TM 11-6625-596-45
resistance reading on the vtvm at SW position #1 is
Control
Position
exactly equal to the reading at SW position #2.
DIAL SPEED CALI-
Fully counterclockwise.
BRATE control 1A4R17.
DIAL BREAK CALIBRATE
Fully counterclockwise
above shall be 25 ohms -+10 percent.
control 1A4R18.
NOISE GENERATOR switch
DRIVER.
6-7.
Driver Distortion Test
1A4S3.
TEST CONDITION switch
COUPLER.
a.
Connect the equipment as shown in figure
1A4S9.
MICROPHONE LOAD switch
OFF.
1A4S1.
RECEIVER LOAD switch
OFF.
0.96 volt rms at 300 Hertz as measured on the vtvm.
1A4S2.
Maintain this voltage throughout the test.
MICROPHONE CURRENT
OFF.
control 1A4R1.
c. Data shall be taken in 100-Hertz
LEVEL A and B controls
Any position.
increments from 300 Hertz to 1, 000 Hertz, and in 250-
1A4AT1 and 1A4AT2.
Hertz increments from 1, 000 Hertz to 5, 100 Hertz.
VALUE C and C controls
Any position.
1A4AT3 and 1A4AT4.
NOTE
d. The total harmonic distortion of
the unit
Changes in these position as required
over the frequency range cited in c above shall not
for each individual test will be specified
exceed 5 percent.
in the test sequence. Leave all controls
and switches in the position of the
6-8.
Coupler-Microphone Distortion Test
previous test unless otherwise specified.
a.
Connect the equipment as shown in figure
6-5.
Sound Source Supply Test
b. Set LEVEL and VALUE controls 1A4AT1
b. Turn power switch 1A4S8 to appropriate on
through 1A4AT4 to 0, TEST CONDITION switch 1A4S9
position (115v or 230v), turn NOISE GENERA-TOR
CALIBRATE control 1A4R12 until the needle of meter
to LOAD.
1A4M1 is at the CAL line.
c.
Terminate the microphone output in 7
c. Read the level on the sound-level meter.
ohms.
The reading shall be 103 dB minimum corresponding to
28 microbars of sound pressure and shall not exceed
104 dB.
control 1A4R12 fully counterclockwise.
sufficient to drive the distortion analyzer.
f.
Data shall be taken in 100-Hertz
increments from 300 Hertz to 1, 000 Hertz, and in 500-
Hertz increments from 1, 000 Hertz to 5, 100 Hertz.
Figure 6-1. Sound source supply test setup.
g. The data obtained in f above shall not
6-6.
exceed 5-percent distortion over the cited frequency
range.
a.
Connect the equipment as shown in figure
NOTE
The coupler-microphone and driver
distortion tests may be conducted
b. Set the audio oscillator at a frequency of 1,
simultaneously.
The
combined
000 Hertz and 1.0 volts rms.
resultant total distortion shall not exceed
5 percent.
c.
6-2