Keysight N9038A, Service Manual, Page: 389 / 745

Keysight N9038A MXE Service Guide 389
Optional Assemblies
A25 Wideband Analog IF Assembly Troubleshooting
2400 MHz Reference Input Verification
The A25 Wideband Analog IF assembly uses a 2400 MHz reference signal that
comes to J301 via coaxial cable W51 from the A16 Reference assembly J718.
Before attributing a fault to the A25 Wideband Analog IF assembly the
presence of this reference signal will need to be verified, as the assembly
cannot function properly without it. The following procedure will verify this.
1. Remove the instrument dress cover (MP24) and top brace (MP10). Refer to
Chapter 18, “Assembly Replacement Procedures” for instructions on
removing these covers
2. Turn the instrument on and allow it to complete its boot up process and
initial alignments
3. Referring to Figure 14-1 , disconnect coaxial cable W51 from A25 J301
4. Connect the loose end of W51 to a spectrum analyzer input to verify the
signal frequency and amplitude
5. Tune the spectrum analyzer to 2400 MHz with a span of 1 MHz
6. Measure the signal level using the peak search function of the spectrum
analyzer. The level of the 2400 MHz signal should be +10.0 dBm, ±4.0 dB,
as shown in Figure 14-3 .
Figure 14-3 2400 MHz Reference Input Verification
7. If the signal level measured is correct the reference input signal going to
the A25 Wideband Analog IF assembly is of the correct level. If not, refer to
Chapter 9, “Reference Assembly” and determine why the signal level
coming from it is not correct