Tektronix 1L20, Инструкция по эксплуатации, Страница: 34 / 117

Performance Check— Type 1L20
b. Insert the Spectrum Analyzer into the oscilloscope,
fasten the securing latch, and turn on the power. Allow
10-20 minutes for warm-up.
c. Connect the oscilloscope Sawtooth O ut (or Sawtooth
A) conector to the Analyzer SWEEP INPUT connector.
CAU TIO N
Be careful w hen m aking this connection, since the
saw tooth v o lta g e can give a p a in fu l shock. Also
be sure to plug the c a b le in to the SWEEP INPUT,
not one o f the nea rb y RF INPUT connectors.
d. Set the oscilloscope Mode (or Horizontal Display)
switch to A or Normal.
e. Set the sweep controls for a free-running 5 ms/cm
sweep.
2. Set Front Panel IF CENTER FREQ CAL Adjust­
ment
a. Preset the controls of the Spectrum Analyzer as follows:
POS
IF ATTEN
IF CENTER FREQ
FINE IF CENTER FREQ
DISPERSION RANGE
DISPERSION-
COUPLED RESOLUTION
VIDEO FILTER
VERTICAL DISPLAY
RF INPUTS (Switch)
Position the trace on the
bottom line o f the
graticule
ALL OFF
Midrange (000)
Midrange
M H z/C M
10
O ff (down)
LIN
BAND 1
b. Apply a 100 MHz signal from the Type 184 Time-Mark
Generator (or a 50 MHz signal if using the Type 180A) to
the Band 1 RF INPUT connector through a 10:1 50 £2 attenu­
ator.
c. Adjust the G AIN control so that the CRT display shows
a signal pip about 4 divisions in amplitude.
d. Set the IF CENTER FREQ CAL adjustment so that the
signal pip does not shift as the DISPERSION— COUPLED
RESOLUTION control is rotated between 10 and .2 (outer
ring).
e. Set the oscilloscope Horizontal Position controls to align
the pip with the center line o f the graticule.
f. Set the DISPERSION— COUPLED RESOLUTION control
to 1 (outer ring). The horizontal shift o f the pip should not be
more than 1 centimeter when the DISPERSION RANGE con­
trol is changed to the kHz/cm position.
3. Set Front-Panel DISP CAL Adjustment
a. Preset the controls o f the Spectrum Analyzer as follows:
POS Position the trace to the
bottom line o f the
graticule.
IF ATTEN
IF CENTER FREQ
FINE IF CENTER FREQ
DISPERSION RANGE
DISPERSION-
COUPLED RESOLUTION
VIDEO FILTER
VERTICAL DISPLAY
RF INPUTS (Switch)
PHASE LOCK
ALL OFF
Midrange (000)
Midrange
M H z/C M
10 (outer ring)
O ff (down)
SQ LAW
BAND 1
INT 1 MHz REF FREQ
b. A pply 10 ns and 0.1 fx s markers (100 MHz and 10 MHz)
from the Time Mark Generator to the RF INPUT connector
through a 50 S3 10:1 attenuator.
c. Adjust the G A IN control for a marker display about
4 divisions high.
d. Adjust the FINE IF CENTER FREQ control to keep the
markers aligned with the graticule lines while setting the
DISP CAL adjustment from one marker per centimeter from
the first to the ninth graticule lines. Ignore the right and
left edges of the graticule— see Fig. 5-1.
First
Graticule
Ninth
Graticule
L
1
ine
r
:
Li ne
r
:......
1
Fig. 5 -1 . Typical display for DISP CAL adjustment (Step 3 ) .
4 . 1 M H z CAL MARKERS Signal Check
a. A pply 10 ns (100 MHz) and 1 jas (1 MHz) markers from
the Time Mark Generator to the RF INPUT connector through
a 10:1 Attenuator.
b. Change DISPERSION to 1 M H z/C M and align the first
marker with the first graticule line as was done in Step 3d
above.
c. Note the horizontal position o f the ninth marker.
d. Disconnect the generator and conect the 1 MHz CAL
MARKER OUT signal in its place.
e. Align the first marker with the first graticule line. The
ninth marker should be in the position noted in step c above.
5. Phase Lock Check and RF CENTER FREQ
Dial Calibration Check
a. Preset the controls of the Spectrum Analyzer as follows:
5 -2