Agilent Technologies 8564EC Service Manual page 426

Synthesizer Section
Unlocked YTO PLL
40.Change the
Table 11-6 Voltages in FM Coil and Main Loop Drivers
Measurement Points
A14U405 pin 6
A14U322 pin 2
A14J17 pin 4
Check main coil 41.The main coil coarse and fine DACs correct any initial pretune
coarse and fine
DACs (steps
41-46)
42.Set the spectrum analyzer to the settings listed below. This sets both
43.Press
44.Place A14J23 jumper in the TEST position and turn on the spectrum
45.Verify the voltages listed in
Table 11-7 Main Coil Coarse and Fine DACs Voltages
Measurement Points
A14J17 pin 2
A14J17 pin 3
A14J17 pin 5
46.Place A14J23 jumper in the NORMAL position.
Check main coil 47.Set the spectrum analyzer to the following settings:
tune DAC (steps
47-49)
48.Place A14J23 jumper in the TEST position.
558
CENTER FREQ
0 Hz. This will change the switch setting of U326A and invert the
voltages listed in Table 11-6 on page
errors in the YTO main coil. The DACs adjust the FM-coil current to
zero before any sweep begins. Refer to function block J of A14
frequency control schematic (sheet 2 of 5).
DACs to 128 (the DAC setting range is 0 to 255).
Center frequency .................................................. 300 MHz
Span .............................................................................. 0 Hz
Trigger ......................................................... SINGLE, EXT
(with no external trigger connected)
,
SAVE PWR ON STATE
analyzer.
Center frequency ........................................................ 300 MHz
Span .................................................................................... 0 Hz
to 678.8 MHz with the SPAN remaining
558.
Voltages
+3.116 Vdc
approx. +1.5 Vdc
>+10 Vdc
and turn off the spectrum analyzer.
Table 11-7 on page
Voltages
−5 Vdc
−5 Vdc
+5 Vdc
558.
Chapter 11