Agilent Technologies 89410A Operator's Manual page 180

Using the Agilent 89411A Downconverter
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If the RF/microwave analyzer is an MMS system:
Several possibilities exist here, depending on the combination of RF and IF
modules present. In addition, the frequency reference connections are
more involved. The conversion gain of the system depends on which IF
module supplies the 21.4 MHz IF signal, and the attenuator setting of the
RF section. The nominal conversion gains in the section that follows do
not include effects of frequency response of the RF section. The
conversion gain is generally smaller at higher frequencies, especially for the
RF sections with preselectors (e.g. 70905, 70906, and 70908). For
simplicity, the stated conversion gains assume the attenuation of the RF
section is set to 0 dB. However, to prevent damage to the mixer in the RF
section, it is recommended that the attenuation be set to at least 10 dB.
You should make sure the reference level and attenuator settings are
appropriate for your measurement. The reference level should be set to a
level equal to or larger than the largest signal you expect to measure.
At this time you should also set the following parameters:
Set the center frequency to the frequency of your signal and the frequency
span to 0 Hz. The reference level should be adjusted so that the signal lies
within 1 division of the top of the screen. You should also set the sweep
time to a large value (e.g. 100 sec.) to prevent the sweep retrace from
causing unwanted transients in your measurement.
The frequency reference module (70310A) should be ordered with the
standard configuration (i.e. do not order opt, 002 which deletes the
ovenized oscillator), unless there will always be a good externally supplied
reference signal present.
1.
If the system contains a 70902A and a 70903A IF section, the signal flow is
normally from the RF section to the 70903A, then to the 70902A. The 21.4 MHz
OUT port on the 70903A drives the 70902A, and the AUX 21.4 MHz OUT port on
the 70902A drives the 89411A IF input. The conversion gain of the system is
nominally −5 dB in this case.
2.
If the system contains only the 70902A IF section, the RF section is connected
to the 70902A, and the AUX 21.4 MHz OUT port of the 70902A drives the IF
input of the 84911A. The conversion gain is nominally −5 dB.
3.
If the system contains only the 70903A, the RF section drives 21.4 MHz input,
and its 21.4 MHz OUT port drives the 84911A input. The conversion gain is
nominally +5 dB.
4.
If the system contains only an RF section (such as the 70904A) then the output
can be taken from it directly to the 89411A input. The conversion gain of the
RF section is nominally 5 dB.
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