
8.
9.
10.
11.
4. Final Display Adjustments (SN
and Above)
For an initial coarse focus, adjust the following potentiometers in
the sequence listed:
FOCUS LIMIT
ASTIG
FOCUS COMP
Press
PRESET
),
then adjust the reference level to bring
the displayed noise to the top division of the graticule. Press
C
ENTER
and key in 1 dB/DIV. The noise should now
completely fill the CRT graticule pattern, illuminating a large
rectangular area. If necessary, adjust the reference level until the
graticule pattern is completely filled.
Press
and then
to turn off the CRT
annotation and graticule pattern.
Connect a 56503 photometer probe to the Tektronix
digital
photometer. Set the photometer to the Xl range.
Place the photometer light probe hood against the IF-Display
Section glass
filter, and adjust
INT GAIN for a
photometer reading of 80 NITS
Note
This reading must be made with the glass
filter in place in front of
the CRT. It might be necessary to slightly trim the top and bottom of
the photometer probe’s hood so that it will fit flush against the glass
filter.
Note
If a standard
photometer is used (instead of metric option
adjust
for a photometer reading of 23.5 fl (footlamberts).
12. Set the LINE switch to STANDBY and then back to ON. The
spectrum analyzer power-up annotation should be visible on the
CRT display. (This includes
the
firmware datecode.)
13. For the best focus near the center of the CRT display, adjust the
following potentiometers in the sequence listed below. Repeat as
needed to optimize center-screen focus.
FOCUS LIMIT
ASTIG
for best focus of annotation (short vectors)
FOCUS COMP for best focus of graticule lines (long
vectors)
14. Adjust
FOC for best focus at the top and bottom of
the display.
15. Adjust
R/L FOC for best focus at the right and left
sides of the display.
16. If the top and bottom (or right and left sides) of the display
achieve best focus at different potentiometer settings, adjust
T/B CTR or
R/L CTR, and then readjust
T/B FOC or
R/L FOC to optimize overall
focus.
Adjustments 3-63
Summary of Contents for 8568B
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