Tektronix 1L20, Instruction Manual

Page: 50 / 117

C alibration— Type 1L20
Fig. 6 -1 2 . Setup for adjusting Swept Frequency Oscillator Center Frequency (Step 5 ) and checking range of IF CENTER FREQ Controls (Step 6 ) .
5. Adjust Center Frequency of Swept O
Frequency Oscillator
a. Connect the equipment as shown in Fig. 6-12.
b. Preset the front-panel controls as follows:
Horizontal Position
(Oscilloscope)
Center the trace on the
center of the graticule
POS
Position the trace to the
bottom line o f the gra­
ticule
IF CENTER FREQ
FINE IF CENTER FREQ
DISPERSION RANGE
VERTICAL DISPLAY
IF CENTER FREQ CAL
(Screwdriver Adjust)
Midrange (000)
Midrange
M H z/C M
LIN
Centered
c. A pply a 100 MHz signal from the generator.
d. Adjust the Center Freq. Range control R253 (see Fig.
6-13) so that the IF feed-through signal does not shift in posi­
tion as the DISPERSION— COUPLED RESOLUTION control is
rotated.
f. Change the DISPERSION RANGE to kHz/CM.
g. Adjust R368 (kHz/CM Cal) so that the signal does
not shift in position when the DISPERSION— COUPLED RES
QLUTION control is rotated between 500 kHz/CM and 20
kHz/CM. Significant changes in the setting o f R368 w ill
affect the accuracy o f the kH z/C M Dispersion. If R368
is changed be sure to recheck the adjustment o f C384 and
C385 (See Steps 2h through 2j).
6. Check Range of IF CENTER FREQ Controls
a. Preset the controls on the Spectrum Analyzer as fo l­
lows:
POS
IF CENTER FREQ
FINE IF CENTER FREQ
DISPERSION RANGE
DISPERSION-
COUPLED RESOLUTION
VERTICAL DISPLAY
Position the trace to the
bottom line of the gra­
ticule
Midrange (000)
Midrange
M H z/C M
10
LOG
e. Set the DISPERSION— COUPLED RESOLUTION control b. Connect the equipment as shown in Fig. 6-12. Set
to 10 and adjust R204 to center the display. the generator for 100 MHz and 10 MHz markers.
6-10