Agilent Technologies 8564EC, Service Manual

Page: 477 / 512

616 Chapter 12
RF Section
A14 Frequency Control Assembly
positive 3.9107 GHz 1st IF offset between the desired harmonic of the
YTO frequency and the center frequency. This signal is 0.5 V/GHz of
tuned frequency and is available at the rear panel. The output can be
set for 0.50 V/GHz or 0.25 V/GHz.
1. On the spectrum analyzer, press
PRESET
, and set the controls to the
following settings:
Start frequency .............................................................. 0 Hz
Stop frequency ....................................................... 26.5 GHz
2. On the spectrum analyzer, press
AUX CTRL
,
REAR PANEL
, and
V/GHz .25 .50
so that .50 is underlined.
3. Monitor the rear panel LO SWP | FAV OUTPUT with an
oscilloscope. The waveform should resemble Figure 12-5 on page
617 .
4. Set the spectrum analyzer controls as follows:
Start frequency ........................................................... 8 GHz
Stop frequency .......................................................... 10 GHz
5. Monitor A14J15 pin 1 with an oscilloscope. The waveform should
resemble Figure 12-7 on page 618 .
6. If the ramp is not correct, confirm the operation of the Main Coil
Tune DAC and Sweep Generator. Refer to “Unlocked YTO PLL” in
Chapter 11 .
7. Set the spectrum analyzer to the following settings:
Center frequency .......................................................... 5 GHz
Span ................................................................................. 0 Hz
8. Monitor A14J15 pin 3 with a DVM. For a center frequency of 5 GHz,
the voltage should measure
−
1.33 Vdc
±
0.2 Vdc. Use the following
formula to calculate the voltage:
EQUATION {\rm V\sb {(J15\ pin\ 3)]] = {\rm {-0.25\ V \over
GHz}\ (freq\ in\ GHz)+offset} EQUATION
Offset voltage:
−
0.98 V in bands 0 and 5
−
0.078 V in bands 1, 2, and 3
+0.98 V in band 4