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Performance Verification
4–22
1780R-Series Service Manual
ae. Select RELATIVE on the Vectorscope CRT menu. Press the REF-
ERENCE SET button. Note that the DV readout is 100.0% on the
Waveform CRT.
af. Move the coaxial cable with the 50 W-to-75 W minimum loss attenuator
from the CH A INPUT connector to the AUX IN connector. (Check that
the 700 mV sine wave signal is applied to the AUX IN connector.)
ag. Select the FILTER–AUX input mode.
ah. Use the Precision Measurement control to set CURSORS 1 and
CURSORS 2 traces to measure the relative value of the AUX IN signal.
ai. Check that the DV readout is between 115.0% and 123.0% on the
Waveform CRT.
aj. Set the FILTER to FLAT and the VOLTAGE CURSORS button to Off.
ak. Disconnect the sinewave signal and minimum loss attenuator from the
AUX IN connector. Disconnect the terminator from the CH A INPUT
connector.
11. Check X1 Gain CH A Frequency Response
Requirement: Flat frequency response from 50 kHz to 10 MHz within ±1%.
50 kHz is used as a reference. Frequency response from 10 MHz to 15 MHz
is within +2% and –5% of the reference amplitude. Frequency response from
15 MHz to 20 MHz is within +2% and –15% of the reference amplitude.
a. Connect the leveled sine wave generator output, through a 50 W-to-75 W
minimum loss attenuator, to the CH A INPUT connector. Do not
terminate the loop-through connector.
b. Connect a Peak-to-Peak Detector Head (Tektronix Part No.
015-0413-00) to the other CH A INPUT connector. Connect a coaxial
cable from the Detector Head to the +Input on the Peak-to-Peak Detector
Amplifier. See Figure 4–8.
c. Connect the Peak-to-Peak Detector Amplifier output to the input of a
DMM.
d. Connect a 75 W termination to the 1780R-Series PIX MON OUT
connector.