Description of Receiver Control

TM 11-2826-228-24

g. Self-test control that energizes the self-teat

NOTE

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

mer control.

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

(OBS).

isolation to the receiver through the use of four

(4) Voice and identification signals to aircraft

vibration isolators. The mounts are designed for

headphone/speaker system.

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

airframe.

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

(fig 1-3)

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

three-lamp system).

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-

functions:

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

trol).

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

nels.

corresponding receivers.

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.

kHz steps.

Table 1-1. Tabulated Data

VOR/LOC Receiver Section:

Frequency range

108.00 MHz through 117.95 MHz

Number of channels

VOR: 160 channels

LOC: 40 channels

50 kHz

Channel spacing

Antenna impedance

52 ohms

Voltage to standing wave ratio (VSWR)

6:1 maximum

1-4

Change 1