HP 70908A, Service Manual

Page: 212 / 335

T est 02. Low Frequency Flatness < 10 MHz
The purpose of this test is to measure the DUT frequency response for input signals from 200
Hz to 10 MHz . It complements T est 01. Flatness . It is only a verication and does not calculate
and store atness correction data in the DUT EEROM.
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 02. Low Frequency Flatness < 10 MHz. Refer to Chapter 2 for
information about running the software .
When performing this verication test, the level generator steps 10 MHz to 200 Hz at the DUT
RF INPUT . At each frequency step , the local oscillator source tunes to produce a response
at the DUT 21.4 MHz OUT . The calibrated spectrum analyzer measures the 21.4 MHz OUT
amplitude . The measured amplitude at each frequency is normalized to the amplitude at
10 MHz input by subtracting the amplitude measured at 10 MHz from each amplitude reading.
A routine compares test limits with atness relative to the 10 MHz amplitude and then to
peak-to-peak atness found by subtracting the lowest amplitude reading from the highest
amplitude reading.
Module V erication T ests 8-7