Technical data

Chapter 3 3-45
Adjustments and Correction Constants
High/Low Band Transition Adjustment
High/Low Band Transition Adjustment
This adjustment centers the VCO (voltage controlled oscillator) of the A12 reference
assembly for high and low band operations.
Analyzer warmup time: 30 minutes.
Required Equipment and Tools
Procedure
1. Press
to observe part of both the low and high bands on the analog bus.
2. Press
to subtract the ground voltage from
the next measurement.
3. Press
.
4. Press and observe the VCO tuning trace:
• If the left half of trace = 0 ± 1000 mV and right half of trace = 100 to 200 mV higher
(one to two divisions, see Figure 3-20): no adjustment is necessary.
• If adjustment is necessary, follow these steps:
a. Remove the upper-rear bumpers and top cover, using a torx screwdriver.
b. Adjust the VCO tune (see Figure 3-21) to position the left half of the trace to
0 ±125 mV. The variable capacitor, C85, has a half-turn tuning range if the A12
Reference Board is part number 08753-60209, and seven turns if the part number
is 08753-60357. Be careful not to overtighten and damage the seven-turn
capacitor.
c. Adjust the HBLB (see Figure 3-21) to position the right half of the trace 125 to
175 mV (about 1 to 1.5 divisions) higher than the left half.
• Refer to Chapter 7 , “Source Troubleshooting,” if you cannot perform the adjustment.
Description HP/Agilent Part or Model Number
Non-metallic adjustment tool 8830-0024
Antistatic wrist strap 9300-1367
Antistatic wrist strap cord 9300-0980
Static-control table mat and earth ground wire 9300-0797
Preset System
SERVICE MENU ANALOG BUS ON
Start 11 M/
µ
Stop 21 M/µ
Meas
S PARAMETERS ANALOG IN Aux Input
22 x1 Format
MORE
REAL
Display
DATA→MEM DATA−MEMORY
Meas
S PARAMETERS ANALOG IN Aux Input
23 x1 Marker 11
M/µ
Scale Ref .1 x1