Chapter 6 149
L.O. Synthesizer/Reference Troubleshooting
A9 L.O. Assembly Troubleshooting
Verifying the 1st L.O. Output Power:
• Turn on the N9000A Signal Analyzer and wait for the instrument to complete
the boot up process.
• Press
FREQ, 50 MHz, SPAN, Zero Span.
• Disconnect W1 cable at J744 (see Figure 6-1).
• Connect J744 1st LO output to the RF input of the functioning spectrum
analyzer using a cable that will function up to 10 GHz.
• Press
Frequency, 3.9975 GHz, Span, 5 MHz, Peak Search on the functioning
spectrum analyzer. If the functioning spectrum analyzer has a preselector peak
or preselector centering function, perform that operation to guarantee the
preselector is optimized for the measurement.
• The analyzer marker should read 3.9975 GHz at +15 dBm ± 3dB.
NOTE If the 3.9975 GHz signal is not measuring the correct power level, the LO
assembly is the most probable cause.
Continue changing the center frequency of the CXA as per Table 6-1 on page 149
and measure the LO output expected frequency and power using the functioning
spectrum analyzer.
NOTE Perform the preselector peak or preselector centering on the functioning spectrum
analyzer if any of the expected 1st L.O. power levels are not within tolerance.
Table 6-1 1st L.O.
Center Frequency of CXA Signal
Analyzer
Expected 1st L.O. Frequency
(GHz) @A14J704
Expected 1st L.O. Power
(dBm) @A14J704
50 MHz 3.9975 +15 ± 3 dB
1.30 GHz 5.2475 +15 ± 3 dB
2.0 GHz 5.9475 +15 ± 3 dB
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