Tektronix 1L40, Инструкция по эксплуатации

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Performance Check/Calibration— Type 1L40
kHz/CM positions. Adjust until there is minimum signal
movement, then make the final adjustment with the DISPER­
SION RANGE in the kHz/CM position and reduce the DIS­
PERSION control to the 20 kHz/cm position.
g. Repeat the IF CENTER FREQ-CAL and the DISP BAL
adjustment since there is some interaction between adjust­
ments. Return the DISPERSION RANGE selector to the M Hz/
CM position and the DISPERSION-COUPLED RESOLUTION
controls to the lO M H z/cm position.
h. CHECK— The display shift between the M H z/C M and
kHz/CM dispersion ranges must not exceed 2 cm. If the
above requirements are not met, proceed with the following
calibration procedure.
NOTE
W hen m aking a Performance Check o n ly , om it the
rem ainder o f this step and proceed to step 2 ( A ) .
i. Set up the equipment as shown in Fig. 5-1. Set the con­
trols and adjustments as directed for Fig. 5-1.
j. Connect the probe of a DC coupled test oscilloscope
to chassis ground on the Type 1L40. Establish 0 V reference
level on the test oscilloscope, then connect the probe to pin
P of the pin connector on the honeycomb assembly, see Fig.
5-2.
k. ADJUST— The IF CF Range R290 (see Fig. 5-2) for — 0.75
zfcO.l volt of trace deflection on the test oscilloscope.
l
. Disconnect the probe from pin P o f the connector.
m. A pply a 200 MHz signal from the Time-Mark Genera­
tor (harmonic of 10 ns marker) through a 20 dB attenuator, a
50 a termination and the proper adapter to the RF INPUT
connector.
n. Adjust the G A IN control for a signal amplitude of
approximately 4 cm. Tune the RF CENTER FREQ control to
minimize converted signal interference. The 200 MHz IF
feed-through signal should be relatively free of spurious
signal interference.
o. ADJUST— the Center Freq Cal R253 (Fig. 5-2) for mini­
mum IF signal shift as the DISPERSION selector is switched
between the 10 MHz and .2 MHz positions. The DISPERSION
RANGE switch must be in the M H z/C M position for this ad­
justment.
p. Return the DISPERSION selector to the 10 MHz position
and adjust the Horizontal Position control to center the
sweep on the graticule.
q. ADJUST— the Sweep Center R204 (Fig. 5-2) to position
the 200 MHz signal to the graticule center line.
2(A) Check Dispersion Accuracy of M H z /C M
Ranges and Range of IF Center Frequency
Control
NOTE
Dispersion accuracy is a measure o f the frequency
dispersion error w ith in the center 8 centimeters o f
a 10 centim eter d isp la y. It is measured by posi­
tio n in g a frequency m arker on the 1st centim eter
Fig. 5 -2 . Location o f sweeper and discrim inator adjustments.
line, then n o tin g the frequency erro r as the dis­
tance the respective m arker is displaced from the
9th centim eter line. See Fig. 5 -3 .
Linearity error is the measured distance th a t any
frequency m arker is displaced from its respective
g ra ticu le line w hen com pared over an lOcentim eter
d isp la y. See Fig. 5 -4 .
REQUIREMENT— Dispersion accuracy for the M H z/C M
ranges is listed in Table 5-1. IF CENTER FREQ control range
for the 5 M H z/C M to .2M H z/cm dispersion should equal or
exceed -|- and — 25 MHz from its centered (000) position.
Dispersion accuracy and display linearity must remain with­
in the listed specifications of Table 5-1.
a. The test equipment setup is shown in Fig. 5-1.
b. A pply .1 /xs and 10 ns time markers from the Time-Mark
Generator (Type 184) through a 20 dB attenuator, 50 Q termi­
nation and the proper adapter to the RF INPUT connector.
c. Set the VERTICAL DISPLAY switch to LOG position. A d ­
just the G A IN control for a display amplitude of approxi­
mately 4 centimeters. Set the oscilloscope Source switch to
Line and adjust the Level control for a triggered display.
d. Center the IF CENTER FREQ controls. Adjust the DISP
CAL adjustment for 1 marker/cm within the center 8 centi­
meters.
e. Check the dispersion accuracy and linearity for each
M Hz/cm setting of the DISPERSION selector as listed in
Table 5-1, (see Fig. 5-3 and 5-4). The Horizontal position
control or the IF CENTER FREQ control may be used to align
the prime markers to the graticule divisions. The RESOLU­
TION control should remain coupled with the DISPERSION
selector.
®
5-5