TM 11-6625-828-45
(5) Set the test set OMNI TRACK switch
with the test set MODULATION switch set first to 90- and
to 180 and set the course checker SELECTOR switch to
then to 150-.
180 to measure the 180-degree angle of the test set.
Check that the course checker DEGREES COURSE
the vacuum tube voltmeter to the filter unit, connect the
ERROR meter indicates 0 0.2 degree.
filter unit to the test set DEMOD output connector, and
(6) All other 30-degree phase angles of
proceed as follows:
the test set can be checked only in a system using Radio
(1) Set the test set MODULATION switch
Set, Receiving AN/ARN-30E. Compare the resulting
and the filter unit switch to 30- and adjust the test set 30-
indicator readings to the track angles of another rf signal
MOD control to obtain a green line indication on the 7%M
generator modulated by the audio signal generator. The
meter. Use a screwdriver to adjust the test set DEMOD
system error tolerance should not be greater than + 2.0
output until the vacuum tube voltmeter indicates exactly
degrees.
0.03 volt.
(7) Set the test set OMNI TRACK switch
(2) Adjust the test set 90- MOD and 150-
to 0 and set the test set MODULATION switch to OMNI.
MOD controls, as required, to obtain a red line indication
on the test set %M
Vary the input line voltage between 105 volts to 125 volts
meter. Set the test set
to the test set and check that the course indication on the
MODULATION switch to AMP LOC (), set the filter unit
course checker does not change by more than 0.2
switch to 90-, and check that the vacuum tube voltmeter
degree. Reset the line voltage to 115 volts.
indicates between 0.019 and 0.021 volt.
(3) Repeat (2) above with the filter unit
i.
90-/150- Phase Test.
switch set to 150- and check that the vacuum tube
voltmeter indicates between 0.019 and 0.021 volt.
(4) Set the filter unit switch to 90- and
NOTE
adjust the test set DEMOD output until the vacuum tube
Allow the test set to warm up for at least
voltmeter indicates exactly 0.02 volt. Set the test set
2 hours before proceeding with this test.
MODULATION switch to AMP LOC i. Check that the
vacuum tube voltmeter indication is as many db (within
(1) Set the test set MODULATION switch
+0.1 db) below 6 db (0.02 volt) with the filter unit switch
to 90- position and adjust the test set 90- MOD control to
at 90- as it is above 6 db with the filter unit switch at 150-
obtain a red line indication on the test set %M meter.
. The amount above and below the 6 db value must be
(2) Set the test set MODULATION switch
1.9 to 2.1 db.
to 150- and adjust the test set 150- MOD control as
(5) Set the test set MODULATION switch to
require to obtain a red line indication on the test set %M
AMP LOC ). Check that the vacuum tube voltmeter
meter.
indication is as many db (within + 0.1 db) above 6 db
(3) Connect the audio, signal generator
(0.02 volt) with the filter unit switch at 90- as it is below 6
30- VAR 0 output connector to the ac X amplifier of the
db with the filter unit switch at 150-. The amount above
oscilloscope and connect the test set DEMOD output
the 6 db value must be 1.9 to 2.1 db.
connector to the ac Y amplifier of the oscilloscope.
(4) Set the test set MODULATION switch
8). Connect the oscilloscope to the test set DEMOD
to AMP
LOC , set the audio signal generator
output connector, adjust the oscilloscope controls to
FUNCTION SELECTOR switch to SPECIFIC SIG, set
display a 1000-cycle waveform, and proceed as follows:
the audio signal generator SPECIFIC SIGNAL
(1) Set the test set MODULATION switch
SELECTOR switch to 30- VAR 0, and adjust the audio
to 1000- and vary the 1000- MOD control over the range
signal generator PHASE ANGLE SELECTOR indicator
of 20 to 80 percent modulation as indicated on the test
until the top dial indicates 180and the lower dial
set % M meter.
indicates 09.
(2) Check that the oscilloscope waveform
(5) Adjust
the
PHASE
ANGLE
is free of distortion and varies in amplitude as the test set
SELECTOR indicator until a equally phased waveform I
1000-
MOD
control
is
adjusted.
is obtained (fig. 3- 9).
(6) Rotate the test set 90- MOD and 150-
MOD controls fully clockwise and check that the
test set '%M. meter indicates at least 24 percent
Change 1 5-4
