Agilent Technologies 8720ES Service Guide

Chapter 3 3-47
Adjustments and Correction Constants
High/Low Band Transition Adjustment
High/Low Band Transition Adjustment
Required Equipment and Tools
Analyzer warm-up time: 30 minutes.
This adjustment centers the VCO (voltage controlled oscillator) of the A12 reference
assembly for high and low band operations.
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. 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.
b. 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
Preset System
SERVICE MENU
ANALOG BUS ON
Start 11 M/µ
Stop 21 M/µ
Meas
ANALOG IN Aux Input
22 x1 Format
MORE
REAL
Display
DATA→MEM
DATA−MEMORY
Meas
ANALOG IN Aux Input
23 x1 Marker 11 M/µ
Scale Ref .1 x1

Agilent Technologies 8720ES Specifications

General

Brand	Agilent Technologies
Model	8720ES
Category	Measuring Instruments
Language	English