TM 11-6625-820-45
AMP TEST pushbutton switch S4 is pressed,
exact 30 increment is selected by BEAR-
it connects 27.5 volts dc to the RMI servo-
ING switch S3. RECEIVER MODEL switch
amplifier and to flag meter relay K2. The
S5 removes transformer T3 from the circuit
f l a g meter r e l a y energizes and connects
and adjusts the remaining circuits for phase
FLAG meter M2 to the RMI servoamplifier
shifting.
output of the radio receiver.
d. Resolver
Circuit. T h e
resolver transmitter circuit consists of pre-
f. Compass Simulator Circuit. C O M P A S S
cision bearing t r a n s f o r m e r s T 2 a n d T 3 ;
S I M U L A T O R DS4 simulates a magnetic
Indicator, Course ID-1347A/ARN-82 (OBS);
heading signal that is applied to the radio
RECEIVER MODEL switch S5; BEARING
receiver.
The simulated magnetic heading
This
switch S3; and BRG-OBS switch S2.
signal is also applied to Indicator, RMI ID-
circuit supplies 400-Hz bearing information
250A/ARN on the test set to drive the RMI
BRG-
to Radio Receiver R-1388A/ARN-82.
card.
OBS switch S2 selects either the OBS resol-
g. Aid Box. The aid box checks the wiring
ver or the simulated resolver comprised of
harness in an aircraft installation of Radio
transformers T2 and T3. RECEIVER MOD-
Receiving Set AN/ARN-82 or AN/ARN-82A
EL switch S5 connects transformers T2 and
and checks the control unit installed in the
T3 to form a simulated resolver and switches
test set or aircraft. It also provides a quick
the input to 400-Hz input. BEARING switch
check of the accuracy of the meters in the
S3 selects the 30 increment equivalent to
The aid box receives frequency
test set.
the OBS resolver position.
information from the control unit in the test
e. Current Measuring Circuits. TO-FROM
set or aircraft. This frequency information
m e t e r M3 connects directly to the radio
lights the lamps on the aid box in specific
r e c e i v e r and measures its to-from current.
The aid box also receives 26
DEVIATION meter M1 and FLAG meter M2
volts, 400 Hz from the test set or from the
a r e connected either to the radio receiver
aircraft. A portion of this voltage is recti-
o r to the glide-slope receiver, depending
f i e d , and then divided to specific levels.
on the position of VOR/LOC-GLIDE SLOPE
Specific levels of dc voltage are applied to
switch S1. These two meters measure the
the meter circuits in the test set or to the
deviation current and flag current from
A portion of the 26
a i r c r a f t indicators.
either receiver.
T h e FLAG meter also
volts, 400 Hz is also used to check the audio
measures the output of the RMI servoampli-
wiring.
f i e r in the radio receiver.
When SERVO
DETAILED CIRCUIT FUNTIONING
Section II.
1-3. Power Distribution Circuits
p i n s A and B, the positive side to pin A,
The test set supplies all the necessary
ground to pin B. The 115 volts, 400 cps is ap-
power connections for the operation of Radio
plied with the low side to pin C and the high
R-1388A/
Receivers
R - 1 3 8 8 / A R N - 8 2 or
side to pin D. The connection from pin A of
A R N - 8 2 or a glide-slope receiver.
The
J5 is made through fuse F1 to pin Z of connec-
o p e r a t i o n of these power circuits is des-
tor P5 of the control unit (fig. 4-9). When
cribed below.
Refer to test set schematic
the control unit power switch is in the PWR or
diagram (fig. 4-9 or 4-9.1) while reading the
TEST position, the 27.5-volt dc circuit is com-
description in a, b, and c below.
pleted in pin M or H of P5. The 27.5 volts
is then routed to TB1, tie point 18. From tie
a. The external sources of power are con-
point 18, the voltage is routed to relay K1. This
nected to J5 by Cable Assembly, Power, Elec-
voltage energizes the relay K1, and the cir-
t r i c a l CX11568/ARM92 (power cable)
C h a n g e 2 1-3
