CHAPTER 3
FINAL TESTING
16. Purpose of Final Testing
Control
Position
The tests outlined in this section to-
gether with the adjustments in paragraphs
20
FREQUENCY dial . . . . . . . . . . . . . . .
Xl
FREQUENCY range . . . . . . . . . . . . . .
30
OUTPUT ATTENUATOR (upper) . . . . .
the performance capability of a repaired
5
OUTPUT ATTENUATOR (lower) . . . . .
equipment.
0
AMPLITUDE . . . . . . . . . . . . . . . . . .
600
IMPEDANCE . . . . . . . . . . . . . . . . . .
OFF
POWER . . . . . . . . . . . . . . . . . . . . . .
17. Test Equipment Required for Final Testing
OFF
LOAD . . . . . . . . . . . . . . . . . . . . . . .
In addition to the test equipment listed in
e. Set the front-panel controls on the
U is also required for final testing and is
spectrum analyzer as follows:
referred to as the spectrum analyzer. The
spectrum analyzer is an electronic ac volt-
meter preceded by a frequency-rejection
Control
Position
filter which is adjustable from 20 cps to
20,000 cps. The fundamental frequency of
MIN
Signal INPUT control . . . . . . . . . . . . .
the input signal to the spectrum analyzer
Frequency RANGE switch . . . . . . . . . .
Xl
is rejected by the filter section while the
20
FREQUENCY tuning dial . . . . . . . . .
total level of all remaining signals (har-
METER
Function switch . . . . . . . . . . . . . . . .
monics, noise, and distortion) is measured
.10 volt
Meter Range switch. . . . . . . . . . . . . .
by the ac voltmeter.
AF-R F selector switch . . . . . . . . . . . .
AF
OFF
Power switch . . . . . . . . . . . . . . . . . .
18. Test Setup
a. The test will be performed under the
f. Always allow at least 20 minutes for
conditions listed below and illustrated in
all equipment to reach stabilized temper-
atures before beginning any of the testing
n e c t i o n s and panel-control settings are
procedures.
made initially and modifications are made
as required.
19. Noise and Distortion Test
amplifier, and the spectrum analyzer, con-
Noise and distortion in the rf amplifier
nect the equipment as shown in figure 9.
are measured by applying an undistorted
c. Set the front-panel controls on the rf
signal into the amplifier and measuring
amplifier as follows:
any noise or distortion present in the out-
put after rejecting the input frequency with
the spectrum analyzer. When the input fre-
Control
Position
quency is rejected, the total level of all
r e m a i n i n g signals is measured by the
Power switch . . . . . . . . . .
Off
s p e c t r u m analyzer. This residual level
GAIN switch . . . . . . . . . .
40 DB
w i l l consist of random noise, line fre-
quency ripple, and harmonics of the test
signal. To test for noise and distortion,
d. Set the front-panel controls on the
connect the equipment as shown in figure
audio oscillator as follows:
17
