HP 8562E, Service Manual

Page: 403 / 482

Table 11-8. Voltages in FM Coil and Main Loop Drivers
Measurement Points
Voltages
pin 6 Vdc
pin 2
0 Vdc
pin 4
Vdc
Check main coil coarse and fine (steps 41-44)
41. The main coil coarse and fine correct any initial pretune errors in the YTO main
coil. The adjust the FM-coil current to zero before any sweep begins. Refer to
function block J of Al4 frequency control schematic.
42. Set the spectrum analyzer to the settings listed below. This sets both to 128 (the
DAC setting range is 0 to 255).
Centerfrequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Single.EXT
(with no external trigger connected)
43. Press (SAVE), and turn off the spectrum analyzer.
44. Place jumper in the TEST position and turn on the spectrum analyzer.
Check main coil tune DAC (steps
45. Verify the voltages listed in Table 11-9.
Table 11-9. Main Coil Coarse and Fine Voltages
Measurement Points
Voltages
pin
2 -5 Vdc
pin 3 -5 Vdc
pin 5
Vdc
46. Place jumper in the NORMAL position.
47. Set the spectrum analyzer to the following settings:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48. Place jumper in the TEST position.
49. Measure the output of the main coil tune DAC pin 3) with a DVM. Refer to
function block E of Al4 frequency control schematic.
Synthesizer Section