peak Detector + Input.
5. Connect the peak-to-peakdetector Output to the digital multimeter or
oscilloscope.
6. Set the leveled sine wave generatorfrequency to 50 kHz and adjust the
generatoramplitude for exactly 100 IRE (700 mV PAL) of display.
7. Adjust the peak-to-peakdetector Plus amplifier and input control until the
green LED is on.
8. Note the digital multimeter readoutlevel or the oscilloscope DC level.
9. Set the sine wave generatorfrequency to 3.58 MHz (4.43 MHz PAL).
10. Adjust the sine wave generatoramplitude for exactly 100 IRE (700 mV
PAL)of display.
11. Check that the digital multimeter readout level, or the oscilloscope DC level
is within 14 mV of the readingnoted in step 8.
12. Set the sine wave generatorfrequency to 6 MHz.
13. Adjust the sine wave generatoramplitude for exactly 100 IRE (700 mV
PAL)of display.
14. Check that the digitalmultimeter readout level or the oscilloscope DC level,
is within 14 mV of the readingnoted in step 8.
15. Set the sine wave generatorfrequency to 50 kHz.
16. Select X5 GAIN from the Operating menu.