Tektronix 1L30 Instruction Manual page 16

Operating Instructions— Type 1L30
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i Fig. 2-7. Vertical display modes showing an amplitude modulated display. Video mode shows the modulation signal.
Oscillator phase lock operation is established as follows:
i Tune the desired signal to the center of the screen with the
RF CENTER FREQ control.
j ton, then adjust the FINE RF CENTER FREQ control for a
j beat frequency indication within the center 4 centimeters of
i the graticule. Adjusting the FINE RF CENTER FREQ con-
j? trol .shifts the output DC level of the phase lock amplifier
and the vertical reference level of the CRT trace. The linear
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operating range of the .phase lock amplifier is near its
limits at the extreme DC levels; therefore, phase iock opera­
tion should be set in the center of this operating range or
with the display near the center of the graticule area.
v g If the beat indication is outside the'center area of the
■ % -graticule,, adjust the FINE RF CENTER FREQ control to cen-
| ter the trace, then adjust the
| shift the signal towards a beat mode (Fig. 2-5) where phase
lock operation can be achieved within the dynamic range
of t;ie amplifier. Adjust the
? a phase lock condition then release the LOCK CHECK button.
2-10
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2
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• 3
■ 4
Depress the LOCK CHECK but-
RF
CENTER FREQ control to
F IN E RF CENTER FREQ
control for
After phase lock operation has been set, the dispersion
may be reduced. To maintain phase lock condition, the IF
CENTER FREQ controls should be used to position the de­
sired signal to the center of the screen. W ith narrow dis­
persion settings (100 kHz or less) when the analyzer loses
its lock condition, the signal will disappear off the screen.
If this happens, a slight adjustment of the FINE RF CENTER
FREQ control will usually return the signal to the display.
Vertical Display Modes
The dynamic range and the appearance of the displayed
signal is dependent on the mode position of the VERTICAL
DISPLAY switch. For example: The LOG (40dB full screen)
position will accentuate the side lobes of a signal while
the SQ LAW position will de-emphasize the side lobes.
Fig. 2-7 illustrates the effect of each, display mode or each
position of the VERTICAL DISPLAY switch.
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