HP 70908A, Руководство по обслуживанию

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T est 10. IF Rejection
The purpose of this verication test is to measure the DUT 21.4 MHz OUT response
corresponding to RF INPUT frequencies equal to the DUT internal IF and IF image frequencies .
(Inadequate IF rejection results in base line lift of the system.)
This is a nal test.
1. Connect the equipment as shown in the test setup illustration for this procedure .
2. Set the mainframe line switch to ON.
3. Load and run T est 10. IF Rejection. Refer to Chapter 2 for information about running the
software .
When performing this verication test, the full microwave source provides 300 MHz,
+0.5 dBm, at the RF INPUT . The local oscillator source tunes to center the RF INPUT signal,
and the calibrated spectrum analyzer stores the 21.4 MHz OUT response amplitude as a
reference .
The full microwave source tunes in sequence to the following frequencies:
21.4 MHz (last IF)
278.6 MHz (image of second IF)
321.4 MHz (second IF)
2978.6 MHz (image of rst IF)
3621.4 MHz (rst IF)
Measurements at the above frequencies are independent of the DUT 1st LO because the LO
frequency does not change . The calibrated spectrum analyzer provides a relative measurement
by subtracting the 21.4 MHz OUT response at each frequency from the reference response . A
routine compares the relative measurement to test limits . These measurements are performed
in bands 1H0, 1L0, 2L0, and 4L0.
Module V erication T ests 8-23