TM-55-1680-351-10

TM-55-1680-351-10
This copy is a reprint which includes
pages from Changes 1 thru 3
TM 55-1680-351-10
DEPARTMENT OF THE ARMY
TECHNICAL MANUAL
OPERATOR'S MANUAL
FOR
SRU - 21/P
Army Vest, Survival
(NSN 8465-00-177-4819) (Large)
(NSN 8465-01-174-2355) (Small)
This manual supersedes TM55-8465-215-10, 9June 1970
"Approved for public release;
distribution is unlimited."
HEADQUARTERS
DEPARTMENT OF THE ARMY
22 APRIL 1987
TM 55-1680-351-10
PRECAUTIONARY DATA
Personnel performing instruction Involving operation procedures and
practices which are included or implied in this manual shall observe the
following instructions. Disregard of warnings can cause serious injury or
death.
WARNING
SIGNAL KIT, FOLIAGE PENETRATING. Do not point a loaded launcher
at personnel. Personnel distress flares burn at a temperature of
approximately 5000°F. and can cause serious bums, or death.
WARNING
The lensatic compass has a luminous radioactive dial and must be
handled with care to prevent damage. When a lens or dial is cracked or
damaged, do not handle compass without gloves and dispose of
immediately by burying compass underground. Do not throw a damaged
compass in a stream or lake. When exposed skin is contaminated by the
luminous dial of compass, cleanse skin immediately with soap and water.
Refer to TB55-1500-31425 for any additional information.
a/(b blank)
TM 55-1680-351-10
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This is a reprint of change 1.
CHANGE
No.
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}
HEADQUARTERS
DEPARTMENT OF THE ARMY
WASHINGTON, D. C., 4 NOVEMBER 1988
ARMY VEST
SURVIVAL
NSN 8465-00-177-4819 (LARGE)
NSN 8465-01-174-4819 (SMALL)
TM 55-1680-351-10,22 APRIL 1987,
is changed as follows:
1. Remove and insert pages as indicated below. New or changed
text material is indicated by a vertical bar in the margin. An illustration
change is indicated by a miniature pointing hand.
2.
Remove pages
Insert pages
2-11 and 2-12
2-17 and 2-18
2-11 and 2-12
2-17 and 2-18
Retain this sheet in front of manual for reference purposes.
TM 55-1680-351-10
C1
By Order of the Secretary of the Army:
Official:
CARL E. VUONO
General, United States Army
Chief of Staff
WILLIAM J. MEEHAN II
Brigadier General, United States Army
The Adjutant General
DISTRIBUTION:
To be distributed in accordance with DA Form 12-31, -10 and CL
requirements for all Fixed and Rotary Wing Aircraft.
TM 55-1680-351-10
C2
Remove pages
2.
Insert pages
2-5 and 2-6
2-6
2-13 and 2-14
2-13 and 2-14
A-1/A-2
A-1/A-2
Retain this sheet in front of manual for reference purposes.
By Order of the Secretary of the Army:
Official:
CARL E. VUONO
General, United States Army
Chief of Staff
PATRICIA P. HICKERSON
Colonel, United States Army
The Adjutant General
DISTRIBUTION:
To be distributed in accordance with DA Form 12-31-E, block no.
1368, -10 and CL maintenance requirements for TM 55-1680-351-10.
This copy is a reprint.
TM 55-1680-351-10
C2
CHANGE
NO. 2
}
HEADQUARTERS
DEPARTMENT OF THE ARMY
WASHINGTON,D.C., 17 JUNE 1991
Operator's Manual for SRU-21/P
ARMY SURVIVAL VEST
NSN 8465-00-177-4819 (LARGE)
NSN 8465-01-174-2355 (SMALL)
TM 55-1680-351-10, 22 April 1987,
is changed as follows:
1. Remove and insert pages as indicated below. New or changed
text material is indicated by a vertical bar in the margin. An illustration
change is indicated by a miniature pointing hand.
Remove pages
Insert pages
i and ii
1-1 through 1-5/
1-6
2-3 and 2-4
i and ii
1-1 through 1-5/
1-6
2-3/2-4
TM 55-1680-351-10
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CHANGE
HEADQUARTERS
DEPARTMENT OF THE ARMY
WASHINGTON, D.C., 30 APRIL 1993
NO. 3
OPERATOR'S MANUAL
FOR
SRU-21/P
ARMY VEST, SURVIVAL
(NSN 8465-00-177-4819)(LARGE)
(NSN 8465-01-174-2355)(SMALL)
DISTRIBUTION STATEMENT
distribution is unlimited.
A:
Approved
for
public
release;
TM 55-1680-351-10, 22 April 1987,
is changed as follows:
1. Remove and insert pages as indicated below. New or changed text
material is indicated by a vertical bar in the margin. An illustration change
is indicated by a miniature pointing hand.
TM 55-1680-351-10
C3
2.
Remove pages
Insert pages
iii/(iv blank)
2-1 and 2-2
2-13 through 2-16
iii/(iv blank)
2-1 and 2-2
2-13 through 2-16
Retain this sheet in front of manual for reference purposes.
By Order of the Secretary of the Army:
GORDON R. SULLIVAN
General, United States Army
Chief of Staff
Official:
MILTON H. HAMILTON
Administrative Assistant to the
Secretary of the Army
04054
DISTRIBUTION:
To be distributed in accordance with DA Form 12-31-E, block no.
1368, requirements for TM 55-1680-351-10.
TM 55-1680-351-10
TECHNICAL MANUAL
HEADQUARTERS
DEPARTMENT OF THE ARMY
WASHINGTON, D.C.
Operator's Manual For
SRU-21/P
ARMY SURVIVAL VEST
(NSN 8465-00-177-4819) (Large)
(NSN 8465-01-174-2355) (Small)
REPORTING ERRORS AND
RECOMMENDING IMPROVEMENTS
You can help improve this manual. If you find any
mistakes, or if you know of a way to improve the
procedures, please let us know. Mail your letter or DA
Form 2028 (Recommended Changes to Publications)
direct to Commander, US Army Aviation Systems
Command, ATTN: AMSAV-MC, 4300 Goodfellow Blvd.,
St. Louis, Mo. 63120-1798. A reply will be furnished to
you.
Change 2
i
TM 55-1680-351-10
Paragraph
CHAPTER
1.
INTRODUCTION
Section
I.
General
Scope ..........................................
Reporting of equipment
manual improvements..............
Description and Data
Description ..................................
Tabulated data .............. ..............
Section
II.
CHAPTER
2.
OPERATING INSTRUCTIONS
Section
I.
Preparation
Donning and fitting of vest ...........
Alteration .....................................
Deleted
Use of Components
General ......................................
Light, marker, distress
SDU-5E, w/flash guard
AGR-FGIB .............................
Signal kit, foliage
penetrating ..............................
Mirror, mark 3, type 1
emergency signaling ................
Receiver-Transmitters,
Radio, ARG-RT-10,
and AN/PRC-90.......................
Revolver .38 caliber,
special......................................
Tourniquet....................................
Compass, lensatic .....................
Section
Section
II.
III.
Change 2
ii
Page
1
1-1
2
1-2
3
4
1-2
1-3
5
6
2-1
2-3
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2-6
11
2-7
12
2-8
13
2-9
14
2-11
15
16
17
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2-12
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TM 55-1680-351-10
Paragraph
Survival kit, ind.,
tropical ...........................................
DELETED
Knife, pocket .......................................
Bag, water, size B ...............................
DELETED
Blanket, combat casualty ................
Whistle, ball, plastic ...........................
Fire starter, magnesium bar ..............
Assembly instruction
sheet ..............................................
TM 5598465-351-10 ............................
Suggested Publications.......................
CHAPTER
3.
RADIO SET AN/PRC-90
Section
I.
Controls and Instruments
Equipment Damage and
Warnings . ......................................
Operator Controls ...............................
Operation Under Usual
Conditions
Preflight Procedures .........................
Modes of Operation ............................
Operational Siting and
Operating Procedures .................
Stopping Procedure ............................
Operating and Storage
Limitations . ....................................
Operation Under Unusual
Conditions
Operation in Desert and
Tropical Areas ................................
Operation in Maritime, High
Altitude, or Rainy Areas .................
Recognition and Identification of Jamming ..............................
Section
Section
II.
III.
APPENDIX A. REFERENCES ................................................
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2-13
20
21
2-15
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24
25
2-16
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2-17
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3-21
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3-21
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TM 55-1680-351-10
CHAPTER 1
INTRODUCTION
Section I. GENERAL
1.
Scope
This manual, issued expressly for the aircrewmember, is the official
document for the vest survival kit used with Army aircraft. The purpose of
this manual is to supply the aircrewmember with the latest information on
kit contents and instructions on their intended uses. Packing instructions,
drawing, and this manual are stored in right, inside pocket of vest.
1-1
TM 55-1680-351-10
2.
Reporting of Equipment Manual
Improvements
Reporting of errors, omissions, and recommendations for improving this
publication by the individual user is encouraged. Reports should be
submitted on DA Form 2028 (Recommended Changes to Publications)
and forwarded direct to Commanding General, U.S. Army Aviation
Systems Command, (AVSCOM), ATTN : AMSAV-QRF, 4300
Goodfellow Blvd., St. Louis, MO 63120-1798.
Section II. DESCRIPTION AND DATA
3.
Description
This vest survival kit is manufactured from raschel knit nylon cloth with a
lacing adjustment at center back and a slide fastener at center front.
Storage pockets are sewed to vest for storage of survival components.
Vest can be worn with body armor, personnel parachute, and underarm
life preservers. Proper donning of the vest with the above equipment is
illustrated.
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1-2
TM 55-1680-351-10
4.
Tabulated Data
SRU-2l /P Vest Kit.
(1) Weight
(2) Dimensions
7 1/2lb
7 x 7 x 12 in. (folded)
NOTE
Holster, revolver is optional. If the vest
is to be equipped with holster, revolver,
it should be fitted to individual prior to
installing on vest. Knife, hunting
sheathed is optional item. If installed,
must be positioned as shown.
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1-3
TM 55-1680-351-10
Figure 1. SRU-21 P with Components
Change 2
1-4
TM 55-1680-351-10
INDIVIDUAL SURVIVAL VEST SRU-21/P
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
SURVIVAL KIT, INDIVIDUAL, VEST TYPE SRU-2 IIP
(LARGE)
SURVIVAL KIT, INDIVIDUAL, VES'I'TYPE SRU-2 I/P
(SMALL)
. VEST, SURVIVAL, INDIVIDUAL (LARGE)
. VEST, SURVIVAL, INDIVIDUAL (SMALL)
.. TOURNIQUET, NON-PNEUMATIC, CAMOUFLAGE
DELETED
.LIGHT MARKER, DISTRESS SDU-5/E
..BATTERY, BA-1574/U
..FLASHGUARD, AGR-FGIB
. SURVIVAL KIT, INDIVIDUAL, TROP. TACT. AIRCREW
. MIRROR, EMERGENCY SIGNALING
. FIRESTARTER, AVIATION SURVIVAL, MAGNESIUM
. BLANKET, COMBAT CASUALTY
. INSECT REPELLENT, I OZ
. BAG, DRINKING WATER STORAGE: 3 PT
. KNIFE, POCKET
FIRESTARTER, AVIATION SURVIVAL, SPARK LITE
. CARTRIDGE, CALIBER .38 SPECIAL BALL M41
. CARTRIDGE, CALIBER .38 SPECIAL TRACER M41
. WHISTLE, BALL: PLASTIC O.D. W/LANYARD
. SIGNAL KIT, FOLIAGE PENETRATOR
W/LAUNCHER AND 7 FLARES L-1 19
. HOLSTER, REVOLVER, NYLON .38 CAL OR 9 MM
. KNIFE, HUNTING W/SHEATH AND
SHARPENING STONE (OPIIONAL ISSUE)
. ASSEMBLY INSTRUCTION SHEET AND DD FORM 1574
TAG
. RADIO SET, ANIPRC-90, SURVIVAL
.. BATTERY, BA-1568/U (FOR PRC-90 RADIO)
. COMPASS, MAGNETIC UNMOUNTED, LENSATIC
.FASTENER, SLIDE, INTERLOCKING: 15 IN. LG
Change 2
1-5/(1-6 blank)
TM 55-1680-351-10
Figure 2. SRU-21/P Vest with Underarm Flotation
2-0
TM 55-1680-351-10
CHAPTER 2
OPERATING INSTRUCTIONS
Section I. PREPARATION
5.
Donning and Fitting of Vest
a.
Body armor is donned.
b.
LPU-10/P life preservers over body armor, underarm.
c. Vest is donned and LPU-10/P life preservers are U pulled through
each arm pit opening to hang over vest, underarm.
d. Personnel parachute is donned last and is adjusted to be as free
as possible from interference from components pockets on vests.
Change 3
2-1
TM 55-1680-351-10
Figure 3. SRU-21/P Vest
2-2
TM 55-1680-351-10
6.
Alteration
When the vest is worn over front and rear body armor, there is a
possibility that the vest will be too small. When this problem arises,
alteration may be accomplished per TM 55-1680-317-23&P. The alteration allows vest to be adjusted to fit anyone wearing body armor with the
front and back plate installed.
Do not leave the drawstrings exposed during
flight operations as they might become caught
or hooked while trying to evacuate the aircraft.
Change 2
2-3/(2-4 blank)
TM 55-1680-351-10
Section II. DELETED
Section III. USE OF COMPONENTS
10. General
This section gives instructions for the use of all components contained in
the vest.
All data on pages 24 and 2-5 have been deleted.
Change 2
2-6
TM 55-1680-351-10
11. Light, Marker, Distress SDU-5E, W/Flash
Guard AGR-FG1B
Figure 4. Distress Marker Light with Flashguard
The distress marker light when activated, produces an intermittent flash of
light visible for a minimum distance of 5 miles and will operate completely
2-7
TM 55-1680-351-10
submerged in water. Also provided is a flash guard which may be used for
directional aiming of the light. Flash guard is equipped with a blue lens so
that flashes can be distinguished from gun fire flashes.
NOTE
Use flash guard with the distress marker light
when in a combat zone. Check the marker light
for operation before departing on a mission.
12. Signal Kit, Foliage Penetrating
WARNING
Do not point a loaded launcher at personnel.
Personnel distress flares burn at a temperature
of 5000° F, and can cause serious burns or
death.
The signal kit, M-201, consists of a rocket launcher and seven red flares.
Flares will reach an altitude of 1100 feet when fired and have a burning
time of 9 seconds. Flare is visible for 2 or 3 miles in daylight
2-8
TM 55-1680-351-10
and for 10 miles at night. Remove flares from plastic retainer and insert
the same end into launcher. Hold projector firmly in hand, point straight up
and pull knurled knob down with thumb. Release trigger with a sharp
sudden motion.
After flare is installed in launcher, do not pull
back on knurled knob unless you are ready to
fire flare.
13. Mirror, Mark 3, Type 1 Emergency
Signaling
The emergency signaling mirror provided in the vest is a glass type, mark
3. To use this mirror, proceed as follows:
a. Hold mirror so that sunlight will reflect on a nearby surface
such as the hand or some other close object.
b. Bring the mirror up to eye level and look through the sighting
device until an intensely bright spot is located. This is the aim indicator.
2-9
TM 55-1680-351-10
Figure 5. Emergency Signaling Mirror
c. Hold the mirror close to the eye and slowly turn it until the bright
spot is on the target.
NOTE
Mirror flashes can be sighted with good
visibility for a distance of 30 miles at an
elevation of 10,000 feet. Mirror flashes are also
effective on cloudy days with poor visibility.
2-10
TM 55-1680-351-10
14. Receiver-Transmitter, Radio ARC-RT-10
To operate the ARC-RT-10, pull the antenna all the way out until the base
ring is visible. To transmit voice, push transmit lever in, hold speaker
microphone close and speak in a normal voice. To transmit and monitor
tone, push transmit lever in and hold, then push tone button down to stop.
The battery provided will operate the receiver-transmitter approximately 30
hours at 68° or 15 hours at 32° on a duty cycle of approximately 50%
transmit and 50% receive. Range of radio for line of-sight operation is
approximately 20 mile for homing and 10 miles for voice contact.
NOTE
For maximum transmit and receive, keep hands
away from antenna when the radio is in
operation and hold in a vertical position with
serial pointed straight up.
2-11
TM 55-1680-351-10
15. Revolver, .38-Caliber, Special
Vest will accommodate a .38-caliber revolver, 17 rounds ball ammunition,
and 6 rounds tracer ammunition. Weapon is for protection in a combat
zone and can be utilized in the hunting of game for food. Tracer
ammunition can be used to assist search personnel in pinpointing a survivor's location.
16. Tourniquet
Stow tourniquet with 8-10 inch loop for one handed manipulation. For use
in case of serious injury or wound by applying pressure at a point to
restrict the flow of blood. Can be used to wrap a sprained ankle, wrist, or
elbow.
17. Compass, Lensatic
The magnetic compass can be your most valuable piece of equipment
when traveling. In the jungle for example, most travel should be done with
the compass in your hand, since it will be the only means of maintaining
direction. The dense vegetation will obscure prominent landmarks and
celestial aids. At night the compass is even more valuable. With the
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TM 55-1680-351-10
lensatic compass, set your course by setting the azimuth of your desired
course under the stationary index which is viewed through the lens. Turn
the glass cover until the long luminous line is over the north arrow. To use
the compass after it has been set, open the compass and rotate the entire
compass until the luminous line is again over the north arrow. Your
desired course will be on a line drawn through the sights.
18. Survival Kit, Ind., Tropical
Survival kit, Ind. Tropical aircrew kit consists of medical and survival
components.
a.
Medical items are as follows:
(1) Pain killer tabs, aspirin tablets 1 or 2 tablets every 4 hours
up to 4 times a day-headache & acute pain.
(2) Anti-malaria tabs-chloroquine and primaquine and
phosphate tablets take 1 tablet per week, with or after food-swallow-DO
NOT CHEW for malaria prevention.
(3) Anti-diarrhea tabs-diphenoxylate hydrochloride
atropine sulfate tablets take 2 tablets 3 or 4 times daily for diarrhea.
2-13
and
TM 55-1680-351-10
(4) Antiseptic solution providone-iodine solution apply to skin
as required, for insect bites rub in. Fungus infections, cuts, bites and
scratches.
b.
Survival components are as follows:
(1) Headnet and mitten set
(2) Compass
(3) Saw, Flexible
(4) Matches safety humidity resistant
(5) Soap, toilet
(6) Bag, food sample carrying water wrapping food, protecting
valuables from water and moisture.
c. Kit, container, has written instructions on its outer surface
covering medical and survival components within.
19. DELETED
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TM 55-1680-351-10
20. Knife, Pocket
Knife is equipped with a screwdriver and two blades, can be used to clean
and prepare small game for eating, and also to construct traps for
catching small game as described in pamphlet stored in survival kit
packet.
21. Bag, Water, Size B
Water bag is used to store water recovered from lakes, streams or
trapped rain water. Use water purification tablets as described in survival
pamphlet prior to drinking.
Change 3
2-15
TM 55-1680-351-10
22. Deleted
23. Blanket, Combat Casualty
Blanket combat casualty is a thin aluminum foil sheet with international
orange or O.D. plastic coloring on one side and polished aluminum on the
reverse side, measures 96 inches long by 56 inches wide, used as a
signaling panel, to reflect heat from fire or body heat when wrapped
around individual.
*U.S. GOVERNMENT PRINTING OFFICE: 1993-757-882/60332
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TM 55-6180-351-10
24. Whistle, ball, plastic
The whistle is used for attracting rescue parties at night or in foggy
weather. The sound of the whistle can reach a far greater distance than
your voice and requires less energy to attract attention to yourself.
25. Fire starter, magnesium bar
This is used to start a fire. Assemble tinder and scrape magnesium into
tinder, making a collection of shaving about the size of a quarter, then use
the sparking device side of the tool and scrape rapidly with pocket knife
causing the sparks to ignite the pile and starting the fire.
26. Assembly Instruction Sheet
A 9" x 12' reproduction of the vest drawing, listing all components by FSN
and their location on the vest is located in the left-hand inside pocket of
the vest.
2-17
TM 55-1680-351-10
27. TM 55-1680-351-10
Operator's manual TM55-1680-351-10 is stored in the right-hand inside
pocket of the vest.
28. Suggested Publications
Deleted.
Figure 6. Inside View of Survival Vest
GPO : 1993 0 - 342-421 (63057)
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TM 55-1680-351-10
CHAPTER 3
RADIO SET, ANIPRC-90
Section I. CONTROLS AND INSTRUMENTS
29. Equipment Damage and Warnings
Radio Set AN/PRC-90 is built with ultimate operator convenience as a
goal and includes provisions for safe operation without limits on control
settings.
3-1
TM 55-1680-351-10
WARNING
Operation of the AN/PRC-90 without adequate rf shielding is prohibited
except during a bonafide emergency situation. Keep the function switch in
the OFF position at all times when not in emergency use and operate the
VOL control in the minimum position during voice transmissions. Failure
to observe these precautions will shorten battery life and could result in
equipment failure or disrupt actual search missions. If the unit is issued in
a sealed container, do not break the seal until the emergency conditions
have stabilized.
30. Operator Controls
Controls and connectors for the AN/PRC-90 are shown in table 3-1.
3-2
TM 55-1680-351-10
Table 3-1. Controls, Indicators, and Connectors
Control, Indicator,
Function
or Connector
Function switch
(4-position rotary
switch)
Selects transceiver operating mode
and turns radio set off.
SW Pos
OFF
VOICE/MCW
243.0
BCN 243.0
VOICE 282.8
(function
switch buttons must be
pressed to
place switch
in VOICE
282.8 position)
3-3
Function
Removes power
from radio set.
Turns receiver on
for reception of
243.0 MHz voice
or MCW signals.
Also permits
243.0 MHz voice
or MCW transmission when
keyed by PUSH
TO TALK or
MCW buttons.
Turns on 243.0
MHz transmitter,
and transmits a
beacon tone.
Swept audio tone
is continuously
transmitted for
rescue aircraft to
home on.
Turns receiver on
for reception of
282.8 MHz voice
signals. Also
permits 282.8
MHz voice transmission when
PUSH TO TALK
button is pressed.
TM 55-1680-351-10
Table 3-1. Controls, Indicators, and Connectors (Cont)
Control, Indicator,
or Connector
Function switch arrow/
pushbutton PUSH TO
TALK button
MCW button
VOL control
Function
Indicates operating mode selected
and locks out VOICE 282.8 position unless pressed.
When pressed, turns receiver off and
turns transmitter on when function
switch is in either VOICE/
MCW 243.0 or VOICE 282.8 position. Best voice transmissions are
obtained when spoken directly into
the TALK microphone. When released, turns off transmitter and
turns on receiver; received signal is
heard from the LISTEN speaker
or earphone.
This button can be used as a telegraph key to transmit morse code
when normal voice transmission
may reveal operator's position.
MCW is only available when the
function switch is in the
VOICE/MCW 243.0 position. When
MCW button is pressed, the radio
set transmits a continuous tone,
receiver is off. When button is
released. transmitter is turned off,
receiver is turned on.
This controls the sound level from
the LISTEN speaker or earphone.
It controls received signals, not
sidetone. When the control is fully
up in the MAX position, greatest
level of sound is heard; when fully
turned down, lowest level of sound,
but radio set is not turned off.
Control setting does not affect
transmitter output.
3-4
TM 55-1680-351-10
Table 3-1. Controls, Indicators, and Connectors (Cont)
Control, Indicator,
or Connector
LISTEN speaker
TALK microphone
EARPHONE JACK
(connector)
Antenna receptacle
(connector)
Battery cap
Function
Sound of received signal is heard;
also the sound of MCW or beacon
transmitter (sidetone) may also be
heard. The LISTEN speaker is
shut off when the earphone is connected.
Picks up voice being transmitted
when PUSH TO TALK button is
pressed and function switch is set
to VOICE/MCW 243.0 or VOICE
282.8 position.
Provides connection for earphone.
When earphone is connected,
LISTEN speaker is shut off, and
sound is heard from the earphone.
Provides connection for radio set
antenna.
Holds battery in place and also externally seals battery compartment.
3-5
TM 55-1680-351-10
Figure 7. Radio Set AN/PRC-90, Controls and Indicators
3-6
TM 55-1680-351-10
Section II. OPERATION UNDER USUAL
CONDITIONS
31. Preflight Procedures
Perform the following steps prior to use for each Radio Set AN/PRC-90.
WARNING
Leave the function switch in the OFF. position.
Refer to paragraph (1) Unauthorized personnel
shall not perform maintenance on the AN/PRC90.
a. Unscrew battery cap and remove battery, if installed. Check date of
manufacture stamped on battery. Battery BA-1568/U has a maximum
shelf life of 3 years in temperate climates and a ma/hr rating of 1,000
(approximately 14 hours of operation maximum in beacon mode). Discard
batteries more than 3 years old. Check for evidence of battery leak- age or
corrosion and condition of copper spring contacts. Install a good battery, if
required, and screw battery cap on fingertight.
3-7
TM 55-1680-351-10
Be sure radio set antenna is installed and
telescopic sections fully extended before
operating radio set. Failure to do this can
damage the radio operating capabilities.
b. Check receiver operation only by releasing the antenna from
stored position, and fully ex: tending telescopic sections; setting function
switch to either VOICE 282.8 or VOICE/MCW 243.0 position; and setting
VOL control towards MAX position. Proper receiver operation will be
indicated by a slight hissing sound in the MAX position. Presence of
squealing, "motorboating", or other abnormal sound (other than normal
AM static interference) is an indication of malfunction. Turn function
switch to OFF position.
WARNING
Do not operate MCW or PUSH TO TALK switches.
c. Check for evidence of obvious structural damage such as
cracked case, perforated seals, or presence of salt, sand, or oil
accumulations.
3-8
TM 55-1680-351-10
d. Check for presence of earphone and check earphone case and
cover.
e. If deviations are noted, take required corrective action.
f.
Replace antenna in stored position, replace in normal stowage
or flight suit in accordance with latest directives.
32. Modes of Operation
a. General. Radio Set AN/PRC-90 will be used only for
emergency (and/or tactical) communications.
The radio can be expected to perform properly, assuming normal
maintenance has been kept current.
b. Operational Modes.
The following operational modes are available:
(1) Beacon mode. Used initially on 243.0 MHz.
(2) MCW mode. Used for transmitting modulated
continuous wave codes (MCW) as required on 243.0 MHz.
(3) Voice mode. Used for two-way transceive
communication with air, sea, or ground radios on 243.0 MHz. 282.8 MHz
can be used as an alternate voice channel as directed.
3-9
TM 55-1680-351-10
33. Operational Siting and Operating
Procedures
a. General. General instructions for correct handling of the
AN/PRC-90 are provided below. Specific instructions are included in
subparagraph b.
(1) The AN/PRC-90 is normally used as a beacon transmitter
which transmits a continuous, "down-going beeper" AM signal for
approximately 14 hrs. Whenever possible, the radio is placed on a high
point, free of obstructions, and left in the BCN 243.0 mode until search
aircraft or other vehicles approach. The antenna should be vertically
oriented (perpendicular to the search vehicle radio) as shown in figure 9.
(2) If a search vehicle appears near the operator he may use
one of two voice channels or transmit international Morse Code (MCW) to
communicate with the search vehicle.
(3) When informed that a firm location has been determined, the
radio can be used to communicate with other crewmen to join forces for
recovery operations.
3-10
TM 55-1680-351-10
Figure 8. Operational Siting Under Search Mission Conditions.
3-11
TM 55-1680-351-10
(4) If the radio is being used for tactical operations only, use
the earphone when enemy forces are near enough to hear the speaker.
Keep transmissions brief in all tactical operations.
b. Emergency or Tactical Operation. Operate the equipment as
follows.
(1) Remove protective cover.
(2) Select highest exposed point (hills, trees, rooftops, or
uppermost portion of airframe) and set radio in a secure and upright
position with the antenna pointing upwards. Avoid antenna proximity to
metal uprights, nearby antennas, or rock formations which may contain
conducting minerals. If in the water, keep unit and antenna as high as
possible above water level and keep the antenna connector and frame
area as dry as possible.
(3) Set the function switch to the BCN 243.0 position
(clockwise).
3-12
TM 55-1680-351-10
WARNING
Leave the radio in the BCN 243.0 posi- tion until
search planes, ships, or vehicles appear in the
immediate vicinity. Failure to do so will interfere with
direction-finding equipment and could result in
termination of search activities. Continue this mode
for at least 14 hours or until search vehicles are
contacted. Battery and beacon failure is indicated by
loss of beacon sidetone in the speaker (or
earphone). If more than one AN/PRC-90 is available,
use only one at a time and share batteries to extend
the transmission period.
(4) Prior to visual contact with search craft, and if reasonable
doubt exists as to proper beacon operation, occasional brief voice or mew
("Mayday" or "SOS") transmissions can be made. Limit such
transmissions to daylight hours for best propagation. Follow a 2-minuteon, 1-minute-off; 3-minute- on, 2-minutes off; and 10-minute-on
procedure. Make the "Mayday" and/or "SOS" transmissions once just
after sunrise, once at noon, and once near sundown to take advantage of
improved propagation. Meteorological conditions will affect transmission
range and quality.
3-13
TM 55-1680-351-10
NOTE
Direction finding in this mode is difficult. The
primary purpose is to ensure continued search
operations. Battery life is reduced to an extent
by voice or mew operation.
To transmit VOICE or MCW. set the function switch counterclockwise to
the VOICE/MCW 243.0 position and either verbally repeat the word
"Mayday" at 2 or 3 second intervals by pressing the PUSH TO TALK
pushbutton or send coded "SOS" by pressing the MCW pushbutton
(modulated carrier wave). Set the VOL control to the MAX position.
NOTE
Attempt to make the code ("SOS') sidetone well
defined and rapid enough for experienced
operators to easily recognize the code. It will
have a "di-di-dit, dah-dah-dah, di-di-dit" sound
with spacing between groups. Refer to the code
explanation on the rear panel.
3-14
TM 55-1680-351-10
(5) If reasonable doubt exists that 243.0 MHz transmitter is
functioning, set the function switch to the VOICE 282.8 position and
transmit speech only as described in step (4) above.
NOTE
The function arrowhead button must be
pressed to release the switch for 282.8MHz operation.
(6) Repeat steps (1 through (3) above.
(7) When a rescue craft is within sight, call the rescue radio
operator as follows. Turn the function switch clockwise to the
VOICE/MCW 243.0 position and use the calling procedure outlined in
table 3-2. Press the PUSH TO TALK button and speak in a normal voice
near the microphone during transmissions. Do not shout. This procedure
will result in a more legible transmission. Place the VOL control in a
position that provides adequate audio volume from the speaker (or
earphone>.
3-15
TM 55-1680-351-10
Table 3-2.
Recommended Voice Operating Practices
Originating Call (AN/PRC-90)
"CQ rescue craft, CQ. CQ,
CQ. Over."
If no reply received, continue
to call "CQ" on voice or MCW
at intervals until reply is
received.
"Roger, roger. Crew status
follows. Over." (Report
crew physical status, missing crew members, and any
emergency logistics or
medical requirements.)
"Roger. Out."
Probable Reply
None or "Roger, roger,
roger." Read you five by five
(or other signal report).
"Roger. Your transmission
understood. Standby for
reply. Out." (Or other
pertinent reply).
35. Operating and Storage Limitations
a. Operation of the AN/PRC-90 will span a wide range of weather
extremes. Although the AN/PRC- 90 circuits are operable over a
temperature range of - 30°to + 50°C. (- 22°to + 122°F.), the battery (BA1568/U) power supply is only effectively operable over a 0°to + 54°C.
(+32°to + 129°F.) temperature range. Operating at low temperature
reduces battery life. The AN/PRC-90 (less the battery) may be stored
over a temperature range of -60°to +60°C.(-76°to +140°F.).
3-18
TM 55-1680-351-10
b. Equipment operated at low temperatures should be kept in low
temperature storage when not in use. Store the equipment in a shipping
carton and cover the carton with water-repellent material.
c. When the equipment is to be operated at freezing
temperatures, perform the following procedure before operating the
equipment.
NOTE
When operational conditions using Battery BA15681UR include temperatures below 50° F., the
radio set and spare battery should be carried
inside flight clothing to prevent cold soaking.
The battery will not supply sufficient power to
operate the radio if permitted to cold soak for
extended periods of time at freezing or below
freezing temperatures. Therefore, the user
should initiate use of radio at low temperatures
with a battery that has been warmed. Batteries
should be rewarmed as soon as possible after
use to insure reliable operation of the radio. The
following exposure times of the battery at the
temperatures indicated are recommended:
3-19
TM 55-1680-351-10
Temperature (°F)
Cold soak time
Plus 32°............................................................30 minutes
0°..............................................................15 minutes
Minus 40°..........................................................5 minutes
(1)
Keep the equipment in low temperature storage when not
in use.
(2) Use water-repellent material (SB 38-100) to cover the
shipping carton during periods of high humidity.
Section III. OPERATION UNDER UNUSUAL CONDITIONS
36. Operation in Desert and Tropical Areas
a. Desert Regions. Before using the equipment in desert regions,
remove all sand and dust. Blow and shake sand out of speaker and
microphone.
b. Tropical Regions. In climates of high humidity, such as tropics,
inspect the equipment daily for fungus, mold, insects and metallic
corrosion.
Do not open the AN/PRC-90 case chassis. Only
higher category maintenance personnel may
work on components. Opening the case will
permit moisture and dust to enter the unit,
resulting in a possible malfunction.
3-20
TM 55-1680-351-10
37. Operation in Maritime, High Altitude,
or Rainy Areas
Keep the AN/PRC-90 in a dry area if possible. Avoid rigging any cover
materials near the antenna in salt atmosphere. Watch for accumulations
of salt between the antenna base and the radio. Remove any fouling
sediment to assure proper operation. No special procedures are required
for high-altitude operation.
38. Recognition and Identification of
Jamming
Under tactical conditions, the AN/PRC-90 may be jammed by the enemy.
This jamming may be planned or accidental and will usually be caused by
a strong signal transmitted on the same frequency as that being used.
The signal being transmitted may be a steady carrier or a modulated
carrier. When it becomes difficult or impossible to receive the desired
signal, switch the function switch to the alternate voice channel or revert
from the voice to the MCW mode and attempt CW contact.
3-21/(3-22 blank)
TM 55-1680-361-10
APPENDIX A
REFERENCES
TM 21-76
Survival, Escape, and
Evasion
TM 55-1680-317-23&P
Maintenance Manual for
Army Aircraft Survival
Kits
Change 2
A-1/(A-2 blank)
By Order of the Secretary of the Army:
JOHN A. WICKHAM, JR.
General, United States Army
Chief of Staff
OFFICIAL:
R. L. DILWORTH
Brigadier General, United States Army
The Adjutant General
DISTRIBUTION:
To be distributed in accordance with DA Form 12-31, -10 and CL
requirements for All Fixed and Rotary Wing Aircraft.
GPO: 1995 0 - 400-279
PIN: 061662-000
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