Tektronix 1L40, Инструкция по эксплуатации

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Operating Instructions— Type 1L40
Fig. 2 -1 2 . To trig g e r the analyzer from the d isp la y requires 0 .2 cm
o f signal. Tune the spectrum null p o in t a w ay from the sweep starting
p o in t w ith the RF CENTER FREQ control.
display; for example, at 0 dispersion, or when slaving the
Type 1L40 to a recorder.
The display may be triggered internally by setting the
oscilloscope Source switch to the Int position and adjusting
the triggering controls to trigger on the display. The oscillo­
scope requires approximately 2 millimeters of signal am pli­
tude to trigger satisfactorily. It may therefore be necessary
to adjust the FINE RF or IF CENTER FREQ control to shift
the sweep start away from a spectrum null point. See Fig.
2
-
12
.
If the signal is time related to the power supply line fre­
quency, it is best to trigger the oscilloscope on the Line
frequency.
---------------------------FREQUENCY
Fig. 2 -1 3 . Formation o f a spectrum. F is the fundam ental or carrier
frequency, Fi and F: are the m odulatin g frequencies.
(A ) CENTER FREQ
DISPERSION
MODE
2 GHz
50 kH z/C M
LIN
This d ispla y shows: C arrier Frequency 2 GHz, m odulating
frequency (1.8cm
X
50 kHz I = 9 0 kHz.
% o f m o dulatio n = (2
X — — X
10 0) = 5 0 %
4 .8
(B) Same as A but resolution ba n d w id th increased so th a t
m odulatio n is b a re ly discernible.
(C) O ver m odulated signal produces extra sidebands. LOG
mode.
Fig. 2-14. Spectrum showing series o f A M signals.
2-14