Model 8904A Adjustments
Adjustment
5
SINE
X/X
COMPENSATION
Description
The output of the Multifunction Synthesizer
in
connected directly to a thermal converter. The output
of the converter
(a
dc voltage proportional to the
rms
input) is read on a digital voltmeter.
A
reference
is determined with the Multifunction Synthesizer set to
1
kHz
at
0.7
Vrms into
50R.
The frequency
is then changed to
550
kHz
and the Sine
X/X
Compensation is adjusted for the same reading as
at
1
kHz.
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.
Equipment
Digital Multimeter
................................................................
HP 3478A
Thermal Converter.
....................................
HP 11050A or Ballentine Labs 1395A-1
The thermal converter
is
susceptible to burnout
if
more than
1
Vrms
is
applied
to its input. Be careful when changing the frequency of the Multifunction
Synthesizer that
the
amplitude does not inadvertently exceed
1
Vrms
(a
displayed setting of
2.8
V
on the Multifunction Synthesizer).
Procedure
1.
Perform Adjustment 4,
Sharp
Cutoff
Low-Pass
Filter
first.
2.
On the Multifunction Synthesizer, press
SHIFT
PRESET.
After the instrument presets, key in
fl
(Channel
Config.)
NEXT
SHIFT
FLOAT
1
OFF
AMPTD
2
V
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.
4.
Connect the ac input of the thermal converter to the Multifunction Synthesizer's
OUTPUTS
1
HIGH
output for the A3 Output Assembly
or
OUTPUTS
2 HIGH
for the A10 Output Assembly.
Connect the dc output of the thermal converter to the input of the voltmeter. Refer to Figure 5-3.
Adjustment
5
5-11
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