Specifications

Account for a calibration performed with loss and later removed for the
measurement.
Problem NOISE FIGURE OVERLOAD error message displayed:
Solution DUT has too much gain (typically >30 dB). Use an attenuator to reduce
the input power to Port 2.
Try usinga5dBENRNoise Source.
Problem Significant difference between Internal and External Noise Source mea
-
surement:
Solution 1. Check for the presence of the Internal ENR Extension Table file
(Nxxxxx.EXT).
2. Check the Nxxxxxx.nfx External ENR Extension Table file if addi
-
tional length is inserted between Port 1 (Internal ENR Extension
Table reference plane) and DUT.
3. If the External ENR Extension Table does not exist, it can be gener-
ated internally by measuring the S-parameters of the extension ca-
ble, creating a “s2p” file and then changing the file extension to “nfx”
by using an external Personal Computer.
Problem Noise Figure response contains irregular discontinuities:
Solution Try the Narrow Bandwidth Measurement Mode.
Perform a Back-end Attenuator calibration (refer to Chapter 5).
NOTE
The irregularity may be caused by contamination (other signals) in the
environment and the spurious response of the DUT.
Problem Noise Figure response contains too many ripples:
Solution Turn Noise Figure Averaging on.
Try using a 15 dB ENR Noise Source.
NOTE
The problem may be caused by the very poor matches of DUT or a
passive DUT. The second stage calculations are less accurate when
measuring Noise Figure for a passive device.
Problem Fails the Noise Figure Assurance Check:
Solution Perform a Back-end Attenuator calibration (refer to Chapter 5).
Replace the Option Module.
TROUBLESHOOTING NOISE FIGURE MEASUREMENT PROBLEM
MS462XX MM 6-25