Tektronix 1L30, Instruction Manual

Page: 50 / 129

Performance Check— Type 1L30
only a partial check is desired, refer to the preceding step
(s) for setup information.
The following procedure uses the equipment listed under
Recommended Equipment. If substitute equipment is used,
control settings or setup may be altered to the requirements
of the equipment used.
Several
checks
require a 200 M H z signal. This IF feed­
through signal'is not tunable. To avoid interference from
the converted signals, it is recommended that any tunable
signals are tuned off screen or aligned with the stationary
markers by adjusting the RF CENTER FREQ control.
Preliminary Procedure
a. Before inserting the Spectrum Analyzer into the oscillo­
scope compartment, set SW201 (slide switch mounted on
the rear plate of the analyzer) to- the appropriate position
for the oscilloscope sweep amplitude.
b. Insert the Spectrum Analyzer into the oscilloscope,
fasten the securing latch, and turn on the power. Allow 20
minutes'for warm up.
c. Connect the oscilloscope Sawtooth Out (or Sweep
A) connector to the analyzer SWEEP INPUT connector.
C A U T IO N
Be careful when making this connection. The saw ­
tooth voltage can give a severe shock. Insure th at
the cable is connected to the SWEEP INPUT, not
to the nearby RF INPUT connector.
d. Set tire oscilloscope Mode (or Horizontal Display)
switch to A or Normal.
e. Set the sweep controls for a free-running, lOms/cm
sweep speed.
|
I
1. Check
| Disperses Balance
j
s a. Requirement— The IF center frequency, with the IF
;] CENTER
FREQ
controls centered, must be adjustable to 200
- M Hz with the IF CENTER FREQ-CAL adjustment. There should
| be less than 2 cm horizontal display shift between the M H z/
I CM and kH z/C M displays.
!r Central Frequency Calibration and
'A
b. Apply a 200 MHz signal (2nd harmonic of 10 ns) from
the Time-Mark Generator (Type 184) through a 20 dB atten­
uator pad and 50 f' termination to the RF INPUT connector.
(Signal input to. the Type 1L30 should be less than — 30 dBm.)
Set
the
Type 1L30 front panel controls as follows:
POSITION Position the trace to the
bottom graticule line
IF CENTER FREQ
Centered (000)
FINE IF
CENTER
FREQ
Centered
DISPER SIO N R A N G E
'M H z/C M
D IS P E R S IO N -C O U P LE D
R E S O L U T IO N
10 M Hz/cm
VERTICAL DISPLAY LIN
VIDEO FILTER . OFF
d. Adjust the G A IN control for a signal amplitude that
is approximately 5 cm.
e. W ith the IF CENTER FREQ controls centered, adjust
the IF CENTER FREQ-CAL for minimum horizontal signal
shift as the DISPERSION control is switched between the
lO M H z /c m and .2 M H z /c m positions. Position the signal
to* the graticule center with the oscilloscope Horizontal Posi­
tion control.
f. Adjust the DISP BAL for minimum signal shift as the
DISPERSION RANGE is switched between the M H z /C M and
kH z/C M positions. Adjust until there is minimum signal
movement, then make the final adjustment with the DISPER­
SIO N RANGE in the kH z/C M position and reduce the DIS­
PERSION control to the 1 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 H z /
CM position and the DISPERSION-COUPLED RESOLUTION
controls to the lO M H z /c m position.
2. Check Dispersion Accuracy of M H z /C M
Ranges and Range of IF Center Frequency
Control
a. Requirement— Dispersion accuracy for the M H z /C M
ranges is listed in Table 5-1. IF CENTER FREQ control range
should equal or exceed -f- and — 25 M H z from its centered
(000) position. Dispersion accuracy and display linearity
must remain with the listed specifications of Table 5-1 to
the + and — 25 M Hz positions of the control.
b. Apply .1 /xs and 10 ns time markers from the Time-
Mark Generator (Type 184) through a 20 dB attenuator and
50 f i termination to the RF INPUT connector.
c. Set the VERTICAL DISPLAY switch to LOG position.
Adjust 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 H z/cm setting of the DISPERSION selector as listed in
Table 5-1. (See Fig. 5-1 and 5-2.) The Horizontal Position
control or the IF CENTER FREQ control may be used to
align the prime markers to the graticule divisions. The RESO­
LUTION control should remain coupled with the DISPERSION
selector.
f. Check the range, dispersion accuracy and linearity
of the IF CENTER FREQ control in the 5, 2, 1, .5 and .2 M Hz
positions of the DISPERSION selector.
Range of the IF CENTER FREQ control should equal or
exceed - f and — 25 M Hz from its centered position. Rotate
the control from center note the frequency shift or the .1 jus
or 10 M Hz markers then rotate the control to the other
extreme position. Dispersion accuracy and display linearity
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