TM 11-6625-2709-40
measures its to-from current, DEVIATION meter M1
BRG-OBS switch S5. These circuits are used to shift
and FLAG meter M2 are connected to either the radio
the phase of the 30-Hz reference signal obtained from
receiver or the GS/MB
receiver, depending on the
the receiver being tested. Either the OBS resolver or
position of IND TEST switch S6. These two meters
precision hearing transformer T2 performs the phase
measure the deviation current and flag current from
shifting; BRG-OBS switch S5 selects the one to be
either receiver.
used. The OBS resolver shifts the phase of the 30-Hz
reference signal anywhere from 0 to 360 degrees;
percision bearing transformer T2 shifts the phase of
the signal in precise 30-degree increments. The exact
f. Compass Simulator Circuit. The COMPASS
30-degree increment is selected by BEARING switch
SIMIULATOR indicator simulates a magnetic
S4. MODE switch S3 removes transformer T3 from
heading signal that is applied to the radio receiver.
the circuit and adjusts the remaining circuits for
The simulated magnetic heading signal is also
phase shifting.
supplied to RMI Indicator ID-250A/ARN on the test
set to drive the RMI card.
d. Resolver Transmitter Circuit. The resolver
transmitter circuit consists of precision bearing
g. Aid Box. The aid box checks the wirimg harness
in an aircraft installation of Radio Receiving Set
transformers T2 and T3, Course Indicator ID-
AN/ARN-82B and checks the control unit installed in
1347C/ARN-82 (OBS), MODE switch S3, BEARING
the test set or aircraft. It also provides a quick check
switch S4, and BRG-OBS switch S5. This circuit
of the accuracy of the meters in the test set. The aid
supplies 400-Hz bearing information to the receiver
box receives frequency information from the control
being tested. BRG-OBS switch S5 selects either the
unit in the test set or aircraft. This frequency infor-
OBS resolver or the simulated resolver comprised of
mation lights the lamps on the aid box in specific
transformers T2 and T3. MODE swith S3 connects
combinations. The aid box also receives 26 volts, 400
transformers T2 and T3 to form a simulated resolver
Hz from the test set or from the aircraft. A portion of
and switches the input to 400-Hz input. BEARING
this voltage is rectified and then divided to specific
switch S4 selects the 30-degree increment equivalent
levels. Specific levels of dc voltage are applied to the
to the OBS resolver position.
meter circuits in the test set or to the aircraft indi-
caters. A portion of the 26 volts, 400 Hz is also used
e. Current Measuring Circuits. TO-FROM meter
to check the audio wiring.
M3 connects directly to the radio receiver and
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