Appendix: Signal Corps Equipment, World War II
The purpose of this appendix is to present a representative assembly of Signal Corps equipment, not only emphasizing the gear which was known in every wartime theater, but also including some items which, although under development or satisfactorily tested before the end of the war, never reached the field or even the production line. The grouping used is employed for convenience, in an effort to simplify the maze. It points out the principal but not necessarily the sole purpose of the equipment.
Military Communications
I. Wire communication
A. Wire and cable
1. Assault wire: very lightweight twisted pair (two conductors, each containing seven strands) which could be quickly laid over the ground
a. W-130: weight 30 pounds a mile, talking range about 5 miles.
b. WD-1/TT: weight 48 pounds a mile, talking range about 14 miles.
2. Field wire: heavier and stronger, for use in long lines on the ground or on poles
a. W-110-B: twisted pair, weight about 130 pounds a mile, talking range 12-20 miles.
b. W-143: parallel pair, talking range up to 27 miles.
3. Cable
a. WC-548: spiral-four cable containing two conductor pairs spirally wound about a core. This most popular cable was used wherever possible in carrier systems. It was supplied in various lengths, or cable stubs, chief of which was CC-358, a quarter-mile length complete with snap couplings and built-in loading coils.
b. Coaxial cable: hollow cable, or wave guide, for conducting VHF radio frequencies to and from the short VHF antennas (monopole whips, dipoles, etc.) and the associated transmitters and receivers.
B. Line-laying equipment
1. Reels for laying or recovering wire or cable
a. DR-4 and 5: small drums or reels for wire.
b. DR-7 and 15: larger reels for cable.
c. CE-11: a reel unit carried by the operator, suspended from his neck for laying 1¼-mile lengths of W-130.
d. RL-16: a two-wheeled handcart carrying two DR-4 drums; replaced during the war by the somewhat larger handcart, RL-35.
e. RL-31: a reel cradle for DR-4 and 5, carried by hand or in a vehicle.
f. RL-26: a heavy reel unit with gasoline engine drive, carried in a vehicle designed in 1932 for slow speed operation. Speedier versions were undertaken in 1945 as RL-108 and 118( )/G.
g. RL-27: an axle or shaft carried between two men and bearing a wire reel, DR-4.
h. MX-301 and 302: cases holding coils of W-130 and W-110 (wound by special machines) for rapid laying of wire at speeds up to 60 miles per hour.
i. CY-196/ATC: container holding several MX-301 dispensers fitted beneath a liaison-type aircraft for laying W-130 from the air.
2. Plow for burying lines (especially spiral-four cable) LC-61: towed by a truck; this device could plough wire or cable into the ground at 5 miles per hour to depths up to 18 inches.
C. Telephone equipment
1. Telephone sets (the telephones themselves are called handsets, see below under Accessories, handsets)
a. EE-8: standard field telephone set, hand-carried in a small case which included ringing equipment and batteries.
b. TP-9: a portable set including the generator and ringing components of EE-8 plus a vacuum-tube amplifier which extended the talking range of the wire line.
c. TP-3: a sound-powered field set, very lightweight, unencumbered by batteries, utilizing instead the energy of the speaker’s voice to produce sufficient current in the wire for ranges of a few miles.
2. Telephone amplifiers to extend the talking range of wire lines
a. Loading coils: inserted at intervals in wire lines, they strengthen weak currents by induction
(1) C-114: used to extend the range of W-110.
(2) C-426: an improved coil for W-110 and W-143. Spaced at one-mile intervals in W-110, these coils extended its talking range to 20 miles. At 5/8-mile intervals in W-143, they could extend its range to over 80 miles.
b. Repeater sets: containing a power source and vacuum-tube amplifiers, repeater sets could boost wire ranges to scores and hundreds of miles
(1) For noncarrier lines, both two and four wires operating on voice frequencies only
(a) EE-89: a lightweight repeater for two-wire operation, weighing but 13 pounds including a dry battery.
(b) TP-14: also for a two-wire line but much heavier, 75
pounds, powered either by standard a-c or by 12-volt storage battery.
(c) TC-29: a portable repeater for four-wire operation. Its major component was repeater EE-99.
(2) For carrier systems (C-type), four (sometimes two) wires operating both on voice and on higher, or carrier, frequencies
(a) TC-23: a repeater set whose major component was CF-3, generally spaced at 25-mile intervals in spiral-four cable line.
(b) TC-37: a two-wire carrier repeater, whose major component was CF-5. CF-5, used in conjunction with converter CF-4 (part of TC-33) which converted four-wire carrier operation to two-wire, could extend the two-wire range to 150 miles.
(c) AN/TCC-5 and 6: small, lightweight carrier equipment developed for AAF. 5 was a miniature version of the four-wire repeater CF-3; 6 a miniature version of both the four-to-two-wire converter CF-4 and the two-wire repeater CF-5.
3. Telephone terminal sets: for four-wire carrier systems (C-type)
a. TC-21: this carrier terminal, whose major component was CF-1, could handle four telephone circuits on four bands between 200 and 12,000 cycles.
b. AN/TCC-3: a lightweight carrier terminal for AAF, a miniature version of CF-1 for use with either wire or radio relay systems.
4. Telephone switchboards
a. BD-71 and 72: portable switchboards of 6- and 12-line capacity respectively, yet quite heavy, about 45 and 75 pounds.
b. SB-5 and 22 ( )/PT: lightweight (about 12 pounds) 4- and 8-line field boards to replace BD’s-71 and 72.
c. SB-18/GT: vestpocket five-pound 6-line emergency board composed of plastic adaptor plugs U-4/GT.
5. Telephone central office sets (telephone exchanges)
a. TC-1, 10, and 20: Army headquarters sets, TC-1 with a capacity of 100 to 300 lines was based on switchboard BD-80; TC-10 was similar but more rugged and more easily transported. TC-10 was built around switchboard BD-110 of go-line capacity, but three to six of these boards could be used in series. TC-20 was built around switchboard BD-120.
b. TC-2 and 4: sets for corps and division headquarters respectively employing switchboards BD-89 and 96.
c. TC-12: a small lightweight telephone central office set for AAF, using BD-91 of 20-line capacity.
6. Interphone equipment, used in tanks, armored cars, and aircraft
a. For tanks
(1) RC-53, 61, 99, and 146: for tanks and armored cars.
(2) AN/VIA-1: an external phone at rear of a tank enabling an infantryman outside to talk with crewmen inside.
b. For aircraft
(1) RC-36, 45, and 51: for use in multiplace aircraft.
(2) AN/AIC-1, 2, and 3: developed for use in rarefied air at great altitudes.
D. Telegraph and teletype equipment, including radioteletype
1. Telegraph
a. TG-5: a portable six-pound field set or buzzer for manual keying and receiving.
b. Boehme equipment: high-speed keying and recording office equipment for automatically transmitting and receiving Morse code signals over radio circuits.
2. Teletypewriters and teletypewriter sets
a. TG-7: a page printer; a tape printer had been developed in the 1930’s as TG-6. Late in the war a lightweight page printer suitable for a backpack was under development as AN/PGC-1 to replace TG-7, which weighed over 200 pounds. Several teletypewriter sets were also developed under nomenclature EE-97, 98, and 102. They included teletypewriters TG-7 and 37 and were capable of operation in the field on such portable power sources as PE-77.
b. TG-15: a heavy office set, 250 pounds, a page receiver and keyboard sender.
c. TC-16: reperforator teletypewriter set including a reperforator transmitter, TG-26. This set could produce from wire-line signals a perforated tape bearing both the message letter text and corresponding perforations in the five-unit teletype code. If the set were in a relay station, the message could be relayed automatically by running the tape through the reperforator transmitter. TC-17 (with TG-27) was identical with TC-16 and TG-26 except for its special keyboard designed for use in weather communications.
3. Teletype (and telegraph) repeaters and repeater sets
a. TG-9: designed to replace TG-4 to extend the wire range of two-way manual or printer telegraph.
b. TG-28 and 29: portable field repeaters to extend the normal telegraph range (60-90 miles) of W-110.
c. TC-18 and 19: repeater sets, terminal and intermediate respectively, for installation at the terminal or at an intermediate point along the wire line for boosting teletype signals. The chief components were repeaters TG-3rd (terminal) and TG-31 (intermediate).
4. Teletype (telegraph) terminals
a. TC-22: a carrier terminal (of which the major component was CF-2) providing four teletypewriter circuits over a single telephone circuit, or twelve such circuits over spiral four since only the three
upper voice frequency bands could be used for teletypewriter operation. Often telephone and teletype operation were combined, as one telephone and twelve teletype circuits. Such operation called for both TC-21 (telephone) and TC-22 (telegraph) equipment at the same terminal.
b. CF-6 (originally TC-28) : a teletype terminal, used in conjunction with TC-22, to provide additional teletype circuits on twoand four-wire systems.
c. TH-1 ( ) /TCC-1 (originally AN/TCC-1) : speech-plus-duplex (S + DX) terminal equipment which provided telegraph transmission over an existing telephone line—allowing a carrier telegraph circuit while retaining the voice circuit.
d. AN/TCC-4: a lightweight carrier terminal developed for AAF, a miniature version of CF-2 providing four telegraph or teletype circuits over a two-wire system or over radio relay equipment.
5. Teletype (and telegraph) switchboards
a. BD-100: providing facilities for 10 telegraph printer lines; a heavy board, weighing about 200 pounds.
b. SB-6 ( )/GG: a lightweight portable switchboard for four-line telegraph or teletype operation, replacing older telegraph boards, BD-50, 51, 52, and 53.
6. Teletype (and telegraph) central office sets
a. TC-3: a small central office set consisting of teletypewriter TG-7, switchboard BD-100, rectifier, and portable power unit.
b. AN/MR C-2: a mobile teletypewriter station providing (duplex) operation over radio SCR-399, a vehicular long-range set.
7. Radioteletype equipment
Much of the foregoing wire teletype equipment could be, and was, used in radioteletype systems, wherein radio waves substituted for wire lines. Additional equipment designed specifically for radioteletype operation included the following:
a. O-5/FR: a signal shifter which, when attached to a transmitter radiating continuous-wave radioteletype mark and space signals, caused the transmitter to send out two different frequencies or tones—one for mark, the other for space.
b. AN/FRR-3: a frequency-diversity radio receiver (2.5-26 mc) designed to receive both mark and space radioteletype signals on two frequencies or tones.
c. AN/FGC-1: a radioteletype terminal set designed to convert the two-tone (or two-frequency) signals received by AN/FRR-3 into suitable impulses to operate a standard teletypewriter.
d. AN/TGC-1: a semiautomatic tape relay set—a reperforator at the receiver punched a tape, on which it overprinted the letter text for the convenience of personnel unable to read the perforation code.
The tape needed only to be manually inserted in the proper transmitter, according to the designation of the message it bore, to be hurried on its way over an outgoing circuit.
II. Ground radio communication
A. Short-range: up to 25 miles (usually five miles or less for radiotelephone sets)
1. Portable sets a. SCR-194 and 195: one-man pack sets providing voice signals only on 27-65 mc; Army’s first walkie-talkies.
b. SCR-284: both portable and vehicular,.providing both continuous wave and voice; rather heavy, weighing complete about 250 pounds.
c. SCR-288: a stopgap set for SCR-284.
d. SCR-300: the renowned walkie-talkie, an FM set, manually tuned over 40-48 mc. Signal Corps developed a version of this set for Field Artillery (FA) as SCR-619 (to substitute for SCR’s 609 and 610) and a version of the 619 in turn for Armored Force as AN/GRC-12.
e. SCR -509: AF-II, an 80-crystal (any two frequencies preset) push-button FM radio; version SCR-709 had fewer crystals.
f. SCR-511: portable Cavalry guidon set, widely used by Infantry.
g. SCR-609 and 809: FA equivalents of SCR-509 and 709.
h. SCR-536: the handie-talkie, smallest of Signal Corps radio transmitter and receiver sets; a very popular AM set, followed by tropicalized and disguised versions, AN/PRC-4 and 6 respectively.
i. SCR-694: both portable and vehicular, successor to SCR-284 to whose crystal control it added two preset frequencies. Its receiver used alone was SCR-714. A late and improved version with continuous-wave range up to 75 miles was AN/GRC-9.
j. AN/PRC-3: a portable microwave transceiver developed for FA to replace signal lamps.
2. Vehicular sets
a. SCR-171 and 178: sets carried in a vehicle but operated on the ground; providing a 15-mile range on continuous wave only, 2-3 mc.
b. SCR-179 and 203: cavalry saddle sets. SCR-179 was a saddle version of SCR-178.
c. SCR-209 and 210: continuous-wave, tone, and voice sets for Armored Force.
d. SCR-293 and 294: first FM sets for the Armored Force; crystalcontrolled, providing voice communications only on 20-27 mc. A related FM set was SCR-298.
e. SCR-508: AF III, an 80-crystal (any ten frequencies preset) push-button radio (transmitter and two receivers) with variations SCR-528 (transmitter and one receiver) and 538 (one receiver). SCR-708, 728, and 738 were crystal-saving versions. All provided voice only on 20-28 mc, FM.
f. SCR-510: similar to the portable SCR-509 but designed for vehicles only. SCR-710 had fewer crystals.
g. SCR-608, 628, and 610: similar to AF sets 508, 528, and 510 but designed for FA with 120 crystals on 27-39 mc. SCR-808, 828, and 810 were crystal-saving versions.
h. AN/VRC-3: an FM set designed for tanks on the same frequency band as SCR-300 to enable crew men to communicate with ground troops using the walkie-talkie.
B. Medium-range: 25 to 100 miles
1. Portable sets
a. SCR-177: carried in a vehicle but operated on the ground, providing continuous wave, tone, and voice.
b. SCR-543 and 593: vehicular and ground sets for CAC; SCR-593 was portable, being the receiver portion only.
c. AN/TRC-2: a version of SCR-694 designed for eight- to ten-man pack for jungle or mountain use providing a continuous-wave range up to 100 miles.
2. Vehicular sets
a. SCR-193: set which could be operated to provide continuous wave, tone, and voice, while vehicle was in motion.
b. SCR-245: popular mobile set providing four crystal-controlled frequencies, selected by switches.
c. SCR-506: AF II; standard medium-range vehicular set providing continuous wave and voice on four preset crystal frequencies.
d. SCR-583: a saddle or vehicular set designed to replace the shortrange saddle set SCR-203.
3. Transportable radio relay equipment, both terminal and relay sets, employing directional beams in VHF, UHF, and SHF; FM or pulsetime modulated
a. AN/TRC-1, 3, and 4: VHF, on 70-100 mc, providing four circuits, FM.
b. AN/TRC-5: UHF, on 1500 mc, designed to provide seven radio circuits, employing pulse-time modulation.
c. AN/TRC-8, 11, and 12: VHF, on 230-250 mc, designed to provide four circuits, FM.
d. AN/TRC-16, 17, and 18: SHF, on 7000-8500 mc, designed as a very lightweight single circuit set for AAF.
e. AN/TRC-6: SHF, on 4300-4900 mc, a heavy duty eight-circuit set, employing pulse-time modulation.
C. Long-range: 100 miles and over
1. Portable sets a. AN/PRC-1 and 5: suitcase continuous-wave sets designed for Military Intelligence Service (MIS).
b. AN/TRC-10: a larger, yet portable set, also for MIS.
2. Mobile sets: operated in trucks in motion or at rest and powered by large generators carried in trailers
a. SCR-197: powerful set but of poor mobility; on 1-18 mc with five preset crystal frequencies.
b. SCR-505 (AF I) and SCR-597: development of the former was supplanted by designs for the latter to provide 100 miles on voice, 350 on continuous wave (up to 5,000 miles from ground to aircraft) having three crystal push-button channels in range 2-20 mc.
c. SCR-299: excellent long-range set mounted in a panel truck and powered by the reliable PE-95 carried in a two-wheel trailer. The 299 replaced SCR-597 and became standard for all the Army. Version SCR-399 was housed in the standard shelter HO-17, mountable in any 2½-ton truck. An air transportable version, SCR-499, became standard for the AAF. These sets radiated about 350 watts of power, yielding dependable loo-mile range on voice while in motion, and many hundreds of miles on continuous wave, in Morse code.
3. Transportable sets
SCR-698: largest of SCR radio sets, a one-kilowatt broadcast transmitter, used (together with receiver and monitor set SCR-696) by MIS (Psychological Warfare Units) for broadcasting to enemy and conquered countries.
D. Radio remote-control devices
1. RM-7 and 14: used respectively with long-range SCR-197 and with short-range 194 and 195, permitting telegraph operation from a distance, or remote-voice operation over telephone set EE-8.
2. RC-47: used with the ground-air liaison set SCR-188 permitting transmission or reception, voice, tone, or continuous wave, over six to ten miles of wire.
3. RM-29 and RC-261, 289, and 290: remote-control units for a number of portable and vehicular short-range sets (SCR-300, 284, 608, etc.) permitting control at distances up to five miles.
4. AN/TRA-2: used with radio-relay sets AN/TRC-1, 3, and 4 permitting control at distances up to two miles.
III. Air radio communication
A. Medium- and long-range command sets
1. Airborne component
a. SCR-183 and 283: HF sets (2-7 mc) operating on 12- and 24-volt airplane batteries respectively and providing continuous wave, tone, and voice for 10-45 miles between planes: 10-20 miles plane to ground.
b. SCR-264: first airborne VHF push-button set on 100-130 mc initiated by Signal Corps Laboratories in 1939, but use of the set was precluded by adoption of British VHF, SCR-522.
c. SCR-274: HF, up to 9 mc (VHF later added), 75 miles on voice, 150 miles on continuous wave.
d. SCR-522: a VHF set (100-156 mc) operating on 24-volt batteries with four preset crystal-controlled push-button channels. A version designed to operate on 12-volt batteries was SCR-542.
e. AN/ARC-3: an improved VHF set providing eight push-button channels.
f. AN/ARC-6: on still higher frequencies (225-285 mc) and especially designed to overcome jamming by the enemy.
2. Ground component a. SCR-562, 563, 567, and 633: VHF transmitters and receivers used with fighter-control system SCS-2, semifixed.
b. SCR-573, 574, and 643: ditto, used with fighter-control system SCS-3, mobile.
c. SCR-643 and 644: fixed VHF transmitter and receiver stations.
d. SCR-624: an adaptation of SCR-522 for ground use, good for 130 miles line of sight ground to plane. A similar adaptation for parachute drop was AN/CRC-1.
e. AN/VRC-1: a jeep-mounted set combining the HF SCR-193 with the VHF airborne command set SCR-542 to provide both ground and air communication—continuous wave, tone, and voice—up to 60 miles.
B. Long-range liaison sets
1. Airborne component
a. SCR-187 and 287: for 12- and 24-volt operation respectively; manually tuned, continuous wave, tone, and voice on 1-12 mc range up to 2,000 miles.
b. AN/ARC-8: derived from SCR-287 but incorporating pushbutton tuning; composed of transmitter AN/ART-13 and receiver BC-348 or AN/ARR-11.
2. Ground component
a. SCR-188: provided continuous wave, tone, and voice on 1-12 mc, the continuous-wave range matching that of the airborne SCR-187 and 287.
b. SCR-237: developed with 10 preset crystal channels with intent to replace SCR-188.
c. SCR-499: a version of the long-range SCR-399, packaged for parachute drop in 200-pound bundles. The set became standard for AAF ground liaison. A lighter weight parachute version was developed as AN/CRC-5.
C. Short-range paratroop and glider sets
1. SCR-585: a modified handie-talkie for use in gliders, talking range up to one mile.
2. AN/ASC-1: having a range of but 500 feet, for talk between glider and tow plane.
3. AN/PRC-2: a VHF set for paratroop liaison.
4. AN/TRC-7: a heavier VHF paratroop liaison set weighing 100 pounds, parachuted in four packages including a hand generator and a 30-foot sectional mast.
IV. Visual communication
A. Flags
1. MC-44: semaphore, 18” square, divided diagonally into red and white portions.
2. MC-113: semaphore flag kit containing two MC-44’s.
3. M-238: set of colored flags for signaling between tanks.
B. Panels and panel sets: cotton cloth strips variously colored to identify ground areas and units for friendly planes
1. AL-119, 120, etc.: square or rectangular, for aerial liaison.
2. AP-30-A and C: in dark colors, for use on snow or light backgrounds.
3. AP-30-B and D: in light colors, for use on normal backgrounds.
C. Lamps, to transmit blinker code by night or day
1. Signal
a. EE-80-A: heavy (194 pounds) 12-inch lamp and tripod signaling by white, red, or green flashes using commercial 115-volt alternating current or direct current, range up to 12-14 miles.
b. EE-84: portable searchlight-type set (42 pounds) operating on dry cell batteries with range up to 5,000 yards in sunlight, far greater at night; white or red flashes.
c. SE-11: highly portable (7-8 pounds) , flashlight-type, aimed like a gun with trigger key, daylight range 1,000-2,000 yards using red filter.
2. Identification: enabling planes to identify friendly ground vehicles and installations
a. AN/VVX-1: delivering intermittent flashes visible in bright sunlight three miles aloft or a mile or more along the ground.
b. AN/PVX-1: similar to above but portable, operating on selfcontained battery to mark front lines, installations, etc. It could also serve as blinker signal lamp.
D. Optiphone (or photophone: i.e., talk by light, by a steady modulated beam, not blinker light)
AN/TVC-1: formerly SE-10, involving a modulated light-beam transmitter and receiver, portable, with minimum range of 5,000 yards in sunlight and able to link telephone lines so as to span obstacles such as a river.
V. Pigeon communication
A. Lofts, transportable, for housing large numbers of birds
1. PG-46: prefabricated sectional housing for fixed use.
2. PG-68/TB: a combat loft, collapsible and easily transported by a truck or trailer.
B. Pigeon equipment including containers for carrying a few birds
1. PG-60, 102/CB, 103/CB, and 105/CB: portable, carrying two to four birds, for combat troops.
2. PG-100/CB and 101/CB: four- and eight-bird containers respectively, with parachutes for dropping to paratroops or isolated ground forces.
C. Message holders to fasten to the legs of the birds
1. PG-14: aluminum holders.
2. PG-52, 53, 54, and 67: plastic substitutes for the PG-14.
D. Pigeon vest, PG-106/CB, retaining a single bird, to be worn by paratrooper
VI. Reproduced communication
A. Public address sets
1. PA-1, 2, 3, 4, 5, and 6: sets varying from heavy systems powered by gasoline engine generators to simple portable microphones and amplifiers powered by batteries.
2. AN/TIQ-1, 4, and 5: powerful outdoor sets with speaking ranges up to 7,000 yards.
3. AN/PIQ-2, TIQ-2, and UIQ-1: portable battery sets.
B. Recorders and reproducers of sound
1. RC-17 and 169: recorders of speech or signals whether telephone, telegraph, or radio. RC-179 and 199 were used in radio intercept work to record any type of signal.
2. MC-364: record player and amplifier.
3. AN/ANQ-1 and 2 and GNQ-1 and 2: airborne voice recorders and ground playback equipment developed for air reconnaissance work.
C. Facsimile
1. RC-58: tape facsimile developed for use in AF vehicles to reproduce hand printed message texts received over vehicular radio sets.
2. RC-120: a page transceiver, to send or receive a seven-inch square page—text, map, picture—transmission or reception requiring seven minutes to complete. A larger version for fixed station use was AN/TXC-1, which could handle a page 12 by 18 inches over voice communication channels.
3. AN/GXC-2 and 3: transceivers for 4½ by 5¼ and for 8 by 10½ copy respectively.
Military Operations
I. Radar
A. Searchlight control
1. SCR-268: standard SLC set employing long waves, 1½ meters, on 205 mc.
2. SCR-668 and 768: experimental SLC sets, the latter patterned after the British “Wigwam” radars enveloped in tents.
3. AN/TPL-1: lightweight microwave set for use with 60-inch searchlights, developed from SCR-668.
B. Early warning: for long-range detection of aircraft. EW radars merged into medium-range EW and GCI sets.
1. SCR-270 and 271: respectively mobile and fixed long wave (3 meters, 109 mc) search sets, giving azimuth and range of aircraft up to 150 miles away. Versions designed to give elevation also were SCR-289, 530, and 531. SCR-539 was a PPI indicator developed for use with the 270 and 271.
2. SCR-548 and 648: experimental outer harbor aircraft detectors, shipborne.
3. SCR-602: copy of the British LW, lightweight warning radar, using long wavelengths at 200 mc.
4. AN/TPS-3: an efficient lightweight radar developed from SCR-548, using medium wavelengths on 600 mc. Other transportable EW radars for use in mobile situations, such as invasions, were AN/TPS-1 and 2, the latter totaling less than 600 pounds.
5. AN/TPS-10: a height finder and lightweight EW with narrow “beaver-tail” beam, for Air Forces use in hilly country; dubbed “Little Abner.”
6. AN/CPS-1: the powerful MEW, or microwave early warning radar, a huge set on 3,000 mc, radiating a 10-cm wave with range up to 200 miles.
7. AN/CPS-2: a medium-range EW developed to employ variable frequencies between 510 and 725 mc in order to evade jamming.
8. AN/CPS-4: a height finder only, to supplement MEW and SCR-270 and 271.
9. AN/TRS-1: electronic fence, employing continuous-wave radiations; a beat-reflection-type radar developed to detect aircraft flying over hilly terrain where ground reflections handicap pulsed-type radar search sets.
C. Ground-controlled interception
1. SCR-516 and 527: the 516 was developed from the SCR-268; the 527 was copied from the British GCI.
2. SCR-588: American copy, built in Canada, of the huge British CHL/GCI using long wavelengths.
3. SCR-615: a large transportable 10-cm microwave radar with range up to 90 miles.
4. AN/CPS-5 and 6: improved microwave sets for GCI applications.
D. Coastal defense and harbor surveillance: for long-range detection of surface craft.
1. SCR-296: a large fixed radar operating on medium waves, 700 mc.
2. SCR-582: a valuable microwave set, on 10-cm at 3,000 mc. Version SCR-682 was transportable.
E. Gun laying
1. For coast defense, against surface vessels a. SCR-598: similar to SCR-296 but of shorter range and greater accuracy for fire control purposes, directing gunfire against such small craft as motor torpedo boats.
b. AN/FPG-1 and 2: fixed sets using very short wavelengths, 3-cm, at 10,000 mc which permit great accuracy.
c. AN/MPG-1 and TPG-1: respectively mobile and transportable 3-cm coastal gun layers, long range and very accurate.
2. For air defense and AA batteries, against airborne targets
a. SCR-547: a “radio height finder,” replacing optical height finders supplying target range and elevation data. Known as “Mickey Mouse.”
b. SCR-545: a gun layer using relatively a long wavelength for search and a microwavelength for tracking or following the target. It was a semiautomatic gun layer, requiring hand tracking.
c. SCR-84: an excellent 10-cm gun layer, completely automatic for fire on unseen targets, very accurate.
3. For aircraft, against airborne and surface targets
a. Aircraft range only, aiding fire on visual targets
(1) AN/APG-5: automatic range finder for turret gunners in B-17’s and 24’s, developed from experimental SCR-523 and 726.
(2) AN/APG-11: designed for toss bombing, from plane to plane.
(3) AN/APG-14: for B-29 gunners.
b. Aircraft gun sight radars, requiring hand tracking
(1) AN/APG-13: effectively used with the 75-mm nose cannon of B-25’s, named “Falcon.”
(2) AN/APG-15: an efficient radar gun sight for tail gunners of heavy bombers.
c. Aircraft gun laying, automatic, for blind firing
(1) AN/APG-1: (SCR-702) used in the Black Widow night fighter, P-61. Weighed 700 pounds.
(2) AN/APG-2: (SCR-580) a 10-cm AI and AGL for bomber gun turrets. A 3-cm version for B-32’s was AN/APG-16.
(3) AN/APG-3: a smaller 3-cm AI and AGL for B-29’s.
F. Tail warning
1. AN/APS-13: a small 20-pound radar for fighter planes; it flashed a red light and rang a bell in the cockpit to warn that another plane was approaching from the rear.
2. AN/APS-16 and 17: similar tail-warning indicators for bombers.
G. Air interception
1. SCR-540: patterned after the British AI Mark IV, which operated on a long wavelength, 1½ meters, at 200 mc.
2. SCR-520 and 720: AI-10, superior 10-cm, 3,000 mc, microwave sets, but heavy, 600 and 500 pounds respectively.
3. AN/APS-4 and 6: smaller improved AI’s, operating on 3-cm wavelengths at 10,000 mc, developed in part from SCR-537
H. Airborne search and bombing: early search types were called air-to-surface-vessel radars, ASV, which developed into low-altitude bombing types, LAB, and bombing-through-overcast, BTO, types.
1. SCR-521: a long wave (1½ meters) ASV, patterned after the British ASV Mark II.
2. SCR-517: ASV-10, a microwave 10-cm radar operating in the S-band at 3,000 mc. Weight 500 pounds. A smaller version for LAB, blind bombing at low altitudes, was SCR-717. Other SCR’s in these categories were SCR-519, a 10-cm search and tracking set, and SCR-667, a 3-cm, X-band, set.
3. AN/APQ-5: an auxiliary bombsight much used in combination with the SCR-517 as a LAB set.
4. AN/APQ-11 and 12: (SCR-626) radar bombsights, designed especially for launching airborne torpedoes.
5. AN/APQ-13 and APS-15: superior BTO’s, 3-cm sets (X-band), known to the Americans as “Mickey,” to the British as H2X. They performed well at high altitudes and showed ground features in considerable detail.
6. AN/APQ-7 and 10: 3-cm BTO’s of even greater clarity than “Mickey.” APQ-7, dubbed “Eagle,” weighed nearly 1,000 pounds.
I. Identification, friend or foe
1. Mark IV, American sets, involving equipment independent of any associated radars, giving instant response
a. Ground interrogator-responsor SCR-532 and 533: for short and long ranges respectively.
b. Airborne transponder SCR-515: 150-mile range.
2. Mark II, adopted from the British SCR-535: airborne transponder, which swept the frequency bands of the early EW radars, and caused its plane’s echo in their scopes to appear large. No ground interrogator-responsor was needed.
3. Mark III, British IFF, standard for all the Allies; it depended upon associated radars for power and design; response was delayed
a. Ground interrogator-responsors, differing for each radar type.
RC-148, 150, 151, 127, 184, etc.: associated with SCR-268, 270, 271, 527, 584, etc.
b. Airborne transponders
SCR-595 and 695: on I-band, 157-187 mc. The 695 including also G-band, 200Mc, for benefits of long-wave GCI radars.
c. Airborne interrogator-responsor
SCR-729: enabling a plane to challenge the identification of other planes, which could answer if they carried SCR-595 or 695. SCR-729 was also much used in radar beaconry, (See under Navigation, Radar) .
4. Mark V/UNB: a universal identification and beacon system developed by U.S., British, and Canadian services, involving pulse sets in UHF.
J. Bomb proximity fuzing: fuzes operating on radar principles, emitting radio waves whose reflection from a nearby target served to explode the missile carrying such a fuze
1. MC-382: designed for aerial rocket bombs.
2. AN/CPQ-1, 2, 3, 5, and 6: designed to detonate bombs just above ground targets.
K. Glide-bomb control
1. RC-171: radar homing bomb equipment, an S-band radar fitting into a winged bomb designed to seek, or home on, a target illuminated by a radar transmitter in the bombing aircraft.
2. AN/APG-7: send-receive radar bomb, similar to RHB above, but containing its own radar transmitter.
L. Mortar location, enabled by radar tracking of the trajectory of the mortar shells
1. AN/TPQ-2 and 4: microwave radars.
2. AN/TPQ-3: a lighter weight medium-wave version, operating on 600 mc, modified from AN/TPS-3.
M. Personnel detection: radars of the continuous-wave, beat-reflection type
1. AN/PPQ-1: a very short-range, hand-carried set, developed to serve as an aid to night patrols, or as a sensory aid for the blind.
2. AN/PPS-1: a lightweight pack set to detect moving objects (tanks, trucks, men) .
II. Radio
A. Mine detection: mine detectors bore Signal Corps designations, were produced and distributed by Signal Corps, but their development was a responsibility of the Engineer Corps
1. Portable: carried and operated by one man
a. SCR-625: standard detector for metallic mines.
b. AN/PRS-2, 3, and 4: portable detectors for nonmetallic mines.
2. Vehicular
a. AN/VRS-2: detector designed to be mounted on a boom projecting ahead of a jeep and to stop the vehicle automatically upon detecting a mine ahead.
b. AN/VRS-3: a similar set designed for use by tanks.
B. Remote mine detonation: remote-control system for detonating mines AN/TRT-1 and TRR-2: transmitter and receiver respectively, the latter designed to operate under water adjacent to a mine, which it could detonate upon receiving properly coded signals from the transmitter miles distant—up to 40 miles when the transmitter was carried by a plane.
C. Bomb control
1. For glide bombs Azon and Razon
a. RC-186 and AN/ARW-16: transmitters to control the bombs.
b. RC-185 and AN/CRW-2 through 5, and 7 through 9: a group of receivers designed to fit within the bombs to receive the controlling impulses and transfer them to flight-control mechanisms.
2. For power-driven bombs, such as rocket bombs and War Weary Willies, which were jalopy bombing planes loaded with explosives and directed by remote control against the enemy
a. AN/ARW-18: transmitter, carried by the mother craft.
b. AN/ARN-1: receiver carried by the missile.
3. Automatic bomb release: whereby the bombardier in lead plane could release the bombs of all planes in his squadron simultaneously
a. AN/ARN-9: controlling transmitter (also used with Azon and Razon) .
b. AN/ARN-10: receiver, which actuated bomb release.
4. Tracking of robot bombs: developed for projected use of American version of the V-1 buzz bomb (JB-2)
a. AN/ART -19: transmitter carried by JB-2.
b. AN/CRD-5: a direction finder to track signals from the above transmitter.
D. Direction finders (DF’s) for fighter-control: VHF DF components of fighter-control (or SCS) systems. The DF’s took continuous bearings on aircraft radio emissions, especially airborne pipsqueak (RC-96), which radiated a signal once a minute. The bearings, laid out on plotting boards at control centers, served to track the planes in flight and enabled groundcontrol officers to guide the planes by radio telephone.
1. SCR-564, 565, and 566: fixed and mobile DF’s, components of SCS-2 (see under Air radio communication, Ground component).
2. SCR-575 and 634: mobile and air transportable respectively, components of SCS-3
3. SCR-645: fixed VHF direction finder.
4. AN/CRA-1: a kit embodying an electric goniometer by which VHF sets (SCR-575 and 634) whose H-Adcock antennas had to be rotated by hand, could be converted so as to provide instantaneous indication of direction in a cathode-ray scope.
5. SCR-552: a VHF DF with unique antenna, a conicle or funnelshaped dipole, which rotated constantly at 75 rpm.
III. Wire
A. The operators at SCS control centers and at information, filter, and operation centers for aircraft warning required rapid communication facilities. These were supplied by extensive wire nets, sometimes supplemented by radio also.
1. SCR-561 and 572: not radio sets but assemblies of telephones, switchboards, DF plotting equipment, filter and intercept tables, boards, etc. employed in coordinating fighter-control systems SCS-2 and 3.
2. SCS-5: an information center assembly, transported by six 2½ ton trucks.
3. SCS-6 and TC-15: mobile information center and filter center respectively, being successively smaller editions of SCS-5.
4. AN/TTQ-1 and 2: filter and operation centers transportable in two and one trucks respectively for plotting flights of aircraft. Still smaller versions for use with gun and searchlight battalions were AN/TSA-1 and 2.
B. Direction-finding and intercept centrals: transportable sets housed originally in K-35 trailers, later in HO-17 and in HO-27 shelters, and manned by radio intelligence units for locating enemy transmitters and for intercepting and recording their traffic
1. TC-8: a DF central set housed in two shelters and linked to associated DF radio sets by wire (or radio) nets.
2. TC-9: a RI (intercept) central housed in three shelters.
IV. Sound, thermal, light
A. Ranging equipment: for determining the range or distance to enemy artillery
1. Sound ranging: utilizing the different arrival times of a muzzle blast received by several spaced microphones to determine the direction and distance to an enemy gun
a. GR-3-C: utilizing a maximum of eight microphone listening posts.
b. GR-8: a lighter weight set using a maximum of six very sensitive microphones; a modified version became AN/TNS-2.
c. GR-6: an extremely accurate set using three microphones; a modification became AN/TND-1.
d. AN/TNS-1: designed to locate enemy mortars by sound ranging up to 5,000 yards.
2. Flash ranging: utilizing the data received by photoelectric cells from muzzle flashes
a. GR-4: standard set in World War II; but it was too heavy and too delicate.
b. AN/GTC-1: a lighter weight, yet more rugged, set.
3. Sound and flash ranging
AN/TSS-1: combined both sound and flash reception at a single observation station. Flash reception was at first accomplished by a photoelectric cell, later by an infrared detector.
4. Hydrocoustic ranging: equipment utilizing underwater sound, developed for Coast Artillery Corps until it was transferred from the Signal Corps to the Navy in June, 1942
GR-5: hydrocoustic tracking set, able to track vessels by their underwater sound to distances of 100,000 yards; a smaller version was GR-7.
B. Bomb-control (television, for remote control of flying bombs)
1. AN/AXR-1: television receiver (formerly SCR-550) for installation in the controlling plane.
2. AN/AXT-2 and 3: transmitters (formerly SCR-549) for installation in the controlled craft or flying bomb.
C. Photoelectric bomb fuze
MC-380: a proximity fuze developed to fit into the nose of a bomb such as the airborne M8 rocket for use against aircraft. The fuze contained a photoelectric cell which, on detecting a reduction in light intensity as the missile came within 60 feet of its target, detonated the bomb.
D. Photoelectric and supersonic detectors, or sensory aids: carried in one hand, these devices (including the radar sensory aid AN/PPQ-1: under Operational radar, Personnel Detection), could aid blind men, or night patrolmen, to detect the direction and distance of nearby objects
1. AN/PVQ-2: utilizing a pulsed beam of light which, when reflected from an object, impinged upon a photoelectric cell. This cell in turn modulated an audio signal, which the user detected in an earphone. The aid was unaffected by nonpulsed light, such as sunlight and ordinary electric light.
2. AN/PNQ-1: utilizing a pulsed-supersonic tone (stealing the secret of the flight control of a bat) . The tone, when reflected, was picked up by a microphone, supersonic like a bat’s ear, and reduced to an audible tone in a hearing aid worn by the user.
E. Thermal detection
Thermal equipment, utilizing infrared or heat radiations, largely occupied Signal Corps laboratories in the early 1930’s at the beginning of
radar development, which soon displaced infrared research. Yet infrared equipment had proved useful in detection both of ships and aircraft, in searchlight directing and in early forms of the radar SCR-268. It had been tried in 1941, as the Thermopticon, aboard a B-18 bomber and had detected a second B-18 up to 1,200 feet away. Late in the war an infrared detector was incorporated in the sound- and flash-ranging set AN/TSS-1 to detect muzzle flashes, replacing a photoelectric cell which had first been used in this set. Also late in the war the Navy desired an infrared ship detector to be used during radar silence, and called upon Signal Corps for
AN/SSS-1: a shipborne heat-radiation detecting equipment to search for and detect ships up to ranges of 15,000 yards.
V. Magnetic
Magnetic airborne detector, or magnetometer
RC-132: an airborne device which, dangled beneath a low-flying plane, could detect a submerged submarine by its magnetic field, which extends from below the water up into the air. RC-132 became AN/ASQ-1, variations of which were designated ASQ-2 and 3.
Navigation
I. Radio
A. Compasses: airborne loop-antenna direction-finding receivers (DF’s)
1. SCR-242: a LF-MF 12-volt set. A 24-volt version was SCR-282.
2. SCR-246: LF, 12 volts. A 24-volt version was SCR-276. Another version developed to home on much higher frequencies in VHF was SCR-256.
3. SCR-263, 273, and 280: dual remote-control compasses, operating in LF and MF.
4. SCR-269 and 279: standard automatic radio compasses for 24 and 12 volts respectively, LF and MF. Later versions of the standard SCR-269 were AN/ARN-6 and 7 (or SCR-599 and 639 respectively) .
B. Beacons operating on radio-directional principles
1. Ground Forces homing equipment
a. Beacon attachments for radio transmitters
(1) RC-163: HF directional attachment, 25-mile range, for vehicular radios SCR-508, 510, 608, 610, etc.
(2) RC-302: attachment converting SCR-284 and 694 into beacons for guiding troops; similar to SCR-277.
(3) AN/TRA-3: all-directional, rotating antenna set, similar to RC-163 but lighter in weight.
b. DF attachments for radio receivers
(1) RC-300 and 303: for SCR-300 (walkie-talkie) and 511 respectively.
(2) BC-309: similar attachment for SCR-508, 608, and 619.
(3) MC-619: similar attachment for the handie-talkie SCR-536.
2. Ground radio range beacons for aircraft guidance
a. SCR-277: a military version of the commercial A-N quadrant type; fixed LF, 200-400 kc.
b. SCR-629: an E-T range, omnidirectional with rotating antenna operating in VHF on 100-156 mc.
c. AN/MRN-2 (formerly SCR-601) and AN/CRN-5: mobile and air transportable respectively, similar to SCR-277 but operating in VHF on 100-156 mc.
3. Air-sea-rescue beacon and receiver
a. SCR-578: an emergency transmitter, hand powered, for use by aviators downed at sea, nicknamed “Gibson Girl”; a modification became AN/CRT-3.
b. AN/ARR-6: an airborne receiver, preset to the frequency of the “Gibson Girl” and automatically giving an alarm upon receipt of the emergency beacon signal.
4. Buoy beacons, locator and sonic, parachuted into the sea
a. AN/CRN-1: a marker beacon, radiating a signal over a 50-mile range, received by aircraft radio compasses, SCR-263 or 269.
b. AN/CRT-1: sonic buoy, picking up submerged submarine sounds and transmitting them over a 10-mile range, received by a special airborne receiver AN/ARR-3.
5. Paratroop beacon
AN/CRN-4: a portable marker radio beacon supplementing Rebecca-Eureka radar types, sending a continuous-wave coded signal every 30 seconds for two hours over a 30-mile range.
C. Navigational direction finders
1. SCR-225 and 551: HF sets with H-Adcock antennas; used by RI units as well as by AAF to assist plane navigation.
2. SCR-291: a very large set developed for AAF from the RI set SCR-502 (see under Intelligence DF’s) having fixed U-Adcock monopole antennas.
3. SCR-292: a smaller set employing rotating vertical-loop antennas.
4. AN/CRD-2: a transportable set, superior to, and much smaller than, SCR-551 and 291.
D. Instrument approach and landing systems: these comprised various ground and airborne components of SCS-51, formerly SCR-241 and 251 (all the ground components included SCR-610 for two-way communication with the airfield control tower)
1. Marker beacons and receivers (75 mc)
a. BC-302 and 902: small beacons employed with SCR-241.
b. AN/MRN-3: a jeep-mounted beacon.
c. RC-20, 39, 43, and 193: airborne receivers to detect the vertical
beams from marker beacons up to 16,000 feet; visual indication only (flashing light on instrument panel as the plane passed over fan marker, CAA beacon, etc.).
d. AN/ARN-12: an improved lightweight receiver, yielding both visual and aural indication.
2. Localizer and glide-path sets
a. Localizer VHF transmitter and receiver (110 mc)
(1) AN/MRN-1: mobile ground transmitter (formerly SCR-591) to guide plane to runway. Air-transportable versions were AN/CRN-7 and 10.
(2) RC-103: airborne receiver actuating a dial which showed the alignment of approaching airplane in relation to the runway.
b. Glide-path UHF transmitter and receiver (330 mc)
(1) AN/CRN-2: mobile ground transmitter located along airstrip (formerly SCR-592).
(2) AN/ARN-5: airborne receiver (formerly SCR-57O).
(NOTE: The foregoing development culminated in SCS-51, an automatic instrument-approach radio system, which involved an airborne localizer, ground glide-path receivers, and a robot pilot.)
II. Radar
A. Altimeters (airborne absolute altimeters or terrain clearance indicators)
1. RC-24: a lightweight continuous-wave beat-reflection radar type (FM), effective only up to 400 feet; renamed AN/ARN-1. An improved version known as AN/APN-1 gave readings up to 4,000 feet.
2. SCR-518 and 718: pulse-type radar altimeters effective up to about 40,000 feet.
B. Beacons
1. Ground
a. Locators developed for determining ground range and azimuth, used to locate a forward observer for fire control purposes.
SCR-599: a portable 35-pound short-range set (interrogator and responsor components were later designated AN/PPN-10 and 11 respectively).
b. Ground “navigation” system, employing fixed base stations which emitted pulsed radiations as in the loran system, providing accurate location for moving tactical units or for mapping purposes: SCR-560.
2. Ground-to-air
a. Portable beacons, having a 50-mile line-of-sight range, triggered or interrogated by airborne radars such as AI, ASV, BTO, or IFF types
(1) AN/UPN-1 and 2: portable S-band sets, operating on 3,000 mc, weighing respectively 115 and 80 pounds.
(2) AN/UPN-3, 4, and 11: X-band sets, 10,000 mc.
b. Transportable beacons having a 100-mile line-of-sight range
(1) SCR-621 and 640: heavy 350-pound sets responding to long wave radars SCR-521 ASV and 540 AI on 170-196 mc.
(2) SCR-620: responding to microwave AI radar SCR-520 and to other 10-cm S-band sets on 3,000 mc; became AN/CPN-3, a bulky half-ton ground set. A similar set was AN/CPN-1.
(3) AN/CPN-8: a much smaller S-band beacon.
(4) AN/CPN-6: an X-band beacon on 10,000 mc responding to airborne X-band radars.
3. Air-sea-rescue beacon
AN/CPT-2: designed to transmit a continuous-pulse signal for 12 to 20 hours automatically. Called “Walter,” it was of lighter weight than the “Gibson Girl” radio (SCR-578) and could be carried in fighter planes.
4. Paratroop beacons (“Rebecca-Eureka”): portable, 25-100-milerange sets
a. AN/APN-2 (developed from SCR-729), 10, and 12: airborne interrogators.
b. AN/PPN-1 and AN/TPN-1, 2, and 3: ground responders.
C. Loran and Shoran
1. Loran: long-range navigation (LRN)
a. AN/APN-4 and 9: airborne receivers, originally SCR-622. A variant, SCR-722, derived from a NDRC development.
b. AN/CPN-11 and 12: (formerly SCR-623) air-transportable slave and master beacon sets.
2. Shoran: short-range precision navigation, aid in blind bombing (formerly SCR-297)
a. AN/APN-3: airborne interrogator.
b. AN/CPN-2: ground transponder station.
D. Blind approach systems
1. AN/CPN-7: blind approach beacon system.
2. AN/MPN-1: ground-controlled approach system, involving two mobile short-range microwave radars, in whose scopes the operators watched an approaching aircraft as they coached it to the landing strip, talking over radio telephones SCR-522 or 274. A small air transportable version of GCA was undertaken as AN/CPN-4.
Intelligence, Security, and Countermeasures
I. Radio intelligence (RI) equipment
A. Radio monitoring sets
1. SCR-243 and 244: low-, middle-, and high-frequency intercept receivers—100 kc to 20 mc.
2. SCR-607, 612, 613, 614, and 616: receivers for frequencies ranging from 15 kc to 600 mc and for continuous-wave, AM and FM types of signals.
B. Direction-finders, DF’s: for locating radio transmitters
1. Short- and medium-range
a. SCR-206 and 503: small loop-antenna sets for MF and HF (up to 18 mc).
b. SCR-504: hand-carried, disguised as a suitcase.
c. SCR-555 and 556: heavy sets with rotatable H-Adcock antennas and extending from HF into VHF (18-145 mc).
d. SCR-700: set extending into UHF range on 140 to 600 mc; intended for use with RI intercept receiver SCR-616.
e. AN/TRD-2: an improved version of SCR-505 (incorporating an oscilloscope indicator for instantaneous indication of signal direction).
2. Long-range, semifixed, and transportable
a. SCR-255 and 551: HF sets having large rotatable H-Adcock antennas (dipoles 12 feet long) for taking bearings on sky waves. Also used by AAF for navigational purposes.
b. SCR-501 and 502: very large HF sets having fixed monopole, U-Adcock antennas, and instantaneous oscilloscope indicators. An air-transportable version of 502 was AN/CRD-2.
c. AN/CRD-3: a very large DF, like SCR-502, but designed for LF and MF reception and extremely sensitive to sky waves originating at very great distances.
C. Combined intercept and DF assemblies
1. SCR-558: consisting of DF’s SCR-206 and SCR-504, intercept receiver SCR-612, and communication radio SCR-284, the whole assembled in one vehicle.
2. AN/VRD-1: a larger assembly, embracing DF SCR-503, intercept receivers SCR-612 and 613, and radio beacon RC-163, the whole mounted in two vehicles, each carrying an SCR-510 for communication with the other.
3. AN/GRA-2: a loop-antenna DF attachment for any HF or VHF intercept receiver in the range of 18 to 65 mc. A similar attachment was AS-4 ( )/GR to provide DF for any receiver in the range of 1.5 to 18 mc.
II. Security equipment, for rendering communications unintelligible, scrambling them at the place of transmission and unscrambling them at the place of reception
1. Cryptographic machines, enciphering and deciphering message texts mechanically
a. M-209: the Haglin converter, small, portable, hand-operated, converting letter by letter into or from a cipher equivalent, and slow.
b. M-134: automatic cipher machine.
2. RC-62: portable speech scrambler for voice communications by radio or wire.
III. Countermeasures equipment
A. Radio
1. Search receivers, airborne equivalents of ground RI sets
a. AN/ARR-5 and 7: receivers covering from .55 to 143 mc. They could be used with radar scope indicators or with panoramic and photographic adapters.
b. AN/ARQ-4 and 5: panoramic receivers for wide and narrow ranges respectively, used in jamming to counter the enemy’s efforts to shift his signal from one frequency to another.
2. Jammers, both ground and airborne, often used with search receivers
a. AN/MRQ-1 and 2: powerful mobile ground jammers for LF, MF, and HF bands, modified respectively from SCR-698 and 399.
b. AN/MRT-1: a very powerful 15-kw jammer developed for use against German ground-air communications in the 37-42 mc band, called “Cigar.”
c. AN/CRT-2 and PRT-1: small expendable jammers to be placed near enemy radios. CRT-2 was an airborne parachute set. PRT-1 was a portable hand-planted jammer, called “Chick.”
d. AN/ARQ-1 (“Sandy”), 7 (“Spotkie”), 8, and 9 (formerly SCR-596) were airborne HF and VHF spot jammers.
e. AN/ARQ-11: a receiver to detect the frequencies of guided missiles and a transmitter to jam them.
f. AN/ART-3, 5 through 11, and 14: a series of high-power barrage jammers called “Jackal,” each set able to jam its entire frequency range continuously and unattended; used against enemy VHF and tank communications.
3. Associated equipment
a. AM-33 ( )/ART: a wide-band amplifier.
b. AN/ARA-3: a device which converted liaison set SCR-287 into a spot jammer.
c. AN/TRQ-1: a transportable radio-control intercept station developed for monitoring and controlling radio-jamming sets.
B. Radar
1. Search receivers
a. SCR-587: earliest radar search receiver, 38-3,300 mc.
b. AN/APR-2: autosearch receiver, which could automatically detect and record radar signals.
c. AN/APR-4, 5, 5A, 6, and 7: improved search receivers covering frequencies up to 6,000 mc.
2. Jammers
a. AN/TPT-1 and 2: ground radar jammers for frequencies from 70 mc to 1,450.
b. AN/APT-1 and 2: low-power radar jammers (“Dina” and “Carpet” respectively) for use in aircraft, able to jam frequencies between 70 mc and 710 mc.
c. AN/APT-3 (“Mandrel”) and 5: respectively a spot jammer, 85-135 mc, and a semibarrage jammer, 350-1,400 mc.
d. AN/APT-4, 6, and 8: powerful magnetron jammers, 15-1,100 mc.
e. AN/APQ-2 (“Rug”) and 9 (“Carpet III”): powerful barrage jammers.
3. Deception devices a. AN/APQ-8 and 15:’”Spoofer” sets which could throw back a strong echo, making one aircraft appear to be many, b. “Chaff” or “Window” aluminum foil strips which, when dropped in quantity, threw back multiple reflections, blinding ground radar scopes. Chaff was also developed for large 60 and 81-mm. mortar shells as reflector RR-7/U, 10/U, 26 and 27 U.
4. Associated radar Countermeasures equipment
a. Panoramic or oscilloscopic devices used with search receivers to enable operators to study and photograph the characteristics of enemy radar signals
(1) AN/APA-6 and 11: panoramic adapters or scopes.
(2) AN/APA-7: movie-camera photo set which provided a permanent record of oscilloscope presentation.
b. Radar DF’s (AN/APA-17 and 24) for attachment to radar search receivers, giving instant cathode-ray indication of the direction of radar-beam source.
c. Automatic tape recorder AN/APA-23 developed to make a record of the frequency and reception time of signals picked up by radar search receivers AN/APR-4, 5, and 7.
d. Automatic tuning adapter (AN/APA-27) designed to detect enemy radar beams and to spot jam them without human assistance.
e. Alarm equipment AN/APR-3: warning to ferret-plane crewmen whenever their craft came dangerously within enemy GCI, AI, and GL radar waves. Dubbed “Boozer.”
f. Monitor set AN/TPQ-1: assembly of broad-band receivers, 40-4,000 mc, both to analyze enemy radar waves and to direct friendly jammers.
Training, Testing, and Maintenance and Repair
I. Training equipment
A. Target control: radio transmitters and receivers for remote control of gun targets
1. Water-target control
SCR-586: receiver and transmitter, the receiver being carried in the target boat to control it on signals from the distant transmitter.
2. Land-target control
a. AN/VRW-1: vehicular receiver controlling motion of target car.
b. AN/TRW-1: transmitter by which a distant operator controlled the receiver and the vehicle in which it was mounted.
3. Air-target control
a. RC-57, 64, and AN/ARW-26: airborne receivers’
b. RC-56 and 65: ground transmitters.
c. AN/ARW-8: airborne transmitter.
B. Firing error indicators
1. For antiaircraft artillery training
a. PH-32: shellburst spotter set including theodolites for observation of shellbursts and a camera to provide a motion-picture record.
b. AN/TVQ-1: shellburst spotter set similar to PH-32.
c. AN/ART-4 and GRR-1: airborne transmitter and ground receiver, the transmitter being carried in a target sleeve aloft, in order to note the projectile’s shock waves and radio the extent of error to the receiver on the ground.
2. For aerial gunnery training
AN/ART-16 and ARR-10: airborne transmitter and airborne receiver.
C. Classroom training sets
1. Trainers in the operation of ground and airborne radars
a. BC-968 and BC-1070: trainers for SCR-268, 270, and 271. BC-1070 modified for PPI became AN/UPS-T2.
b. RC-110, 225, and 253: AI trainers for SCR-540, 520, and 720.
c. RC-111, 227, and AN/APS-T1, 1A, and 2: ASV trainers for SCR-517, 717, and 521.
d. AN/APQ-T1: aircraft gun-laying trainer.
2. Trainers in navigational aids a. RC-242 and 252: for instruction in loran usage, b. AN/APN-3 T1: for instruction in shoran usage.
3. Countermeasure trainers
a. AN/TPQ-T1 and 2: radar-jamming trainers to teach oscilloscope men to use their radars successfully despite jamming effects.
b. AN/URA-T1: radio-jamming trainer to teach radiomen to copy messages amid jamming effects.
4. Code training sets
a. EE-81, 94, 95, and 96: classroom practice code and tape sets.
b. AN/GGQ-1 and GSC-T1: visual and audible code practice sets.
II. Testing equipment
(NOTE: for practically every new radio and radar set and tor every new wire system it distributed, the Signal Corps had to provide suitable equipment for testing and maintenance. The items enumerated in categories II and III are selected from huge numbers of test, maintenance, and tool repair sets.)
A. Radio and radar
1. Testing sets for general and specific uses
a. 1-56: a universal radio test set.
b. AN/GPM-1 and MPM-1: basic radar test sets.
c. IE-9 and 26: large sets for use by Signal Corps repair and service units.
d. IE-17 and 75: for testing handie-talkie SCR-536.
e. IE-30 and 57: for testing ASV and AI radars, such as SCR-517 and 520.
f. RC-68: for testing the radar SCR-268.
g. TS-20/APN-4: for testing airborne loran receiver.
h. AN/APM-28 and 29: for testing radars in L-band, 50 cm.
i. AN/APM-10, 33, 34, and 37: for testing S-band radars, 10 cm.
j. AN/APM-21, 22, 41, and 42: for testing K-band radars, 1 cm.
2. Frequency meters: for measuring and correcting the frequencies of radio and radar transmitters
a. SCR-211 and BC-221: for LF, MF, and HF to 20 mc.
b. TS-174/U: for VHF extending to 280 mc.
c. TS-175/U: for VHF and UHF, from 85 to 1,000 mc.
d. TS-213/U: for UHF and SHF, from 300 to 5,000 mc.
3. Phantom antennas, used in testing (or in practice sending) to suppress actual radiation and so keep the set “off the air”
a. A-55, 56, 57, and 58: for SCR-177, 183, 188, and 193.
b. A-31, 32, 33, 34, and 62: for vehicular radios in the “500” series.
B. Wire
1. General test sets
a. IE-10, 29, 53: for testing telegraph and telephone equipment, carrier terminals, repeaters, etc.
b. TS-2/TG: teletypewriter test set.
2. Specific test equipment
a. Telephone and telegraph test boards, to locate and clear wire circuit troubles
(1) BD-101: 120-circuit board for testing in a central office.
(2) BD-103: 20-circuit board for roadside testing in the field.
b. Fault locator, detecting short-circuits along wire lines TS-26 and 27/TSM: volt-ohm meters.
III. Maintenance and repair equipment
A. Radio and radar
1. Maintenance and tool sets
a. ME-9, 13, 34, and 35: for general radio maintenance.
b. ME-104, 105, 108, etc.: maintenance and tool sets for specific radars, SCR-584, 545, 268, etc.
c. ME-53 and 67: for maintenance of walkie-talkie SCR-300.
d. TE-41, 46, 113, 114: tool sets for radio repair.
2. Suppression of radio noise (vehicular interference) and static
a. AN/URM-3: radio-interference meter.
b. AN/ASA-1 and 3: discharge assemblies to drain static electricity from a plane in flight.
3. Tropicalization: protecting electrical equipment against moisture and fungus
a. MK-2 and 1/GSM: kits containing infrared lamps, water-repellent and fungus-proofing varnishes, spray guns, etc.
b. 68-Q-4 and 5: kit developed to tropicalize radar SCR-268.
4. Mobile repair stations: mounted in trucks and trailers, for third echelon maintenance
a. AN/MRM-1: for radio maintenance only.
b. AN/MSN-1: for both radio and wire.
B. Wire
1. Construction and maintenance sets
a. ME-4, 11, and 30: for telephone centrals TC-1, 4, 10, and 12, of which these sets were usually component parts.
b. ME-22: for maintenance of field telephone set EE-8.
c. ME-10: for general maintenance and repair of telephone and telegraph equipment.
d. ME-7, 18, and 37: for teletypewriter maintenance.
e. TE-16: cable-splicing set.
f. ME-44, 47, 49, 75, 111, 112: tool sets for repair of wire equipment both telephone and telegraph.
g. TE-50: tool set for repair of teletypewriter equipment.
h. TE-27 and 58: for pole line construction.
2. Mobile repair stations
a. AN/MTM-1: mounted in a truck and trailer to provide fourth echelon maintenance.
b. AN/MTM-2 and 3: similar mobile sets designed for third echelon maintenance.
Photography
I. Cameras
A. Still pictures
1. General use
a. PH-120, 150, 195, and 205: portrait and view cameras taking large pictures, 8 by 10 inches.
b. PH-47 and 324: taking average pictures, four by five inches, and small 33-mm. pictures respectively.
2. Special use
a. PH-518 ( ) /PF: camera especially developed for use in combat areas, stoutly constructed and tropicalized, taking 70-mm. film (pictures 2½ by 2¾ inches).
b. AN/TFQ-6: a photoflash camera developed for recording surgical operations.
B. Moving pictures
1. PH-270 and 274: heavy newsreel-type 35-mm. cameras.
2. PH-330: standard movie camera in World War II, 35-mm.
3. PH-430 and 431: small, 16-mm. movie cameras.
II. Projectors
A. PH-131 and 398: 16-mm. sound projectors.
B. PH-331 and 405: 35-mm. sound projectors.
C. PH-526/UF: projector for large audiences (up to 2,000).
D. AN/TFQ-4: projector for small audiences (up to 600) ; rugged, for use under any conditions from arctic to tropical.
E. PH-420-A: small portable projector screen for use in daylight.
F. PH-222: small projector of film strip and slides.
III. Other photographic equipment
A. Identification sets
1. PH-385: for field use, including a 35-mm. camera, fingerprint set, lamps, etc.
2. PH-261 and AN/TFQ-1: field sets including printing and enlarging equipment.
B. V-mail equipment
1. PH-512: rapid developer, machine-driven, for developing and drying loo-foot rolls of 16-mm. film or 50-foot rolls of 35-mm. film.
2. PH-542: enlarger for 16 or 35-mm. film.
C. Miscellaneous equipment
1. PH-524/PF: low tripod, permitting the camera man to “shoot”
while lying prone.
2. PH-515/MF: photographic equipment pack for jeep transport, in eluding a tripod for operating a movie camera on the jeep.
3. PH-253, 298, 406, 413: sets for processing and developing films of various sizes and types.
4. PH-13, 67, 129, 395: printers.
5. PH-275, 285, 511: enlargers.
6. PH-261, 383, 390, and 392: darkroom sets, housed in small tents.
7. S-11/GF and AN/TFQ-7: darkrooms housed in HO-27, the former a mobile shelter, the latter a transportable laboratory completely equipped for developing still and movie negatives in the field.
Meteorology
I. Instruments of measurement
A. Barometers and barographs
1. ML-2 and 330/FM: mercury barometers.
2. MIL-9, 102, 331, 332, and 333/TM: aneroid barometers.
3. ML-3: barograph with clock mechanism and ink-recording equipment.
B. Thermometers and thermographs
1. ML-4, 5, and 7: mercury and alcohol thermometers.
2. ML-352/UM: thallium amalgam for use at temperatures below the minimum of mercury thermometers.
3. ML-77 and 277: thermographs with ink recorder and clock-regulated mechanism.
C. Psychrometers: for measuring humidity
1. ML-24 and 224: relative humidity gauges, rotated by hand.
2. ML-313/AM: automatic, for upper-air readings.
3. ML-341/GM: for use in sub-zero temperatures.
D. Anemometers
1. ML-62 and 80: the former a small hand-carried set; the latter a standard wind speedometer with three cup-shaped wind scoops on a vertical axle.
2. ML-107: portable set, including a wire transmitter, which noted wind direction and velocity as far away as 1,000 feet.
3. AN/GMQ-1: similar to ML-1O7 but designed to operate with fixed ground or mobile weather stations.
E. Helionephoscope and hygrometer
1. ML-385 ( )/UM: helionephoscope, an illumination meter to measure intensity of sunlight.
2. ML-342 ( )/GM: hygrometer to determine dew point at low temperatures.
F. Cloud height indicators
1. ML-121 and 318/TMQ-2: ceiling-light projectors, used only at night with clinometer ML-119.
2. AN/GMQ-2: projector, detector, and recorder; capable of continuous operation unattended.
3. AN/AMQ-4: optical device for use from a moving airplane.
G. Theodolites and plotting equipment: telescopes, plotting boards, etc., for visually tracking ascending pilot balloons to determine wind direction and velocity
1. ML-47 and 247: telescopes mounted on tripods.
2. ML-120 and 122: lightweight wood and plastic plotting boards.
II. Data-gathering instruments
A. Radiosonde equipment
1. Airborne radiosondes, transmitters which were carried aloft by balloons or planes
a. ML-141: standard audio-modulated transmitter and associated weather instruments; became AN/AMQ-1.
b. AN/AMT-1, 2, 3, and 4: balloon and parachute sets.
2. Ground receivers and DF’s, the function of the latter being to track the emissions of the drifting radiosonde so as to determine wind direction and velocity at all levels through which the transmitter may pass.
a. SCR-658: both a DF and a receiver of the radiosonde transmissions; developed from SCR-258, originally designed as a radiosonde DF only.
b. AN/CRD-1: lightweight DF and receiver on UHF developed for postwar radiosondes.
3. Ground receivers and recorders.
a. AN/TMR-1 (AN/TMQ-5) and 2: transportable receivers and recorders used in conjunction with SCR-658.
b. AN/FMQ-1: device automatically recording radiosonde data on a printed graph.
B. Wire sonde equipment
AN/UMQ-4: instruments held aloft by a captive balloon and transmitting data to ground over wires running along the balloon cable.
C. Aerographs: automatic weather recorders
1. ML-175 and 195: attached to exterior of airplane and transmitting data to recording equipment inside.
2. AN/AMQ-2 and 3: comparable instruments, but attached to interior of plane and automatically recording pressure, temperature, and relative humidity for four hours to elevations of 23,000 feet.
D. Spherics equipment
AN/GRD-1: semifixed direction finder designed to take bearings on static, or lightning flashes, at distances up to 1,500 miles.
E. Ionospheric equipment
AN/CPQ-7: set developed to measure, by means of radar reflections, the height of the ionosphere and obtain data valuable to HF (skywave) radio transmission.
F. Radar trackers: radar sets to track special radar reflectors which were carried either by balloons or by parachutes released from rockets
1. SCR-525: massive radar with large triple antenna array, the whole weighing 15,000 pounds.
2. SCR-825: much lighter set, air transportable.
III. Weather station sets
A. Mobile, attended stations
1. SCM-1: mounted on a truck and trailer; designed for the AAF.
2. SCM-9 and 10: respectively, radiosonde and ballistic wind stations, developed for Field Artillery. The sets were subsequently combined and became AN/TMQ-4.
3. SCM-13: radiosonde and wind station developed for Coast Artillery.
4. AN/TMQ-1: air-transportable station with complete meteorological station equipment; for the AAF. AN/TMQ-4 was a meteorological station for the Field Artillery.
B. Automatic unattended stations, including telemetering devices
1. SCM-17: a station developed to transmit, by radio pressure, temperature and relative humidity data up to 300 miles over a month; controlled by clock mechanism and powered by batteries.
2. SCM-18: parachute set designed to begin operation upon reaching ground and to transmit its data up to 100 miles for a week.
3. SCM-19: large semipermanent set powered by a gasoline engine and able to collect pressure, temperature, humidity, wind, rainfall, and sunlight data and to transmit it over distances up to 500 miles for a three-month period.
IV. Other meteorological equipment
A. Balloons
1. Pilot balloons: small, for revealing winds aloft a. ML-50, 51, 64, 155, 156, 157, 158: of various colors and composition; all for observing low-level wind conditions, b. ML-159, 160, and 161: larger, loo-gram rapid ascent balloons for observation (by theodolites) of high-level winds.
2. Sounding balloons: large, for carrying radiosondes to the stratosphere
a. ML-131: 350-gram balloon (14 feet in diameter when fully inflated).
b. ML-162: a still larger balloon, 700 grams.
B. Hydrogen generators
1. ML-165 and 185: heavy generators for field use.
2. ML-303, 304A, and 305A/TM: one- or two-pound can of calcium hydride, each capable of inflating a small balloon.
3. AN/TMQ-3: portable generator for inflating 350-gram balloons.
Accessories
I. Power equipment
A. Electric generators, powered by
1. Gasoline
a. PE-49 and 210: lightweight one-cylinder engined d-c generators for powering SCR-177 and 188 and for charging batteries.
b. PE-77: a portable 70-pound one-cylinder unit for field teletypewriter set EE-97.
c. PE-201: a 300-pound one-cylinder unit which powered telephone and telegraph carrier equipment.
d. PE-75 and 95: respectively a 300-pound one-cylinder unit and a 1,500-pound four-cylinder unit both widely used with many Signal Corps sets to supply standard 120-volt 60-cycle alternating current.
e. PE-74, 84, and 85: heavy (2½-tons) four-cylinder-engined generators used with radars such as SCR-268, 270, and 271.
f. PU-6/TPS-1: a compact 130-pound unit used with LW radars such as AN/TPS-1 and 3.
(NOTE: by 1945 the Signal Corps had many other gasoline engine generators in the PU category under development to replace the PE types which served throughout the war.)
2. Wind
AN/CSQ-1: an air-transportable generator with a wind-driven propeller mounted atop a 60-foot tower designed to charge storage batteries, which in turn powered automatic weather stations developed for the AAF.
3. Hand: the electric generator, laboriously hand-cranked during the operation of the radio, yielded sufficient current for small portable sets
a. GN-35: used with SCR-131, 161, and 171.
b. GN-45 and 58: used respectively with SCR-284 and 694.
4. Heat: thermoelectric power units PP-19, 107, 131-133, were experimental generators of low power (20 watts or less) which converted heat (derived from burning gasoline) to electric current. These generators were not adopted in the field because of the weight of fuel which they required and because of the smoke they produced.
B. Electric power converters
1. Dynamotors and vibrators: devices which draw direct current from storage batteries of low voltages (usually vehicular) and convert it to the various high voltages required by the multiple needs of radio transmitter and receiver components
a. Dynamotors
(1) DM-34 and 35: used to power vehicular radios SCR-508 and
608 from 12-volt storage batteries. DM-36 and 37 were similar but operated from 24-volt vehicular batteries.
(2) PE-55: drawing current from a 12-volt vehicular battery to operate the SCR-245.
(3) PE-194: used to convert energy from an airplane battery to operate the command VHF radio SCR-522.
b. Vibrators
(1) PE-157, which provided power for the SCR-511 when used in vehicles, drawing energy from the storage battery.
(2) PE-212: power pack developed for use with the walkie-talkie SCR-300. It included a small storage battery and a vibrator to convert the battery energy to the voltage requirements of the radio set.
2. Rectifiers: devices which convert standard commercial alternating current to direct current as required
a. RA-43 and 120: used to power the teletypewriter central TC-3 and portable radios SCR-510 and 610, drawing on standard power lines, when available.
b. RA-36 and 87: used to recharge storage batteries.
C. Batteries
1. Dry (primary) batteries
a. Single and multiple units or cells containing an activating paste, usually sal-ammoniac, and weighing from a few ounces to several pounds
(1) BA-23, 30, 65: 1½-volt single cells.
(2) BA-1, 205/11, 209/U: 3-volt cells.
(3) BA-9, 216/U: 4½-volt cells.
(4) BA-203/U and 207/U: 6 and 9-volt cells respectively.
(5) BA-2, 8, 219/U: 2½-volt cells.
(6) BA-56, 59: 45-volt cells.
(7) BA-27, 39, 40: multiple-unit batteries consisting of a number of cells and having an increased power output.
(8) BA-102, 127, 130, 140: similar to BA-2, 27, 30, 39, and 40
but especially designed to operate efficiently in cold climates.
b. Special batteries activated by mercury compounds or by sea water
(1) BA-38, 49, 70, and 80: mercury dry-cell batteries used late in the war in SCR-300, 511, 536, and 694.
(2) BA-229 ( )/CRN: battery intended to be immersed in sea water, which activated its silver-chloride and magnesium electrodes; developed for use with radio buoy beacon AN/CRN-1.
2. Wet (storage or secondary) batteries a. BB-54, 205/U: 2-volt batteries.
b. BB-29 and 213/U: 4-volt batteries.
c. BB-49, 51, 55: 6-volt batteries, similar to automobile 6-volt storage
batteries except for the BB-51 which weighed only a few ounces.
d. BB-46, 50, 201/U: heavy 12-and 14-volt batteries (BB-46 weighed 120 pounds).
e. BB-52: a 36-volt battery, tiny like the 6-volt 66-51 and the 2-volt BB-54, each of which weighed only about one third of a pound, used to power radiosondes when borne aloft by meteorological balloons.
II. Radio antennas and antenna masts
(NOTE: in general, antennas were furnished as integral parts of radio sets, such as radio relay antenna AS-19/TRC-1, the 3-element horizontal dipole and 40-foot tube steel mast used with AN/TRC-1, 3, and 4.)
A. AN-29: fishpole antenna used with the short-range radios SCR-609 and 610.
B. AN-130 and 131: short and long whip antennas, for walkie-talkie SCR-300.
C. RC-63: a lightweight 32-foot mast (of fir wood in four sections) and wire providing a vertical half-rhombic (inverted V) antenna for the short-range radios SCR-194, 195, and 609.
D. RC-291 and 296: special antennas designed to extend the range of the walkie-talkie SCR-300 by elevating its radiations above jungle tree tops. RC-291 consisted of a vertical whip from whose base radiated four horizontal whips, the whole elevated upon a pole or tree top. RC-296 was a single vertical whip mounted upon a lightweight sectional mast 30 feet high.
E. RC-292: somewhat similar to RC-291 but accompanied by 30-foot mast and designed to extend the short ranges of SCR-608 and 628.
F. AN/GRA-4: equipment which permitted the construction of several types of antennas for use with short and medium range sets such as SCR-177, 193, 245, and 284.
G. MS-49 through 56: lightweight tubular steel sections comprising a 25-foot mast for SCR-178, 179, 203, and 284. Some of these sections were also commonly used to form a 15-foot vehicular whip antenna (fishpole), set into mast bases MP-37 or 57. Similar sections MS-116, 117, and 118 were used with mast bases MP-48, and AB-15/GR to provide six- and nine-foot whips.
H. MS-65 through 73: aluminum sections providing a 45-foot mast for the long-range mobile radio SCR-197.
I. MA-6 and 7: heavy sectional masts supporting the antennas of the Air Forces VHF ground radios SCR-573, 574, and 624. MA-6 was a 90-foot mast assembled from 11 three-inch steel tube sections. MA-7 was a 50-foot plywood mast.
III. Headphones, microphones, handsets, and chest sets
A. Headphones (or double receiver headsets)
1. P-11, 16, 18, 20: radio headphones.
2. HS-18, 23, 33, 38: headphones used with airplane radio and inter
phone sets, adapted for use within helmets and at high altitudes.
3. HS-30: very lightweight headset widely used by ground forces, having ear inserts patterned after the phones of hearing aids.
B. Microphones
1. T-17: standard radio microphone, held in the hand, switched on for talking.
2. T-30: throat microphone leaving the user’s hands free.
3. T-45: lip microphone, attaching to the upper lip of the speaker and used when the surrounding noise was high, because it does not reproduce “ambient” sound as hand-held microphones usually did.
C. Handsets: both radio and telephone, being the hand-held receivertransmitter unit only
1. TS-9: standard telephone handset (carbon type), part of the battery-powered telephone set EE-8.
2. TS-10: special telephone handset (magnetic type) used with the sound-powered telephone set TP-3.
3. TS-13: standard radio handset incorporating a switch button which the operator pushed when he wished to transfer from reception to transmission.
4. TS-15: handset which combined parts of TS-9 and 13, and which was used with the walkie-talkie SCR-300.
D. Chest sets: transmitter attached to the speaker’s chest, with press-totalk switch mounted on the chest plate (receivers were of headphone type).
1. TD-1 and 2: radio chest sets replacing HS-19.
2. TD-3: chest set designed for use with a gas mask, employing a lip or throat microphone.
3. TD-4 and 5: improved chest sets for use by vehicular or aircraft radio operators.
IV. Trucks, trailers, and shelters
A. Trucks and trailers
1. For wire line construction work
a. K-43: telephone maintenance and construction truck with a tripod derrick for raising and setting poles.
b. K-44: truck mounting (1) an earth borer to drill holes and (2) a single derrick mast to set poles.
c. K-36, 37, and 38: trailers, the first and second for hauling poles, cable reels, etc., the third for transporting cable splicing set TE-56.
2. For transporting and housing large radio and radar sets, communication centrals, meteorological station sets, etc.
a. K-18 and 19: truck and trailer for transporting and housing the long-range SCR-197. Trailer K-19 was developed into a 4-wheel house trailer, K-35, for mobile telephone, telegraph, RI, DF, and message centrals.
b. K-51: a panel truck used with the long-range radio SCR-299.
c. K-53: a special van body mounted on a standard 2½-ton 6x6 truck.
d. K-55: a semitrailer, lighter weight than K-35, used similarly to house central office sets. It was also used for meteorological (SCM) and fighter-control (SCS) components. It was usually hauled by trucks K—53 or K-60.
e. K-56 and 60: trucks with van bodies to house and transport large radar sets.
f. K-75 and 78: large van trailers, the former for SCR-545; the latter for SCR-584.
B. Shelters
1. HO-17: a plywood shelter similar to a van truck body but an independent unit. It could be carried by any standard 2½-ton truck and could be removed and placed on the ground. Its plywood walls included built-in wire screening to provide electrical shielding. Its dimensions were approximately 11 by 6 by 5 feet. It was widely used for housing large sets, for wire and message centrals, intercept units, and so on.
HO-27: a transportable shelter similar to HO-17 but lacking the wire screen shielding.
Blank page