HP 8560A

6. Sampling Oscillator Adjustment
Procedure
1. Set the HP 8560A m switch to off and disconnect the line power cord. Remove the
analyzer cover and fold down the Al5 RF and Al4 Frequency Control assemblies. Prop
up the Al4 Frequency Control assembly. Reconnect the line power cord and set the (LINE)
switch on. Connect the equipment as illustrated in Figure 2-8.
2. Press (PRESET] on the HP 8560A and set the controls as follows:
CENTER FREQ
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .661 MHz
CF STEP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...30 MHz
SPAN
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Hz
3. Set the HP 3456A controls as follows:
FUNCTION
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DCVOLTS
RANGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lOV.MANUAL
Phase Detector Bias Adjustment
4. Connect the negative DVM lead to A15J200 pin 6, and the positive lead to A15J200 pin
5. Adjust A15R453 PHASE DET BIAS for a DVM reading of +1.8 f0.02 Vdc.
Sampling Oscillator Fine-Tune Adjustment
6. Connect the positive DVM lead to A15J200 pin 13. Leave the negative DVM lead
connected to A15J200 pin 6.
7. Adjust A15C210 VCO RANGE for a DVM reading of t5.18 &to.05 Vdc.
Note
If A15C210 cannot be adjusted for 5.18 Vdc, perform the coarse-tune
adjustment located at the end of this procedure.
Power and Sampler Match Adjustments
8. Connect the negative DVM test lead to A15J400 pin 6, and the positive DVM test lead to
A15J400 pin 1.
9. Press (-1 and set the HP 8560A center frequency to 511 MHz. This sets the
sampling oscillator to 288 MHz.
10. Adjust A15ClOO SMPL MATCH 1 to peak the voltage displayed on the DVM.
Note
If a peak cannot be obtained, the sampling oscillator power might be too low.
Adjust A15R237 SMPL PWR ADJ clockwise one-eighth turn and repeat step
10. If necessary, continue increasing the oscillator power, but do not allow the
displayed voltage to exceed +3 Vdc when peaked.
11. Adjust A15R237 SMPL PWR ADJ to set the displayed voltage to to.9 f0.2 Vdc.
2-34 Adjustment Procedures