TM 11-6625-596-45
f.
Connect a vtvm to terminals 1A3J1-A and
control 1A4R14 to obtain a CAL line reading on meter
1A3J1-K.
1A4M1 and note the reading on the vtvm.
g. Data shall be taken in 100-Hertz
d. Turn METER SENSITIVITY CALIBRATE
increments from 300 Hertz to 1, 000 Hertz, and in 250-
control 1A4R14 counterclockwise to obtain a read-ing of 30
Hertz increments from 1, 000 Hertz to 5, 100 Hertz.
on meter 1A4M1. This action shall produce a change of -6
dB +0.5 in the reading on the vtvm.
h. The data obtained in g above shall show a
constant gain of 60 dB (.3V) +2 over the cited frequency
e. Adjusting 1A4R14 to obtain a reading of 40 on
range.
1A4M1 produces a change of -3 dB *0.5 in the reading on
the vtvm. Adjusting 1A4R14 so that the needle of 1A4M1
6-10.
rests on the left-hand edge of the green area produces a
a. Connect the equipment as directed in para-
change of -1.5 dB +0.5 in the reading on the vtvm.
graph 6-9, except connect the distortion analyzer to the
output.
f.
Adjusting 1A4R14 to obtain a reading of 70 on
1A4M1 produces a change of +5 dB +.5 in the reading on
b. Measurements may be made and data
the vtvm.
taken simultaneously with those olf the frequency re-
g. Adjusting 1A4R14 to obtain a reading of 60 on
1A4M1 produces a change of +3 dB +0.5 in the reading on
c.
Total harmonic distortion shall not exceed
the vtvm.
2 percent over the frequency range specified in par-
agraph 6-9g.
h. Adjusting 1A4R14 so that the needle of 1A4M1
rests on the right-hand edge of the green area produces a
6-11.
Meter Amplifier Gain Test
change of +1.5 dB +0.5 in the reading on the vtvm.
a. Set the controls as
indicated in
paragraph
6-13. Circuit Tests Requirements
a.
General. Set front panel controls as specified in
b. Depress NOISE GEN ADJ button 1A4S6A
LEVEL A control 1A4AT1 set to 10, LEVEL B control
1A4R12 to obtain a CAL line reading on meter 1A4M1.
1A4AT2 to 8, VALUE C control 1A4AT3 to 6, VALUE D
control 1A4AT4 to 9, and NOISE GENERATOR switch
c.
1A4S3 to LOAD.
LOAD.
b. Positioning Microphone. Position the coupler
d. Set METER SENSITIVITY CALIBRATE
microphone directly over and touching the screen of the,
control 1A4R14 fully clockwise.
driver unit.
e. Measure the input voltage (rms) between
c. Preliminary Adjustments. Turn power switch
1A3J2-S and 1A3J2-P (ground).
1A4S8 to on and perform the following:
(1) Depress NOISE GEN ADJ button 1A4SA.
f.
Measure the output voltage (rms) between
(2) Adjust NOISE GENERATOR CALI-
1A3J2-D and 1A3J2-P (ground).
BRATE control 1A4R12 for a CAL line reading on 1A4M1.
(3) Depress METER ADJ button 1A4S6.
g.
The minimum gain shall be 62 dB.
(4) Adjust METER SENSITIVITY CALI-
BRATE control 1A4R12 for a CAL line reading on 1A4M1.
6-12.
Meter Scale Test
a. Connect the vtvm leads to 1A3J2-D and
d.
Varistor Test.
1A3J2-P (ground).
(1) Depress VARISTOR button 1A4S6F.
(2) Meter 1A4M1 shall read on green scale.
control 1A4R12 to obtain a CAL line reading on meter
e.
Earphones Test.
1A4M1.
(1) Depress EARPHONES button 1A4S6G.
(2) Meter 1A4M1 shall read on green scale.
c.
Adjust METER SENSITIVITY CALI-BRATE
6-4