Tektronix 491 Service Manual

ELECTRICAL CHARACTERISTICS (cont)
Characteristic
Performance Requirement
Supplemental Information
Dispersion
MHz/DIV RANGE
Range .2 MHz/Div to 10 MHz/Div In a 1-2-5 seauence
Accuracy
See Table 1-2
Linearity ±3% (over an 8 division display)
kHz/DIV RANGE
Range
1 kHz/Div to 500 kHz/Div in a 1-2-5 se-
quence and zero dispersion.
Accuracy
±3% of each setting
Over the ±2.5 MHz range of the IF
CENTER FREQ control. Measured over the
center 8 divisions of the graticule.
Linearity ±3% (over an 8 divisions display)
Resolution
≤1 kHz to ≥100 kHz; in 11 uncalibrated
May be coupled with the DISPERSION con-
steps.
trol or switched separately.
IF Center Frequency
Control Range”
IF CENTER FREQ
FINE
1 kHz/DIV to 500 kHz/DIV
Dispersion
≥(+ and – 2.5 MHz) ≥(+ and – 50 kHz)
0.2 MHz/DIV to 5 MHz/DIV
≥(+ and – 25 MHz) ≥(+ and – 1 MHz)
10 MHz/DIV
≥(+ and – 10 MHz) ≥(+ and – 1 MHz)
IF Attenuation
Range 0 to 51 dB
In combinations of 1, 2, 4, 8, 16 and 20 dB.
Accuracy
±0.1 dB/dB
IF GAIN Control
Range ≥50 dB
Display Flatness with IF CENTER
3 dB maximum amplitude variations from
Band 1 (10 MHz to 275 MHz) 50 MHz dis-
FREQ at 000
10 MHz to 12.4 GHz.
persion.
6 dB maximum amplitude variations from
Bands 2 through 8 (275 MHz to 40 GHz]
12.4 GHz to 40 GHz
100 MHz dispersion.
Incidental FM
IF
≤200 Hz
Typically 100 Hz. Up to 400 Hz if power
line frequency drops to 48 Hz.
IF + LO
≤300 Hz (at LO fundamental and with
phase lock operation)
Phase Lock
Internal Markers
1 MHz ±0.1% (Control next to OFF posi-
tion.)
INT REF FREQ Range
At least 1 kHz but not more than 1.3 kHz
above measured frequency with the INT
REF FREQ control counterclockwise (next to
OFF position.)
Stability; Ref. Osc.
≤1 port in 10
7
.
(Short term FM)
External Phase Lock
Reference Input
Frequency
1 MHz to 5 MHz
Voltage
1 to 5 volts peak to peak.
Display Functions
Dynamic Range
LOG
LIN
SQ LAW
Maximum Input Power
≥40 dB with 8 division display
≥26 dB with 8 division display
Instrument must be inside the dust cover.
≥13 db with 8 division display
-30 dBm for linear operation
See Fig. 2-8
+15 dBm diode mixer, power limit
1-2

Tektronix 491 Specifications

General

Brand	Tektronix
Model	491
Category	Measuring Instruments
Language	English