Table 9-3. Sweep Width Settings
Sweep Width Sweep Time Res BW RANGE MA1
MAO
Adjusted
A4U105
A4U105
A4U105
Pin6
Pin2 Pill5
20
kHz
5 ms
10 kHz
+5
v
ov ov
10
kHz
10 ms
3 kHz
+5 v
ov
+5 v
4
kHz
30 ms
1
kHz
+5 v
+5v
ov
2 kHz
15 ms
300 Hz
+5
V
+5 v +5 v
Automatic IF Adjustment
The spectrum analyzer performs an automatic adjustment of the IF Section whenever needed.
The cal oscillator on the A4 assembly provides a stimulus signal which is routed through the
IF during the retrace period.
The A3 Interface assembly measures the response using its analog-to-digital converter (ADC).
The spectrum analyzer turns the cal oscillator off during a sweep.
When IF ADJ is ON, the spectrum analyzer readjusts part of the IF circuitry during each
retrace period to readjust the IF completely every 5 minutes.
Automatic IF adjustment is performed upon the following conditions:
n Power on: (unless STOP
ALIGN
is pressed). The IF parameter variables are initialized to
values loaded in program ROM and all possible IF adjustments are made. If STOP
ALIGN
is
pressed, the adjustment is halted.
n If
REAXGI?
LO
&
IF is selected: All possible IF adjustments (and LO adjustments) are
made with the most recent IF parameter variables used as the starting point.
w
If FULL IF
AD3
is selected: All possible IF adjustments are made with the most recent IF
parameter variables used as the starting point. (FULL IF ADJ is located in the (CAL) menu.)
. If ADJ
Cm
IF STATE is selected: All amplitude data and some resolution bandwidths
are adjusted. The bandwidths adjusted are a function of the currently selected resolution
bandwidth setting.
H
Between sweeps: IF ADJ must be set to ON. When IF ADJ is OFF, an A is displayed along
the left side of the graticule.
If a FULL IF ADJ sequence cannot proceed beyond the amplitude portion, check the output
of the cal oscillator on the A4 assembly as follows:
1. Disconnect cable W52 (coax 9) from
A5J4.
Connect cable W52 to the input of a second
spectrum analyzer.
2. Set the second spectrum analyzer center frequency to 10.7 MHz and the reference level to
-30
dBm.
3. On the spectrum analyzer under test, press
FULL IF ADJ and observe the display of the
second spectrum analyzer
IF Section 9-9