TB 9-6625-1998-35
11. Distortion
a. Performance Check
(1) Connect OUTPUT to audio analyzer INPUT high.
(2) Set ATTENUATOR switch to X10V and OUTPUT CONTROL for 1.0 on
OUTPUT RMS (VOLTS RMS) meter.
(3) Set FREQ RANGE MULTIPLIER switch and frequency dial to positions listed
in table 5 and measure distortion at each frequency. Audio analyzer will indicate within
limits specified.
b. Adjustments. No adjustments can be made.
Table 5. Distortion
Test instrument
Audio analyzer indications
FREQ RANGE
MULTIPLIER
settings
AN/URM-127
AN/URM-127A
switch settings
X1
20
< 1%
< 2%
X10
100
< 1%
< 2%
X100
200
< 1%
< 2%
X1K
100
< 1%
< 2%
NOTE
Do not perform power supply check if all other parameters are
within tolerance.
a. Performance Check.
Connect digital multimeter between test points listed in
table 6. If digital
multimeter does not
indicate within
limits specified, perform b below.
b. Adjustments.
Perform corresponding adjustments as
listed in
table 6.
Table 6. Power Supply
indications
(V dc)
Adjustments
Model
Test points
Min
Max
(R)
AN/URM-127
46
48
AN/URM-127A
48
52
11