Agilent Technologies 89410A Operator's Manual page 181

Using the Agilent 89411A Downconverter
In some of the situations listed above, the combination of input signal
level, attenuation, and IF section employed may result in a IF level at the
89411 input which is too large. The conversion gain switch on the rear of
the 89411A should be set to provide a lower amount of conversion gain in
this case. To obtain optimum performance from the 89411A, its conversion
gain should be set, if possible, to give −15 dBm at the 89411A front panel
output for the largest measured signal. In some cases the amplitude may
be too small and you should lower the range setting of the 89411A to
obtain the best dynamic range.
Example If you have an RF signal level of +10 dBm into the MMS spectrum analyzer
configured as in (1) above, you would probably want to use the following setup.
The MMS spectrum analyzer's reference level is set to +10 dBm resulting in 20
dB of RF attenuation and the signal at the 70902A AUX 21.4 MHz OUT port is
−15 dBm. The conversion gain of the 89411A should be set to 0 dB and the
signal provided to the 89411A is −15 dBm, as desired.
For more complete information on MMS system components, refer to the
operation manual supplied with your system, and to the Modular
Measurement System catalog.
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