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WAR DEPARTMENT
BASIC
FIELD MANUAL
VOL. IV
SIGNAL COMMUNICATION
ILLINOIS
BASIC FIELD MANUAL
VOL. IV
SIGNAL COMMUNICATION
PREPARED UNDER THE DIRECTION OF
THE CHIEF SIGNAL OFFICER
FEB 15 1932
UNIVERSITY OF ILLINOIS.
UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON : 1931
For sale by the Superintendent of Documents, Washington, D. C.
Price 50 cents
WAR DEPARTMENT,
Washington, April 6, 1931.
Basic Field Manual, Volume IV, Signal Communication, is
published for the information and guidance of all concerned.
[A. G. 062.11 (5-7-30).]
By order of the Secretary of War:
DOUGLAS MacARTHUR,
General,
Chief of Staff.
Official:
C. H. BRIDGES,
Major General,
The Adjutant General.
II
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LIST OF FIELD MANUALS
A MANUAL FOR COMMANDERS OF LARGE UNITS. (M. C. L. U.)
y Vol. I. Operations. — A guide for commanders and staffs for tactical operations of
cO large units.
II. Administration. — A guide for the administration of large units in a theater
of operations.
STAFF OFFICERS’ FIELD MANUAL. (S. O. F. M.)
Staff principles and functions applicable to the staffs of all units, together
with pertinent reference data.
BASIC FIELD MANUALS. (B. F. M.)
Training, administrative, and reference data applicable to more than one
arm, with special reference to the smaller units.
Vol. I. Field service pocketbook. (F. S. P.) — The individual.
II. Infantry drill regulations. (I. D. R.) — Drill, dismounted ceremonies and
inspections; the infantry pack, display of equipment and tent drill.
III. Basic weapons. (B. W.) — Marksmanship and mechanical training of
the rifle, automatic rifle, pistol, machine gun, 37-mm. gun, 3-inch trench
mortar, bayonet and grenade instruction, technique of fire (37-mm. gun,
3-inch trench mortar and machine gun) ; musketry and combat practice
of small units; instruments.
IV. Signal communication. (S. C.) — Signal regulations and technical infor¬
mation needed by officers and enlisted men on signal communications*
duty of arms other than the Signal Corps.
V. Transport. (T.) — Equitation, training remounts, use and care of animals
and of animal-drawn, pack, motor, and tractor transport.
VI. Administrative regulations. (A. R.) — Army Regulations essential to small
units.
VII. Military law. (M. L.) — The Manual for Courts-Martial, including the
Articles of War; the Rules of Land Warfare, including recent conven¬
tions relative to the sick and wounded of armies in the field and to
prisoners of war; an epitome of the legal principles applicable to military
forces when aiding the civil power.
VIII. Operations of combined arms ( small units). (O. C. A.) — The principles,
doctrines, and methods governing the tactical employment of combined
arms with reference to the small units.
FIELD MANUALS FOR THE ARMS
The manual for each arm contains, primarily, the principles, doctrines, and
methods governing the employment of that arm and pertinent reference
. data.
Infantry Field Manual. (I. F. M.)
Vol. I. Units other than tanks.
II. Tank units.
Ill
56
IV
LIST OF FIELD MANUALS
Vol.
Vol.
Vol.
Cavalry Field Manual. (C. F. M.)
Field Artillery Field Manual. (F. A. F. M.)
I. Organization and drill.
II. Tactics and technique.
Coast Artillery Field Manual. (C. A. F. M.)
I. Harbor defense, railway and tractor-drawn units.
II. Antiaircraft artillery units.
Air Corps Field Manual. (A. C. F. M.)
Engineer Field Manual. (E. F. M.)
I. Engineer troops.
II. Military field engineering.
Signal Corps Field Manual. (S. C. F. M.)
TABLE OF CONTENTS
Chapter 1. General. Para-
Section I. Objective of this and other texts relating to signal com- graphs Page
muni cation _ _ _ 1-2 1
II. Staff duties of signal communication officers _ 3-5 2
III. Organization for signal communication . . 6-9 4
Chapter 2. Field wire systems.
Section I. General . . . . . . 10-22 6
II. Technique of field wire line construction _ 23-42 18
III. Installation and operation of telephones and centrals-. 43-66 53
IV. Installation and operation of field telegraph sets and
stations _ 67-70 81
V. Maintenance of field wire systems. . 71-86 84
Chapter 3. Radio.
Section I. General _ 87-93 111
II. Operating regulations _ 94-103 114
III. The call up and answer _ _ 104-109 118
IV. Station records _ 110-112 124
V. Tactical radio nets... _ 113-118 129
VI. Message forms and classification _ _ 119-122 135
VII. Methods of sending messages _ 123-126 140
VIII. Message handling _ 127-138 145
IX. Artillery fire control. _ _ 139 155
X. Procedure signals _ 140-141 167
XI. Dry batteries _ _ 142-143 178
XII. Storage batteries _ 144-158 180
Chapter 4. Visual signaling.
Section I. Lamps _ 159-166 184
II. Flags _ 167-174 189
III. Pyrotechnics _ 175-179 192
IV. Panels _ _ _ 180-183 195
Chapter 5. Dropped and pick-up airplane messages.
Section I. Dropped messages _ 184-187 197
II. Pick-up of messages _ 188-193 198
Chapter 6. Message center.
Section I. General _ 194-199 202
II. Military cryptography _ 200-206 204
III. Description and use of the cipher device, type M-94... 207-214 211
IV. Procedure in divisions and higher units _ 215-221 220
V. Procedure in brigades and lower units _ 222-225 241
VI. Related procedures _ 226-232 243
VII. Pigeons at message centers _ 233-239 248
Chapter 7. Orders and instructions for signal communication troops. . 240-244 260
Chapter 8. Meteorological information _ _ 245-251 266
Chapter 9. Signal supply _ 252-255 280
Appendix. Table of radio communication equipment _ Faces 281
Index . . . . . . - . - . . 283
V
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BASIC FIELD MANUAL, VOLUME IV
SIGNAL COMMUNICATION
(This pamphlet supersedes paragraphs 3, 8, 9, 14, 16, 18-21, 24, 25, 27-30, and 32 and
Sections V, IX, X, and XI, TR 160-5, June 28, 1929; TR 160-6, June 29, 1929; TR 160-10,
June 28, 1929; Sections II, III, and IV and paragraphs 27-29, TR 162-5, April 20,
1926; and TR 163-5, October 1, 1929.)
CHAPTER 1
GENERAL
Paragraphs
Section I. Objective of this and other texts relating to
signal communication _ 1-2
II. Staff duties of signal communication officers _ 3-5
III. Organization for signal communication _ 6-9
Section I
OBJECTIVE OF THIS AND OTHER TEXTS RELATING
TO SIGNAL COMMUNICATION
1. Objective of this text. — This text includes signal reg¬
ulations and technical information needed by officers and enlisted
men of arms other than the Signal Corps engaged in signal com¬
munication. It supplements the matter contained in chapter 7,
Basic Field Manual, Volume VIII, and prescribes in detail the
installation, maintenance, and operation of signal communica¬
tion agencies which are employed at and forward of brigade
headquarters.
2. Other official texts relating to signal communica¬
tion. — a. Chapter 7, Basic Field Manual , Volume VIII , includes
information of signal communication required by officers of all
arms whether or not on communication duty. This chapter
prescribes general principles and methods which apply to the
signal communication systems of all units.
b. Signal Corps Field Manual gives information relating to
systems and services handled by Signal Corps personnel. The
Signal Corps Field Manual supplements this manual (B. F. M.,
Vol. IV) and covers systems, equipment, and methods of greater
1
2
BASIC FIELD MANUAL
technical complexity than those used at and forward of brigade
headquarters. The Signal Corps Field Manual is ordinarily
required by Signal Corps personnel only.
c. Technical Regulations give technical information and detailed
description of communication equipment. At present this in¬
formation is published as training, wire communication, and
radio communication pamphlets. When reprinting is necessary,
however, these pamphlets will be renumbered in the Technical
Regulations series.
d. Training Manuals describe methods of training signal com¬
munication specialists.
Section II
STAFF DUTIES OF SIGNAL COMMUNICATION
OFFICERS
3. Communication officer member of staff. — The unit
signal or communication officer is a member of the staff of his
commanding officer. He is responsible to his commanding officer
that both tactical and technical control of signal communication
are properly exercised throughout the command. This control
is exercised, upon the approval of his commander, through the
normal channels of command, except that technical control over
routine matters may be exercised directly among the signal or
communication officers concerned.
4. Responsibility for signal communication. — The re¬
sponsibility for signal communication, being a function of com¬
mand, can not be delegated by the commander. However, each
commander is provided with a member of his staff who is trained
as a specialist in signal communication, and this staff officer is
charged with the execution of all command functions pertaining
to signal communication, under such restrictions as may be pre¬
scribed bjr the commander. This officer is called the signal officer
or the communication officer. In this manual the term “signal
officer” will be used irrespective of the name applied to this
officer by Tables of Organization. It should be noted that two
channels are utilized in securing control over signal communica¬
tion. All orders affecting the tactical employment of agencies
of signal communication are issued through the normal channels
of command and are coordinated with orders issued to other
tactical or technical agencies by the appropriate staff section
prior to issue. But orders which are issued for the technical
BASIC FIELD MANUAL
3
control of an agency of signal communication in routine matters,
which do not need coordination with orders issued to other
elements of the command, may be issued in the name of the
commander, direct by the signal officer of the superior unit to
the signal officers of subordinate units. The employment of the
direct channel by signal officers depends upon the relation exist¬
ing between the individual commander and his signal officer. In
well-trained organizations only those matters which need coor¬
dination with other than signal activities follow the normal
channels of command. All purely signal communication activ¬
ities are controlled by the signal officers concerned, in accordance
with the general policies prescribed by the commander. The
above principles govern the method of issuing orders to signal
communication troops of subordinate units by unit signal
officers. The unit signal officer must first secure the approval
of his commander to all plans for signal communication prior
to their issue in the form of orders. The approval of the com¬
mander is secured by one of three methods:
a. Routine matters are covered by general policies promul- .
gated by the commander.
b. Plans for furnishing signal communication wffiich affect
functions which have been delegated to other staff sections are
approved by the chief of the staff section concerned.
c. Plans for furnishing signal communication maj^ be approved
by the commander in person.
5. Duties of unit signal officer. — The general duties of the
unit signal officer may be divided under two headings:
a. Duties during training periods. — During training periods the
unit signal officer —
(1) Prepares the training programs for signal communication
troops of his unit and lower units under the general policies laid
down by his commander and by higher authority.
(2) Organizes and supervises such specialists’ schools as may be
authorized by his commander or required by orders of higher
authority.
(3) Makes such inspections of the signal communication per¬
sonnel and equipment of his own and subordinate units as his
commander may direct or authorize and submits recommenda¬
tions to the latter concerning action that should be taken to cor¬
rect deficiencies that may exist or to improve training methods
or doctrines.
4
BASIC FIELD MANUAL
(4) Takes steps to secure and supply ample training and organ¬
izational signal equipment throughout the command.
(5) Prepares such orders, regulations, and signal operation
instructions as may be needed for the efficient training of the
signal communication personnel of the command.
(6) Personally conducts the training and secures the training
and organization equipment for the signal communication troops
of his unit in brigades and smaller units.
b. Duties during combat or under simulated combat conditions. —
During combat or under simulated combat conditions he —
(1) Prepares or secures from higher authority such orders and
signal operation instructions as may be needed to insure the
technical and tactical control of the signal communication sys¬
tems of his unit. He insures the proper distribution of such
orders and signal operation instructions throughout his unit.
(2) Acts as technical adviser to his commander and his staff
on all matters pertaining to signal communication.
(3) Submits recommendations as to the location of the axes of
signal communication and command posts of each subordinate
unit and of his own unit when not prescribed by higher authority.
(4) Prepares the plans for the employment of the signal com¬
munication agencies of his own and subordinate units so as to
insure the most efficient employment of these agencies at his own
command post and the necessary coordination and technical
control of the agencies of subordinate units, subject to orders
received from higher authority. He submits these plans to his
commander or appropriate staff officer for approval.
(5) Prepares all orders to signal communication troops based
upon the approved plan and insures the promulgation of these
orders.
(6) Supervises the signal communication systems employed by
* his own and subordinate units, to correct deficiencies and secure
coordination between systems during combat.
(7) Takes steps to procure and supervises the replacement of
signal equipment and personnel of his own and subordinate units.
Section III
ORGANIZATION FOR SIGNAL COMMUNICATION
6. Division of duties. — Signal communication within brigades
and smaller units is conducted by the personnel of the unit con¬
cerned. Other signal communication is handled by the Signal
BASIC FIELD MANUAL
5
Corps. Provision is made in the organization and equipment of
each unit for the conduct of its own communication.
7. Communication agencies. — The principal communication
systems relied upon are messenger, wire, and radio, but visual
and acoustic signaling are used for special purposes. It is unwise
to rely upon one means to the exclusion of others, because special
circumstances may make that preferred system inoperative when
communication is urgently needed. Communication units are
therefore organized for the operation of the several agencies ap¬
propriate to the special needs of the unit concerned.
8. Each unit system a part of a larger system. — By the
organization outlined above there are in a large tactical unit
many small communication systems each installed, maintained,
and operated by personnel of a separate unit. Each of these
systems, however, is so conducted as to form a part of the general
system so that messages may be transmitted rapidly and effi¬
ciently from one headquarters to any other headquarters in the
system. Economy of equipment and labor frequently requires
that a system installed by one unit be turned over to another. It is
evident therefore that there should be uniform methods of pro¬
cedure and construction throughout all units.
9. Cooperation between communication units. — To insure
successful signal communication the communication troops must
work as a team regardless of arm or service. There should exist
a spirit of mutual helpfulness and cooperation. Personnel of ad¬
jacent units should take every suitable opportunity to become
personally acquainted, to understand the special problems and
conditions in neighboring systems, and to offer such assistance
and cooperation in the solution of difficulties as may be practi¬
cable.
CHAPTER 2
FIELD WIRE SYSTEMS
Paragraphs
Section I. General _ 10-22
II. Technique of field wire line construction _ 23-42
III. Installation and operation of telephones and
centrals _ 43-66
IV. Installation and operation of field telegraph
sets and stations _ 67-70
V. Maintenance of field wire systems _ 71-86
Section I
GENERAL
10. Purpose and scope.— The purpose of the following
instructions is to standardize the installation, maintenance, and
operation of the field wire systems of tactical units of the different
arms. This standardization is necessary in order to secure more
efficient signal communication service for the Army. The term
“signal” as used in this manual applies to all personnel, units, or
agencies employed in signal communication work. In providing
methods of technique, a standard practice is prescribed, disre¬
garding the individual duties assigned to the personnel of signal
communication units. These duties are specifically explained
in the training publications pertaining to the different arms and
tactical units.
11. Composition of wire systems. — a. The wire system
of a tactical unit consists of the telephone and telegraph commu¬
nication normally installed and operated by the signal personnel
assigned to the headquarters of such a unit. The collective wire
system of a tactical unit comprises its own wire system and the
wire systems installed and operated by all subordinate units.
For example, the division wire system includes only the wire
communication installed and operated by the division signal
company or troop, whereas the collective division wire system
includes its own wire system and all other wire communication
installed and operated within the division by subordinate units.
b. A wire system includes all means of signal communication
utilizing wire lines. From the viewpoint of materiel, it consists
6
BASIC FIELD MANUAL
7
of wire circuits, connecting and operating equipment, and certain
special apparatus for testing the circuits.
c. A general classification of wire circuits is made according to
their use, as follows:
(1) Trunk circuits, which connect telephone centrals.
(2) Local circuits, which connect telephones to centrals or
other telephones.
d. A further special classification of wire circuits is made
according to the number of physical wires used in the circuit:
(1) Metallic circuits, in which two wires form a complete path
for the electric current.
(2) Ground return circuits, in which one wire is used, with the
earth taking the place of the second wire.
Of the two circuits the metallic has proved to be the more
satisfactory. It is less susceptible to interference from other
circuits, earth currents, or conversation interception by hostile
listening stations. The communication range may, however, be
usually increased by the use of a ground return circuit.
e. Additional special circuits may be derived from these me¬
tallic circuits by the use of repeating coils, as follows:
(1) A single metallic circuit may provide both a telephone and
a telegraph circuit without mutual interference. This type of
telegraph circuit uses a ground return and is known as a simplex
circuit.
(.2) Two metallic circuits may provide a third telephone or
telegraph circuit without interference from one another. This
third circuit is known as a phantom circuit.
/. Connecting and operating equipment includes telephone and
telegraph instruments, switchboards and auxiliary supplies.
g. Testing apparatus includes telephone and telegraph in¬
struments and special test sets.
12. The telephone; powers and limitations. — a. The
greatest advantage of the telephone is that it affords immediate
personal contact between two individuals. Disadvantages of
the telephone are the lack of record of the conversation, and the
tendency to consume too much time in conversation.
6. The efficiency of the telephone system depends upon a
number of factors, the most important of which are —
(1) Type of wire line construction.
(2) Types of telephones, switchboard, and other equipment.
(3) The weather.
8
BASIC FIELD MANUAL
(4) The training of the personnel operating and using the
system.
c. The distance over which telephone conversation is possible
is limited by the electrical characteristics of the complete tele¬
phone circuit. A given type of wire circuit, under normal con¬
ditions, has a definite talking range. The wire factors which
increase the talking range are —
(1) Better electrical conductivity of the material of which
the wires are made.
(2) Larger diameter of the wire.
(3) Greater spacing between wrires and between wires and
ground, within certain limits.
(4) Better electrical insulation between wires and between
wires and ground.
The converse of these factors decreases the range of telephone
conversation.
d. The following conditions tend to decrease the efficiency of
telephone circuits and the range of telephone conversation:
(1) Snow, ice, rain, heavy dew, or fog.
(2) Moisture in the telephone instrument, especially in the
transmitter.
(3) Exhausted dry batteries in local battery (magneto)
telephones.
(4) Additional telephones (party line).
(5) Additional switchboards.
13. The telegraph; powers and limitations. — The wire
telegraph is one of the most rapid and accurate electrical means
of transmitting messages. The simultaneous transmission of
telephone conversations and telegraph messages over the same
circuit is common practice. The ranges of telephone and tele¬
graph circuits are limited by the same factors. Most telegraph
instruments have a much greater range than telephones over a
given circuit. A failure to utilize telegraph channels over¬
burdens the telephone system.
14. Wire communication during movement of com¬
mand posts. — The maintenance of wire communication is
usually more difficult during the movements of command posts
than at any other time. The initial installation of each wire
system should be planned with the objective in view of main¬
taining continuous wire communication with subordinate units
during and after the movement of command posts. A satis¬
factory solution in any given situation is normally a combination
of the general methods described below.
BASIC FIELD MANUAL
9
a. Single-axis method. — In Figure 1 (for a description of
symbols see par. 20), assume that the command post of a unit
is located at 3 and that the command posts of its subordinate
units are at 1 and 6, respectively: The axes of signal com¬
munication of these units are 3-5, 1-2, and 6-7, respectively.
The superior unit runs one circuit from 3 to 1 via 4 and another
circuit from 3 to 6 via 4. Prior to the movement of the com¬
mand posts of the subordinate units to 2 and 7, respectively,
two circuits are run by the superior unit from 4 to 5, one circuit
is continued from 5 to 2 and the other circuit from 5 to 7. When
the command post of the* subordinate unit at 6 moves to 7, the
3-4-6 circuit is used until the moment the command post closes
□
P7
o
(subordinate)
UNIT j
2.
(3UBORD I NATE)
UNIT J
P7
9
/subordinate)
\ UNIT ]
<P
3
(SUPERIOR \
UNIT j
, -4
(A POINT ON THE)
\ 3-5 AXIS )
P"
5 x
/superior)
\ UNIT j
TL-600
n
7"
T
, 6
(subordinate:)
UNIT J
\
7
(SUBORDINATE 1
UNIT
JINATE )
,T /
P7
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/subordinate)
\ UNIT /
Figure 1. — Schematic location of command posts for selection of wire axis
at 6 and opens at 7. At this instant the 3-4-6 circuit is dis¬
connected at 4 and the 3-4 section of this circuit is connected
to the 4-5-7 circuit. The 4-6 circuit may then be recovered or
assigned to some other unit. The procedure during the move¬
ment of the other command post from 1 to 2 is similar.
b. Multiple-axis method. — (1) In Figure 1, assume the same
initial location of command posts and axes of signal communi¬
cation as before. The superior unit runs two circuits, one from
3 to 1 and the other from 3 to 6. It then lays one circuit along
the axis of signal communication of each subordinate unit, pass¬
ing through 2 and 7, respectively. When the command post of
the unit at 6 moves to 7, the 6-7 circuit is connected to the 3-6
circuit. The superior unit maintains the 3-6-7 circuit. The
10
BASIC FIELD MANUAL
procedure during the move of the command post of the other
subordinate unit from 1 to 2 is similar.
(2) As compared with the single-axis method, this multiple-
axis plan often results in a saving of wire. The following disad-
vantages of the multiple-axis method may be noted:
• (a) Personnel is dispersed during installation and main¬
tenance.
(6) Resulting system is not so flexible as in the single¬
axis method.
(c) More personnel is required for installation and main¬
tenance of the system than in the single-axis
method.
c. Joint-axis method. — In Figure 1, assume that the initial
command post of the unit is located at 3, and that the initial
command posts of its subordinate units are 1 and 6, respectively.
The axes of signal communication of these units are 3-1-2-9,
1-2-9, and 6-7-8, respectively; the axis of the superior unit
coinciding with the axis of its left subordinate. The superior
unit makes the initial trunk installation by laying circuits 3-1
and 3-6. Should all three units move to position from a com¬
mon assembly area, or from the same column in march, these
circuits might, by agreement, be laid by the subordinate units
en route to position. Should the left subordinate desire at any
time to advance to another command post, as 2, it will lay cir¬
cuit 1-2, and having decided to open at 2, circuit 1-2 will be
joined to 3-1 at 1, and communication maintained over circuit
3-1-2. The movement from point 1, and the joining of circuits
at that point will be accomplished without interruption of wire
traffic. (Several suitable methods of joining circuits appear in
Sec. III.) Assume that the subordinate units have advanced,
by the above method, to points 9 and 8, respectively. At this
time the superior unit decides to advance to 2, located on the
axis shared jointly with its left subordinate unit. The superior
unit will first lay a circuit 2-8 and so install a switchboard at 2
that traffic may be handled over circuits 3-1-2, 2-8, and 2-9.
At a suitable time, the board at 3 will be removed and the
board at 2 will begin to serve the new command post. Should a
circuit from 3 to the rear exist, this circuit will be joined at 3
to the circuit 3-1, no traffic being interrupted.
d. (1) In the methods described above, if the command post
of either subordinate unit moves to the new location, prior to
the extension of the circuit by the signal personnel of the superior
BASIC FIELD MANUAL
11
unit, wire communication will be interrupted. In rapidly mov¬
ing situations, continuous wire communication between any unit
and its subordinate units can be insured only by coordination be¬
tween those units. The following method is based upon this
coordination.
(2) In Figure 1, assume the same initial location of command
posts. Assume also that each unit installs its wire system by
the single-axis method, but that the 4-5-2 and 4-5-7 circuits
are not completed by the superior unit until after the movement
of the command posts of the subordinate units to 2 and 7.
Each subordinate unit has laid at least one circuit along its
axis, passing through 2 and 7, respectively. When the com¬
mand post at 6 moves to 7, the 6-7 circuit laid by that unit is
connected to the 3-4-6 circuit laid by the superior unit. When
the 4-5-7 circuit laid by the superior unit reaches 7, the 3-4-6-7
circuit is disconnected at 4 and the 3-4 section of the circuit is
connected to the 4— 5-7 circuit. Communication is then main¬
tained bjr the superior unit over the 3-4- 5-7 circuit. The 4-6-7
circuit may be recovered or assigned to another unit. The pro¬
cedure during the movement of the command post of the other
subordinate unit from 1 to 2 is similar. This method makes use
of circuits previously laid, but no longer required, by a subor¬
dinate unit. It conserves personnel, simplifies construction and
maintenance, makes the maximum use of the initial system,
and facilitates the continuity of wire communication during the
movement of command posts.
15. Test stations. — Test stations are installed on a wire
line to facilitate the testing and reallocation of circuits. They
may be located at points where circuits diverge, at the end of a
wire line not terminating in a switchboard, near points where
circuits are most liable to damage, at probable future locations
of a command post, or at other convenient points on the line.
For example, in the situations described in paragraph 14a and c,
the location of test stations at points 4 and 5 would facilitate
the reallocation of circuits after the movement of the command
posts of the subordinate units. If a command post is estab¬
lished where a test station has been previously installed, the
test station can be easily converted into a central. Test sta¬
tions are usually given a geographical designation; e. g., Jones
Farm Test.
16. Switching centrals. — A switching central is a telephone
central, installed at a point other than a command post, for the
12
BASIC FIELD MANUAL
principal purpose of trunk switching. Switching centrals permit
flexibility in the interconnection of trunk circuits. Their judi¬
cious use enables better telephone service to be furnished with
the same number of trunks. On the other hand, switching
centrals require additional personnel and equipment, necessi¬
tate an additional switching operation, and add a sensitive spot,
subject to damage and interruption of service. They are used
habitually in the wire systems of corps and larger units and
whenever expedient in the systems of smaller units.
17. Orders and instructions. — a. Telephone codes and
directories and general instructions for the operation or use of
the telephone system are issued as required. If of interest to
the entire command, such information or instructions may be
published in general orders or circulars. If of interest to signal
personnel only, they are usually published as signal operation
instructions.
b. In divisions and higher units, general instructions concern¬
ing the wire system for a particular operation are usually
included in a signal communication annex or an appendix
thereto. In brigades and lower units the corresponding instruc¬
tions are usually issued orally. In either case the plan of
installation can best be shown by the use of a line route map
and a circuit diagram.
18. Line route map. — a. A line route map is a map or map
overlay containing the following information:
(1) Map or overlay proper:
(a) At least two orientation points (if an overlay) .
( b ) Location of each headquarters or establishment
served by the wire system.
(c) Locations of telephone centrals, switching centrals,
and test stations.
(d) Locations of local telephones not installed in the
immediate vicinity of the telephone central.
(e) Route of each wire line showing whether installed or
proposed, the type of line construction and the
number of physical circuits (trunks and long
locals) in each section of line.
(/) Explanation of any special symbols not regularly
authorized.
(2) Heading, legend , and authentication. — When the line route
map is issued by a headquarters for the guidance of units not
BASIC FIELD MANUAL
13
forming a part of that headquarters, or as an annex or appendix
to formal field orders, it will include the following information:
(a ) Heading and legend:
1. Unit issuing.
2. Title, showing whether issued as an appendix
to a signal communication annex, as signal
operation instructions, or as a part of the
orders of the commander of a signal com¬
munication unit.
2. Date and hour effective.
4- Map with which used (if an overlay).
MAP*. GEOLOGJCAL SURVEY. SCALCItt^OO BLUE FIELD SHEET.
fCOPY TO SiG. a 1C OlV, I
©Y COMMAND OP BRIGADE GENERAL 6 : •
v 900
TL-Goe •-»
Figure 2. — Line route map, brigade
(b) Authentication:
1. When intended for the information or guidance
of lower units, it is issued in the name of the
commander. It is authenticated by the
assistant chief of staff, G-3, in divisions or
higher units, and by the appropriate staff
officer in lower units.
2. When intended only for the signal troops of the
tactical unit in which issued, it is signed by
the unit signal officer.
b. The line route map should contain as few lines, symbols,
and notations as is consistent with its purpose. It should show
line routes rather than the actual connections at telephone
centrals or test stations.
14
BASIC FIELD MANUAL
c. Figure 2 is an example of a line route map, showing a
brigade wire system for an attack in a meeting engagement.
19. Circuit diagram. — a. A circuit diagram is a schematic
illustration containing the following information:
(1) Diagram 'proper:
(a) Units on establishments served by telephone centrals,
indicated by conventional signs and telephone code
names.
( b ) Number of circuits, including trunks and long locals
in each section of line.
(c) Numerical designation of each circuit.
( d ) Telephone centrals and switching centrals; circuit
connections at each.
DRAGOON DRAB
l-COPY TO SIG. o. |STD1V BY COMMAND OP BRIGADIER GENERAL BI
Y
S-3
YL.-607
Figure 3.— Circuit diagram, brigade
(e) Test stations; circuit connections at each.
(/) Simplexed circuits.
(gr) Phantomed circuits.
(h) Local circuits, in special cases.
(i) Type of line construction.
(2) Heading and legend. — As for a line route map.
(3) Authentication. — As for a line route map.
h. Figure 3 is an example of a circuit diagram to accompany
the line route map shown in Figure 2.
20. Special symbols. — The following special symbols are
authorized for use as indicated:
BASIC FIELD MANUAL
15
a. Basic symbols for circuit diagrams, indicating circuits, con¬
nections, and installations.
Terminal frame
Circuit ending at telephone central
Simplexed circuit _
Simplexed circuit bridged around switch¬
board or test station _
Telegraph way station on simplexed
circuit _
TL-654
Circuits entering and leaving terminal
frame but not entering a switchboard-
Circuit terminating in a telephone _
Method of numbering circuits
- 203 -
— 1M-IBDW—
Ground return circuit
HD
TL-655
b. Basic symbols for line route map, indicating circuits.
Wire line _ _
Indicating number of circuits in a wire
line _ _ ±
Standard pole line
"T" VT»
TL-656
16
BASIC FIELD MANUAL
c. Symbols for circuit diagrams and line route maps indicating
wire installations.
(1) Basic symbols.
Telephone central at a command post _
Switching central _
Test station _
Probable future locations of a cavalry
command post to indicate a point on
the axis of signal communication _
Probable future locations of an infantry
command post to indicate a point on
the axis of signal communication _
Probable future locations of an artillery
command post to indicate a point on
the axis of signal communication _
Note. — The foot of staff points to the actual location on
the line route map or to the symbol on the circuit diagram.
r
r
r
(2) The above symbols may be used in combination with basic
symbols and special abbreviations to show the various units or
activities to which they pertain, as prescribed in the Staff Officers’
Field Manual. The following examples illustrate a few possible
combinations:
Telephone central at command post 3d re^3
Infantry _
Probable future location of a command
post 2d Squadron, 7th Cavalry (a series
of such symbols indicates the axis of
signal communication) _ ;
Division switching central _
u x
Brigade test station _
TL-657
d. Basic symbols for traffic diagram.
Telephone channel _ _ _ —
Indicating number of telephone channels. _ §.
Telephone central
Switching central
Telephone _
TL-658
BASIC FIELD MANUAL
17
21. Designating lines and circuits. — a. Wire lines and
circuits are given individual designations by the organization
installing them. These designations are used in orders and
reports.
b. In large wire systems, as those of corps or armies, each
important wire line is designated by a name or number, for
example, cable No. 2 or GETTYSBURG-CHAMBERSBURG
line. In such systems, each wire circuit is given a number,
for example, circuit No. 612. The designation of wire circuits in
such a system consists of the number of the circuit followed by
the name or number of the line, for example, circuit No. 50, cable
No. 6, or circuit No. 561, NEW YORK-WASHINGTON line.
c. In smaller wire systems, circuits are not normally desig¬
nated by name. A wire circuit in such a system is designated
by Its individual number, followed by the title of the organ¬
ization constructing the circuit. For example, “No. 101-lst
Div.” In battalions and smaller units, the numbering of cir¬
cuits may also be omitted whenever the omission will not render
prompt identification,- test and maintenance more difficult.
However, in such cases, the name of the unit to which the cir¬
cuit belongs and the purpose it serves should be given, for
example, “1st Bn 2d FA — OP.” The complete circuit desig¬
nation should be used in circuit diagrams, orders or reports,
whenever necessary to avoid confusion.
d. In assigning numbers to wire circuits the following general
rules should be observed:
(1) No two circuits in a named or numbered wire line are
given the same number.
(2) No two circuits constructed by the same organization
during a single operation are given the same number.
(3) All wire lines are divided into sections. A section be¬
gins and terminates at successive centrals, test stations, or
(in the case of a long local) at a telephone. A circuit passing
from one section to another is given a different designation on
entering the new section.
e. In the wire systems of divisions and lower units, construc¬
tion and maintenance are facilitated by a numbering system
which identifies the general position of each circuit with respect
to other circuits in the same system. Figure 3 illustrates one
system of numbering which is given only as a guide. How¬
ever, any system of numbering that will meet the requirements
of the situation and which in general conforms to the pro¬
vision of this paragraph may be used. The system of num-
18
BASIC FIELD MANUAL
bering illustrated herein provides for the allotment of a block
of numbers to each section of the line along the axis and to each
section of the line laterally from the axis both to the right and
left. Beginning at the rear echelon of the division (the rear¬
most central in the wire system) each section of the line along
the axis is allotted a block of 10 numbers of three digits each —
hundreds, tens, and unit. The hundreds begin at 1 and in¬
crease in arithmetical progression for each section of the line.
The last two digits are from 01 to 10, in each section of the line.
Laterally to the left each section of the line is allotted a block
of nine numbers, the hundreds number, being the same as the
section of the axial line, terminating at this point of divergence.
The last two digits are from 11 to 19. The next section to the
left maintains the same hundreds number and takes the next
block of nine numbers beginning with an odd number; i. e.,
31 to 39, etc. The same method is applied to the allotment
of numbers to the sections to the right of the axis, using how¬
ever, for the last two digits, blocks of nine beginning with even
numbers; i. e., from 21 to 29; 41 to 49, etc.
22. Reports and records. — a. In order to make the most
efficient use of the collective wire system, the signal officer
should keep himself informed of the condition of the systems
of his own and subordinate units. Subordinate units report
to next superior units when the wire system is first installed
and thereafter whenever important changes are made. These
reports are usually made by telephone or telegraph, supple¬
mented by line route maps and circuit diagrams.
b. The signal officer requires the signal troops under his imme¬
diate supervision to keep such records relating to the wire system
as are absolutely essential to their efficiency. These records
cover installation, maintenance, and operation. Such records will
seldom be kept in small units where few circuits are maintained.
Reports are made by the chief of construction on the installation
or recovery of wire lines. When necessary the operating person¬
nel keep station logs and test and trouble reports. (See pars. 64
and 720 Section II
TECHNIQUE OF FIELD WIRE LINE CONSTRUCTION
23. Types of field wire. — There are four types of wire in
common use in the field: Field wire, single-conductor, type W-39;
field wire, twisted pair, type W-40; outpost wire, single-conduc¬
tor, type W-43; and outpost wire, twisted pair, type W-44.
The characteristics of these wires appear below.
BASIC FIELD MANUAL
19
.Standard field wires
Type
No.
Num¬
ber of
con¬
duc¬
tors
Composition of
conductors
Type of
insulation
Weight
per
one-half
mile
w/o
spool
Tensile
strength
(approx¬
imate)
Miles
equiv¬
alent to
trans¬
mission
over 30
miles
stand¬
ard
cable
Resist¬
ance
per mile
of single
conduc¬
tor, in
ohms
W-39_ _
1
10 steel 12 mils twisted
Moisture
Pounds
45
Pounds
160
20
52. 46
W-4CL _
2
about 1 copper 28
mils.
_ do _
proof.
...do _
92
320
15
53. 51
W-43_-
1
1 bronze and 3 steel 13
-_.do _
32
60
11
160. 90
W-44__
2
mils twisted about
1 bronze 14 mils.
_ do _
....do _
65
120
9
163. 90
24. Skinning wire. — In all types of splices made with insu¬
lated wire, the insulation is skinned or removed from that portion
of the wire used in making the splice. Insulation is best removed
by using pliers. The side-cutting pliers issued to all signal per¬
sonnel are suitable. The insulation should be bruised and
removed by squeezing it in the heel of the pliers, as shown in
Figure 4. Next grip the bruised insulation between the jaws of
the pliers and pull it off the wire. If a sharp line of demarcation
is made between the bruised and unbruised insulation, the insula¬
tion will part at this point. The edges of the plier’s jaws should
not touch the wire during the process. After the insulation is
removed the wire should be cleaned and brightened to free it from
corrosion, by scraping carefully with the jaws of the pliers.
25. Wire splices. — a. General. — The type of splice depends
upon the types of wire to be connected. Installation of field
wire systems requires the splicing together of various types of
stranded and solid conductor wire, stranded wire to solid conduc¬
tor wire, and single conductor to twisted pair.
(1) When splicing two pieces of twisted pair wire, the splices
in the two wires should be staggered at least 6 inches apart to
prevent possible short circuits. This method of staggering
splices is shown in Figure 5. To stagger the splices in twisted
pair wire, the ends of the two pieces of wire should first be cut
off even. The ends of each piece should then be untwisted a
distance of at least 14 inches. One wire of one pair — the tracer
20
BASIC FIELD MANUAL
wire if there is one — is cut off about 7 inches from the end. The
end of the short wdre should then be held against the end of the
corresponding wire in the other pair. The long end of the first
WVVWMM'WWWW * ' ^
~r» ■ ■ ■'■■wwQWi
6" OR MORg
SPLICE SPLICE -
WIRES SAME LENGTH
TL-700
Figure 5.— Splices staggered in twisted pair wire
pair will then lie along both wires of the second pair. Cut the
proper wire of the second pair so that the ends of each pair will
abut and the joints will be about seven inches apart. The long
BASIC FIELD MANUAL
21
wire of one piece should then be spliced to the short wire of the
other piece. After completing this splice, the remaining long
wire should be carefully wrapped about the splice with the
original lay. Wrappings may be extended at least 6 inches
beyond the first splice. The remaining long end should then
be spliced to the remaining short end. The second splice should
be made at least 6 inches from the first so that the two wires
in the completed splice are exactly the same length. If one
wire has been left shorter than the other at the completed
splice, the short wire will bear all strain at that point and will,
therefore, be easily broken.
(2) Stranded wire is normally connected to solid conductor
wire only where it is necessary to splice a stranded wire circuit
INSULATED WIRE SPLICED TO
in a field line to a solid conductor wire circuit on a pole line. In
this case the stranded wire should be tied in to some solid object
(cross arm or pole) near the splice and a little slack left between
the tie and the splice, as shown in Figure 6. In the tie, the knot
should take the strain, since the splice is not strong enough to
withstand a strong pull.
b. Splices, description, and method of making. — (1) Standard
field wire splice. — The standard field wire splice is used to splice
wire, type W-39, W-40, or other stranded wire with a copper
core. To make the splice, strip off the insulation for a distance
of 6 inches on the ends of the wires. Separate the copper core
strands from the steel strands. Clean the strands so they are
bright and free from corrosion. Tie a square knot in the wires,
leaving three-eighths of an inch or less between the knot and the
22
BASIC FIELD MANUAL
insulation on the wires. The knot should be tied with the steel
strands only, the core strands being left free. To tie the square
knot, hold one wire in each hand, ends to the front. Lay the
end of the right-hand wire over the left and pass it toward the
left once completely around the left-hand wire until the point
is again to the front. Turn it back in the direction of and along¬
side its starting point over the original left end. Bring the latter
up around the first, down through the loop, and pull taut.
Caution: The standing and running parts of each wire must pass
through the loop of the other part in the same direction, other¬
wise a useless knot known as the granny is formed. Figure 7
illustrates the steps in
making the square knot.
Continuing with the
splice, cut off the protrud¬
ing ends of the steel
strands just short of the
insulation. Place the core
strands from both wires
along the wire parallel to
its axis, allowing them to
extend beyond the knot
on either side. Take the
-j [-less than3/8 core strand on the right-
hand side of the knot and
bend it at a right angle to
the axis of the wire just
beyond the knot. Then
Figure 7— Method of tying a square knot proceed to wrap it firmly
around the wire and other core strand, seizing them firmly to¬
gether. The wrappings extend back onto the insulation for
several turns, each turn being placed close to the preceding
turn, as shown in Figure 8. Next wrap the remaining core strand
about the left-hand side of the knot in a similar manner. W rap
the splice with two layers of friction tape. The tape wrappings
begin and end in the center of the splice and extend over the
insulation of each wire for a distance of one inch, as shown in
Figure 9. The tape must be drawn tightly against the insula¬
tion, particularly at the ends, to insure a secure wrapping and
thereby prevent seepage of water into the bare wire joint.
(2) Standard outpost wire splice. — The standard outpost wire
splice is designed for wire, type W^-43, W^-44, or other stranded
BASIC FIELD MANUAL
23
core: wire
FANNED OUT
AT LEAST
OF INSULATION
REMOVED
LESS THAN S/a*
STEEL STRANDS
CUT OFF HERE
WRAPPINGS EXTENDED
(ONTO INSULATION
~-\QORE from
RIGHT-HAND WIRE
CORE FROM
RIGHT-HAND WIRE
CORE FROM
left-hand wire
TL-693
Figure 8. — Standard field wire splice
wire without a copper core, but may be used with any stranded
wire. It is least satisfactory for wire, types W-39 and W-40,
because of the stiff steel strands found in these ttvo types of
wire. To make the splice,
strip off the insulation for
a distance of 6 inches
from the ends of the wires.
Clean the wire strands so
they are bright and free
from corrosion. Tie a
square knot in the wires,
leaving three-eighths of an
inch or less between the
knot and the insulation
on the wires. Take the
protruding ends of the
wires and bend them
back onto the opposite
sides of the knot. Wrap
the ends tightly around
the main wire, drawing the turns up close against one another.
Extend the wrappings back onto the insulation of the main
wires for several turns. With the pliers, bend down the ends so
that the points of the strands will not puncture the tape wrap¬
pings. Figure 10 illus¬
trates the manner of
making this type of splice.
The splice is wrappe d
with two layers of friction
tape. The tape wrap¬
pings begin and end at
the center of the splice
and extend back onto the
insulation of the wire on
both sides of the splice
wrappings for at least 1
inch.
(3) Combination seiz¬
ing wire splice. — The combination seizing wire splice is used to
connect stranded wire without a copper core to a solid conductor
wire. To make the splice, strip off about 1 inch of insulation
from the end of the stranded wire. Clean both wires by remov-
j o.'fi ‘ aW'wwwT
BEGINNING OF TAPE WRAPPING
TAPE EXTENDS
I' OVER INSULATION^)
TWO LAYERS OF FRICTION TAPE
TL-729
Figure 9. — Splice wrapped with tape
24
BASIC FIELD MANUAL
ing the corrosion so that they are bright. Lay the stranded wire
bared end along the solid conductor wire. Take a piece of
seizing wire 12 inches
LESS THAN 3.
AT LEAST 6'0F
BARE WIRE ON EACH
END BEFORE TYING,
STRANDED WIRE
WITHOUT CORE
NO SPACE LEFT
BETWEEN ADJACENT
TURNS
ENDS CROSSED
BEFORE WRAPPING
TURNS EXTEND
ONTO INSULATION
[END OF
RIGHT-HAND WIRE
END
LEFT-HAND WIRE
TL-6S5
Figure 10.— Standard outpost wire splice
long, which has been
cleaned and brightened,
and wrap it about the
bundle, seizing the
stranded wire firmly
against the solid conduc¬
tor wire. Begin the seiz¬
ing by several turns at a
point on the solid conduc¬
tor wire ahead of the base
end of the stranded wire.
Continue the wrapping,
including the bare end,
several turns over the in¬
sulation of the stranded
wire and finishing with
several turns only around
the solid conductor. Wrap the seizing wire tightly and draw
the turns close against one another. Tape the splice with two
layers of friction tape.
The first layer begins at
the left-hand side of the
splice and continues to the
right-hand side, with the in¬
sulated stranded wire being
brought out between the
turns of the tape which goes
beyond it, as shown in
Figure 11. Reaching the
end, the tape wrappings
are reversed and the outer
layer wrapped about the
splice in the opposite
direction.
(4) C ombination core
splice. — T h e combination
core splice is used to con¬
nect stranded wire with a
ductor bare wire.
SEIZING W/RE IE" LONG
STRANDED WIRE
r
SOLID CONDUCTOR
SEIZING WIRE -
TL-696
Figure 11.— The combination seizing wire
splice
copper core strand to a solid con-
To make the splice, strip off the insulation
BASIC FIELD MANUAL
25
for a distance of 12 inches from the end of the stranded wire.
Separate the core strand from the steel strands. Cut off the
steel strands, leaving only about 1 inch protruding from the
insulation. Clean the wires (core strand, steel strands, and the
part of the solid conductor bare wire, where the splice is to be
made) so that all are bright and free of corrosion. Lay the
copper core bare end of the stranded wire along the solid con¬
ductor wire. Bend the core strand at right angles to the wire
and using it as a seizing wire, wrap the steel strands firmly against'
the solid conductor wire. The turns are placed close against one
another continuing for several turns beyond the steel strands,
and around the solid conductor alone, for several turns. The
splice is wrapped with two
layers of friction tape.
The first layer begins at
the left-hand side of the
splice and continues to the
right-hand side. The in¬
sulated stranded wire is
brought out between the
turns of the tape which is
further wrapped around
the solid conductor wire
for several turns. Reach¬
ing the end, the tape
wrappings are reversed
and the outer layer
wrapped about the splice
in the opposite direction.
Figure 12 illustrates the
manner of making this type of splice.
(5) Combination splice. — The combination splice is used to
connect the end of a stranded wire to the end of a solid conductor
wire without the use of seizing wire. To make the splice, strip
off the insulation from each wire for at least 6 inches. Clean
both wires so that every strand is bright and free from corrosion.
Tie an overhand knot in the stranded wire close to the insulation
and slip it over the solid conductor to within three-eighths of an
inch of the insulation. On that wire pull the knot tight, and
wrap the stranded end around the solid conductor from the knot
to the insulation. Cut off the protruding end. Next bend the
26
BASIC FIELD MANUAL
solid conductor back at the knot, and seize the stranded wire,
continuing up over the insulation for several turns. Cut off
the end, making sure that no protruding tip will cut through the
insulation tape. Wrap the solid conductor over the stranded
wire in a direction opposite to the wrapping of the stranded wire,
otherwise the solid wire will fail to hold the strands in place.
Tape the splice with friction tape. Figure 13 illustrates the splice.
(6) Commercial splice. — The commercial splice is used to con¬
nect a solid conductor wire with a free end to another solid con¬
ductor wire without
^STRANDED WIRE.
LESS THAN 3/3"-^
SOL/D CONDUCTOR WIRE
I +LESS THAN l/&"
AT LEAST 6" OF BARE
WIRE ON EACH END
BEFORE TYING
NO SPACE LEFT
BETWEEN ADJACENT
TURNS
a
free end. An example
of this type of splice is its
use in splicing an insu¬
lated solid conductor wire
to a bare copper wire in
an overhead line. Here
the wire should be tied in
to the pole or cross arm.
(See fig. 6.) I11 all cases
where insulated twisted
pair wire is to be tied in,
the tie should be made to
a w'ooden support. For
example, tie to a cross
arm and not to a cross
arm brace since the insu¬
lation wears more quickly
when tied to a metal sup¬
port. To make the splice,
remove the insulation for
a distance of 6 inches
from the end of the ware and clean the wires so that they are
bright and free from corrosion. Lay the bare end of the insu¬
lated wire along the bare line wire. Bend this end at right
angles to the line wire. Wrap the end around the line wire,
making at least five turns, drawing them tightly and closely
together. Wrap the splice with two layers of friction tape.
Figure 14 illustrates the splice.
(7) Western Union splice. — The Western Union splice is used
to connect two solid conductor wires. It derives the name from
its use in commercial telegraph line construction. To make this
END OF STRANDED WIRE
■TURNS EXTEND ONTO INSULATION
Ttsae
END OF SOLID CONDUCTOR WIRE
Figure 13. — The combination splice
BASIC FIELD MANUAL
27
INSULATED SOLID CONDUCTOR
BARE WIRE
BEND AT
RIGHT ANGLES)
splice, remove the insulation for about 6 inches from each end
of the wires and clean the wires. Twist the bared ends together
in the center, for about 1
inch, as shown in Figure
15. Bend the ends at right
angles to the length of wire,
and wrap each end around
the wire at least five times.
Cut off the ends as close as
possible, being careful not
to leave a sharp point that
will work through the tape.
Tape the splice with two
layers of friction tape.
26. Wire ties. — The
kind of tie used to secure
wire to an object depends
upon the type of wire and
the nature of the object.
The following kinds of ties
should meet all conditions
A T LEAST FIVE TURNS
TL-6S3
Figure 14. — The commercial splice
in field wire system construction.
TWISTED FOR F
MAKE AT LEAST 5 TURNS
CUT END OFF'
TL-699
Figure 15. — The Western Union splice
Where the wire is tied above
equipment to which it is
connected, arrange a drip
loop in the wire. To make
a drip loop, bend the wire in
the slack part between the
tie and the connection to
the equipment so that the
wire falls from the tie to a
point below the connection
and then runs up to the
connection. Figure 16
shows a drip loop at a
terminal strip. Water
running down the wire
will drip off from the
bottom of the loop and
will not be led into the
equipment, thereby causing possible short circuits. See para¬
graph 59, reference protection of equipment against moisture.
' 1143°— 31 - 2
28
BASIC FIELD MANUAL
which the wire is to be tied.
a. Clove hitch tie. — The clove hitch tie is used in tying wire
to a knob, insulator, stake, post, or other small object where
one end of the object is exposed so that the wire may be placed
over it. To make the clove hitch, stand facing the knob to
Make a loop in the wire with the
standing part (that end of the wire
coming from the point where the
wire laying began) behind the
running end (the end of the wire
coming from the spool being laid).
Place the loop over the knob.
With the standing part of the
wire, make another loop with the
standing part behind the running
end and place it over the knob
beside the first loop. Draw the
loops tight. Forming the two
loops and placing them on the
knob may be accomplished in a
TL-70J
Figure 16. — A drip loop formed in
wire leading to a terminal strip
number of different ways, any of which are satisfactory so long
as the results described herein are obtained. Figure 17 shows
the clove hitch made over a knob and Figure 18 shows the
same tie around a post.
h. Square knot tie. — The square knot tie is used in tying wire
to a tree, pole or other object around which the wire can be
placed, but which does not have an exposed end. Stand facing
the tree or other object on the side on which the wire is being
laid. Pull in enough slack to make a bight to go around the
tree, with about 6 inches left over. A bight is a loop formed on
the wire, so that the two parts lie alongside one another. Place
the bight around the tree from the front, going around the side
BASIC FIELD MANUAL
29
toward which the wire is to be laid. With the end of the bight
and the two wires forming the neck of the bight, tie the first half
of the square knot. Then with the end of the bight and wire
leading to the reel, complete the square knot, as shown in
Figure 19.
c. Loop knot tie. — The loop knot tie is used in tying field wire
to a tree, pole or other object around which the wire can be
Figure 18.— Clove hitch tie around a post
placed. This tie has the advantage of untying and falling away
from the tree when the protruding loop is pulled. To make the
tie, stand facing the tree on the side on which the wire is being
laid. Pull in enough slack to make a turn around the tree with
about 18 inches left over. Form a bight in the wire and place
Figure 19. — Square knot tie around a post
it around the tree from the front, going around . the side
toward which the wire is being laid and returning to the front
on the side from which the wire has been laid. Bring the bight
out underneath the neck formed by the standing part and
running end, and pass it around the neck for one turn. The V
opening formed in front of the tree when the bight was placed
30
BASIC FIELD MANUAL
about the tree is divided into a front and rear section by the
turn. Reach through the front opening and pull through it a
small bight formed by doubling the standing part of the original
bight. Snugly draw up this resulting bow knot. The steps in
making this type of tie are shown in Figure 20.
d. Knob tie. — The knob tie is used in tying twisted pair wire
to a knob, insulator, stake, small post, or other small object, one
Figure 20. — Loop
knot tie around a tree
TL-705
end of which is exposed so that the wire may be placed over it. It
is not suited to ties over an object larger than an insulator or
knob. To make a knob tie, form a loop in the twisted pair wire.
Separate the two wires in the loop and bend each back around
its side of the length of wire, so that they again touch each other
180° opposite the original position of the loop. Place the loop
Figure 21.— Knob tie made with twisted pair
over the knob and draw it tight around the knob. Figure 21
illustrates this method of tying.
e. Standard U tie. — The standard U tie is used in securing
bare wire to an insulator. Hold the line wire in the insulator
groove. Take a piece of wire about 8 inches long, placing the
center of this piece in the insulator groove on the side opposite
BASIC FIELD MANUAL
31
the line wire. Bend it around the insulator, with the ends under
the line wire. Wrap each end around the line wire. Make at
least five complete turns with each end and cut off the remaining
ends. Figure 22 shows this tie.
/. Marline tie. — The marline tie is used in tying wire where it
is desired to suspend it from an iron cross arm, or other metal
support. Take a piece of marline which, when doubled, will
reach from the wire in its suspended position, twice around the
support and down to the wire again, with about 4 inches left
over for tying. Double the marline and place it around the wire.
Insert the ends through the loop and draw the marline tight
around the wire on one side .of the support. Pass the doubled
marline twice around the support and back to the wire, tying it
securely with a double
overhand knot. To tie
an overhand knot as
shown in Figure 23,
placethe marline around
the wire and pass the
running ends over the
standing part and down
through the loop. Draw
the knot tight.
q. Marline knob He. —
The marline knob tie is
used in tying wire to a
wooden knob. (See fig.
24.) This tie is used principally where most of the wire circuit
is supported on knobs or insulators and where marline is avail¬
able. It is applicable to either single conductor or twisted pair.
For occasional ties to knobs, the knob tie, described in d above,
is generally used for twisted pair.
27. Circuit marking- tags. — A field wire circuit is identified
by means of a designation appearing on a tag tied to the wire.
The tag should be of rope stock or other fairly waterproof sub¬
stance which will show- the marks made by a soft pencil or crayon.
A short length of soft iron wrire is fastened to one end of the tag
for fastening to the circuit wrire. The designation of the circuit
is marked on the tag. (See par. 21.) Figure 25 shows a circuit
marking tag. The tag is fastened to the wire about a foot from
where the wire is connected to an instrument, terminal strip, or
switchboard when installed without a terminal frame. This
facilitates the identification of the circuit at the installation.
32
BASIC FIELD MANUAL
! !>
Tags may also be desirable along the wire route, especially at
points where the type of construction changes, as from surface
to overhead.
28. Terminal strips. — A terminal strip comprises a block
of insulating material to which is fastened a number of binding
posts or stud bolts with washers and nuts. The binding posts
are connected in pairs by metal strips, so that a wire connected
to a binding post on one side will be joined electrically to another
wire connected to the opposite post. Terminal strips are now
issued in several styles.
The type TM-84 (fig.
26) is provided with 10
through connections and
will handle five pairs of
wires. The connections
are made by means of
wing-nut binding posts
fitted with a washer and
skinner lug. The skinned
wire is connected by plac¬
ing the wire in the skinner
lug and around the bolt
under the washer in the
direction that the wing
nut tightens, then back
through the skinner lug.
The protruding end of
the wire is cut off. The
wing nut is then tight¬
ened. The type TM-
84— A (fig. 27) is also a
5-pair terminal strip and
differs from the TM-84
only in the structure of
the binding posts.
29. Wire laying equipment. — a. Field wire is carried for¬
ward and laid by any one of the following means, depending
upon the condition of the roads and terrain, traffic •conditions,
and character of hostile fire: Motor trucks; specially constructed
horse and motor-drawn carts and reels; escort wagons; reel carts,
hand drawn or towed behind communication carts; pack reels;
breast reels; spools or coils carried by hand.
TL-708
Figure 23. — Marline tie to
a metal support
TL-709
Figure 24.— Marline
tie to a knob
BASIC FIELD MANUAL
33
TL-7/0
Figure 25-
-Circuit marking tag
b. If issued on wooden spools, wire may be laid by inserting
an iron bar through the axial opening in the spool and paying off
from the spool, or the wire may be rewound onto a spool of spe¬
cial design used with a horse or motor-drawn cart or reel, reel
cart, breast reel, or pack reel.
(1) Motor trucks are used for laying wire but no special design
exists for this purpose.
The wire is either paid off
from the spool as issued,
or from a pay-out reel of
commercial or improvised
type. This method is ap¬
plicable where the route
lies along a hard-surfaced
road not subject to enemy,
shell fire.
(2) Specially constructed horse-drawn wire carts are authorized
for brigades and larger units within the cavalry and infantry
divisions. The carts are designed for a 2-horse team and are so
used within the infantry division. Cavalry units commonly use
a 4-horse team. The wire cart embodies features for paying
out and reeling up the wire. Each cart has two reels for holding
wire with a combined capacity of 5 miles of type W-39 or ap¬
proximately 2 miles of type W-40 wire. It is necessary to trans¬
fer the wire from the issue
spools to the cart reels.
skinner lug'') One or both reels may be
operated at the same time.
(3) Field artillery units
are equipped with spe¬
cially designed horse or
tractor-drawn reels, which
are used to lay wire for
their fire-control and com¬
mand systems. The bat¬
tery reel (4-horse) carries
approximately 1.7 miles of type W-40 wire. The artillery reel
(6-horse) carries 3.2 miles of type W-40 ware. This type is used
in field artillery battalions, regiments, and brigades.
(4) When conditions warrant, escort wagons may be used in
the same manner as motor trucks for paying out wire. Here
also the wire may be laid by inserting an axle through the wooden
tl- 711
Figure 26. — Terminal strip, type TM-84
34
BASIC FIELD MANUAL
BRASS KNOB!
BLOCK
SLOTTED /
BRASS STUD'
EBY TYPE
BINDING POST
COMPOSITION
BASE
reel or by using a pay-out reel. The escort wagon is not so
mobile as the horse-drawn wire cart, but carries more wire and
affords an additional means of laying when other facilities are
not available.
(5) Hand reel carts, shown in Figure 30, are issued within the
division. These small carts are pulled by hand or may be
towed behind communi¬
cation carts. Each cart
carries two steel spools
of wire. The spools may
be removed from the cart
chassis and replaced by
filled spools when they
become empty. Each
spool has a capacity of
approximately one-half
mile of type W— 44 wire.
The cart is so designed
that it may be taken
apart for packing.
(6) Pack reels are de¬
signed for the pay out
and recovery of wire from
a pack animal. They are
normally used by cavalry and pack artillery.
(7) Breast reels, as shown in Figure 31, may be strapped onto
the breast or back of a mounted or dismounted man. The
TL-7/2
Figure 27.— Terminal strip, type TM-84-A
Figure 28. — Truck adapted to wire laying
BASIC FIELD MANUAL
35
wire may be recovered by the use of a crank. The breast reel
holds about 600 feet of type W-44 wire.
(8) In laying wire by hand, the wire may be paid out by
placing the spool of wire on a stationary axle and carrying the
wire away from the spool; by carrying the spool on an axle and
paying out the wire while walking along the route; or by making
up coils of wire into such weights that a man can carry a coil and
pay out the wire while walking.
c. After the wire has been laid from the wire-laying device it
should be removed promptly from the path of the vehicle to
protect it from traffic. In this case the wire-laying device is
followed by personnel who use wire pikes (wooden poles with
hooks on the end) or the hand for moving the wire into its
36
BASIC FIELD MANUAL
desired position. Likewise, in the recovery of wire, the reel is
preceded by a lineman, who, with the use of a pike or the hand,
places the ware back on the road or path of the reel.
SO. Pole climbing. — a. Description of equipment. — The line¬
man’s equipment for pole climbing is a pair of climbers, lineman’s
belt, and safety strap. Each climber is provided with a top and a
bottom strap. The top strap is for the purpose of holding the
climber securely against the leg, while the bottom strap secures
the climber near the ankle. The top strap is equipped with a
leather pad which is placed between the upper end of the shank
of the climber and the leg to prevent the climber from chafing the
leg. The lineman’s belt is provided with loops for carrying the
various lineman’s tools and two rings to which the safety strap
is fastened. The safety strap is placed about the pole for safety
and ease while working.
b. Fitting equipment. — Climbers should be fitted to the leg so
that the end of the shank rests about 2 inches below the knee
joint. Both straps should fit snugly around the leg. Care
should be taken that the buckles do not rest on the shin or the
instep. The belt should fit loosely around the body but suffi¬
ciently tight to prevent its falling down over the hips. The
safety strap should be fastened to the belt by snapping both ends
to the ring on the left-hand side of the belt. (See fig. 32.) The
equipment should be carefully inspected before it is put on.
BASIC FIELD MANUAL
37
c. Procedure in climbing. — (1) To ascend the pole, take a natural
standing position at the foot of the pole, with the toes about 6
inches from the pole. Raise and extend the arms to a horizontal
position, grasping the pole with the palms of the hands, at the
same time allowing the body to fall backward to the full length
of the arms. Raise the right foot about 10 inches from the
ground, keeping it about 1 inch from the pole. With a downward
thrust, engage the spur of the climber in the face of the pole
about 8 inches from the ground. Lift the
body by straightening the right leg and plac¬
ing the weight on the spur which is engaged
in the pole. Let the left leg hang free and
keep the body away from the pole, as shown
in Figure 34. From this position raise the
left leg and repeat the thrust in the same
manner as before. At the same time raise
the left hand about 10 inches on the pole,
balancing the body with the right hand.
Continue to climb in this manner.
(2) Use of safety strap. — Climb to the de¬
sired height. Thrust the spur of the right
foot into the pole and shift the weight of
the body to the right foot. Pass the left leg
around the pole in such a manner as to aid
the right hand in supporting the body.
Keep the right knee about 5 inches away
from the side of the pole. Grasping the pole
with the right hand, unsnap one end of the
safety strap and pass the end around the pole
to the right hand. Aid the support of the
body with the left hand and with the right
hand fasten the loose end of the safety strap
to the right ring on the belt, as shown in
Figure 37. Clasp the pole with both hands,
leg from around the pole and with a downward thrust engage
the spur of the climber in the pole on a level with the right foot.
The heels when in the proper and most comfortable position
should be 3 inches apart. Lean backward gradually, placing
the weight of the body on the safety strap, as shown in Figure
38. Adjust the safety strap to its proper position on the pole.
Figure 32. — M e t h o d
of wearing pole-climb¬
ing equipment
Remove the left
38
BASIC FIELD MANUAL
(3) To descend the pole, unhook the safety strap, using the
above procedure in the reverse order. Climb down the pole,
throwing the weight of the body slightly on the right or left leg,
alternately, in order to place more force on each downward
thrust.
31. Wire lines, definitions and types. — A wire line con¬
sists of one or more wire circuits along the same route. Mili¬
tary wire lines are classified according to their general type of
Figure 33. — First position in
climbing
\
RL-P-SSS?
Figure 34. — Second position in
climbing
construction as cable lines, standard pole lines, semipermanent
pole lines, and field wire lines.
32. Surface line construction. — During movement of units
in combat, field wire lines are laid hastily on the ground. This
type of wire line is termed a surface line. Surface lines must
be protected from traffic at command posts, road crossings or
other places where traffic lanes cross the line. Surface lines
are laid loosely in order that the wire may be flat on the ground
and so as to provide sufficient slack for repairing breaks and
facilitating subsequent changes in the type of construction.
BASIC FIELD MANUAL
39
At suitable intervals, surface lines should be attached to objects
such as trees or posts in order to leave sufficient slack, and so
as to prevent passing troops and transports from pulling the
wire into traffic lanes. The wire is tied to the tree or post at
the ground level. When surface lines are routed along a road,
the wires must be kept off the traffic lane. If the road curves
in one general direction, the line should, if practicable, be routed
along the concave side. When surface lines are routed along
the convex side of a road, the line must be secured at several
Figure 35. — Third position in Figure 36. — First position in
climbing using the safety strap
points along the curve. Advantage should be taken of objects,
such as trees or posts, along a curve in the road to prevent the
wires being pulled into the traffic lane. Connections between
surface lines and standard pole lines are made preferably at
existing terminals of the standard pole line; if such terminals
are not conviently located a test station may be established.
When surface lines connect with permanent overhead construc¬
tion, the surface line must be securely tied at the base of the
pole at which the connection is made and again just above the
cross arm or terminal can where the connection is to be made.
40
BASIC FIELD MANUAL
If more than one surface circuit is to be connected to a permanent
line, a test station should be installed at the junction of the two
types of lines. Connections to aerial or buried cables are made
only at standard cable terminals.
33. Overhead construction. — Field wire lines are placed
overhead by fastening the wire to small knobs attached to trees,
buildings, or existing poles at a height of 14 feet above the ground.
In case knobs are not available, the wire is fastened to the sup-
Figuke 37.— Second position
in using the safety strap
Figure 38. — Third position
in using the safety strap
ports by means of standard field ties. This type of construction
is employed near command posts, test stations, overhead road
crossings, and other points along surface lines where traffic lanes
cross the wire. Test stations should be installed at the head of
construction and at the junctions of overhead lines with other
types of construction. At junctions between overhead and other
types of construction the wires are tied securely to the bottom
of the support and tagged.
34. Road crossings. — a. Where possible, - field wire lines
should cross roads at culverts. The wires are passed through
the culvert and tied at the entrance and exit to prevent contact
with water.
BASIC FIELD MANUAL
41
b. Wires which cross roads overhead must clear the crown of
the road by 14 feet. When a surface line crosses a road on poles
or other objects, the wires should be tied at the base and top of
the object on each side of the road. The strain which occurs
along the line is met by the tie at the base.
c. If neither of the above methods can be used, the line wires
should be buried in a trench, crossing the road at right angles.
The wires must be laid
snug and secured at both
ends of the trench to pre¬
vent their being pulled
out. A small amount of
slack wire should be left
at each side of the road to
permit replacement of the
portion under the road
should it become worn
or water soaked. Lines
are tied to trees, posts, stakes, or other suitable objects.
d. Circuits crossing roads in any of the above methods are
tagged at both sides of the road.
e. The passage of captive balloons along roads requires that
their movements be unhampered by interference from overhead
Figure 39. — Method of tying wire at ground
level; (a) correct, (b) incorrect
Figure 40. — Method of tying wire along curve in road
wires. Therefore, when practicable, wires should be routed
underneath roads. When overhead construction is necessary
provision should be made to permit the wires to be lowered to the
road surface. Little or no damage will result to the wires by the
occasional passage of balloon vehicles over them.
42
BASIC FIELD MANUAL
35. Railroad crossings.- — Field wire lines should cross rail¬
roads under the rails. If a bridge or culvert is available, the wire
should be laid through
the bridge or culvert, as
described in paragraph 34.
36. River crossings. —
a. Overhead. — Small
stream crossings are made
in the same manner as
overhead road crossings,
except that the wires need
be only high enough to
clear traffic. A span of
more than 150 feet should
not contain a splice. Long
spans can be made with
Figure 41.— Method of tying wire at junction of ggld wire but special
surface line with overhead construction
construction is necessary
for resisting the strain. Figure 46 illustrates methods which
have been adopted for military telegraph lines in Alaska, where
it was necessary to cross swift rivers and mountain gorges.
Figure 46 a and 6 shows two methods of providing support for
BASIC FIELD MANUAL
43
excessive strain on long spans. The line wire is made fast at G,
laid in the saddle at D, pulled up at saddle at C, and made fast
at strain insulator attached to H. As much sag as practicable
should be allowed, as the strain increases rapidly as the wire is
pulled taut. Figure 46 c and d shows method of constructing
saddles for supporting long spans. Figure 46 e shows an addi-
Figure 44. — Wire crossing under road in trench
tional method of terminating a long span wire, the wire having
passed over a saddle not shown in the figure. A modification of
the above method must be made to fit the material at hand in
44
BASIC FIELD MANUAL
each case, but the principles of guying illustrated above should be
followed.
b. Submerged. — When field wire lines must cross bodies of
water, such as rivers, where it is impracticable to make overhead
crossings as described above, the wire should be submerged. The
wire is tied in securely on the near bank, laid by paying out from
reel across the water, and tied in securely on the far bank.
When the water level is affected by tidal raises the ties should
be above the high-tide level. The insulation on the wire should
be sound. If the width is such as to necessitate the splicing of
more than one length of wire together, the splicing should be
done on the near shore and the entire length of wire made up into
a single coil or placed on one reel. Such splices should be
wrapped with rubber tape and then with friction tape. When the
width is one-half mile or less a reel cart, type RL-16, may be
placed in a pontoon or small skiff and the wire payed out from
the reel while the boat is rowed across the water. When the
current in the water is such as to wash the wire in the direction of
the current, weights should be placed on the wire at suitable
intervals during the laying to insure the wire will submerge to the
full depth. The current of moving water should be considered
and the effect of the current on the path of the boat computed to
determine the approximate length of wire required for the cross¬
ing so that it may be prepared prior to the crossing. Splicing
in midstream is impracticable.
BASIC FIELD MANUAL
45
37. Construction at circuit terminals. — The following
procedure should be followed as far as practicable in the laying of
field wire away from a terminal and approaching a terminal:
a . At the starting point, the free end of the wire is tagged to
show the circuit designation, as in Figure 25. This tag is placed
about 1 foot from the end of the wire.
b. Leaving sufficient wire at the free end to reach the terminal
frame or other fixed installation, the wire is tied in to some object.
c. The free end of the wire is connected to the binding posts on
the terminal frame or instrument. If a terminal frame is to be
Figure 46. — Construction of terminals for stream crossings
installed later, the wire is connected to a telephone or other
instrument, which may be used in making tests on the circuit
until the frame is installed.
d. The chief of construction directs the laying of the wire. He
follows the general route prescribed by the signal unit commander.
e. The wire is laid to the designated point. It is tagged and
tied in and a free end left with sufficient slack to run to the oper¬
ating installation (terminal frame or instrument). The circuit
is then tested. When the circuit is found to be in order, it is
turned over to the operating detail, who connect it to the ter¬
minal frame or instrument. After the circuit is connected, the
chief of construction calls back over this completed circuit to
46
BASIC FIELD MANUAL
the starting point or wire chief, reporting the installation and
receiving confirmation as to its operating condition. If the
circuit has been connected to a switchboard or a terminal frame
through which it is connected to a switchboard, he places his
call through the switchboard. If connected to a local instru¬
ment, the call is made from this instrument. Thus, any fault in
the terminal connection is detected and corrected before the
chief of construction makes his report over the circuit. If the
operating detail has not arrived at the terminal, the chief of
construction will leave a member of his detail at the end of
the wire. This man is equipped with a telephone or suitable
test instrument which he connects to the circuit. He remains
to turn the circuit over to the operating detail on their arrival
and to test back over the circuit after it is connected, or awaits
competent orders directing otherwise.
/. The chief of construction makes any additional notes neces¬
sary on his line route map and circuit diagram to complete the
record of the circuit. He turns this information over to his im¬
mediate superior at the first opportunity.
38. Test station construction. — a. Test stations are in¬
stalled in a field wire system to facilitate testing and cross
connecting circuits within the adjoining sections. For identifica¬
tion, a test station is given a name derived from its geographical
location, for example, Knob Hill Test. Test stations are located at
points along wire lines where it is considered desirable to adapt
the construction of the line for ready testing, or at points where
command posts have been, or are likely to be, located.
b. Test stations are constructed when the wire lines are ini¬
tially laid or are cut in on the lines later, and are cut out when
their use is no longer advantageous. The site selected for the
location of the test station should afford cover from hostile ob¬
servation and fire and protection from friendly troop move¬
ments and should be accessible for testing. A test station con¬
sists of one or more terminal strips. The circuits are connected
to pairs of binding posts on the right-hand side of the terminal
strip. Circuits are cut through the test station by jumpering the
corresponding binding posts on the left-hand side of the terminal
strip. The jumpers for this purpose are pieces of flexible insu¬
lated wire. The terminal strips are fastened to a support such
as a tree or fence post. The wire circuits are tagged and tied in
before being connected to the terminal binding posts.
BASIC FIELD MANUAL
47
(1) Construction of test station during initial installation of wire
lines. — Locate the site of the test station. Lay wires to this
location. Tag and tie in circuits near the terminal-strip posi¬
tion. Secure the terminal strip or strips to a support. The
number of strips used depends upon the number of circuits en¬
tering and leaving the test station, as there must be a pair of
binding posts for each circuit. Connect the lowest numbered
circuit entering the test station to the top right-hand pair of
binding posts on the terminal strip. Connect the next lower
numbered circuit to the next lower pair of binding posts and
continue in this manner until all are connected. The wires ex¬
tending forward from the test station are laid, being tied in near
the terminal strip. The lowest numbered of these circuits is con¬
nected to the pair of binding posts at the top of the lower half
of the terminal strip, and so on until all are connected. When
an even number of ter¬
minal strips is used, the /^Trunks -
number of pairs of bind¬
ing posts wdll be even
and can be evenly
divided into an upper
and lower half. If the
number is odd, the num¬
ber of pairs of binding
posts will be odd. In
this case, leave the odd
pair between the upper
and lower halves. Take
jumpers, prepared from
lengths of flexible insu¬
lated wire, which are suf¬
ficiently long to reach from the top binding post to the lowest
binding post on the terminal. Connect the proper circuits to¬
gether. The installation is shown in Figure 47. A telephone or
other suitable instrument is connected to the designated test cir¬
cuit as prescribed in paragraph 75.
(2) Construction of test station after initial installation of wire
lines. — Locate site of the test station along the route of the line.
Secure the terminal strips to a support. Take the lowest
numbered circuit and pull in slack on the wire. Tie in the wire
near the terminal strip. At a point where the wire reaches the
terminal, strip off about 2 inches of insulation from one wire
and attach it to the top right-hand binding post. Remove the
PL-P-550G
Figure 47
Twisted Pair
Fie/d Wire or
Outpost Wire -
-Test station constructed during
initial installation of wire lines
48
BASIC FIELD MANUAL
same amount of insulation from the other wire and connect it
to the lower binding post of the pair, as shown in Figure 48.
Measure off a sufficient length of wire to reach to the binding
posts of the pair from which the circuit is to leave the terminal,
and by removing the insulation as before, connect the wires to
these binding posts in the same order. Tie in the wires near
the strip. Jumpers are now connected to the corresponding
binding posts on the left-hand side of the terminal strip. The
loop in the circuit wire between the upper and lower pair of
binding posts is cut away, cutting the wire close to the binding
posts. Other circuits are cut in to the test station terminal strip
Figure 48. — Method of connecting wires to terminal strip in
construction of test station after initial installation
in a like manner. Beginning at the top with the lowest num¬
bered circuit, circuits will be cut in in numerical order.
c. Removal of a test station. — When a test station is to be
abandoned, it is the usual practice to leave the terminal strip
connected. It may happen that, due to shortage of terminal
strips, it is necessary to remove the terminal strip and splice the
circuits through. Before removing any circuit from the strip,
the lineman on duty at the test station first listens in on it and
satisfies himself that it is not in use. He then calls on the circuit
and notifies the switchboard operator that the test station is to
be removed and the circuits cut through. Then, taking two
wires that are connected together by the same jumper, he
BASIC FIELD MANUAL 49
removes them from the binding posts and splices them together.
The other wires of the pair are then spliced in a like manner.
Other circuits are removed from the strip and spliced similarly.
39. Routing field wire lines. — a. The signal officer pre¬
scribes the general route to be followed. The chief of construc¬
tion is usually allowed considerable latitude in the selection of
the actual route.
b. Maintenance is facilitated by using the minimum number
of routes. The route should be adapted to the means available
for laying the wire. It should be so located that the line can
probably be used by the same or another friendly unit after the
movement of command posts. It should afford cover from
hostile observation and fire. Main traffic routes, shelled areas,
and the areas over which tanks or tractors are likely to pass
should be avoided wherever practicable.
40. Construction orders.— a. The chief of construction
should receive orders prescribing the number of circuits to be
installed, the priority of installation, and the action to be taken on
completion of the installation. He should receive the following
descriptive information relative to each circuit to be laid:
(1) Numerical designation.
(2) The route.
(3) Whether a trunk or local circuit.
(4) Whether a metallic or ground return circuit.
(5) Type of wire.
(6) The centrals and test stations which it will connect or
pass through, including code names and organizations served.
(7) Approximate length.
(8) Type of construction.
(9) Nature of roads and terrain.
(10) Precautions to avoid damage from friendly troops and
materiel.
(11) Tests and reports required.
b. This information is imparted by the use of a line route map
and circuit diagram, supplemented by oral or written instruc¬
tions from the signal unit commander.
41. Procedure in laying field wire. — a. The wire for the
circuits is tested before starting to insure the continuity of each
spool. Spools of wire which when tested do not show a con¬
tinuous circuit are not used until the trouble is corrected.
b. The terminal connection is made as prescribed in para¬
graph 37. The detail then moves out and the chief of con-
50
BASIC FIELD MANUAL
struction directs the laying of the wire over the detailed route.
When necessary, he causes the wire to be placed to the side of
the path of the wire-laying vehicle, so as to give the required
protection to the wire. He determines the type of construc¬
tion to be used if not already prescribed in his orders, as well as
any changes in the type of construction, directing when and
where they are to be made. He causes a test to be made back
Figube 49. — Wire trench construction
to the starting point before and after making a splice in the
wire being laid, in order to insure the continuity of the splice.
When connections are made at terminal strips, he causes the
circuit to be tested from the far side of the connection back to
the starting point. Should the wire be laid to any location
where a central is to be installed but where the equipment for
the installation has not arrived, the chief of construction leaves
BASIC FIELD MANUAL
51
a man at this point to inform the arriving personnel of the lo¬
cation of the circuit and to assist in making the terminal con-'
nections. Sufficient slack is left at these places to permit
running of the circuit to the probable location of the central.
c. The wire having been laid to the designated installation,
the terminal connections are made and the circuit tested and
reported, as prescribed in paragraph 37.
42. Trench, line construction. — a. In zone defense, field
wire lines are often installed in trenches. In general, two kinds
of trenches are used:
(1) Wire trenches constructed for this purpose, and
(2) Trenches that are constructed primarily for other pur¬
poses, such as fire and approach trenches.
b. (1) Wire trenches vary in size from 10 inches wide by 10
inches deep to 36 inches wide by 30 inches deep. They afford
considerable protection from shell fire but offer an obstacle to
friendly traffic. The wire may be fastened to cross arms which
are attached horizontally to short poles or rest against or pro¬
ject into the sides of the trench. Instead of using cross arms,
the wire may be fastened to the sides of vertical poles. Twisted
pair may be tied directly to these supports with wire or string,
but it is preferable to tie the wire to wooden or porcelain knobs
or insulators.
(2) The wire trench route should be chosen with a view to
concealment, cover, and ease of construction. The wire is
kept in the main trunk-line trenches as much as practicable.
Switching centrals may be installed at important trench junc¬
tions.
(3) In digging the trench, the workers are divided into groups
of two men each, each group equipped with a pick and shovel.
Two men can dig from fifteen to thirty-five lineal yards of
trench per day in good ground, depending on the type of trench.
(4) Trench posts are set in the ground at intervals of fifteen
to twenty-five feet. They are guyed at turns and at the ends
of the line. When fastening wire to vertical poles, insulators
may be nailed on opposite sides of each pole. As many as 14
twisted pairs can be carried on a single pole line of this type in
a trench about thirty inches deep. A liberal allowance of wire
should be made for sag.
(5) Trench lines may be terminated by running directly into
a telephone central or test station or connecting to some other
type of construction.
52
BASIC FIELD MANUAL
(6) When necessary to cross a road with a wire trench, the
line should preferably be placed in a buried conduit of wood,
clay, or iron. If this is impracticable, the wires should be
carried overhead on poles.
c. (1) When it is impracticable to construct wire trenches,
field wire may be installed in fire or approach trenches. This
will be normal within the intrenched area of the infantry regi¬
ment. Owing to the great use made of these trenches by combat
troops, they are not satisfactory except for temporary wire
installations.
(2) Except in narrow fire trenches, wire lines should be kept
ordinarily on the side of the trench nearest the enemy. Wire
placed at heights between 10 and 30 inches from the duck
boards or bottom of the trench is least subject to damage from
cave-ins, water, and traffic.
(3) Field wire may be fastened to the side of a trench, as
shown in the composite Figure 50, by —
(a) Staples made of stiff wire and about 12 inches long.
The staples are driven into the ground as far as
possible, thus holding the wire closely against the
side of the trench.
(b) Attaching the wire to insulators mounted on boards
which are fastened to the sides of the trench by
rods or staples.
BASIC FIELD MANUAL
53
(c) Attaching the wire to insulators nailed to the ends of
wooden stakes or pegs which are driven into the
trench wall.
(d) Attaching the wire to insulators nailed to posts which
are driven into the bottom of the trench close to
the side.
(e) Passing the wire through supports made of No. 9 or
heavier GI wire. One end of the support wire is
attached to a stake driven into the ground just
outside the edge of the trench.
(/) Attaching the wire to revetment posts, either directly
or on insulators.
d. Trench wire lines are tagged at intervals of not more than
150 feet or at junctions with other lines.
Section III
INSTALLATION AND OPERATION OF TELEPHONES
AND CENTRALS
43. General. — This section furnishes information for both
the operating and using personnel. It prescribes in detail the
training needed for the operating personnel with a few cautionary
references of value for the using personnel and message centers.
44. Telephone centrals. — a. A telephone central is es¬
tablished at each echelon at a headquarters where two or more
local telephones are installed and at junctions of wire lines
where interconnecting is desired.
b. The telephone central serves the following purposes:
(1) To provide flexible intercommunication between local
telephones and to afford connection to circuits leading to other
units.
(2) To serve as a switching central at a junction of wire lines,
thereby reducing the number of circuits required and adding
flexibility to the system.
(3) To furnish a place at which all circuits are accessible for
test and from which maintenance may be directed.
45. Telephone conversations. — a. Telephone conversations
should be brief, as long conversations deprive others of the use of
the circuits. This can best be accomplished by mentally pre¬
paring the subject matter of telephone conversations before the
call is made. The telephone should not be used for long re¬
ports, orders, or messages when messenger or telegraph would
54
BASIC FIELD MANUAL
serve as well or better. Telephone conversations must be
discreet, since secrecy is never assured. Telephone conver¬
sations may be intercepted by direct tapping of the line, by
induction from our own lines, and by leaks to the ground and
thence to enemy listening sets.
b. No unnecessary conversation should be held with the
switchboard operator. In case it is desired to make a com¬
plaint regarding the service ask for the chief operator or com¬
munication officer. The operator should not be directed how
to route a call. The switchboard operator should be spoken to
in a civil manner.
46. Use of telephone code names. — a. To simplify and
expedite the operation of a telephone system, and to conceal the
identity of tactical organizations, code names are assigned to
tactical units. These code names are prepared by division
signal officers for use throughout the division. In corps and
armies the signal officer prepares code names for the unit head¬
quarters and for corps and arnw troops. A telephone central
takes the code name of its tactical unit.
b. The manner in which code names may be assigned is illus¬
trated in the following partial list for the 1st Division. These
coded names are given as examples only. They do not remain
fixed, but are changed from time to time.
Unit Code name
Headquarters, 1st Division _ Danger.
1st Signal Company _ Daylight.
1st Field Artillery Brigade _ Denver.
1st Field Artillery _ Dollar.
1st Battalion _ Dollar Red.
2d Battalion _ _ Dollar White.
1st Brigade _ Dig.
1st Infantry _ Deer.
1st Battalion _ Deer Red.
2d Battalion _ Deer White
3d Battalion _ Deer Blue.
47. Designations for officers and offices. — a. Enlarging
upon this system of unit code names, officers, and offices at a
BASIC FIELD MANUAL
55
headquarters are given code designations for use in telephone
conversations. The complete designation consists of the unit
code name and a distinguishing number.
b. The following list shows the assignment of code-number
designations to officers and offices at a headquarters. This
assignment remains fixed.
Title Code number
Commanding officer orC. G _ 6
Adjutant (not G-l) _ 7 .
Chief of staff or executive officer _ 5
S or G-l or administrative officer _ 1
S or G-2 or intelligence officer _ 2
S or G-3 or operations officer, or plans and training officer. _ 3
S or G-4 or supply officer _ 4
Ordnance officer _ : _ 8
Inspector - 9
Signal or communication officer _ 10
Message center _ 11
Machine-gun officer or machine-gun and howitzer officer _ 12
Aide-de-camp _ 13
Air officer _ 14
Engineer officer _ 15
Surgeon or medical officer _ 16
Judge advocate _ 17
Finance officer _ 18
Chaplain _ 19
Postal officer _ 20
Quartermaster (not supply officer) _ 21
Chief of artillery or artillery officer _ 22
Gas officer _ 23
Liaison officer _ 24
Munitions officer _ 25
Pigeon loft _ 26
Provost marshal, commanding officer special troops or
headquarters commandant _ 27
Radio station _ 28
Reconnaissance officer _ 29
Telegraph office _ : _ 30
Telephone wire chief or trouble chief _ 31
Veterinarian _ 32
Public telephone _ 33
56
BASIC FIELD MANUAL
c. In placing a telephone call, the code name of the organiza¬
tion and the designating number of the office or individual are
used rather than the organization name and individual’s title.
For example, in calling the executive officer of the 1st Brigade,
call for “Dig five,” and to call the commanding officer, 1st
Battalion 1st Infantry, call for “Deer Red six.” Code name
and number lists should be posted at each telephone instrument.
48. Use of phonetic alphabet. — Certain letters of the
alphabet have similar sounds and are often confused in telephone
conversation. To avoid this difficulty, the following pronuncia¬
tion of letters over the telephone should be used habitually.
Words that are liable to be misunderstood will always be spelled
out. For example, in transmitting the plain text words BARTS
CHURCH the word BARTS is apt to be misunderstood. Its
phonetic spelling would be as follows: BOUGH-ACK-R-TOC-
ESSES. The phonetic alphabet has its especial value in the
transmission of telephone or cryptograph messages in which groups
are almost entirely unpronounceable; for example, the code group
XISV would be spelled X-I-ESSES-VIC. Do not use the expres¬
sion “A as in ACK.”
A pronounced ACK.
B pronounced BOUGH.
C pronounced CAW.
D pronounced DON.
E pronounced E.
F pronounced F.
G pronounced GOGO.
H pronounced H.
I pronounced I.
J pronounced JIG.
K pronounced K.
L pronounced L.
M pronounced EMMA.
N pronounced N.
O pronounced O.
P pronounced PIP.
Q pronounced QUASH.
R pronounced R.
S pronounced ESSES.
T pronounced TOC.
U pronounced U.
V pronounced VIC.
W pronounced W.
X pronounced X.
Y pronounced YOKE.
Z pronounced ZED.
This list is posted on each telephone instrument for the con¬
venience of the using personnel.
49. Pronunciation of numerals. — a. The following pro¬
nunciation of numerals is used habitually in telephone conver¬
sation :
BASIC FIELD MANUAL
,57
Nu¬
meral
Pronounced
Principal sotmds
0
Ze-ro _ _ -
Long O.
1
Wun _ _
Strong W and N.
2
Too.. - -
Strong T and long OO.
3
Th-r-ce.-- - ..
Slightly rolling R and long EE.
4
Fo-wer _ ..
Long O, strong W and final R.
5
Fi-iv _
I changing from long to short and long V.
6
Siks _
Strong S and KS.
7
Sev-ven.
Strong S and V, and well-sounded EN.
8
Ate
Long A and strong T.
9
Ni-yen . .
Strong N, long I, and well-sounded YEN.
This list is posted on each telephone instrument for the con¬
venience of the using personnel.
b. When transmitting numbers, each numeral will be pro¬
nounced separately except in the case of even hundreds, thou¬
sands, or millions, when the word “hundred,” “thousand,” or
“million” will be used. For example:
44 is pronounced Fo-wer fo-wer.
80 is pronounced Ate ze-ro.
136 is pronounced Wun th-r-ee siks.
500 is pronounced Fi-iv-hun-dred.
1478 is pronounced Wun fo-wer sev-ven ate.
7000 is pronounced Sev-ven thou-sand.
12084 is pronounced Wun too ze-ro ate fo-wer.
16000 is pronounced Wun siks thou-sand.
c. When calling a number, speak the name of the central
deliberately and distinctly, pausing between the name and the
first digit. Speak each digit separately, pausing slightly between
digits. In the following examples a short dash represents a pause
of about one second, and a long dash indicates a slight pause.
Table 44; “Ta-ble - Four— Four.”
Turkey 80, “Tur-key - Eight — Zero.”
Track 6100, “Track - Six — one — hundred.”
50. Preparing cable for monocord switchboards. — Each
monocord and camp switchboard is equipped with a switch¬
board cable and terminal strip as a part of a central installation
prior to its use in the field. Once the cable and strip are con¬
nected to the switchboard they remain an integral part of it and
should not be disconnected except for replacement. Cable for
the monocord switchboard may be improvised in the following
manner:
58
BASIC FIELD MANUAL
a. Take any type of twisted pair wire (outpost twisted pair is
suitable, as it is flexible and light) and cut it into 1 1-foot lengths,
cutting one more length than there are units on the switchboard.
b. Stand facing the switchboard, connect one pair of wires to
the left-hand line circuit terminals of the switchboard and
temporarily attach the other end of the pair to the upper left-hand
pair of binding posts on a terminal strip, placed about 8 feet
from the switchboard. To connect to the switchboard line
circuit terminals, skin off only enough insulation from the end of
each wire, so that when the wire is fully inserted in the binding
post the insulation will touch the binding post. Similarly con¬
nect the other circuits in order from left to right on the switch¬
board and from top to bottom on the terminal strip. Leave the
unused pair sufficiently long so that each free end will reach to
any pair of binding posts; this is a spare pair for use in case one
of the others becomes unserviceable.
Figure 51. — The lock stitch
c. Take a piece of lacing twine or other stout cord and, begin¬
ning at the switchboard, lace the wires together neatly and se¬
curely, using a lock stitch, as shown in Figure 51. Each pair of
wires should leave the cable together as a pair (see fig. 52) rather
than as individual wires. Work toward the terminal strip in
lacing, spacing the stitches about l}i inches apart and pushing
the slack in the wires ahead of the lacing so as to make a neat
and compact cable. At the terminal strip the wires of each pair
should come out as a pair, opposite the desired left-hand binding
posts on the terminal strips. Cut the wires so that each will be
of the proper length for attaching to its proper binding post and
then attach them in the same order as before. Leave the ends
of the spare pair free until the cable is completed, then lace
them down with a separate piece of twine so that when needed
it will not be necessary to cut the main lacing of the cable.
d. Secure the cable to the switchboard to relieve the binding
post connections of all strain. Route the cable down the left or
right hand side of the switchboard. The arrangement as shown
in the figures is for illustrative purposes only. Equipment should
be so arranged that it can be most effectively operated under
BASIC FIELD MANUAL
59
existing conditions. Secure cable to wooden back by clamping
it, with strips of leather held down with brass screws. Terminal
strips may be mounted on a wood strip and cable secured to wood
to relieve the terminal strip binding post connections of strain.
Cable is coiled during transportation to prevent injury.
51. Installation of terminal frames. — a. Terminal strips
are installed to provide terminal connections for line circuits.
Where line circuits terminate in a terminal strip it is known as a
line terminal strip. Where a switchboard cable terminates in
a terminal strip it is known as a switchboard terminal strip. The
two together constitute the terminal frame. The terminal frame
should be located near the switchboard and to the rear or to one
side, either right or left, so that the switchboard operator will
not be disturbed by personnel working at the frame. When
1143°— 31 3
60
BASIC FIELD MANUAL
two sets of terminal strips are used as a line terminal strip and a
switchboard terminal strip, they are placed about 8 to 12 inches
apart and the corresponding circuits are connected by jumpers.
Figure 53. — Terminal frame installation
Circuits connected by jumpers are spoken of as jumpered. Sets
of terminal strips to be used as line and switchboard terminals
are not made up as a unit for central installation. The procedure
BASIC FIELD MANUAL
61
of converting a test station into a central or cutting out a central
and leaving a test station is built on the principle that the line
terminal strips are an integral part of the line and not a part of
the central equipment. When it is desired to mount the terminal
strips on boards for convenience in installation, the switchboard
terminal strips are mounted on one board and the line terminal
strips on another board.
b. To connect field or outpost wire to the binding posts:
(1) On type TM-8/h terminal strips. — Skin off 3 inches of in¬
sulation from the end of the wire to be connected. Pass the
wire through the skinner lug and around the binding post under
the washer, going in the direction the wing nut is turned in
tightening, and again through the skinner lug. Tighten the
Figure 54. — Wire connected to terminal strips; (a) type
TM-84-A and (6) type TM-84
wing nut. Cut off the projecting loose end and about one-eighth
of an inch beyond the skinner lug without leaving loose strands
projecting that might touch adjacent connections.
(2) On type TM-84— A} terminal strip. — Skin off about three-
quarters of an inch of insulation from the end of the wire to be
connected to the binding post. Open the slot in the post to the
full extent. Insert the wire end into the slot so that it projects
through the post. Firmly tighten the knob clamping the wire
with the fingers. Do not use pliers to tighten these binding
posts, as their threads may become stripped.
c. Jumpers are prepared from flexible insulated wire of suffi¬
cient length to permit their being connected between the top and
bottom binding posts on the strips. The ends may be con¬
nected in the same manner as stated in b above, or may be fitted
62
BASIC FIELD MANUAL
with either lugs or clips for rapidity in making connections to the
type TM-84 strip.
52. Repeating coils — use and installation. — a. Repeating
coils now issued are of commercial design. The ends of the coils
are brought out to terminals numbered 1 to 8 as shown in Figure 55.
b. Repeating coils are
used in field wire systems
for the construction of sim¬
plex and phantom circuits.
Additional telephone or tele¬
graph channels may be se¬
cured by the use of these
coils.
• (1) A simplex circuit is a
ground-return circuit super¬
imposed on a metallic cir¬
cuit. The simplex circuit
may be used for telephone
or telegraph. This permits
the simultaneous use of the
simplex circuit for telephone or telegraph and the metallic
circuit for telephone, without mutual interference.
(2) A phantom circuit is a metallic circuit constructed from
two physical metallic circuits. This installation permits the
simultaneous use of the phantom circuit for telephone or tele-
Figure 56. — Simplex circuit constructed with repeating coils
graph and the two physical metallic circuits for telephone,
without mutual interference. The two physical circuits are
known as side circuits. The third metallic circuit is known as a
'phantom circuit. The combination of the three circuits is known
as a phantom group.
BASIC FIELD MANUAL
63
c. The simplex circuit .■ — A simplex circuit is constructed by
placing a repeating coil at each end of a metallic circuit as shown
in Figure 56. Nos. 1 to 8 refer to terminals as marked on the
repeating coil shown in Figure 55. Nos. 9 and 10 are the ter¬
minals of the telephone circuit which may be connected to a
switchboard, local telephone, or another telephone line. Nos. 11
and 12 are the terminals of the simplex circuit which may be
connected to a switchboard, local telephone, or another telephone
line for use as a telephone line or which may be connected to
telegraph instruments for use as a telegraph line. The connec¬
tion to the mid-point of the line side of the repeating coil is some¬
times termed the telegraph leg or Morse leg.
d. The phantom circuit. — A phantom circuit is constructed by
placing a repeating coil at both ends of each of two physical
3 2 A LINE A 2 S
Figure 57.— Phantom circuit constructed with repeating coils
circuits and connecting the center points of the line sides of the
Wo repeating coils at each end of the side circuits as shown in
Figure 57. Nos. 1 to 8 refer to the terminals on the four repeat¬
ing coils, as marked on the repeating coil shown in Figure 55.
Nos. 9 and 10 are the terminals of the two side circuits. Nos.
11 and 12 are the terminals of the phantom circuits. The
terminals of the side and phantom circuits may be connected to
a switchboard, telephone, or another telephone line. Telegraph
instruments may be connected to the terminals of the phantom
circuit if a metallic telegraph circuit is desired.
e. Effect of repeating coils on transmission range. — -The intro¬
duction of a repeating coil reduces slightly the efficiency of the
64
BASIC FIELD MANUAL
metallic circuit to which the coil is connected. Simplex circuits
and phantom circuits are more efficient than the physical or
side circuits upon which they are superimposed.
/. Mutual interference. — In the above types of construction
mutual interference results only when each wire in the simplex
or phantom group does not have the same impedance. It is
important that the repeating coil be connected as shown, as the
half of the repeating coil connected to the line is more carefully
constructed than that intended for connection to the local
instrument or switchboard. If the two halves of the complete
electrical path between terminals 3-8 on one coil and terminals
3-8 on the coil at the far end of the circuit are not exactly of the
Figure 58. — Resistance (R) connected to balance simplex circuit
same impedance the circuit is said to be unbalanced, and inter¬
ference between simultaneous signals passing over the side
circuit and phantom circuit on the physical circuit and the
simplex circuit will occur. It is impossible to obtain a perfect
balance in a field wire system, but the mutual interference may
be reduced to a negligible value. Poor splices are the primary
cause of unbalance in field wire lines. A variable resistance
may be inserted in the low resistance side of an unbalanced field
line to improve the balance. The low resistance side is deter¬
mined by trial first with the resistance in one side and then in
the other. After determining the low resistance side the resist¬
ance is varied until the line is balanced or the interference is
reduced to a minimum.
Figure 58 shows the method of connecting the variable resist¬
ance unit in an unbalanced simplexed line. Nos. 1 to 8 refer to
the numbers on the twro repeating coil terminals. Li and L2 are
the two wires of a twisted pair. L2 is slightly defective. The
variable resistance R is inserted in Li between the repeating coil
BASIC FIELD MANUAL
65
terminal and the terminal of the wire at one end of the circuit
and is varied until an approximate balance is obtained.
g. Installation of repeating coils. — (1) Prior to being taken
into the field, repeating coils of commercial types should be
prepared for field installation as shown in Figure 59. Terminals
1 and 6 and 3 and 8 are’ connected together. Terminals 4 and 7
are connected to binding posts marked Li and L2. Terminals 2
and 5 are connected to binding posts marked Tpi and Tp2.
Terminals 3 and 8 are connected to a
binding post marked Tg. All connec¬
tions must be soldered and all wires
must be protected from mechanical
injury. The binding posts are screwed
to a thin piece of wood on which the
repeating coil is mounted.
(2) Repeating coils installed at a
switchboard are mounted between the
line and switchboard terminal strips
either above or below. (See fig. 60.)
(3) Repeating coils installed at a
test station are mounted to the left of
the terminal strip.
(4) Repeating coils must be protected
from moisture.
53. Installation of monocord
switchboard. — a. The monocord
switchboard with cable and switch¬
board terminal strip attached is
Installed in the following manner:
Figure 59. — Repeating coil
adapted for field use
(1) Secure the switchboard to a support. Holes in the
wooden back permit the tying of the switchboard to a support
with a piece of wire or stout cord. Unit and operator’s cords
should hang free without allowing the plugs to touch the ground.
The switchboard should be vertical or tilt slightly forward to
permit the drops to fall when released.
(2) Complete the terminal frame by installing the switchboard
terminal strip between 8 and 12 inches to the left-hand side of
the line terminal strip. Route the cable from the switchboard
to the terminal strip so as to afford maximum protection against
injury.
66
BASIC FIELD MANUAL
(3) Jumper circuits from line terminal strip to appropriate
binding posts on switchboard terminal strip.
(4) Connect the operator’s telephone to the switchboard
terminals marked Li and L2. Connect the ground rod to the
terminal marked G. Connect the night bell to the terminals
A and Aj and the bell battery to terminals B and Bi. Move
the shutter locks of the units to be connected to line circuits to
a horizontal position. Write with a lead pencil (not ink or in¬
delible pencil) the de¬
signation of the cir¬
cuits on the small
white celluloid strips
on each switchboard
unit.
(5) Test the instal¬
lation to insure satis¬
factory operative con¬
dition. Tests appli¬
cable are described in
paragraph 74.
b. Caution. — The
arrangement of the
equipment as shown
in the illustrations is
not mandatory but
for illustrative pur¬
poses o n ly . The
equipment should be
so arranged as to per¬
mit the most effective
operation of the installation under the existing conditions.
54. Installation of monocord switchboards in parallel. —
a. Circumstances may arise where one monocord switchboard is
insufficient for the number of circuits. In this case two or more
monocord switchboards may be connected in parallel. Usually
only two will be necessary, as organizations requiring more will
be equipped with switchboards of a type having a greater num¬
ber of drops. The number capable of being installed in parallel,
except as in b below, is limited by the length of the cords, wffiich
must be sufficiently long to reach any jack in the group. In¬
stallation is made as follows:
SW ITCH B OAR 0
TERMINAL STRIP
LINE
TERMINAL STRIP
TL-666
Figure 60.
-Repeating coil mounted at terminal
frame
BASIC FIELD MANUAL
67
(1) Install first monocord switchboard as prescribed in para¬
graph 53, leaving sufficient space between the switchboard and
operator’s telephone to place the desired number of additional
switchboards.
(2) Install additional monocord switchboards to the right-
hand side of the first. Installation is the same, except that only
Figure 61. — Installation of monocord switchboard
certain terminals are connected and these are connected in
parallel to the corresponding terminals on the first switchboard
as shown in Figure 62; to ground the switchboard, connect
terminals G to G; to make use of the night alarm, connect ter¬
minals Ai to Ai and Bi to Bi; when the operator’s cord on the
first switchboard is not sufficiently long to reach all units on the
additional switchboards connect terminals Li to Li and L2 to L2.
68
BASIC FIELD MANUAL
6. When the monocord switchboards connected in parallel are
installed in a manner which prohibits the plugging in of any
unit cord in all of the other unit jacks, full use may be made
of the switchboards by trunking the switchboards together.
This is accomplished by reserving for trunking one or more units
on the right-hand side of the left-hand switchboard and a like
number of units on the left-hand side of the right-hand switch¬
board. Plug the cord of the. unit of the left-hand switchboard
into the jack of the unit of the right-hand switchboard and leave
this connection up throughout the operation of the switchboards
in parallel. Any connection to be made between the switch-
Figuke 62. — Two monocord switchboards in parallel
boards where the unit cords will not reach may be made through
these two units which are trunked together.
55. Installation of telephone centrals. — a. Installation of
a telephone central includes installing the switchboard with
operator’s telephone and auxiliary equipment, connecting line
circuits through to the switchboard terminal strips, installing
testing equipment, installing local circuits, and connecting instru¬
ments thereto, testing the installation to insure its proper
functioning, preparing and posting a traffic diagram and tele¬
phone code, and making a# record of the installation. These
several operations are described below:
(1) Select a convenient site for the location of the telephone
central affording as much shelter as possible.
BASIC FIELD MANUAL
69
(2) Install the switchboard with its auxiliary equipment and
line terminal strips as prescribed in paragraphs 53 and 54.
Connect the line circuits to the line terminal strip and jumper
to the switchboard terminal strip. If a line terminal strip is
not to be used, connect the line circuits direct to the switch¬
board terminal strip. If the switchboard is to be used without
Figure 63. — Telephone central using double terminal strips
a cable and switchboard terminal strip, connect the line circuits
direct to the switchboard unit terminals.
(3) Short local circuits are installed by the operating details
in the manner prescribed in paragraph 37. These details install
the local telephones and maintain the local circuits. When cir¬
cuits which have been laid by the construction details are turned
over, the chief of the operating detail has them connected to the
proper pairs of binding posts on the line terminal strips.
(4) Install the testing equipment as prescribed in paragraph
73.
(5) Test each circuit and when in satisfactory operative con¬
dition report the fact to the chief operator, record the time the
70
BASIC FIELD MANUAL
circuit is connected, and inform the message center of the
available service.
(6) After the central is installed and the circuits are working,
rearrange the equipment to improve the appearance of the layout
and to facilitate maintenance. Prepare a traffic diagram and
telephone code and place them in a convenient location for the
operator.
b. Care must be exercised that the circuits radiating from a
telephone central are not an obstacle to troops and traffic at
the headquarters. They should be buried or placed overhead.
c. The use of circuits should not be delayed pending the in¬
stallation of the telephone central. If trunk circuits are avail¬
able before they can be connected to the switchboard, they
should be connected directly to telephones to give temporary
service pending the installation of the switchboard.
d. Priority in which telephones are installed at a headquarters
varies with the situation and the orders of the commander.
(1) At a command post, telephones are normally installed in
the following order of priority:
Message center.
Commander and C. of S. or Ex.
Signal service.
Operations and training section.
Intelligence section.
Personnel section.
A general utility telephone for personnel not furnished in¬
dividual telephones.
Other staff officers and activities as required.
(2) At small headquarters, as in battalions and regiments,
one telephone ordinarily serves two or more staff officers. At
larger headquarters, more than one telephone may be required
in each staff section.
(3) At rear echelons telephones are reduced to minimum
requirements. All routine administration is handled personally
or by messenger so far as practicable, leaving the telephone
system free for urgent messages. Telephones are normally
installed in the following order of priority:
Message center.
G— 4 representative.
Ordnance or munitions officer.
Quartermaster.
Adjutant.
BASIC FIELD MANUAL
71
A general utility telephone for personnel not furnished in¬
dividual telephones.
Other staff sections and activities as required.
56. Installation of switching centrals. — Switching cen¬
trals are installed in the same manner as telephone centrals.
Figure 64. — First step in converting test station into a central
Only trunk circuits are normally handled at a switching central.
57. Converting a test station into a telephone central. —
The switchboard is set up so as to allow the switchboard terminal
strip to be installed to the immediate left of the test station
terminal strip. Take four jumpers, preferably one having test
72
BASIC FIELD MANUAL
clips fitted to the ends. Temporarily jumper each circuit,
one at a time, from the right-hand side of test station terminal
strip to the left-hand side of the switchboard terminal strip. At
the switchboard, plug through the two units to which the 2-line
circuits are to be connected, so as not to interrupt any possible
Figure 65. — Second step in converting test station into a central
conversation over the circuits during the installation of the
central. With the temporary jumpers still on, remove the
jumpers on the left-hand side of the test station terminal strip
that connect this circuit through the test station. Cross connect
the circuit between the two terminal strips. Remove the tem-
BASIC FIELD MANUAL
73
porary jumpers. Repeat this procedure on the remaining
circuits. Listen in on each circuit entering the switchboard and
if a circuit is not busy remove its plug, thus clearing the through
connection. Call on each circuit and inform the answering
operator that the test station has been converted into a central,
giving the code name and any special information applicable.
This procedure is reversed when a central is to be converted
into a test station.
58. Installation of field telephones. — To connect a field
telephone to a metallic circuit, connect the two wires to the
74
BASIC FIELD MANUAL
2-line terminals of the telephone. When connection is made to a
ground return circuit, connect one line terminal to the line wire
and the other to a ground rod. Place the telephone in a position
convenient for the user. Tie in the circuit near the instrument,
leaving sufficient slack between the tie and the instrument to
permit some movement of the telephone. If the circuit enters
the place of installation (building, dugout, or tent) from an over¬
head line, provide a drip loop to drain the water away from the
telephone. The telephone code name and office number are
marked on a tag fastened to the telephone; this is for the con¬
venience of the user, who is notified as soon as the telephone
has been tested and found ready for use. A copy of the telephone
code should be with each telephone for the information and use
of the user.
59. Shelter for equipment. — Whire operating equipment
should be provided with shelter during inclement weather. Ex¬
cessive moisture will affect the operation of telephones, telegraph
instruments, test sets, switchboards, terminal strip connections
and repeating coils. This shelter must frequently be improvised.
Improvised shelter may be secured by using paulins, shelter
halves, tent flys, or lean-to structures built from foliage, metal,
or wood, the design of which must be left to the ingenuity of
the detail. Terminal strips can be mounted in weatherproof
BASIC FIELD MANUAL
75
boxes with sufficient space to permit using the box either as a
test station or as a terminal frame housing. Light wagons or
trucks may be used to house centrals and telegraph stations.
60. Operation of telephones. — a. Two types of field tele¬
phones are in common use on field wire systems, the type EE-4- A
and the type EE-5. In addition to these the service buzzer,
type EE-63, can be used.
b. These instruments have common operating characteristics
but vary in details of construction.
(1) The type EE-4- A telephone is equipped with a magneto
for ringing, and a hand set, hung from a hook switch, for talking
and listening.
(2) The type EE-5 telephone is equipped with a magneto for
ringing and a hand set for talking and listening. The push
Figure 68. — Improvised shelter box for terminal strips
button on the hand set must be pressed down while talking but
should be released when one is merely listening, as it uses up the
talking battery when depressed.
(3) The service buzzer employs a buzzer call. The receiver is
used for buzzer and telephone reception. A special telephone
transmitter is provided. The push button switch on the trans¬
mitter must be pressed down while talking. This instrument
should not be used for signaling a switchboard operator as its
buzzer call interferes with all telephone conversations through
his switchboard.
76
BASIC FIELD MANUAL
c. Adherence to the following rules is essential for efficient
telephone operation:
(1) To signal the operator with a field telephone, turn the mag¬
neto crank several times, holding the instrument firing. Do
not remove the hand set from hook when ringing on a type
EE-4-A. Do not press the push button when ringing on a type
EE-5 telephone. Lift the hand set from the hook or press the
button while talking. When the switchboard operator answers
the call, state the connection desired, for example “Magic — one-
zero." When the called party answers, identify yourself and
proceed with the conversation.
(2) To answer a call on the telephone instrument, remove the
hand set from the hook, or press down the button. Hold the
hand set in a natural position with the head erect. Never say
“hello" in answering. State the designation of the telephone
and of the individual answering, for example “Magic — one-
three speaking. "
(3) When through using the telephone or when it is desired to
again attract the attention of the operator, replace the hand set
on the hook, or release the button. Turn the magneto crank to
“ring off," indicating to the switchboard operator that the con¬
nection may be removed, or that you want some other service
from him.
(4) Always speak directly into the transmitter mouthpiece.
Speak distinctly and in a natural tone. Raise the voice slightly
when necessary, but never shout.
61. Operating phrases. — The following phrases are pre¬
scribed for use by switchboard operators and should be used by
them in all cases where they apply, to the exclusion of other
phrases of similar meaning:
a. “Magic operator." Used by operator at “Magic" in
answering any incoming call, either from a local telephone or
other centrals.
b. “Captain Blank’s code number is Magic — four; 1 will con¬
nect you." Used by an operator when a call comes in by name
or by some designation other than a telephone code number.
c. “Waiting?" Used by an operator in challenging on a con¬
nection to determine whether the called party has answered and
in supervising a connection.
d. “Hello, Magic," or “Hello, Magic — three." Used by an
operator when there is confusion or interruption on a connection
through two or more centrals and he is trying to get a distant
operator or called party back on the line.
BASIC FIELD MANUAL
77
e. “Here’s your party.” Used by an operator whenever it is
necessary for him to start the conversation over a connection.
For example, if the called party should answer before the operator
has connected him through to the calling party, the operator
after completing the connection should start the conversation
by using this phrase.
/. “I can give you the message center.” Used by an operator
in appropriate cases, after reporting that the called party’s tele¬
phone is out of order, the called party does not answer, or that
the called party has no telephone; if the called party has no tele¬
phone but answers over another number this latter phrase does
not apply.
g. “I will ring again.” Used by an operator when he has cut
in on an incompleted call and has been told that the called party
did not answer.
h. “What number were you calling?” May be used by an
operator when a party calls and reports that he has been given
a wrong number. In case a connection between two parties is
broken before they have finished and either party tells the opera¬
tor that he was eut off from his party, the same phrase may be
used.
i. “Magic — one-one?” Used by operator in repeating the
call to a calling party or another operator when such a call has
been given him to put through.
j. “Magic — one-one does not answer.” Used by an operator
in reporting to the calling party that the called party does not
answer.
k. “Magic — one-four has no telephone.” Used by an opera¬
tor in reporting to the calling party that the called party has no
telephone.
l. “ Magic — one-one is busy.” Used by an operator in report¬
ing to the calling party that the called party’s circuit is busy.
m. “ Magic— three-zero has no telephone, but I will give you
Magic — one-one. You may get him there.” Used by an opera¬
tor when the called party has no telephone but can be reached
over another telephone.
n. “What number is calling?” Used by an operator if, after
challenging, he has been given a new number to call. This
phrase enables the operator to determine which one of the two
parties previously connected is now requesting a new connection.
62. Operation of monocord switchboards. — The following
procedure is prescribed for use by an operator in handling calls
on a monocord switchboard.
78
BASIC FIELD MANUAL
a. To make a local connection. Example. — Magic — three calls
Magic — one-one. The telephone at Magic — three is connected
to drop No. 2 and that at Magic — one-one to drop No. 5 on the
switchboard. When the shutter on drop 2 falis, the operator’s
plug is inserted into the jack on unit 2. The operator answers
the call by stating his code designation, “Magic operator.”
The calling party states the number desired, “Magic — one-one.”
The operator repeats back “ Magi c-^-one— one,” then removes the
operator’s plug from the jack of unit 2 and inserts it into the jack
of unit 5. He rings, then immediately inserts No. 5 plug into
No. 2 jack.
b. To make a trunk connection. Example. — Magic — one calls
Mutton — one. The telephone at Magic — one is connected to
drop No. 1 on the Magic switchboard. The circuit to Mutton
passes through Maytime switchboard, and is connected to drop
No. 7 on Magic switchboard. The circuit from Magic is con¬
nected to drop No. 3, and the circuit to Mutton to drop No. 4 at
Maytime. When the shutter on drop No. 1 at Magic falls, the
operator’s plug is inserted into No. 1 jack. The operator answers
“Magic operator.” The calling party states, Mutton — one.”
The Magic operator repeats back “Mutton — one,” then removes
the operator’s plug from No. 1 jack, inserts it into No. 7, and
rings. When the Maytime operator answers, the Magic operator
states, “Mutton — one.” After the Maytime operator repeats
back “ Mutton— one,” the Magic operator inserts No. 7 plug
into No. 1 jack. The May time operator (at the intermediate
switchboard) inserts his operator’s plug into his No. 3 jack when
the shutter falls on the Magic operator’s signal, and answers the
call, stating, “ Maytime operator.” The Magic operator states
the connection desired, “ Mutton — one.” The Maytime operator
repeats back “ Mutton — one,” removes the operator’s plug from
No. 3 jack and inserts it into No. 4 jack and rings. When the
Mutton operator answers, the Maytime operator states, “Mut¬
ton — one.” When the Mutton operator has repeated “Mut¬
ton — one,” the Maytime operator inserts No. 4 plug into No. 3
jack. The Mutton operator then handles the call as a local
connection.
c. To supervise a connection. — A switchboard operator super¬
vises each connection: (1) To insure that conversation is estab¬
lished between the calling party and the called party, and (2) to
remove the connection as soon as possible after the conversation
is completed. The operator listens in after making a connection,
BASIC FIELD MANUAL
79
waiting to hear the called party answer and conversation begin.
He then removes the operator’s plug and restores the shutter.
Should another call enter his switchboard before he has super¬
vised this connection he removes the operator’s plug and answers
this latter call. The shutter is not restored until he has gone
back to the connection and supervised it. In supervising the
first call, the operator inserts his plug into the jack of the called
party and listens. If no conversation is heard he challenges by
questioning, “ Waiting?” If he receives no response he takes
down the connection. If he is notified that a called party has
not answered, he answers, “I’ll ring again,” and proceeds to do
so. If he receives an answer informing him that the connection
is being used he removes the operator’s plug and restores the
shutter. When a shutter falls on a completed connection, the
operator inserts his operator’s plug into the jack corresponding to
the fallen shutter and challenges by questioning “Waiting?”
If he receives no response, he takes down the connection and
restores the shutter. If a new number is given him, he repeats
the new number and adds “What number is calling?” After
receiving the number of the calling party he takes down the old
connection and completes the new call in the usual manner.
Connections that remain up for more than a reasonable time are
supervised in a manner similar to the above method.
d. To take down a connection. — The operator inserts his plug
in the jack of the called party and listens. If no conversation is
heard, he challenges “Waiting?” If no answer is received to the
challenge, he removes both plugs and restores the shutters if
down.
63. Records and reports.— At each telephone central, such
records covering its operation are kept as may be necessary in
preparing the required reports. These records may include a
station log, a traffic diagram and test and trouble records. (See
par. 72 for preparation of test and trouble records.) Reports on
the operation are normally rendered to the signal officer through
the message center.
64. Station log.— The station log should contain the fol¬
lowing information:
Place, date, and hour station opened.
Place, date, and hour station closed.
Schedule of operators.
Time of connecting or removing a circuit.
Interruptions to circuits (duration and nature if known).
80
BASIC FIELD MANUAL
This record is kept by the switchboard operator on duty,
under the supervision of the chief operator. A simple blank
form prepared for a station log is shown below,
STATION LOG
STATION: _
OPENED
CLOSED
PLACE
DATE
HOUR
PLACE
DATE
HOUR
•
SCHEDULE OF OPERATORS
CIRCUIT
NO.
TIME
CONNECTS
TIME
REMOVED
INTERRUPTIONS
OF SERVICE
NATURE
OF
REMARK5
FROM-
TO-
TROUBLE
signature of chief operator
Tl- 673
Figure 69. — Station log for a telephone central
85. Traffic diagram. — a. A traffic diagram shows by number
the telephone channels connecting telephone centrals and distant
local telephones in a net. The actual circuits connecting any
BASIC FIELD MANUAL
81
two centrals are shown as one line with a figure indicating the
total number of telephone channels between the two centrals.
The units to which each switchboard or distant local belongs
are indicated by the telephone code name and conventional
sign of the unit.
6. Figure 70 shows a traffic diagram.
c. The traffic diagram is prepared at each switchboard from
data contained on the circuit diagram. Special symbols for this
purpose are shown in paragraph 20.
66. Reports to message center. — The operating personnel
should keep the message center informed of telephone communi-
Figure 70. — Traffic diagram, 1st Division, 11 p. m., May 15, 1927
cation available to other centrals in the net. Interruptions and
other changes should be reported promptly to the message
center.
Section IV
INSTALLATION AND OPERATION OF FIELD TELE¬
GRAPH SETS AND STATIONS
67. The buzzer phone. — a. The buzzer phone, type EE-l-A,
is a portable wire telegraph set, designed to provide an additional
channel of wire communication over any existing field wire sys¬
tem. Its advantages are —
82
BASIC FIELD MANUAL
(1) It provides an extra channel of communication over lines
that at the same time carry telephonic communication without
interference from buzzer phone, except when the call signal is
used.
(2) It may be operated by radio operators with little addi¬
tional instruction.
(3) Its secrecy. Messages sent by buzzer phone can be inter¬
cepted only by a similar instrument cut in on the line.
(4) It does not cause interference with other types of electrical
signal communication, except with its call buzzer.
Its disadvantage is that it does not work well over leaky or
long lines.
b. The buzzer phone can be used on ground return, metallic
simplexed, or phantom circuits, except that v/hen more than two
buzzer phones are to be connected to the same circuit, all of the
stations are either connected between a line wire and ground or
are bridged across a metallic circuit.
c. To operate a buzzer phone, connect the line circuit to the L
and G terminals. To call a distant operator press the switching
key to the position marked call. This produces a highly induc¬
tive signal which interferes with telephone conversation, and
therefore should not be used except during the minimum time
required for calling. In the normal or nonoperating condition,
the switching key is in the position marked normal. The re¬
ceiver is then across the circuit and will produce a signal when
the distant operator calls with his call buzzer. After such a call
signal is made or received, the switching key is moved to the
send-receive position. Then, when the sending key is depressed,
an audible signal is produced in the distant receiver. When the
switching key is in the send-receive position and no signals are
being sent, a steady tone in the receiver indicates a difference in
potential between the two ground connections. A potenti¬
ometer is provided to compensate for this condition. Move the
potentiometer key slowly to right or left until the tone is least
apparent.
68. The service buzzer. — a. The service buzzer, type EE-63,
is a combination telephone and telegraph instrument. (See
par. 60 for use as a telephone.) When used as a telegraph instru¬
ment, messages are transmitted by producing a series of buzzes
instead of the double clicks common to Morse telegraph sounders.
(1) Its advantages are —
(a) It may be operated by radio . operators with little
additional instruction;
BASIC FIELD MANUAL
83
(b) It works great distances over leaky lines; and
(c) It is readily portable and very rugged.
(2) Its disadvantages are —
(а) The signals are readily intercepted;
(б) It produces interference on neighboring electrical
signaling equipment, and consequently cannot be
used ordinarily over simplexed telephone circuits.
b. The service buzzer may be operated over metallic or
ground return circuits. The line circuit wires, or line circuit
wire and ground, are connected to the L and G terminals, re¬
spectively. When the change-over switch is thrown to the buzz
position, telegraph transmission is accomplished by working the
key. Incoming signals are heard in the receiver, which is cut
into the circuit wdien the sending key is up. If the buzzer is to
be operated over existing Morse telegraph lines, the switch for
short-circuiting the line condensers should be opened; this places
the line circuit condensers in the line circuit of the service buzzer
and prevents grounding the Morse telegraph circuit.
69. Simplex circuits. — Telegraph circuits used in field wire
systems are obtained generally by simplexing the existing tele¬
phone circuits, thus eliminating the necessity for constructing
additional circuits for telegraph purposes. Repeating coils are
used for this purpose, as explained in paragraph 52. It is im¬
portant that the repeating coils be installed at the telephone
terminal frame, rather than at the telegraph station, so that
telephone trunk circuits, for the maintenance of winch the
telephone line personnel is responsible, will not run through
instruments or equipment for which the telegraph operating
personnel is responsible. If the repeating coils were installed at
the telegraph station, telephone trunk-line circuits would have
to run from the telephone terminal frame to the telegraph station
and back again to the same frame. With the repeating coil at
the telephone terminal frame, only one wire is run to a terminal
telegraph station from the “Tg” terminal of a repeating coil
at that frame, this wire being the telegraph leg providing the
wire connection to the telegraph circuit. The ground for the
telegraph ground connection can be located at the telegraph
office. Such a method saves time and line material, reduces
possibilities of trouble on the telephone circuits, and facilitates
the testing of the telephone circuits, without in any way inter¬
fering wdth the telegraph circuit.
84
BASIC FIELD MANUAL
70. Telegraph operating procedure. — Operating procedure
for the buzzer phone and service buzzer follows radio procedure.
(See ch. 3, Sec. II.)
Section V
MAINTENANCE OF FIELD WIRE SYSTEMS
71. General. — Field wire systems are subject to interruption
due to injury or physical destruction and from defective circuit
equipment. All such interruptions are termed troubles. Main¬
tenance of a field wire system includes the prevention, location,
and correction of trouble in the system. Such maintenance is
continuous. The means of preventing trouble and of locating
it after it occurs in a field wire system are —
a. Careful packing of all wire and equipment and careful
handling while it is in use.
b. Protection of equipment from moisture while in storage,
in transit and, in so far as possible, after it is installed.
c. Training of all operating and using personnel in the care
and use of wire equipment.
d. The inspection, cleaning, testing, and repair of the wire
lines and associated equipment, when removed from storage
for training or field service, and periodically during use.
e. Special tests for wire and equipment found to be defective.
/. Routing of wire lines and locating of centrals and stations
so as to avoid hostile shell fire, and so as to protect the lines
from the traffic of friendly troops or transport. Friendly tanks,
balloon units, artillery, and tractors are especially destructive
of wire lines.
g. Establishment of test stations at important wire-line
junctions and near points at which trouble is anticipated.
72. Periodic tests of line circuits and installed equip¬
ment. — a. Orders and instructions concerning the wire system
usually include instructions relative to periodic tests and the
frequency with which these tests are to be made. (See par. 17.)
Tests of line circuits include the testing of the operating equip¬
ment connected to such circuits.
b. Tele-phone line circuit testing. — (1) In the division or larger
units frequent calls from the telephone central for the purpose
of testing local telephone circuits and equipment may become a
nuisance to the users. Such calls may be avoided by having a
trouble man go to each local telephone and test back to the tele-
BASIC FIELD MANUAL
85
phone central. In smaller units, where the number of main¬
tenance personnel is more limited, the local circuits are usually
tested in the same manner as the trunk circuits. (See (2) below.)
(2) Inasmuch as the telephone operator will generally not
have time to make periodic tests, the wire chief should make
such tests from his terminal frame. However, the operator may
be called upon to make periodic tests when such testing does not
interfere with the expeditious handling of traffic.
(3) In making periodic tests at a point designated for testing
telephone circuits, each circuit is first tested by ringing the party
or central connected to it. If an answer is obtained, the test man
TEST AND TROUBLE RECORD
STATION _ DATE _
Circuits tested every minutes
CIRCUIT
TESTED
CLEARED
REMARKS
TIME
BY
TIME
BY
(Nature of trouble fikA
•
CHIEF OPERATOR
'TL-7E7
Figure 71. — Form for test and trouble record
states the code name of his central, followed by “testing, thank
you,” thus: “Surprise testing, thank you,” and then goes on to
test the other circuits. A busy telephone circuit is not inter¬
rupted to make a test; the fact that it is busy shows that it is
not in trouble. In case trouble is found on a circuit, the proper
maintenance personnel is immediately given all available infor¬
mation as to the nature and location of the trouble.
(4) Records of tests and troubles found on the trunk circuits
are kept by the wire chief at each telephone central on the test
86
BASIC FIELD MANUAL
and trouble record. (See pa#. 63.) This record gives the follow¬
ing information:
(а) Frequency at which periodic tests are to be made.
(б) For a circuit found to be in trouble; the number of
the circuit, when and by whom tested, when and
by whom cleared, and the nature and location of
the trouble. A form for the test and trouble
record is shown in Figure 71.
c. Telegraph line circuit testing. — Periodic testing of telegraph
circuits in a field wire system follows the same general princi-
Figuke 72. — Universal test set, type EE-65
pies stated above for telephone circuits. The telegraph operator
makes the tests and notifies the wire chief of the results.
73. Equipment used for testing. — a. The Signal Corps
test set. — (1) Figure 72 shows the test set, type EE-65, which
is an instrument designed to provide, in a compact portable
form, circuit testing equipment particularly adapted to field
use. The set can be used either in a vertical or horizontal posi¬
tion. If the voltmeter fails to read zero when all keys are in the
normal, straight-out position, properly adjust the needle by
means of the screw on the face of the voltmeter. The following
BASIC FIELD MANUAL
87
tests which can be made with this test set are described as for
line circuits. However, this test set is equally convenient in
testing the circuits of Signal Corps wire equipment. For such
tests, the frame of the instrument being tested is generally con¬
sidered as the ground. Before beginning any test be sure that all
keys on the test set are in the normal or center position. In the
following directions the keys are considered to be numbered from
1 to 5 from left to right. Prior to making any voltmeter tests with
this set the voltmeter battery of the set should be tested by moving
No. 4 key to the BAT position. The voltmeter will then indicate
the voltage of the voltmeter battery. This battery consists of two
BA-2 batteries connected in series and, if new, should register 45
volts. If BA-2 batteries are not available, other batteries, con¬
nected to give from 40 to 50 volts, may be connected to the bind¬
ing posts marked EX BAT. When using external batteries
remove the BA-2 batteries from the set. The cylindrical BA-1
battery of the test set, used as the transmitter battery, should
also be tested by removing it from the set and proceeding as in.
(3) below.
(2) Circuit tests. — These tests are described in the order they
are made during the normal testing of circuits in trouble.
(а) Ringing and talking test.— Connect the ends of the tele¬
phone circuit under test to the Li and L2 binding posts
on the test set. If the circuit is a ground return cir¬
cuit, connect Li to the metallic side of the circuit and
L2 to ground by means of the ground rod and its lead.
Adjust the receiver to the ear so that it is held com¬
fortably in place by means of the elastic band.
Operate No. 1 key to the RING position. Turn the
generator crank through at least three complete turns.
Then operate No. 1 key to LISTEN position. If the
called party answers, press the button on the trans¬
mitter; conversation may then begin. After conver¬
sation has been completed, return No. 1 key to its
normal position.
(б) Test for a complete short or open circuit. — Connect the
ends of the metallic or ground return circuit under test
to the Li and L2 binding posts on the test set. Oper¬
ate No. 3 key to the VMB position. If the circuit is
complete the voltmeter will give a continuous reading;
if open, there will be no continuous reading. If a
ground return circuit is to be tested at a place where
88
BASIC FIELD MANUAL
the lead to the ground connection of the circuit is not
available, connect the metallic side of the circuit to the
Li binding post on the test set and make certain that
the test set binding post marked GND is connected to
ground by means of the ground rod and its lead.
Operate No. 3 key to the VMG position. If the cir¬
cuit is grounded, the voltmeter will give a continuous
reading; if open there will be no continuous reading.
Upon completion of these tests, return No. 3 key to
normal position.
(c) Test for a condenser.— If in the test described in (6)
above a circuit tests open, leave No. 3 key in the
VMG position and operate No. 2 key several times
between its normal and LR positions. If there is a
condenser across the circuit there will be a voltmeter
reading only while the key is being operated. If this
test shows a condenser across the circuit, there is
probably an EE-4-A telephone or other instrument
with a condenser across the line circuit. An EE-5
telephone, or a monocord or camp switchboard con¬
nected to a line circuit, shows a complete circuit.
The set can be calibrated by reading the deflection
on lines having one bell and condenser, two bells and
two condensers, and so on. The condenser at the
station is charged and then discharged by the opening
and closing of the circuit under control of key No. 2.
id) Test for a grounded circuit. — Connect the ends of the cir¬
cuit to be tested to the Li and L2 binding posts on
the test set. Make certain that the GND binding
post on the set is connected to ground. Operate
No. 3 key to the VMG position. A voltmeter read¬
ing indicates a ground on the circuit. If the circuit
tested open in the test for an open circuit, the circuit
wire connected to the Li binding post is grounded.
Leaving No. 3 key in the VMG position, operate No.
2 key to the LR position to reverse the connections
of the external circuit. If the circuit previously
tested open, a voltmeter reading then indicates a
ground on the circuit wire connected to the L2 binding
post. Upon completion of the test for a grounded
circuit, return No. 2 and No. 3 keys to normal posi¬
tion.
BASIC FIELD MANUAL
89
(e) Test for a cross with another circuit. — Connect the ends
of the circuit under test to the Li and L2 binding posts
on the test set. Connect one wire of the circuit with
which the circuit under test is believed to be crossed
to the GND binding post on the set. Be sure that
for this test the ground binding post is not grounded.
Operate No. 3 key to the YMG position. A voltmeter
reading indicates a cross between the circuit wire
connected to the Li binding post and the circuit wire
connected to the GND binding post. To test for a
cross between the circuit wire connected to the L2
binding post, and the wire connected to the GND
binding post, operate No. 2 key, down, to the LR
position, leaving No. 3 key in the VMG position. A
voltmeter reading indicates a cross. Remove the
wire connected to the GND binding post, connect
the other side of this other circuit to the GND binding
post and repeat above tests to determine if either side
of the circuit under test is crossed with this second
wire of the other circuit. Upon completion of these
tests, return No. 2 and No. 3 keys to normal position.
(3) Measuring voltage of a battery. — Connect the battery to the
terminals marked BAT TEST. Be sure to have the positive
terminal of the battery connected to the plus ( + ) or left-hand
binding post. Operate No. 5 key to the EX BAT TST position.
The voltmeter is thereby connected across the terminals of the
battery. The voltage of the battery can be read from the volt¬
meter scale. Do not make this measurement on a battery whose
voltage is likely to be greater than the maximum-voltage reading
of the voltmeter scale.
b. Field telephone, type EE—J+—A, as a test instrument. — This
type of field telephone may be used for testing line or instrument
circuits. Prior to using a particular telephone for testing, it
should be tested as described in paragraph 81 b to determine
whether the instrument is in operating condition.- In using the
telephone for test purposes it is essential that the feel of the hand-
generator crank of the telephone used in making the test be
known. The manner in which it turns on ringing over an open
circuit, a short circuit, a complete circuit to which another
serviceable telephone or switchboard is connected, and for a
grounded circuit in the case of a ground-return circuit, should be
determined prior to its use for testing purposes. The following
tests may be made with this type of telephone:
90
BASIC FIELD MANUAL
(1) Ringing and talking test. — Connect the ends of the tele¬
phone circuit to be tested to the Li and L2 binding posts of a
serviceable telephone. If the circuit to be tested is a ground-
return circuit, connect Lx to the metallic side of the circuit and
L2 to ground by means of a ground rod and lead. Move the
hook-switch lever out and suspend the hand set from it. Turn
the hand-generator crank through at least three complete turns.
If the line circuit and the signaling apparatus of the distant
instrument are in serviceable condition, the crank should turn
with a slight drag. Remove the hand set from the hook switch
and place the receiver to the ear, holding the head vertical in a
normal position with the transmitter before the mouth. If the
called party answers, and can hear, the test shows that both the
line circuit and the instruments are in serviceable condition.
After conversation has been completed, return the hand set to
the hook switch and turn the hand-generator crank through at
least one complete turn, to ring off.
(2) Test for an open circuit. — Connect the ends of the metallic
or ground return circuit to be tested to the Li and L2 binding
posts on the telephone. Leaving the hand set suspended from
the hook switch, turn the hand generator crank through at least
three complete turns. If the circuit is open the bells should ring
and the crank should turn freely without any drag.
(3) Test for a short circuit. — Connect the ends of the metallic or
ground return circuit to be tested to the Li and L2 binding posts
on the telephone. Suspend the hand set from the hook switch
and turn the hand generator crank through at least three com¬
plete turns. If the circuit is short, the crank should turn with
difficulty as though a heavy drag had been placed on it, and the
bells should not ring.
(4) Test for a grounded circuit. — Connect one side of the
metallic circuit to be tested to the Li binding post of the tele¬
phone. Connect the L2 binding post to ground by means of a
ground rod and lead. With the hand set suspended from the
hook switch, turn the hand generator crank through at least three
complete turns. If the circuit wire connected to the Li binding
post is grounded, the results noted upon turning the crank will
be the same as for a short circuit, i. e., the crank should turn with
difficulty and the bells should not ring. Remove the circuit
wire connected to the Li binding post and connect the other side
of the circuit to Li. Repeat the above test to determine if this
side of the circuit is grounded. To test a ground return circuit
BASIC FIELD MANUAL
91
for a ground, have the circuit opened at the distant end and
then test as described above.
(5) Test for a cross with another circuit. — Connect one side of
the circuit to be tested to the Lj binding post of the telephone.
Connect one wire of the circuit, with which the circuit under test
is believed to be crossed, to the L2 binding post on the telephone.
Make a test for a short circuit, outlined in (3) above. If these
two wires are crossed, the test should indicate a short circuit.
If the two wires are not crossed, the test should indicate an open
circuit. Remove the circuit wire from the L2 binding post,
connect the other side of the same circuit to that binding post,
and repeat the test. Next remove from the Li binding post the
circuit wire being tested and connect the other side of this
Figure 73. — Voltmeter and battery connected for use in testing circuits
circuit to Li. Repeat above test to determine if this side of
the circuit being tested is crossed with either of the wires in the
other circuit.
c. Field telephone, type EE-5, as a test instrument. — The
methods of testing with this type of telephone are the same as
with the field telephone, type EE— 4- A, with the following modi¬
fications:
(1) A buzzer is used for signaling purposes instead of a bell
and it should never operate when the hand generator crank is
turned; and
(2) Substitute L for Li and G for L2.
d. Voltmeter and battery used in testing. — Figure 73 shows a
voltmeter and battery connected in series and equipped with
wire leads. This provides a simple arrangement for testing
equipment circuits. The terminals of the wire leads may be
1143°— 31 - 4
92
BASIC FIELD MANUAL
fitted either with test clips or short lengths of stiff copper wire
for convenience in making contacts with the equipment circuits.
This apparatus is suitable for making the following tests:
(1) Test for a complete circuit. — Connect the test leads to the
ends of the circuit to be tested. Complete the circuit by depres¬
sing the push-button switch on the voltmeter. If the circuit is
complete the voltmeter needle will indicate a reading.
(2) Test for an open circuit. — Connect the test leads to the ends
of the circuit to be tested. Complete the circuit by depressing
the push-button switch on the voltmeter. If the circuit is open,
the voltmeter needle will not indicate a reading.
(3) Test for a short circuit. — Connect the test leads to the ends
of circuit to be tested. Open the other end of the circuit. Com¬
plete the circuit by depressing the push-button switch on the
voltmeter. If the circuit tests short, the results will be the same
as for a complete circuit; i. e., the voltmeter needle will indicate
a reading.
(4) Test for a grounded circuit. — Connect one test lead to the
circuit to be tested. Connect the other test lead to ground.
Complete the circuit by depressing the push-button switch on the
voltmeter. If the circuit is grounded, the results noted will be
the same as for a complete circuit, i. e., the voltmeter needle
will indicate a reading.
(5) Test for a cross with another circuit. — Connect one test lead
to the circuit to be tested. Connect the other test lead to the
circuit with which the circuit to be tested is believed to be crossed.
Complete the circuit by depressing the push-button switch on the
voltmeter. If the circuit is crossed with the other circuit, the
results noted will be the same as for a continuous circuit; i. e., the
voltmeter needle will indicate a reading.
e. Receiver and battery used in testing. — Figure 74 shows a tele¬
phone switchboard receiver connected in series with a battery
and fitted with leads for testing. The terminals of the test leads
may be equipped either with test clips or short lengths of stiff
copper wire. The apparatus is suitable for making the tests out¬
lined for the voltmeter and battery in d above. However, in¬
stead of a reading indicating a complete circuit, in this case when
the circuit is completed by touching or connecting the test leads,
a click in the receiver indicates a complete circuit. A failure to
obtain a click on completing the circuit indicates an open
circuit.
BASIC FIELD MANUAL
93
74. Testing defective line circuits — locating and clear¬
ing trouble. — Defective line circuits are tested and their trou¬
bles are located with the aid of testing equipment employed in
the general manner laid down in paragraph 73. The special sup¬
plementary procedures applicable for locating the various line
circuit troubles are set forth below.
a. Telephone line circuits . — A trouble developing in a telephone
line circuit is detected either by telephone personnel while making
prearranged tests or by a telephone operator or user when the
circuit fails to give satisfactory service. In either case the
trouble should be reported immediately to the chief operator,
Figure 74. — Receiver and battery connected for use in testing circuits
wire chief, or other individual detailed to handle such cases, who
proceeds as follows:
(1) A short local circuit in trouble.
(a) First determine the nature of the trouble, i. e.,
whether open, short, ground or cross, by tests
described in paragraph 73. If the trouble is
caused by an open; place a short on the defective
circuit at the line side of the line portion of the
circuit leading to the switchboard. If the trouble
appears in this part of the circuit, short the circuit
at the switchboard side of the switchboard terminal
strips and repeat the test. If this test shows an
open circuit, place a short at the switchboard line
terminals and again repeat the test. If it is deter¬
mined that the trouble is in the switchboard, test
the fuses, jack, and drop unit as described in para¬
graph 82. If the trouble is caused by a short,
94
BASIC FIELD MANUAL
ground, or cross, open the defective circuit at the
line board side of the line terminal strip and test
that portion of the circuit toward the switchboard.
If the trouble is in this part of the circuit, open the
circuit at the switchboard terminal strip and repeat
the test. If the trouble is still present, open the
circuit at the line terminals of the switchboard and
repeat the test. If the trouble is in the switch¬
board, test the fuses and drop unit as described in
paragraph 82. If the trouble is in the terminal
strip, either repair or change to another pair of
binding posts on the strip. If the trouble is in the
cable, substitute a spare pair for the unserviceable
pair. If the trouble is in the fuses, replace the
defective fuses. If the trouble is in the drop circuit,
either connect the circuit to another drop circuit on
the switchboard, or in the case of a monocord
switchboard, replace the unserviceable unit with a
serviceable unit. In any of the above tests, make
ringing and talking tests, test for a short and open
circuit, test for a grounded circuit, and, if applica¬
ble, test for a cross with another circuit. It is
always proper to assume that the trouble may lie
within the equipment of the telephone central,
and time will generally be saved by first testing
this side of the circuit.
(6) If, upon making the first test described above at the
line terminal strips, the trouble is found to be to¬
ward the user’s telephone, reconnect the circuit, if
opened, and dispatch a troubleman with a service¬
able telephone, to the user’s instrument. On his
way he should inspect the circuit for visible sources
of trouble and repair any that he finds. He should
then make a ringing and talking test with the user’s
telephone. If he can not signal the operator with
it, he should replace the local instrument with his
own instrument, and repeat the test. If he can
now signal and converse with the operator, the
trouble was in the local telephone which should be
tested as in paragraph 81, and either repaired or
replaced. If he can not signal the operator, the
trouble is probably in the local line circuit, and he
BASIC FIELD MANUAL
95
should first test for a short and an open circuit, then
test for a grounded circuit, and if applicable, test
for a cross with another circuit. If trouble is
located in the line wire, work back toward the tele¬
phone central, testing at frequent intervals until the
trouble is found.
(c) After trouble has been located and cleared, notify the
user that the service is again available.
(2) Trunk circuits in trouble .
(a) Determine the nature of trunk circuit trouble and
„ whether it is in the telephone central or outside
thereof in the same manner as described for local
circuits, and if the trouble is found to be inside,
locate and repair. Proceed as in (1) (a) above.
If the trouble is found to be outside, proceed as out¬
lined below.
( b ) An open circuit. — If an additional circuit is available
call the distant operator and request him to place
a short on the defective circuit at the line terminal
strip. If this short completes the circuit, it indi¬
cates that the circuit between the two centrals is
:
in order and that the trouble is at the distant
central. So inform the distant operator and
request him to have the trouble cleared. If the
short does not complete the circuit, the trouble is
between the tw'O centrals, in which case a lineman
should be dispatched to locate and clear the
trouble. If an additional circuit is not available,
send a lineman out on the defective circuit to
locate and clear the trouble. In either case the
lineman proceeds as outlined in ( d ) below.
(c) A short or grounded circuit.— If an additional'circuit is
available, call the distant operator and have him
open the defective circuit at the line terminal
strip. If this clears the circuit it indicates that
the circuit between the two centrals is in order and
that the trouble is at the distant central. Inform
the distant operator to this effect and request him
to have the trouble cleared. If the open does not
clear the circuit, the trouble is between the two
centrals, in which case a lineman should be dis¬
patched to locate and clear the trouble. If an
96
BASIC FIELD MANUAL
additional circuit is not available send a lineman
out on the defective circuit to locate and clear
the trouble. In either case the lineman proceeds
as outlined in (d) below.
(d) The wire chief should determine as accurately as his
instruments permit the approximate location of the
trouble. This will facilitate the testing and
materially shorten the time required to locate and
clear the trouble. The lineman, starting at the
telephone central, carefully examines the circuit as
he proceeds on his inspection, particularly scru¬
tinizing the insulation, splices, underground and
overhead road crossings and places where the
wire has been passed over or pulled out of place
by traffic. Fouled insulation, poor splices and other
evidences of possible trouble should be repaired
and the circuit tested in order to determine if the
trouble has been cleared.
The lineman in testing the defective circuit for
an open connects his testing equipment across
the circuit without opening it. To test for a short
or grounded circuit he opens the circuit and then
tests in both directions. On completion of the
test the circuit is reconnected. In case it is neces-
. sary to open the circuit it should be done at a
splice or at a test station, if practicable.
( e ) A defective circuit may have more than one case of
trouble. These may be of the same nature or
different. It is essential that the lineman, after
clearing a case of trouble, test the circuit in both
directions to insure that it is in order. If trouble
still exists he continues his inspection u
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