Agilent Technologies 8590 Series Service Manual page 414

Analyzer Options and Block Diagrams
Tracking Generator 8593E, 8594E, 8595E, 8596E Option 010
If flatness is out of tolerance
The output level flatness of the tracking generator is specified at a
−1 dBm output power setting. In general, most flatness problems will
be a result of a failure in the A3A15 Tracking Generator microcircuit.
However, the PWR_LVL signal from the A10 Tracking Generator
Control assembly and the 1ST LO IN signal from the A3A14 First LO
Distribution Amplifier assembly can also contribute to flatness
problems.
1. Check the function of the PWR_LVL signal from the A10 Tracking
Generator Control assembly. Set the SRC POWER setting to a level at
which the flatness is out of tolerance. Monitor A10J1 pin 8 with a
DVM, step the center frequency setting in 100 MHz increments from
100 MHz to 2.9 GHz, and plot the voltage variation versus frequency.
A discontinuity in the plot near the frequency at which the flatness
is out of tolerance indicates a problem on the A10 Tracking
Generator Control assembly.
2. Check the flatness of the 1ST LO IN signal. Perform the LO
OUTPUT amplitude check as described in
unlevelled (TG UNLVL message displayed)."
• If the check passes, the fault is most likely in the A3A15 Tracking
Generator assembly.
• If the test fails, note the center frequency setting at which the
power level was out of tolerance and compare against the
frequencies at which the flatness was out of tolerance. Repeat the
check with the power sensor connected to the end of W41 that is
nearest the A3A15 assembly, noting the center frequency of any
out of tolerance power levels. The power level should be
+16.5 dBm ±2 dB.
If the power level is within tolerance at W41, but out of
tolerance at the LO OUTPUT connector (rear panel), and the
center frequency settings of the out-of-tolerance power levels
are close to the frequencies at which the flatness is out of
tolerance, suspect the A3A15 assembly.
If the power level at W41 is also out of tolerance, suspect
either the A3A14 First LO Distribution Amplifier or the A3A7
YTO assembly. Refer to
for 8592L, 8593E, 8594E, 8594L, 8594Q, 8595E, and 8596E
Analyzers."
3. Check all coax cables, especially semi-rigid cables. A fault in one of
these cables can cause a very-high-Q power hole.
414
"RF and LO Section
in Chapter 9.
"If the output goes
in this section.
Chapter 10