HP 8904A - Page 269

Adjustments
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Model 8904A
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R3J6 OR fl10J6
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Adjustment 4
SHARP CUTOFF LOW-PASS FILTER
SOURCE OUTPUT
Description
The frequency response of the Sharp Cutoff Low-Pass Filter is adjusted so that three stopband notches
are centered at three specific frequencies.
If the notches for this elliptic-function filter are set correctly,
then the filter’s flatness in the passband and
its rejection throughout the stopband should be adequate.
The adjustment is made to the A3 or A10 Output Assembly. If the instrument has only one Output
Assembly (A3), the adjustments are made only
to it. If the instrument has Option 002 with two Output
Assemblies
(A3 and AlO), adjustments are made to one or both assemblies. Accessing A3 will require
extra disassembly.
If the instrument has Option 006 (balanced output), adjustments are made on the
A3 assembly with the balance transformer disconnected.
A
Equipment
Network Analyzer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP 3577A
NOTE
A spectrum analyzer with a tracking generator that covers 0 to 5 MHz is also
suitable.
He 8904R NETWORK
MULTIFUNCTION ANALYZER
SYNTHESIZER
fl3J5 OR fll0J5
i
INPUT
Figure 5-1. Sharp Cutoff Filter Adjustment Test Setup
Procedure
1. Turn the Multifunction Synthesizer’s LINE to OFF and unplug the power cord. (It can remain
unplugged throughout the test.) Remove the instrument’s bottom cover.
2. If the instrument has Option 002 (a second output assembly) and Output 1 (the output from the
A3 Output Assembly) is to be adjusted, move the A10 Output Assembly out
of the way. (Refer
to the disassembly procedure in Figure
5-4.)
3. If the instrument has Option 006 (balanced output), disconnect the coax cable from A3J400
(OUTPUT HIGH) at the front edge of the A3 assembly. In the steps that follows, when a
reference is made to the
OUTPUTS 1 HIGH connector, make the connection to A3J400 instead.
5-8 Adjustment 4
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