TM 11-5826-225-35
parallel to the longitudinal axis of the air-
craft and two are perpendicular to this line.
Each set of physically parallel coils is connect-
ed in parallel to provide maximum gain. T h e
antenna provides the basic information neces-
sary to determine the direction of the received
signals. Refer to paragraph 15 for a discus-
sion on how this is accomplished. An RF in-
ductance compensator is required between the
loop antenna and the receiver to compensate
for the deflection of arriving radio signals by
the fuselage of the aircraft. For this reason the
RF inductance compensator is selected during
installation. Figure 115 is a schematic dia-
gram for a typical RF inductance compensator.
1-25. Direction Finder Control
C-6899/ARN-83
Detailed functioning of the control unit is
contained in section IV of this chapter. Section
1 24, Antenna AS-1863/ARN83
IV describes interunit circuit functioning. Fig-
Antenna AS1863/ARN83 consists basically
of four ferrite-cored coils, two of which are
control unit.
Section IV. INTERUNIT CIRCUIT FUNCTIONING
selection in the receiver is accomplished
126.
General
through the interunit autopositioner circuit
Interunit functions are included in this sec-
illustrated in figure 512. The function and
tion to provide an understanding of certain
range-switching mechanism in the receiver
interrelations between the control unit and re-
consists of a motor-driven, multisection switch
ceiver in various types of operation. Such
combining both function and range selection
knowledge will enable maintenance personnel,
into one ganged switch. Since the control unit
when troubleshooting, to sectionalize troubles
function switch has three operating mode posi-
to a defective unit and, in some cases, to local-
tions (ADF, ANT, and LOOP) requiring three
ize trouble to a defective part within a unit.
frequency range positions of range switch
Circuit functioning of components in the con-
S304 for each operating mode, it requires nine
trol unit and receiver is discussed only where
positions of the receiver motor-driven stwitch
individual circuits are interconnected in a com-
to select all operating modes and frequency
mon circuit,
ranges. In the receiver, switch wafers S1-M
through S1R are 12-position switches having
1-27. Function and Frequency Range
nine effective switch positions over three sec-
Selection
tors or quadrants of the switches (leaving
three blank positions). Each switch wafer is
divided into three equal areas or sectors with
Change 1 1-25
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