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Performance Verification
1780R-Series Service Manual
4–49
o. Leave the MEASURE button set to On.
p. Leave the 5-Step Staircase test signal from the CH A INPUT connector.
41. Check Recursive Filter
SUPPLEMENT Approximately 15 dB signal-to-noise reduction with filter
selected.
a. Check that a Modulated 5-Step Staircase signal from the television test
signal generator is applied to the 1780R-Series CH A INPUT connector.
Check that CH A INPUT is terminated.
b. Check that the 1780R-Series MEASURE button is set to On. Check that
DIFF PHASE and DOUBLE are selected on the menu.
c. Check that the VECTOR GAIN–VAR is set to On. If necessary, turn the
variable VECTOR GAIN control to place the vector dot on the compass
rose.
d. Check the noise reduction circuitry by toggling between NOISE
REDUCTION–ON and OFF. Noise on the Waveform CRT display
should noticeably decrease when NOISE REDUCTION–ON is selected.
e. Select the NOISE REDUCTION–ON setting. Set FREEZE to On.
f. Check that the Waveform CRT display does not move as the Precision
Measurement control is rotated.
g. Select the NOISE REDUCTION–OFF setting. Press MEASURE button
exit the menu.
h. Disconnect the 5-Step Staircase signal from the instrument.
42. Check Internal Sync Input
Requirement: Internal Reference Sync Separator: 0.2 V to 2.0 V peak-to-
peak composite video. Internal Sync Separator: 0.5 V to 2.0 V peak-to-peak
composite video.
a. Connect the television test signal generator Black Burst signal to the
1780R-Series CH A INPUT connector. Do not terminate.
b. Set the 1780R-Series control as follows: REF–INT.
c. Check that the Waveform CRT display is locked.
d. Connect five 75 W feed-through terminators to the 1780R-Series CH A
INPUT loop-through connector.