Type 491
FINE RF CENTER FREQ
Centered
PHASE LOCK Controls
Display of nominal
INTENSITY
INT REF FREQ
ON
brightness
Test Oscilloscope
Adjusted for optimum
FOCUS
and
ASTIGMATISM
Time/Cm
1 ms
display definition.
Volts/Cm
SCALE ILLUM
As desired
.005
Input Coupling
POSITION
(Horizontal
and
AC
Adjusted for a horizon-
Trigger
Int
Vertical]
tally centered sweep on
the graticule baseline
TIME/DIV
20 ms
o
36. Adjust the Wide Band Amplifier
VARIABLE
CAL
Response and Check the System Response
TRIGGER
Flatness
+
SLOPE
LEVEL
FREE RUN
NOTE
SOURCE
INT
The Type 491 response flatness and sensitivity
RANGE
MHz/DIV
is dependent on the combined response of the
DISPERSION-COUPLED
5 MHz/DIV
wide band amplifier, the bandpass filter, the low
pass filters and the RF mixer. Each circuit assem-
RESOLUTION
bly must be adjusted as part of the complete
IF ATTENUATOR dB
20 dB switch on
system, since the circuit response for each unit is
IF CENTER FREQ Controls
Midrange (000)
dependent on the impedance presented by the
VIDEO FILTER
OFF
preceding and following circuit.
VERTICAL DISPLAY
LIN
The low-pass and bandpass filters should require
GAIN
Midrange
recalibration only after circuit components have
POWER
ON
been replaced.
If recalibration is required, the
MIXER PEAKING
Manual
analyzer should be returned to Tektronix for cali-
