High/Low Band Transition Adjustment - HP 8753D Option 011 Service Manual

High/Low Band Transition Adjustment

Required Equipment and Tools
Non-metallic adjustment tool
Antistatic wrist strap
Antistatic wrist strap cord
Static-control table mat and earth ground wire
Analyzer warm-up time:
This adjustment centers the VCO (voltage controlled oscillator) of the A12 reference assembly
for high and low band operations.
1. ress
PRESET 5 SYSTEM 5
to observe part of both the low and high bands on the analog bus.
2. ress
PARAMETER
MEAS 5
DATAMEM DATA-MEMORY
DISPLAY 5
measurement.
3. ress
PARAMETER
MEAS 5
4. ress
SCALE REF 5 . 5 x 5
If the left half of trace = 0 1000 mV and right half of trace = 100 to 200 mV higher
(one to two divisions), no adjustment is necessary. See Figure 3-21.
If the 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 3-22) to position the left half of the trace to 0 125
mV. This is a very sensitive adjustment where the trace could easily go o of the
screen.
c. Adjust the HBLB (see Figure 3-22) 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 \Source Troubleshooting" if you cannot perform the adjustment.
Figure HIGHLOW here.
Figure 3-21. High/Low Band Transition Adjustment Trace
3-48 Adjustments and Correction Constants
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0 minutes.
ERVICE MENU ANALOG BU ON
ANALOG IN Aux Input
to subtract the ground voltage from the next
ANALOG IN Aux Input
and observe the VCO tuning trace:
H
H
H
H
START 5 5 M/ 5 STOP 5 2 5 M/

MORE REAL
22 5 x 5 FORMAT 5
23 5 x 5 MARKER 5 5 M/
3/21/106 15:11
/N 8830-0024
/N 9300-1367
/N 9300-0980
/N 9300-0797
5

.
5

RAFT