Checks and Adjustments
5–16
1720/1721
Perform parts i. through p. only if internal jumpers J920 and J921 (Main
board) are set to High Gain mode.
i. Connect the Function Generator output to pin 11 (+X HIGH GAIN) and
ground pin 9 (+X) of the 1720/1721 rear-panel XY INPUT connector.
See Figure 5-5.
j. Set the Function Generator frequency to approximately 10 kHz and
adjust its amplitude for a display equal to the width of the graticule
compass rose.
k. Set the Function Generator to 100 kHz.
l. CHECK – that the display reaches the –3 dB gaps in the horizontal axis
or beyond.
m. Connect the Function Generator to pin 15 (+Y HIGH GAIN) and ground
pin 13 (–Y) of the 1720/1721 rear-panel XY INPUT connector.
n. Set the Function Generator frequency to approximately 10 kHz and
adjust its amplitude for a display equal to the height of the graticule
compass rose.
o. Set the Function Generator to 100 kHz.
p. CHECK – that the display reaches the –3 dB gaps in the vertical axis or
beyond.