Section V
Paragraphs 5-1 to 5-4
SECTION V
OPERATIONAL AND ORGANIZATIONAL MAINTENANCE
Sect ion VI, paragraph 6-5 for isolation of trouble and
correct ive procedure.
5-2. INTRODUCTION. The following paragraphs list
k. Connect a cathode ray oS Cilloscope to test point
the minimum standards of performance for Signal
O AUDIO OUT connector J1408, behind the louvered
Generator SG-13/ARN. When making these tests, if
access cover on the right side of the signal generator
it is found that the result is below the minimum per-
front panel.
formance standards, check all logical causes of trou-
ble (paragraph 5-10) before undertaking realignment
1. Set AUDIO SELECTOR switch to each of its nine
of the circuit. See Section VI, paragraph 6-37.
positions and check waveforms obtained as described
in Section VI, paragraph 6-13. Excessive distortion
following checks to determine the operability of the
may be an indication of a defective tube or component
in the audio chassis. Noise or ripple on the wave-
signal generator.
forms is often an indication of defective dynamotor
a. Turn SET LINE TO 21V control to OFF position.
operation. See Section VI, paragraph 6-16.
b. Connect either Power Cable Assembly CX-1095/U
or CX-1506/U to the 21V DC-29V DC connector on
the signal generator and connect the other end of the
a. Connect the signal generator through a 6-db, 53-
cable to a 21 to 29-volt power source.
ohm attenuator pad UG-528/U to an AN/ARN- 14 navi-
gation receiver equipped with omni bearing selector
c. Set METER switch to LINE position and adjust
(OBS) and Course Indicator ID-249A/ARN. See A of
SET LINE TO 21V control for a meter reading of 21
0. 5 volts.
b. Set the frequency of the signal generator and re-
d. Allow 3 minutes warm-up and set METER switch
ceiver to 114.9 mc and set NAV-GS switch to NAV.
to B+ position. Note the voltage reading on the meter.
It should be approximately 230 volts.
c. Turn on the signal generator and adjust SET LINE
TO 21V control for 21 0. 5 volts on the meter.
e. Set METER switch to CAR position and CARRIER
SET control fully counterclockwise past the click.
d. Allow the signal generator to warm up for at least
15 minutes and set METER ZERO and adjust CARRIER
f. Check the meter for a zero reading. If the meter
SET for a red line indication on the meter.
does not give a zero reading, adjust METER ZERO
control. The METER ZERO control is located behind
e. Set AUDIO SELECTOR to VOR, VOR switch to 0,
the small louvered access cover on the. right side of
and MICROVOLTS dial to 1000. Check 30% FRE-
the signal generator front panel.
QUENCY adjustment as given in Section VI, para-
graph 6-44.
NOTE
f. Adjust SET control on Course Indicator ID-249A/
ARN until the crosspointer is centered with SET con-
T h i s adjustment is not critical. The meter
trol at approximately 0 with TO-FROM indicator
may be off zero by several divisions with only
reading TO.
a small error in r-f attenuator calibration.
g. Disconnect the signal generator and substitute
g. Set MICROVOLTS control to its maximum (200K).
Modulator MD-83A/ARN modulating Signal Generator
SG-l/ARN with a standard VOR signal. See B of fig-
h. Set METER switch to CAR position and set the
ure 5-1 for connections and omit the microammeter.
meter to the red line with CARRIER SET control at
Do not change the setting of SET control on Course
each MEGACYCLES control position of its outer knob
Indicator ID-249A/ARN.
l-me steps from 135.5 down to 108.5 mc.
h. Set the SG-l/ARN output level for 500 microvolt
i. Set the outer knob of MEGACYCLES control to
and vary the MD-83A/ARN VOR dial setting until the
108 me and red line the meter with CARRIER SET
crosspointer is again centered with TO-FROM indi-
control at each tenth megacycle step of the inner knob
cator reading TO.
of MEGACYCLES control.
i. Note the MD-83A/ARN VOR dial reading and sub-
j. If the meter cannot be set to the red line, faulty
tract the SG-13/ARN VOR switch setting (in this case.
operation of the r-f chassis is indicated. Refer to
0) to obtain the VOR error.
