HP 8560A, Руководство по обслуживанию

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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 I of Al4 Frequency Control Schematic (sheet 2 of 5).
42. Set the HP 8560A to the settings listed below. These set both to 128 (the DAC
setting range is 0 to 255).
C E N T E R F R E Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TRIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..CONT
43. Verify the voltages listed in Table 10-14.
Table 10-14. Main Coil Coarse and Fine Voltages
Measurement Points Voltages
pin 2
-7.0 Vdc
pin 3
-7.0 Vdc
pin 5
+8.1 Vdc
44. Place jumper A14J23 in the NORMAL position.
Note The All YTO has an initial pretune accuracy of MHz. However, when
the Roller Oscillator frequency is MHz this is changed to MHz.
If the Roller Oscillator frequency is MHz, the accuracy is changed to
MHz. This is done by changing the Main Coil Coarse DAC to keep
the Sampler IF within the acquisition range of the YTO Loop. When dealing
with the Sampler IF and an unlocked YTO, the same frequency differences
apply to the Sampler IF.
45. Set the HP 8560A to the following settings:
C E N T E R F R E Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Hz
46. Place jumper A14J23 in the TEST position.
47. Measure the output of the Main Coil Tune DAC pin 3) with a DVM.
Refer to function block C of Al4 Frequency Control Schematic (sheet 2 of 5) in the
Component-Level Information binder.
48. If the HP 8560A’s center frequency is 300 MHz, the voltage at pin 3 should
measure -3.35 V V. The voltage may also be determined from the following
equation:
V = -(lst LO Frequency-2.95
49. The voltage at pin 2 should measure 3.4 V Vdc. This represents a current
setting the YTO to approximately 2.95
Synthesizer Section 1