Main Coil Coarse And Fine Dacs Voltages - HP 8562E Service Manual

Check main coil coarse and fine DACs (steps 41-44)
41. The main coil coarse and fine DACs correct any initial pretune 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 Al4 frequency control schematic.
42. Set the spectrum analyzer to the settings listed below. This sets both DACs to 128 (the
DAC setting range is 0 to 255).
Centerfrequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz
Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Single.EXT
43. Press (SAVE),
44. Place jumper A14J23 in the TEST position and turn on the spectrum analyzer.
Check main coil tune DAC (steps 4549)
45. Verify the voltages listed in Table 11-9.
46. Place jumper A14J23 in the NORMAL position.
47. Set the spectrum analyzer to the following settings:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz
48. Place jumper A14J23 in the TEST position.
49. Measure the output of the main coil tune DAC
function block E of Al4 frequency control schematic.
Table 11-8. Voltages in FM Coil and Main Loop Drivers
Measurement Points
and turn off the spectrum analyzer.
Table 11-9. Main Coil Coarse and Fine DACs Voltages
Measurement Points
pin
2
pin 3
pin 5
Voltages
0 Vdc
(with no external trigger connected)
Voltages
-5 Vdc
-5 Vdc
pin 3) with a DVM. Refer to
Synthesizer Section 11-29