HP 70908A, Service Manual

Page: 266 / 335

T est 29. Noise Figure
The purpose of this verication test is to measure DUT gain and noise as a function of
frequency . Noise gure is a function of DUT noise and DUT gain at a particular frequency .
A noise gure within a specied limit ensures acceptable DUT noise contribution to system
displayed average noise level.
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 29. Noise Figure . Refer to Chapter 2 for information about running the
software .
When performing this verication test, the local oscillator source connects to the DUT 1st LO
IN. The synthesized source provides 300 MHz, 0 dBm, at the 300 MHz IN. The 21.4 MHz OUT
of the DUT connects to the input of the noise gure meter . The output of the noise source
connects to the RF INPUT of the DUT . DUT input attenuation is 0 dB .
The local oscillator source tunes to 1st LO frequencies corresponding to RF INPUT test
frequencies . At the test frequencies and at the reference frequency , the test collects DUT gain
and noise gure data. The DUT gain at the reference frequency is required for determination
of displayed average noise level.
Module V erication T ests 8-61