Agilent Technologies 8564EC Service Manual page 425

31.As the signal generator frequency is increased to 76 MHz, the
32.Set the signal generator to the following settings and repeat step 30.
33.If the voltage monitored in step 30 is correct with a 0 dBm output
34.Place A14J23 jumper in the NORMAL position and reconnect W32
Check YTO FM 35.To troubleshoot the YTO FM coil driver, refer to step 6 of "1st LO
coil driver and
main loop error
36.Steps 36 through 40 verify that the YTO-loop error voltage is
voltage driver
(steps 35-40)
37.Remove A14J23 jumper and connect a dc power supply to A14J23
38.Verify the nominal test-point voltages listed in
39.Change the input voltage to −7.5 volts and re-verify that the voltages
Chapter 11
voltage at A14J17 pin 1 should change from approximately +12 V to
−12 V.
Frequency .................................................................. 56 MHz
Amplitude ................................................................ −15 dBm
but not with −15 dBm output, suspect the limiting amplifier function
block AE.
to A14J501.
Span Problems (2.01 MHz to 20 MHz)."
reaching the FM coil. The main loop error voltage driver has a gain
of either 1.5 or 15; the analyzer firmware controls the gain during
the locking process. The error voltage is read by the ADC on the A3
interface assembly. U324D calibrates out any offsets from true
ground. A14U326A inverts the sense of the YTO loop to lock the
YTO on lower sampler-sidebands (YTO frequency (sampler
frequency × sampler harmonic)). The fractional N frequency
indicated in the FREQ DIAGNOSE menu will be negative when
locking to lower sidebands. Refer to function blocks E, M, and N of
A14 frequency control schematic (sheet 2 of 5) in the 8560 E-Series
Spectrum Analyzer Component Level Information binder.
Set the spectrum analyzer to the following settings:
Center frequency ..................................................... 300 MHz
Span ................................................................................. 0 Hz
pin 2. Connect ground to A14J23 pin 3. Set the dc power supply to
+7.5 Vdc.
558.
listed in Table 11-6 on page 558
polarity.
Table 11-6 on page
are the same except for a change in
Synthesizer Section
Unlocked YTO PLL
557