Tektronix 491 Maintenance Manual page 5

The Type 491 Spectrum Analyzer is a wide band,
general purpose portable spectrum analyzer with an RF
center frequency range from 10 MHz to 40 GHz. The ana-
lyzer displays signal amplitude as a function of frequency
for a selected portion of the
played along the horizontal
amplitude on the vertical axis
Characteristic
RF Center
Frequency Range
CW Sensitivity
( S + N = 2 N )
Dial Accuracy
Band and
Scale RF CENTER FREQUENCY
10-275 MHz
A-1
B-2 275-900 MHz
3 800-2000 MHz
C-4 1.5-4.0 GHz
5 3.8-8.2 GHz
6 8.0-2.4 Ghz
7 12.4-18.0 GHz
8 18.0 -26,5 GHz
!
26.5-40.0 GHz
D I S P E R S I O N / D I V
Setting
1 0 M H z
5 MHz
2 MHz
1 MHz
.5 MHz
.2 MHz
SECTION 1
CHARACTERISTICS
spectrum, Frequency i dis-
S
axis (dispersion) and signal
of a self-contained system.
ELECTRICAL CHARACTERISTICS
Performance
10 MHz to 40 GHz—See Table 1-1
See Table 1-1
Within ± (2 MHz +1% of dial reading)
I
TABLE 1-1
Minimum CW
S e n s i t i v i t y ( S + N = 2 N )
1 kHz RESOLUTION
–100 dBm
–110 dBm
–105 dBm
–110 dBm
–100 dBm
–95 dBm
–90 dBm
–80 dBm
–70 dBm
TABLE 1-2
Accuracy
—
± 3 % ( ± 0 . 3 M H z / D i v )
± 3 % ( ± 0 . 1 5 M H z / D i v )
± 5 % ( ± 0 . 1 M H z / D i v )
±7% (±70 kHz/Div)
±10% (±50 kHz/Div)
±15% (±30 kHz/Div)
The following electrical characteristics apply at an ambient
temperature of 25° C (±5°C) after an initial warmup period
of approximately 20 minutes.
Requirement
I
IF CENTER FREQ central at 000, FINE IF
CENTER FREQ control and FINE RF CENTER
FREQ controls centered.
100 kHz RESOLUTION
–80 dBm
–90 dBm
–85 dBm
–90 dBm
-80 dBm
–75 dBm
–70 dBm
-60 dBm
-50 dBm
Over the ±25 MHz of the IF Center FREQ control ex-
cept the 10 MHz/DIV position (± 10 MHz). The DIS-
PERSION CAL adjust can be reset to improve the ac-
curacy at a specific IF CENTER FREQ control setting
by using the front panel 1 MHz CAL MARKERS OUT as
a calibrated signal.
Measured over the center 8 divisions of the graticule.
S u p p l e m e n t a l I n f o r m a t i o n
Supplemental
Information
50 Ω source impedance.
All voltages are RMS.
Remarks
1-1