HEADQUARTERS OH-58A, Техническое руководство

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TM 55-1520-228-10
Change 11 3-17
d. Continuous tone could also indicate a cryptoa-
larm. If this tone occurs at any time other than as indi-
cated in paragraph 3-34.c above, equipment failure
may have occurred.
T o clear this tone, repeat the “Load-
ing Procedures” in TM 11-5810-262-OP. If this tone con-
tinues, have the equipment checked out by
mainte-
nance personnel.
e. Single beep, when RCU is not in TD (Time
Delay), can indicate any of three normal conditions:
(1) Each time the PTT button is pressed when
the KY-58 is in C (cipher) and a filled storage register is
selected, this tone will be heard. Normal use (speaking)
of the KY-58 is possible.
(2) When the KY-58 has successfully received
a cryptovariable, this tone indicates that a “good” crypto-
variable is present in the selected register.
(3) When you begin to receive a ciphered mes-
sage, this tone indicates that the cryptovariable has
passed the “parity” check, and that it is a good variable.
f. A single beep, when the RCU is in TD (Time
Delay) occurring after the “preamble” is sent, indicates
that you may begin speaking.
g. A single beep, followed by a burst of noise after
which exists a seemingly “dead” condition indicates that
your receiver is on a different variable than the distant
transmitter. If this tone occurs when in cipher text mode:
Turn RCU FILL switch to the CNV and contact the trans-
mitter in PLAIN text and agree to meet on a particular
variable.
SECTION II. NAVIGATION
3-35. DIRECTION FINDER SET (AN/
ARN-89).
3-36. DESCRIPTION – DIRECTION FINDER
SET(AN/ARN-89).
The direction finder set (ADF) AN/ARN-89 (figure 3-9)
is used in conjunction with gyromagnetic compass and
intercommunications systems. ADF bearing information
is indicated on the heading-radio bearing indicator (fig-
ure 3-10). The bearing pointer displays either the ADF
bearing or the VOR bearing depending on the position
selected on the RMI BRG PNTR switch. The ADF set
operates in the 100 to 3,000 KHz frequency range and
is used to receive continuous wave (cw) or amplitude
modulated (am) radio frequency signals. The three
modes of operation for the ADF set include automatic
homing in the COMPASS mode, manual homing in the
LOOP mode, and as a communications receiver in the
ANTenna mode. A beat frequency oscillator is included
to provide an audible indication for identification and
tuning and is activated by the CW switch. The radio set
control unit is marked ADF RCVR and is mounted in the
center section of the instrument panel. Antenna loca-
tions are shown in figure 3-1.
3-37. CONTROLS AND FUNCTIONS – DI-
RECTION FINDER SET (AN/ARN-89).
Refer to figure 3-9.
3-38. OPERATING PROCEDURES – DI-
RECTION FINDER SET (AN/ARN-89).
a. COMPASS Mode.
(1) Function selector COMP.
(2) Frequency – Select. Tuning may be accom-
plished with function selector in COMP, ANT, or LOOP
positions; however, less noise is encountered in the
ANT position.
(3) AUDIO – Adjust.
(4) TUNE meter – Select. Tune for maximum up
deflection of needle.
(5) CW VOICE TEST switch – TEST then re-
lease.
(6) Observe ADF needle indications.
b. LOOP Mode.
(1) Function selector – LOOP.
(2) AUDIO – Adjust.
(3) CW VOICE TEST switch – CW.
(4) LOOP switch – Move left and right as re-
quired to obtain aural null.