g. Self-test control that energizes the self-teat
When used as part of the AN/ARN-123 Sys-
circuitry of the VOR and marker beacon receivers.
tem, the ZERO SWITCH on the rear of the
h. Automatic frequency selection of a 200-channel
ID-1347C/ARN-82 must be set to the
distance measuring equipment receiver. The DME fre-
R-1388A/ARN-82 position. If the switch
quencies are paired with the 200 VOR/LOC channels.
i. Control panel lighting, 28 vdc red (or white)
cover reads R-1388.ARN-82, the cover must
be removed, the switch underneath must be
color. The lighting system allows control of the inten-
repositioned, and the cover must be rein-
sity of the panel lighting from the aircraft master dim-
stalled in the reversed position. so that the
R-1388A/ARN-82 label is facing outward.
1-11. Description of Receiver Mount
(2) Three RMI pointers of three Azimuth Indica-
Mounting Base, Electrical Equipment MT-4834/
tors ID-250/ARN, ID-998/ASN or equivalent.
ARN-123(V) and MT4980/ARN-l23(V) are light-
(3) 400 Hz output to an omnibearing selector
weight mounting frames which provide vibration
isolation to the receiver through the use of four
(4) Voice and identification signals to aircraft
vibration isolators. The mounts are designed for
remote-located mounting and contain a holddown
c. Glideslope (GS) Receiver Section. The GS receiver
clamp to secure the receiver into place in the mount.
section receives and processes glideslope signals over
Flexible metal ground straps across each of the
the frequency range of 329.15 to 335.00 MHz; 40
resilient absorbers provide electrical ground to the
channels, with a channel spacing of 150 kHz. The
glideslope receiver section provides the outputs for the
operation of ID-1347C/RN or equivalent.
1-12. System Application
d. Marker Beacon (MB) Receiver Section. The MB
receiver section receives and processes 75 MHz marker
beacon signals and converts them into an output that
a. The airborne receiver basically consists of several
drives a single marker beacon lamp system (or optional
operational sections. The glideslope receiver section
provides the up/down deviation and flag alarm infor-
mation to drive the glideslope loads of the VOR/ILS
1-10. Description of Receiver Control
indicator (CDI) and the flight guidance systems. A
Receiver Control C-10048/ARN-123(V) or C-
VOR/LOC receiver section provides the left/right
10049/ARN-123(V) is installed in the aircraft con-
deviation, flag alarm and to/from information to drive
sole or cockpit panel. The unit is used primarily to con-
the VOR/LOC loads of the VOR/ILS indicator (CDI)
trol Radio Receiver R-2023/ARN-123(V) or
and the flight guidance systems.
R-2139/ARN-123(V) and provides the following
b. Automatic conversion of the VOR bearing pro-
vides relative bearing for driving the pointer of a radio
magnetic indicator (RMI). An audio output is also pro-
a. Power ON/OFF control.
vided for voice and identification purposes. Finally,
b. VOR/LOC audio volume control.
the marker receiver section provides a marker beacon
c. Marker beacon audio volume control (controlled
output capable of driving a standard one-lamp system
independently from the VOR/LOC audio volume con-
or, optionally, a three-lamp system. An audio output is
provided for identification purposes. Three separate
d. Marker beacon HI/LO sensitivity control.
antenna jacks (glideslope, VOR/LOC (NR), and mark-
e. GS/LOC energize function (ground) on ILS chan-
er) are provided to accept the rf inputs for each of the
f. VOR/LOC/GS frequency selection (2-out-of-5).
The glideslope and localizer frequencies are auto-
1-13. Tabulated Data
matically paired. Display of selected frequency in read-
Technical characteristics of the receiver set are listed
out window from 108.00 through 117.95 MHz in 50
in table 1-1.
Table 1-1. Tabulated Data
VOR/LOC Receiver Section:
108.00 MHz through 117.95 MHz
Number of channels
VOR: 160 channels
LOC: 40 channels
Voltage to standing wave ratio (VSWR)