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Section V
Paragraphs 5-1 t o 5-7
Model 204B
5 - 1 .
I N T R
U
I
S E C T I O N V
M A I N T E N A N C E
N .
5-2. This section provides maintenance and service
information for the Model 204B Oscillator. Required
test equipment, replacement and adjustment proce-
dures, and a troubleshooting summary
are
included
in the section. Also includedare performance checks
which verify proper instrument operation,
5 - 3 .
R E Q U I R E D T E S T E Q U I P M E N T .
5-4. Test equipment required for maintaining and
checking performance of the Model 204B is listed in
table 5-1. Equipment having similar characteristics
can be substituted for the equipment listed.
5 - 5 .
P E R F O R M A N C E CHECKS.
5-6. The performance checks verify that the Model
204B is operating normally and
is accurately cali-
brated. These checks may be used
after
maintenance
or as part of incoming quality control inspection. In
the following checks be s u r e the test equipment used
has been recently calibrated.
5-7. DIAL ACCURACY CHECK.
a.
Connect frequency counter and 600-ohm load t o
oscillator output
as
shown in figure 5-1.
b. Set Model 204B controls as follows:
R A N G E . ,
. . . . . . . . . . . . .
XI
F R E Q . .
. . . . . . . . . . . . . . .
5
AMPLITUDE.
. . . . . . . . .
MAX.
VERNIER
. . . . . . . . . .
centered
Instrument Type
Oscilloscope
Distortion Analyzer
AC Voltmeter
DC Voltmeter
Clip-On
Milliammeter
Frequency Counter
01369-3
5 2 3 2 A / S 3 2 A
FOR DIAL ACCURACY
@
2040
I
I
I
I
0 3 3 0 C/D
I
-6OOn
Figure 5-1. Test Setup f o r Dial Accuracy
or Distortion Checks
c . Set frequency counter controls
as
follows:
Function.
,
100 PERIODS AVERAGED
SENSITIVITY,
. . . . . . . . . . . .
3
DISPLAY.
maximum counterclockwise
d. Counter should read 200 i 6 milliseconds.
e.
Set FREQ. dial t o 20, counter should read 50.0
i 1 . 5 milliseconds.
Table 5-1. Required Test Equipment
Required Characteristics
Passband: d c t o 600 k c
Sensitivity: 0 . 1 volts/cm
Input Impedance: 1 megohm
Measure distortion to -40 db
Frequency Range: 5 cps to
Voltage Range: 1 mv to 5 volts
Accuracy: *l%
Voltage Range: Positive and
1 kc
600 kc
negative voltages from 100
m
to 15 volts
Input impedance: a t least 10
megohms
Range: 5 to 11 milliamperes
Accuracy: *3%
Counting Range: 5 cps to 600 kc
Accuracy: 0.03%
Us e
Waveform checking
Distortion measurement
AC voltage measurements
DC voltage measurements
Charge current
Frequency measurements
measurements
Recommended Model
@ Model 175A with
plug-in Model 1753A
@
Model 330B/C/D
@ , I Model 400H
@ Model 412A
@ Model 428A
@ Model 5232A/5532A
5-1
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