Tektronix 1L40, Инструкция по эксплуатации

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Operating Instructions— Type 1L40
18. Uncouple the RESOLUTION control and turn the con­
trol clockwise. Note the bandwidth increase as the resolution
bandwidth is increased. The resolution bandwidth may be
varied from approximately 1 kHz to 100 kHz. Return the
RESOLUTION control to the coupled position with the DIS­
PERSION selector.
e. Set the DISPERSION control to the 5M H z/cm position.
Position the signal to the graticule center with the Oscillo­
scope Horizontal Position control. If the signal is more
than 1 centimeter from the sweep center, it should be center­
ed with the internal Sweep Center adjustment R204. See
Calibration section.
Front Panel Calibration Adjustments
Three screwdriver adjustments provide calibration adjust­
ments for the DISPERSION, IF CENTER FREQ and the DIS­
PERSION RANGE balance. These front panel adjustments
must be recalibrated, if the Type 1L40 is shifted to another
oscilloscope, to compensate for differences in sawtooth
amplitudes. It is also advisable to check the adjustments
periodically during regular use. Adjustment and a calibra­
tion check may be performed as follows:
3. DISP-BAL Adjustment
a. Tune the RF signal to the screen center as described in
step 2.
b. Adjust the DISP BAL for minimum signal shift as the
DISPERSION RANGE selector is switched between the M H z/
CM and kHz/CM positions. (Start the balance adjustment
with the DISPERSION RANGE switch in the kHz/CM position
and the DISPERSION in the 5 MHz - 500 kHz position, then
decrease the DISPERSION to the .2 MHz - 20 kHz position.)
1. Balance and Calibration Check
a. Set the INT REF FREQ control to OFF position.
b. Tune a signal on screen with the RF CENTER FREQ con­
trol.
c. Tune for minimum signal shift as the DISPERSION
RANGE is switched from M H z/C M to kHz/CM positions.
d. W ith the DISPERSION RANGE selector at the M H z/C M
position, adjust the IF CENTER FREQ control for minimum
signal shift as the DISPERSION selector is switched through
the 10 MHz to .2 MHz positions.
e. Set the DISPERSION RANGE selector to kHz/CM posi­
tion and the DISPERSION to 500 kHz/cm.
f. Center the signal in the graticule area with the Horizon­
tal Position control. Check the signal position on the sweep.
The signal should locate within ± 1 cm of the sweep center
with the sweep extending over the 10 centimeter width of
the graticule.
Front panel calibration is required if this
requirement is not met. Perform the following adjustments
if front panel calibration is required.
NOTE
These adjustm ents in te ra ct, and must be perform ed
in sequence.
Final adjustment is made with the DISPERSION RANGE
selector in the kHz/cm position and the DISPERSION in the
1kHz position. Fine adjustment of the DISP BAL (with the
IF CENTER FREQ set to 000) permits dispersion changes
from lO M H z/cm to 1 kHz/cm with minimum shift in signal
position on the screen.
NOTE
If dispersion balance ca n n o t be achieved by the
above procedure, the instrum ent requires in te rn a l
adjustm ent. Refer to the C a lib ra tio n section o f the
m anual.
4. DISP-CAL Adjustment
a. Set the Analyzer front-panel controls as follows:
IF ATTEN dB
IF CENTER FREQ
DISPERSION RANGE
DISPERSION-COUPLED
RESOLUTION
VERTICAL DISPLAY
INT REF FREQ
All OFF
000 (centered)
kHz/CM
500 (inner ring)
SQ LAW
CCW (next to OFF posi­
tion, but not switched
to OFF OR EXT REF
FREQ IN position)
2. IF CENTER FREQ CAL Adjustment
a. Set the IF CENTER FREQ control to 000 and center the
FINE control. Center DISP BAL and the IF CENTER FREQ-
CAL adjustments. Set the DISPERSION RANGE switch to
the M H z/C M position and the DISPERSION control to 5 M H z/
cm position.
b. A pply a stable RF signal to the RF INPUT connector.
Adjust the G A IN control to obtain a usable signal am pli­
tude.
c. Adjust the RF CENTER FREQ and the FINE RF CENTER
FREQ controls for minimum signal shift as the DISPERSION
RANGE is switched between the M H z/C M and the kHz/CM
positions.
d. W ith the DISPERSION RANGE in the M H z/C M position,
adjust the IF CENTER FREQ-CAL for minimum signal shift
as the DISPERSION control is switched through the MHz
(10 MHz - .2 MHz) positions.
b. Connect the 1 MHz CAL MARKERS OUT signal through
a coaxial cable to the RF INPUT connector.
c. The display w ill probably have one set of calibration
markers superimposed with another set of markers. (One
set of markers only when W aveguide M ixer Adapter is
used.) If this is the case, adjust the RF CENTER FREQ controls
to bring the tunable markers into horizontal alignment with
the feed-through or fixed markers.
d. Adjust the DISP-CAL for 1 marker/centimeter. See Fig.
2-7. Use the Horizontal Position control or the IF CENTER
FREQ control to align the markers to the graticule lines.
Dispersion is calibrated over the center 8 centimeters of the
display.
e. Remove the 1 MHz CAL MARKER signal from the RF
INPUT connector.
This concludes the front-panel calibration adjustments for
the Type 1L40.
®
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