TM 11-6625-928-35
tion, the C-6533/ARC that is contained in and
nals are applied through connectors J1T and U,
part of the maintenance kit is referred to as
respectively. H o m i n g signals are applied to
comm cent No. 2.
H e a d i n g - R a d i o Bearing Indicator ID-1351/A
through connector P2 (G, fig. 5-2).
performed with the selector switch on comm cent
u. W i t h R A D I O A N T E N N A F U N C T I O N
No. 2 and COMM CONT NO. 1 set to ICS (in-
switch S1 set to HOMING LEFT, relay K2 is en-
t e r c o m ) . When HEADSETS 2 switch S7 is
ergized and relay K6 is deenergized (F, fig. 5-
placed at INTERCOM, a ground from E15 is ap-
plied through TB3-6, 5, 4, 3 and 2; COMM
connector J12 is applied to SIGNAL OUTPUT
CONT NO. 2 connector J3-M; cable CX-10893/
LEFT AND RIGHT connectors J13 and J14,
A R ; COMM CONT NO. 2 connector J1M;
respectively. The signal is applied from connec-
connector J1K; connector J3-K; closed contacts
tor J12 through connector P4; coaxial adapters
2 and 1 of switch S7; connector J3-E; and con-
CP1 (9.5 db), CP8, and CP9; attenuator AT2
nector J1E to the microphone intercom con-
(12 db); adapter CP2; and connector P9, and
trol line. Application of the ground signal to the
through terminals B1 and B2 of energized relay
unit under test enables the switching circuitry
K2 to connector J13. The signal is applied from
and the microphone amplifier in comm cent No.
connector J12 through connector P4, coaxial
2. Any audio input picked up by Headset-Micro-
adapters CP1 (9.5 db), CP4, CP5, attenuator
phone H101A/U (microphone) connected to
AT3 (15 db), adapter CP3, connector P7 and
HEADSETS 2 connector J16 is applied to comm
terminals B3 and B2 of deenergized relay K6 to
cent No. 2 microphone amplifier, and amplified
connector J14 (fig. 39). Since AT3 provides at-
and applied to the switching circuitry (contain-
tenuation 3 db greater than AT2, the signal out-
ing an isolation network) in COMM CONT NO.
put at connector J14 is 3 db lower than the sig-
1. The audio from the switching circuitry is am-
nal output at connector J13.
plified by COMM CONT NO. 1 headset simpli-
v. W i t h R A D I O A N T E N N A F U N C T I O N
fier, and can be monitored on the associated
switch S1 set to HOMING RIGHT, relay K6 is
HEADSETS 1 Headset-Microphone H-101A/U
energized and relay K2 is deenergized (F, fig.
(headset). Comm cent No. 2 microphone ampli-
fier audio, which is indicated as the interphone
PUT connector J12 is applied through the con-
l i n e signal at connector J1DD, is applied
nectors, adapters, and attenuators identically as
through COMM CONT NO. 2 connector J3-d
described in u. above, except that with the ener-
to terminal board TB11 and developed across
gization of both relays K2 and K6 reversed, the
resistor R2 on assembly Al. With COMM CONT
outputs from adapters CP2 and CP3 to SIG-
TEST switch S3 set to 1, microphone amplifier
NAL OUTPUT LEFT and RIGHT connectors
audio output from the unit under test can be
J13 and J14, respectively, are reversed and the
monitored on t h e multimeter connected to
signal output at connector J13 is 3 db lower than
the signal output at connector J14.
COMM CONT TEST OUTPUT connector J20.
2-4. Communication Control Test Circuit
formed with the selector switches on comm cent
Analysis
No. 2 under test and COMM CONT NO. 1 set
to ICS (intercom). With HEADSETS 1 switch S6
set to INTERCOM, a ground is applied from
a. The communication control tests are per-
E15 through TB3-6, 5, 4 and 3; COMM CONT
formed with the C6533/ARC under test (comm
NO. 1 connectors J1-M and K; terminals 1 and
cent No. 2) connected to COMM CONT NO. 2
2 of switch S6, and connector Jl-E to the switch-
connector J3. A l s o , the following pieces of
ing circuit of COMM CONT NO. 1 to enable
equipment are connected to the maintenance kit:
the microphone amplifier in COMM CONT NO.
one H101A/U is connected to HEADSETS 1
1. Audio applied to the microphone connected to
connector J15 through cable CX10888/U. A
HEADSETS 1 connector J15 is amplified by this
second H-101A/U is connected to HEADSETS 2
microphone amplifier. The audio output line at
connector J16 through a second cable CX-10888/
TB1-1 is 150 ohms above ground (A1R2), and
U; an audio generator is connected to COMM
the output line at TB210 is at ground. The au-
CONT TEST INPUT connector J19; and a mul-
dio output from COMM CONT NO. 1 micro-
timeter is connected to COMM CONT TEST
phone amplifier is applied through switching cir-
OUTPUT connector J20. For ease of explana-
cuit to the switching circuitry of comm cent No.
2-5
Change 3
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