Total gain can be measured by injecting the specified power into
and measuring the
total gain provided by
and
The following procedure provides a means of
troubleshooting the linear amplifiers:
1. On the HP 85623 spectrum analyzer, press
OFF, (FREQUENCY), 1
-50
MORE,
AMFTD UNITS,
and [AMPLITUDE).
2. Disconnect W27 (coax 3) from
and connect the output of a signal generator to
3. Set the signal generator controls as follows:
Amplitude
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. Simultaneously decrease the signal generator output and HP 85623 spectrum analyzer
REF LVL in 10
steps to -90
At each step, the signal displayed on the spectrum
analyzer should be within one division of the previous position.
5. If a problem exists, isolate it by comparing the actual gain of
and
with
those listed in the above gain guidelines.
6. Reconnect W27 (coax 3) to
Refer to function block P of A4 Log Amplifier Schematic Diagram (sheet 3 of 4) in the
HP 8560 E-Series Spectrum Analyzer Component Level Information.
The circuit provides a programmable video offset, with a step size of 5
from -300
to
1. On the HP 85623 spectrum analyzer, press (PRESET),
SPAN,
1
-50
(CAL), IF AD3 OFF.
2. Disconnect W27 (coax 3) from
and connect a signal generator to
3. Set the signal generator controls as follows:
Amplitude
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. Simultaneously decrease the signal generator output and HP 85623 spectrum analyzer
reference level in 10
steps down to -110
At each step, the signal displayed on the
spectrum analyzer should be close to the reference level.
5. Reconnect W27 (coax 3) to
and cycle the spectrum analyzer power. Press
STOP
when it appears.
On the HP 85623 spectrum analyzer, press
SINGLE, (CAL), and IF
.
7. The offset DAC,
pin 2, should now be at its default value of approximately
V. The voltage at
pin 3 should be approximately 0 V for a DAC output
of 2.45 V.
8. If this default offset voltage is incorrect, DAC
is the most probable cause.
IF Section 9-15
Summary of Contents for 8562E
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