To center the PPI VENIER control, the PPI VENIER control
must be turned fully clockwise and then counterclockwise.
It is centered when it is set at the mid-position between
the two extremes.
e. Rotate the IF GAIN, AZ control fully clockwise while observing
the CRT, located on control radar set C-2074/FPN-33 (Figure 42).
f. Rotating the PPI DELAY control (R1903) will cause the main
bang (video) to move toward the touchdown marker (Figure 44).
correct setting for the PPI DELAY control (1903) is when the
innermost edge of the video return (main bang) just touches the
touchdown marker (Figure 45). The touchdown marker is often referred
to as the TD marker.