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Fig. 2-1. Initial calibration waveform.
USING THE ANALYZER
Impedance Matching
When the L3 module is installed, the input impedance
of the 7L5 Spectrum Analyzer is determined by the setting
of the INPUT TERMN Z switch. Impedance mismatch
between a signal source and the module's
in~ut
connector
causes reflections or standing waves in the interconnec-
ting transmission line. Standing waves at the input
connector may cause amplitude errors in the display and
an overall degraded performance of the analyzer. To
minimize the probability of an impedance mismatch, all
cables and transmission lines fastened to the input
connector should have the same impedance as the plug-in
module. All cables used should be of minimum length and
of good quality with connector center conductors not
worn, protruding or recessed. Degraded display caused
by impedance mismatch may be improved by selecting
the 7L5's INPUT BUFFER control.
Signal Amplitude
High amplitude signals (refer to Electrical Char-
acteristics) should not be applied to the INPUT connector.
Signals of unknown amplitude should be routed through a
series
attenuator.
If spurious or multitone
inter-
modulation signals are present in the display, or if
saturation of the mixer is suspected, select the 7L51NPUT
BUFFER. This control adds 8 dB of attenuation in series
with the input signal, and compensates with 8 dB of
amplLfication in the 7L5. If the displayed signals show little
or no amplitude change with the buffer on, the inter-
modulation is probably geing generated priortothe input.
If the displayed signals decrease in amplitude, they are
being generated within the analyzer as a result of ex-
cessive input signal amplitude.
REV. A APR 1978
Operating Instructlons-L3
2-3
Scans
by
ARTEK MEDIA
=>
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