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Performance Verification
1780R-Series Service Manual
4–53
e. Disconnect the Remote Sync Input Connector from the instrument.
Leave the Color Bar signal connected to CH A INPUT.
47. Check Digital Phase Shifter
Requirement: Phase Accuracy: 0.1_.
a. Check that a television test signal generator Color Bar signal is applied
through a 75 W feed-through terminator to the 1780R-Series CH A
INPUT connector.
b. Connect the television test signal generator front-panel Subcarrier signal
to the EXT CW REF connector. Connect a 75 W end-line termination to
the remaining EXT CW REF loop-through connector. Check that Black
Burst is applied to the EXT REF connector.
c. Set the 1780R-Series controls as follows: REF–EXT–CW.
d. Set the television test signal generator Subcarrier Phase dial to 0.
e. Check that the vector display is locked.
f. Press the CONFIGURE button; select PAGE 3. Check that CW
SYNC–EXT is selected. Push the CONFIGURE button to exit the menu.
g. Press the MEASURE button to On; select DIFF PHASE, DOUBLE, and
NOISE REDUCTION–ON. Set the front-panel WAVEFORM GAIN to
X5.
h. Adjust the variable VECTOR GAIN control so that the red vector dot is
located on the compass rose.
i. Use the Precision Measurement control to position the red vector dot on
the 180_ graticule line. (For PAL, use the +V component red dot.)
j. Turn the Precision Measurement control so that the red bars overlay on
the Waveform CRT.
k. Press the REFERENCE SET button. The PHASE readout on the
Waveform CRT should be 0.00_.
l. Turn the Precision Measurement control counterclockwise to overlay the
magenta bars on the Waveform CRT. Check that the magenta vector dot
is located on the 180_ graticule line.
m. The PHASE readout on the Waveform CRT should be between 42_ and
43_. Note your own exact reading.
n. Turn the Precision Measurement control clockwise to reposition the red
vector dot on the 180_ graticule line. (For PAL, use the +V component
red dot.)