Agilent Technologies 8590 Series Service Manual page 416

Analyzer Options and Block Diagrams
Tracking Generator 8593E, 8594E, 8595E, 8596E Option 010
If harmonic/spurious outputs are too high
Harmonic and spurious outputs may be generated by A3A15 itself or
may be present on either the 600 MHz drive or 1st LO drive signal.
There is a direct relationship between spurious signals on the 1st LO
and spurious signals on the tracking generator output. There is a
five-to-one relationship between spurious signals on the 600 MHz drive
and the spurious signals on the tracking generator output. For example,
if the 600 MHz signal moves 1 MHz, the tracking generator output
signal will move 5 MHz. This is due to the multiplication in the
pentupler.
1. If the Harmonic Spurious Responses performance test failed,
The 1st LO typically has a higher harmonic content than the tracking
NOTE
generator output. For the purposes of this check, it is the variation in
harmonic content versus frequency which is important.
If the variation of the harmonic level of the 1st LO versus frequency
tracks the harmonic level variation of the tracking generator output,
repeat
nearest A3A15. If there is little variation in the 1st LO harmonic level
between the LO OUTPUT connector and W41, and the relative
variation in harmonic level tracks with the tracking generator output
harmonic level, suspect either the A3A14 First LO Distribution
Amplifier assembly or the A3A7 YTO assembly.
If the harmonic level variation of the 1st LO versus frequency does not
track the harmonic level variation of the tracking generator output,
suspect A3A15.
2. If sidebands are present at the same frequency offset at every output
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connect another analyzer, such as an 8566A/B, to the 8594A LO
OUTPUT connector. Set the 8594A to each frequency as indicated in
the performance test, with the SPAN set to 0 Hz. The 1st LO
frequency will be 3.9214 GHz greater than the center frequency
setting. Use the 8566A/B to measure the level of the second and
third harmonics of the 1st LO signal.
step 1 while measuring the 1st LO signal at the end of W41
frequency, use another analyzer to check the spectral purity of the
1st LO and the 600 MHz drive signals. When checking the 1st LO,
the 8594A must be set to zero span. The 1st LO frequency will be
3.9214 GHz greater than the center frequency setting. A 1 MHz
sideband on the 1st LO will appear as a 1 MHz sideband on the
output signal.
To verify that the 600 MHz drive or 1st LO signal is responsible for
the sidebands, substitute a clean signal for the 600 MHz drive or 1st
LO signal. If the sidebands on the output disappear when using the
clean signal, the substituted signal was responsible for the
sidebands.
Chapter 10