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PERFORMANCE TESTS
MODEL
8559A
PERFORMANCE
TESTS
4
-
13.
RESIDUAL
FM
SPECIFICATION:
Less than 2 kHz peak
-
to
-
peak for a time interval 10.1 second; less than 2 kHz peak
-
to
-
peak in a 180
-
series
display mainframe with
220/240 line voltage.
DESCRIPTION:
This test measures the inherent short
-
term instability (residual FM) of the LO system in the spectrum analyzer.
A stable signal (supplied by a comb generator) is applied to the spectrum analyzer input and slope
-
detected with
the linear portion of the 10
-
kHz bandwidth filter in zero span (fixed
-
tuned receiver
-
see Figure
4
-
6).
Variations
of the spectrum analyzer's LO frequency (residual FM) can be measured as an amplitude shift on the CRT
display (1 kHz
=
0.7 major division with LIN Amplitude Scale).
SPECTRUM
ANALYZER
COMB
GENERATOR
ADAPTER
P
P
ADAPTER
FIGURE
4-5.
RESIDUAL FM TEST SETUP
EQUIPMENT:
Comb Generator
........................................................
HP 8406A
Adapter, Type N (m) to BNC
(f)
(2 required)
...............................
HP 1250
-
0780
PROCEDURE:
1.
Set equipment controls as follows:
Spectrum Analyzer:
FREQUENCYBANDGHz
..................................................
.01-3
TUNING
..............................................................
3.000GHz
FREQUENCY SPAN/DIV
..................................................
100 kHz
RESOLUTIONBW
........................................................
lOkHz
INPUT ATTEN
.............................................................
30 dB
REFERENCELEVEL
....................................................
-20dBm
REFLEVELFINE
..............................................................
0
Amplitudescale
..............................................................
LIN
SWEEPTIME/DIV
........................................................
AUTO
SWEEPTRIGGER
.....................................................
FREERUN
.....................................................................
ALTIF OFF
.................................................................
SIGIDENT OFF
BLCLIP
....................................................................
OFF
VIDEOFILTER
.............................................................
OFF