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By Alan D. Tasker, WA1NYR

(atasker@ix.netcom.com)

This is the story, as best I can tell it, of the progress that the U.S. Military has made over the past sixty+ years in mainstream portable voice communications (transmit and receive) radios, with a concentration on the later, more convenient-to-use units (i.e. SCR-536/BC-611 and later, SCR-300/BC-1000 and later, i.e. units with integral battery packs). For completeness, there is a summary of earlier concepts in portable radio design on page 5. A “Portable” is defined as a unit capable of being operated while a person is in motion. Mainstream is defined as having reached some fair production level. Not included in this discussion are clandestine radios (see reference 19), and only passing reference is made to code sending units/beacons. Satellite communication units (SATCOM is datacom only, i.e. e-mail, maps, etc.) are discussed in a separate section since it would appear that these units have LOS (line of sight) capability as well. Also included below is some information on non-mainstream products. The reader should note that this is a list of “what was” with some information on the “why and wherefore.” Not generally included here is information relating to the success or failure of the individual radios in their intended application.

In any work such as this, there is a tendency to pigeonhole items in an attempt to organize and simplify. This, plus the fact that one is always working with incomplete information, may lead to some inaccuracies. If you find something with which you do not agree, or if you have something to add, please contact me at atasker@ix.netcom.com.

If you are unfamiliar with military nomenclature, you might want to visit references 6 and 12 first.

Pictures for many of these radios appear in various web sites, and these are so indicated in the “Sources” section.

General Goals

In general, the goals in the development of new radios were, for many years, as follows (some of which are interdependent with, and some of which are contrary to, some of the others).

·         Lower Power Consumption

·         Smaller Size/Lighter Weight

·         Wider Frequency Coverage

·         Closer Channel Spacing

·         Synthesized Frequency Operation

·         Higher Reliability

In more recent years, additional goals have been imposed.

·         Internal anti-jam, i.e. Frequency Hopping

·         Internal Comsec (ICOM), i.e. voice scrambling

·         Data send/receive capability along with voice

In addition, there has sometimes been at least a perceived need to develop radios that operate within more than one band (i.e. the AN/PRC-70, 113, 117D/E/F, 128, 138, 139, 148, and the AN/URC-100/200 series). These radios help “interoperability” with other fighting force elements, as well as communications with local civilian elements such a police and fire when they exist.

The Simple Six

One way to analyze the history of the portable would be to group the types into the following six categories, four of which are tactical and two of which are non-tactical. Not every service purchases all types, nor are all types procured in the same quantities.

·         Tactical

1.       The Squad Radio, VHF FM (wide band US, narrow band in Europe), a small hand held unit for very local communications within ground forces. Also included here are sets originally intended to be used by paratroopers.

2.       The main ground force communications device, a VHF FM (wide band US, narrow band in Europe) backpack, for longer distance communications than the squad radio can provide.

3.       An FAC (Forward Air Controller) radio, generally a backpack, UHF or UHF/VHF AM for communications with aircraft and/or with SATCOM capability.

4.       A Special Forces radio, HF SSB, backpack/manpack, for longer distance communications than can be provided by the VHF Backpack.

·         Non-Tactical

5.       SAR (Search and Rescue) radios for downed airmen or other rescue duties, originally on 140.58 MHz (for voice, other frequencies being available for MCW), then 121.5 MHz, then 243 MHz only, then multi channel UHF, all AM, and now with 406 MHz coded burst transmissions added for better satellite tracking.

6.       Guard Duty/Fire Rescue/Other Use types, generally Low band (30-50 MHz) or High Band (152-174 MHz), or UHF (450-470 or 512 MHz), and/or the closely associated Government frequencies, narrow band FM.

The Charts

The seven charts along with the introductory paragraphs for each summarize these six types of portable radio sets from the beginning (just before World War II) to the present. Your comments are welcome and are encouraged.

Recent Trends, Program Management Lead

In recent years, certain trends have been evident. For instance, the Air Force and Army have tended to collaborate and use the same hardware when both services needed the same function. This can be seen in the charts, especially in SAR and non-tactical radio usage. Other trends are as follows.

·         The Army has been the Lead in the Squad radio, although the Navy/Marines have contributed heavily.

·         The Army is also the Lead in the VHF backpack area.

·         The Air Force has traditionally been the Lead in the UHF FAC area with the Navy and Army tending to use what was developed. The notable exception is the PRC-75, which was developed for the Marines only. Additionally, there is little evidence to suggest that the Army has had a need for a UHF FAC radio later in time than the PRC-41 era (although they could very well have them, there is no evidence to that I can find to show what they have).

·         The Army generally Leads the effort in HF radio development.

·         The Air force is currently the Lead in SAR system development.

·         The Air Force is the Lead in the Scope Shield program, which is essentially non-tactical, although the Army has the PRC-127 project.

The Beginning Steps in Ground Force Portable Radios, Pre WWII-Chart 2

The style developed in the beginning (battery on the bottom, rigid antenna on the top center or side, front panel controls) was employed for the SCR-194 (Artillery) and SCR-195 (Infantry) for the Army and the TBY for the Navy. These were not really hand held devices, but were intended for backpack use, although they were not built like the backpacks with which we are familiar today. Operating in VHF AM mode, they enjoyed some measure of success.

The Squad Radio, WWII to Present-Chart 1

.

The first units developed that more or less conform to our present day expectations for handheld devices were the SCR-511 and the SCR-536. The SCR-511/BC-745 (HF-AM) was designed to be used while riding a horse. However, the cavalry was abolished at the beginning of WW II, so it would seem it was a bit awkward to use on foot. It was, however, a marvelous example of good applied engineering, i.e. how to design a radio that was operable with just one hand while riding.

Nevertheless, the honor must go to the SCR-536/BC-611 (along with the SCR-585/BC-721 glider version) paratrooper sets for being the first true handheld transceiver. (All of the above units were made, in the beginning, by Galvin Mfg. Co, which is now Motorola.) Packing a walloping 36 mW of Tx power, and subject to all the interference the HF AM band musters, it was still more or less a success. The Navy’s MAB and DAV paratrooper sets were also fairly small units that operated in the same AM frequency band, but were not quite handheld. Instead, they were what we might call “shoulder strap” radios, a style that has, overtime, not been too prevalent here in the US.

The Korean War vintage PRC-6 (although there is some debate as to whether it made it through development and production in time to actually see wartime service), making use of the relatively new sub-miniature (pencil sized) tubes, improved greatly on the SCR-536. A VHF-FM unit (all tactical radios after this were VHF-FM) with 250-mW output, the higher frequency of operation and the FM mode of this unit reduced the interfering noise level greatly, which led to a much more useable radio.

After a long and drawn out research effort (basically waiting for transistor and integrated circuit technology to develop), the PRC-68 was produced, a very neat little package indeed. There had been an interim stop at the PRR-9/PRT-4, the first all solid state implementation, but they never really saw much use. The PRC-68 was to prove to be the father of five additional designs, the 68A, 68B, 126, 128, and 136.

The 1” longer PRC-68A followed, which was one of the first microprocessor-controlled units. It allowed random frequency programming, but you had to stay within one of the four sub-bands. 

The present unit, the PRC-126 is a PRC-68A with a frequency display and external frequency settability. It is microprocessor controlled and allows more latitude in channel placement than even the PRC-68A because it has an external antenna loading control.

The VHF-FM Backpack Radio, WWII to Present-Charts 2 and 7

By all accounts, the first true backpack, the SCR-300, was a very successful design. It should be noted that when fielded, there was no other radio in its frequency band (40-48 MHz FM), so it communicated with like units only (including the AN/VRC-3 tank mounted version). It was followed by the Korean War vintage (although they may have just missed actual war service) PRC-8, 9, and 10 (Armor, Artillery, and Infantry respectively). Using sub-miniature tubes, these offered wider frequency coverage than before. 

The PRC-25 was the first synthesized unit, offered wider yet frequency coverage, and had just one tube (RF power output stage). Over 125,000 were produced. The all solid state but otherwise identical PRC-77 followed, with a large quantity produced as well. Tone squelch (150 Hz) was introduced during this period (i.e. PRC-25 and later).

PRC-77 Clones

Although the PRC-77 design is not perfect, it did mark a milestone. It is an uncomplicated (therefor easy to use) wide frequency coverage all solid state unit that achieved a good reliability record in the field. As a result, there have been a number of manufactures who have built clones of this radio (i.e. uses the same accessories), some offering improvements such as 25 kHz channel spacing, selectable output power, and/or updated circuitry to improve reliability. Some of these companies are listed below. NOTE: Most of these PRC-XXX numbers are not official. Companies sometimes assign their own out of sequence numbers for advertising purposes, especially in trying to promote themselves as having a PRC-77+.

·         NAPCO International of Hopkins, MN, which offers,

·         A 25 kHz kit for retrofit into existing PRC-77 units.

·         “HR” modules, i.e. a module set made with fewer parts, thus enhancing reliability. Modules are interchangeable with the old ones.

·         PRC-770, a PRC-77 built with the 25 kHz channel spacing.

·         DATRON WORLD COMMUNICATIONS (Datron and Trans World merged), Vista, CA

·         PRC1077. A clear-channel (i.e. no jamming present) replacement for the AN/PRC-77 that has 25 kHz channel spacing, 3 selectable power levels (0.1, 2, or 5W), and 10 preset memory channels. A 50-Watt mobile system is available. Uses same external accessories as the AN/PRC-77.

·         PRC1088. A redesigned version of the Rockwell/Collins MP-83 (PRC-124). 25 kHz channel spacing, 2 and 5 W power outputs, 9 memory channels. Can operate in either single-channel or frequency hopping mode with embedded digital encryption.

·         PRC2100V. 30-88 MHz, 12.5 or 25 kHz channel spacing, 100 memory channels, adjustable RF output to 10W. Proprietary frequency hopping and digital encryption. Embedded GPS. Software-driven radio with menu screens in user native language.

·         TADIRAN, Israel

·         PRC-2077 offers 25 kHz channel spacing along with highly updated circuitry.

After the AN/PRC-77

A competition was held to choose a design for the PRC-77 replacement. The entries were as follows.

·         PRC-116, the Racal Jaguar V, 30-88 MHz ECCM unit, Racal #BC-66H

·         PRC-124 (Collins MP-83), a PRC-77 type with 25 kHz channel spacing and FH, now being offered by Datron World Communications as the PRC-1088.

·         PRC-117 by Harris

·         PRC-119 by ITT, the eventual winner (General Dynamics is now the follower)

·         PRC-??? by Cincinnati Electronics

The current backpack unit is the PRC-119 SINCGARS (SINgle Channel Ground and Air Radio System). It has an ability to FH (Frequency Hop) in order to avoid jamming (RT-1439). In addition, the “A” model (RT-1523) is called ICOM (Internal COMsec). Comsec stands for COMmunications SECurity, i.e. voice scrambling in order to prevent intelligent interception of message content by the opposition, or anyone else. This model also sports a much longer battery life.

Meanwhile, there is an improvement program underway that has developed and purchased a small number of trial radios. The following was taken from the Web in 1999 (reference 18).

“The Single Channel Ground and Airborne Radio System (SINCGARS) SIP (SINCGARS

Improvement Program) Compatible Portable Radio, the RT-1753(C)/U, is a compact portable version of the SINCGARS radio. This portable radio will be used along with the Light weight Internet Controller (LINC) and Dismounted Soldier Unit (DSSU) in TF XXI (Task Force XXI) to support dismounted soldier operations and is designed to operate from a dismounted soldier’s vest pouch. The radio replaces the current manpack version of the SINCGARS radio. The portable radio includes all SIP performance enhancements to include additional data mode features, embedded COMSEC, an external RS-232 Data Interface and packet switching for access into the tactical Internet. The radio weighs no more than 5 pounds (with battery and antenna), is approximately 1.9 inches by 10.6 inches in size (with battery) and provides selectable output RF transmit power up to two (2) watts and communication range of 3 to 4 kilometers. The portable radio uses a rechargeable NiCad battery pack. Battery life is approximately 6 hours. The portable radio shall consist of a portable radio, an antenna, and battery pack. Improvements have continued, and the following article appeared in 2001or so (ref 25). SINCGARS is the primary Combat Net Radio (CNR) for the US Army, designed primarily for voice command and control for the infantry, armor, and artillery units. It is a VHF-FM radio system that operates on any or all of the 2,320 frequencies between 30 and 87.975 MHz in 25 kHz increments. SINCGARS employs frequency hopping, as it's primary means of communications against a hostile (jamming) environment. SINCGARS is capable of processing voice, analog and digital data in either the frequency hopping or single channel mode, and will replace the existing AN/PRC-77 and AN/VRC-12 series radios from the Army inventory. An airborne version of the SINCGARS (ARC-201) is also in production and is replacing the standard aircraft radios, the AN/ARC-114, AN/ARC-131, and the AN/ARC-186 (FM mode only). The first SINCGARS radio produced was the RT-1439. This radio required an external KY-57 VINSON Communications Security (COMSEC) to encrypt and de-encrypt the messages. Working closely with the National Security Agency (NSA), approval was granted to embed COMSEC within the SINCGARS radio to reduce the load of the manpack user and at the same time reducing the amount of external crypto devices needed for the Army. This subsequent version of SINCGARS radios produced, was the RT-1523. The RT-1523 was termed the Integrated COMSEC (ICOM) radio, and in hindsight, the RT-1439 radio was referred to as the Non-ICOM radio. To meet the demands of fielding, the Department of the Army (DA) authorized a second source to produce SINCGARS ICOM radios, that are Form, Fit, and Function (F3) interchangeable at the LRU level. Along with a production capability, the second source introduced improvements to the product in terms of Cosite performance, improved battery life and enhanced low speed operation, these enhancements were incorporated back into the initial source product line, and the resultant products produced were the RT-1523A and RT-1523B ICOM radios. In line with the Army's move toward digitization, the user expressed the need to increase their communications functionality and capability. This led to the development of the SINCGARS System Improvement Program (SIP), to which the Tactical Internet is mainly based. The SIP radio (RT-1523C and RT-1523D) incorporated features such as an interface to an external PLGR, improved Forward Error Correction (FEC), and Packet routing. These improvements along with the introduction of the Internet Controller (INC) card, provided the mechanics for Internet Protocol (IP) routing between radio nets and other communications systems (ELPRS, LAN's, etc) which revolutionized the way data is moved across the battlefield. The current production radio is the Advance SIP (ASIP) RT-1523E. The ASIP radio is a repackaged RT-1523C SIP radio, and is physically one half the width, and one-third the weight of a full size radio. Recent improvements to the INC include a more powerful microprocessor with increased memory. The ASIP configuration is targeted towards the dismounted soldier and will finish out the SINCGARS production. Unlike other major weapon systems where carbon copies of the same product is produced over and over again, the SINCGARS radio program has continuously evolved to provide the latest in improvements and capabilities to the soldier and strive to meet the Army's objectives for digitization.

Jerk-And-Run

There are a number of instances where the portable RT (Receiver/Transmitter) unit forms the basis of a number of nomenclatured systems (i.e. AN/PRC, AN/VRC, AN/GRC, etc.). The RT unit can, for instance, be attached to a vehicular mount that allows it to run on vehicle supplied power. Usually there also exists an associated vehicular mounted amplifier that boosts the transmitter power, and boosts audio power as well in order to drive a speaker. Some of these systems even have a “jerk-and-run” capability, i.e. a quick way to disconnect and turn the RT into a portable again. This “multi use” need has resulted in a philosophy change in data plate nomenclature for the newer radios. For many of them, this plate simply states “RT-xxxx.” It is the application that tells what the “usage” nomenclature is, i.e. PRC, VRC, etc. Examples of this include the following.

RT-1439, RT-1523 for the SINCGARS RT (PRC-119)

RT-1319 for the VHF/UHF LOS RT (PRC-113)

RT-1209 for the HF set (PRC-104)

Older Concepts

In a similar vein, there is an older concept where communication devices that have a “Primary Application” also have a "Secondary Application.” Examples of primary and secondary applications are as follows.

·         Mobile use

·         Portable use

·         Transportable use

Sometimes there was only one use. In any event, all radios shown in the following list could, when attached to the correct backpack (rucksack) frame, and when connected to the correct battery box with the correct cables, turn into a useful portable.

·         SCR-510/BC-629, two channel 20-27.9 MHz FM.

·         SCR-610/BC-659, two channel, 27-38.9 MHz FM, replaced by

·         SCR-619/BC-1335, two channel 27-38.9 MHz FM.

·         RT-70/PRC-16, 47-58.4 MHz FM, tunable

·         RT-53/TRC-7, 100-156 MHz AM, 2 channel (there may not have been a frame for this one)

Additionally, there is a closely allied type of radio that is almost portable, and is defined as transportable (by one or two men), and must be set up to operate. These are sometimes called packsets or manpacks (Note: “Transportable” was defined slightly differently in WWII.) Some of these have additional applications as discussed above. Examples of these are as follows.

·         TBX, 2-5.8 MHz AM/CW, Tunable (Tx optional crystal controlled)

·         SCR-178/179/BC-186/187/188, 2-5 MHz AM/CW, tunable

·         SCR-288/BC-474, 2.5-6.3 MHz AM/CW, tunable

·         SCR-284/BC-654, tunable, 3.8-5.8 MHz AM/CW, replaced by

·         SCR-694/BC-1306, tunable, crystal option, 3.8-6.5 MHz AM/CW, replaced by

·         RT-77/GRC-9, tunable, crystal option, 2-12 MHz AM/CW, replaced by the RT-671/PRC-47 (see chart 4, a packset even though it has a PRC designation)

·         GRC-109 (T-784, R-1004, PP-2684 or 2685), 3-22 MHz CW Tx, AM/CW Rx, 1 channel, more of a clandestine set but mentioned for completeness as it has a military designation

·         TRC-2, 2-3.4 MHz AM/CW (RT-12), tunable, crystal option, plus included a BC-1306

·         RT-46/TRC-12, 2-12 MHz CW, Tx 1 ch, Rx tunable

·         RT-654/TRC-77, 3-8 MHz CW Tx, AM/CW Rx, 6 channels

Alternate Overview

By looking at the development of the portable in the above-mentioned way, certain important information concerning radio development strategy before and during the WWII period becomes obscure. This is especially the case for the tactical series of radios that encompass both handheld, shoulder carried, and backpacks. Therefore, if we were to choose, just in this paragraph, to look instead at a timeline and intended application approach, we would make the following observations. This should bring a better perspective to the grand scheme of things in the pre and mid WWII time period.

·         The SCR-194/195 (VHF-AM) artillery and infantry radios, developed in the early to mid 1930s, were in reality obsolete when WWII came upon us. They were, however, used anyway because they were available. Based upon the tube technology available at the time (large tubes numbered with two digits, such as 33 and 67), there is only so much performance that the two tubes for which there was room could yield.

·         The WWII (VHF-FM) dual use sets (mobile/ground) mentioned in the above “older concepts” paragraph made use of a smaller tube, but did not necessarily obtain good results. For instance, the not as successful as needed SCR-610 was replaced with the SCR-619 (designed with miniature tubes) with much better results.

·         The development of the miniature tube led to a series of Paratrooper radios in HF-AM. These included the SCR-536, SCR-585, MAB, and the DAV. The SCR-511 cavalry radio also used these miniature tubes.

·         The miniature tube also led to the development of the SCR-300/VRC-3 (infantry/armor) radio, a very successful design in VHF-FM, which turned out to be the forerunner of things to come.

·         After the WWII period, the sub-miniature tube, even smaller yet, led to the eventual development of the Korean War vintage PRC-6 (handheld), 8, 9, and 10 (backpacks for the Armor, Artillery, and Infantry respectively).

The UHF Backpack for FAC (Forward Air Control)-Chart 3

Before the US Military Aircraft Band changed to UHF, it was located in mid VHF, 100-156 MHz. The Navy had a 10 channel portable called the MAW. The Army had a two channel unit called the AN/TRC-7 which, in one of its intended applications, operated as a portable (using the same type of batteries developed for the SCR-300/BC-1000, i.e. BA-70, BA-80).

With the growth of civilian aviation and other services following WW II, there were some revisions made to the frequency band allocations. The US Military Aircraft Band changed to high VHF/low UHF, 225-400 MHz. (It should be noted that foreign countries did not necessarily ever change over to the UHF band, making communications with their aircraft difficult when they were fighting with us.) The first portables to cover this new band were the MAY (Navy) and the AN/PRC-14 (Air Force/Army); both four-channel crystal controlled units. The MAY was a manpack unit, while the PRC-14 consisted of two main parts, a transceiver worn in the front, and a power supply with internal battery worn on the back. They were connected with a cable, and the antenna was mounted on top of the helmet. The synthesized (full band coverage, but in only 100 kHz steps) and partially transistorized PRC-41, another manpack unit, followed the MAY/PRC-14.

There was an effort by the Air Force during the mid 60s to develop prototype FAC units that would operate on all three tactical bands plus VHF Air. Rather than being a single radio with four bands inside, they were actually four separate radios, each with its own battery, fastened together on a frame, but arranged so they could be separated and operated independently if desired. Sylvania developed the PRC-71, while Bendix developed the PRC-72. Some number of units were produced (my guess is about a hundred or so) and tested in Vietnam. They hit the surplus market in the very early 70s, so their short life indicates to me a certain lack of success (too big, too heavy?). Later, there was a definition of a better system, the PRC-82, with the four bands designated PRC-83 through 86. All four radios were to be synthesized (the PRC-72 HF section was the only synthesized unit in the previous efforts, all the others were channelized with 2 to 6 channels). It appears that the PRC-82 venture never proceeded too far either. For completeness, the four parts of each of the above mentioned three radio sets were nomenclatured as follows.

Band                AN/PRC-71                   AN/PRC-72                   AN/PRC-82

HF-SSB            RT-778/PRC-71                  RT-835/PRC-72                  AN/PRC-83      

VHF-FM            RT-777/PRC-71                  RT-836/PRC-72                  AN/PRC-84

VHF-AM            RT-776/PRC-71                  RT-838/PRC-72                  AN/PRC-85

UHF-AM            RT-775/PRC-71                  RT-837/PRC-72                  AN/PRC-86

The PRC-71 and 72 had very different form factors. The PRC-71 consisted of four identically sized transceivers, each in the form factor we have come to expect in a backpack unit, i.e. like a PRC-8/9/10, 25/77, 74, etc. When put on the ground, either singly or in the group of four, the antennas attached to the front panels, (which were in a horizontal plane, making the antennas vertical). When the group of four were carried in the rucksack (hippack) frame, however, only the two units carried on the top would have vertical antennas (if attached). The two units stacked in the lower section were in a horizontal position and could not be operated, since the antenna, if attached, would have been horizontal.

The PRC-72 had a synthesized HF section. Given the technology of the day, the front panel took up a large area in order to accommodate the frequency selection switches. The three other transceivers were smaller and were identical in size with each other. Unlike the PRC-71, the PRC-72 was not designed to be operated lying on its back. It was, like the GRC-9, etc, designed to sit on its side (bottom) with the front panels facing you in a vertical plane. In the backpack, the HF section was on the bottom and took up the whole width and half the height. The other three units were stacked side by side the slim way, on top of the HF unit. This means the panel markings were rotated 90 degrees from what we are used to so that they could be easily read when configured like this. The antenna connections were not on the front panel, but were on what we normally think of as the side. Thus, when in a backpack, the antennas all were vertical, and the units could be operated.

Next

Next, the Air Force developed the AN/PRC-66B; a conventional backpack mounted unit. The Marines evidently did not want a backpack (perhaps because they envisioned an FAC with a PRC-70 (HF/VHF) or 77 (VHF only) on his back), so they went for a two piece design called the PRC-75. The radio and battery box fit into a two pocket front (belly) mounted canvas harness, and were connected with a cable. Both the 66B and the 75 were all solid state Collins Radio (Iowa, USA for the 75, Toronto, Canada for the 66B) designed units employing transistors, ICs and hybrid circuits to effect as small a size as possible.

Dichotomy

From here on out, development of radios in this frequency band took two different directions. Some incorporated both the civilian and military aircraft bands. Other units were aimed at UHF only, but were configured for dual use, i.e. LOS (line of sight), 25 kHz steps with AM modulation, and SATCOM, 5 kHz steps with FM modulation.

Two Band Radios for FAC Use

Today we have a two-band Navy/Air Force unit, which covers both aircraft communications bands, i.e. 108-136 MHz AM and 225-400 MHz AM, in 25 kHz steps. It allows for Air-band interoperability wherever you are, and with whomever you are working. The first model was the AN/PRC-113 (now called the PRC-113 (V) 1), and it was followed by the newer model AN/PRC-113 (V) 3, which incorporated frequency hopping (Have-Quick Program, part of Pacer Speak).

NATO, particularly concerned with anti-jam technology, has defined SATURN (Second generation Anti-jam Tactical UHF Radio for NATO), which is backward compatible with Have-Quick and Have-Quick II. Motorola developed the AN/PRC-140 for this application (it apparently does AM and FM). Its top panel looks very much like the PRC-113 in he only picture I have seen.

LOS/SATCOM Radios (see also radios listed in the “multi-band” discussion below)

These units operate in the 225-400 MHz band in LOS (line of sight) mode (25 kHz steps in simplex mode, AM voice modulation, 2-5 Watt RF output power), or in SATCOM mode (5 kHz steps with Tx to Rx offset, FM, primarily data modulation, 15-30 Watt RF power out). For success in the SATCOM mode, a satellite “dish” style antenna must be employed. Dorne and Margolin have been the manufacturer of choice for many of these. For data communications, there is a seemingly endless array of accessories available, including, but not limited to: ANDVT, PSG-2, 5, UGC-74, GXC-7, UYA-7, UGC-29, CSZ-1, DMDG (OA-8990), etc.

Examples of radios in this series include the following.

AN/PSC-3, An outgrowth of the AN/PSC-1. Cincinnati Electronics.

AN/PSC-5, Spitfire Terminal, a Hughes (Raytheon?) and ViaSat produced follow on to the Magnavox MXF-420 NDI Terminal. It covers 30-88, 108-156, 156-174, and 225-400 MHz in 2.5 kHz steps. Part of the EMUT program (Enhanced Manpack UHF Terminal).

AN/PSC-7, a Cincinnati Electronics designed MST-20 Plus.

HST-4 (Handheld Satellite Terminal?) A product of Cincinnati Electronics, the HST-4A went through improvements as the “B,” “C,” and now the much improved MST-20 (Miniature Satellite Terminal).

LST-5 (Lightweight Satellite Terminal) A product of Motorola, now up to LST-5E revision (and recently designated AN/PSC-10 I think).

HF Backpacks for the Special Forces-Charts 4 and 7

There is not a lot of information on early HF units, such as the crystal controlled PRC-52, 62 and 64. There is some evidence to suggest that some or most of the PRC-64 units (Delco)(a Special Forces replacement for the GRC-109) were converted to the PRC-64A variant that had an improved interface to the GRA-71 burst keyer (300 WPM)(see references 6 and 17).

It would appear that the first unit to reach widespread use was the partially transistorized (four tubes) synthesized AN/PRC-47. It is actually a two man portable (the second man carried the separate Silver battery in its case, amongst other things) with quite an antenna system for the occasions when a temporary fixed station is called for. 

The all-solid state PRC-74 with its variants 74A, 74B and 74C backpack units followed this.

The dual band PRC-70, born out of the PRC-42 research effort, appeared next. It does not appear that it ever completely replaced the PRC-74. It also appears there are still PRC-74 units in the field.  

The current HF unit is the IHFR (Improved High Frequency Radio) AN/PRC-104, with variants “A” (changed to LCD readout) and “B” (which added provisions for STAJ, Short Term Anti Jam). 

Rumored to be on the horizon is the “Joint Tactical Radio,” some information on which is beginning to appear. The term “software radio” seems to be mentioned quite often.

SAR-Rescue Radios-Chart 5, PRC, URC, ICU, UCMe

The Search and Rescue function has produced at least eighteen different radio designs over the years, very prolific indeed. Intended to be packed with life rafts/boats, ejection seats, or, if small enough, with the airman himself, these units were generally powered by Mercury batteries because of the long shelf life of this particular chemistry. However, environmental concerns related to spent battery disposal have led the government to recently ban the further use of Mercury batteries. It looks like Lithium batteries will inherit this role. 

Many of these radios have seen service in roles other than SAR. Their small size lends itself to specialized communication duty, as evidenced in many of our conflicts, especially Vietnam.

It should be mentioned here for the purposes of completeness that the first life raft rescue radio was a code-sending transmitter nicknamed the “Gibson Girl.” Nomenclatures included the BC-778 (SCR-578) and the AN/CRT-3. At 500 kHz it needed a long antenna, so it was furnished with both a kite and a balloon to loft the long wire. A chemical kit made hydrogen to inflate the balloon.

The Navy’s AN/CRC-7 was the first two-way voice radio. Intended for life raft and other uses, it may have been used by the Air Force as well.

While in the midst of the aircraft frequency band plan change (see discussion in FAC section above), there was a need to have the SAR radios cover both 121.5 and 243 MHz. This made the radio rather large and heavy. The Air Force/Army went with the AN/URC-4 while the Navy went with both that and the AN/PRC-17. In a personal interview with a SAC Airman during this time frame, he stated that the mass of the radio was so large, and the jerk of the parachute opening so great, that “the radio and its battery ripped through the vest and kept on going upon chute deployment.”

When the switch in frequencies was completed, the Air Force/Army went with the URC-11, while the Navy used them as well, and also developed the PRC-32. Both of these operated on 243 MHz only and were much smaller than their two frequency predecessors. Since they still employed sub-miniature tubes, the battery was still big and heavy, however.

The push for a solid state radio resulted in the URC-10 (just one of many derivatives of the ACR designed RT-10 (243 MHz), such as RT-20A for training, (251.9 MHz), PRC-93 for the Marines  (252.8 MHz), the RT-60 (243/282.8 MHz), and the RT-60B (121.5/243)), which saw use by all branches, and the PRC-49 Navy developed unit, which most likely was the first all solid state rescue radio to make it into service. The Navy continued and developed the ultimate in small size…the PRC-63, the cutest little thing you ever did see. 

However, the age of single frequency SAR radios had ended. The number of ELT (Emergency Locator Transmitter, sometimes automatically activated upon chute deployment) beacon transmissions crowding the 243 MHz frequency during battle in Vietnam proved the need for a second voice frequency, ultimately chosen to be 282.8 MHz.

The Air Force developed the URC-64 four-channel device. The Army opted instead for the URC-68, a four channel two-band (VHF/UHF) radio for the OV-1 aircraft and for helicopters. It allowed downed airmen to communicate directly with ground troops as well as with aircraft. Both of these were manufactured by Magnavox, and were ultimately replaced by the Navy developed PRC-90, and improved PRC-90-1 and then –2, all of which are two-channel units (243 and 282.8 MHz), the first tri-service SAR radio.

This was followed by a COTS (Commercial Off The Shelf) device from Motorola, the PRC-112. Sporting five different frequencies, circuitry was included which allowed aircraft equipped with the AN/ARS-6 to develop range and bearing information (DME), certainly a great help in aiding rescue efforts.

Current Para-Rescue (in the water, voice or chin activated) radios include the PRC-103 AF unit, a spin off from the PRC-90, and the PRC-125 for the Navy. The current Naval lifeboat radio is the PRC-96. All units mentioned in this paragraph (and maybe even the PRC-106) were first designed by GTE/Sylvania, although most were produced by others, especially after GTE’s decision to exit this business segment. 

The big news today in SAR is CSEL (Combat Survivor Evader Locator); a new Air Force managed tri-service program being run through Boeing. Racal has the contract for the new radio, which carries the nomenclature AN/PRQ-7. It will be capable of transmitting on at least 121.5, 243, and 406.025 MHz (the COSPAS-SARSAT satellite tracking SAR system). It will also receive GPS information.   

As a short-term stopgap, Motorola produced 1000 pieces of an interim solution for use in the hot spots around the globe. It is called the HOOK-112, and it is a PRC-112 with an internal GPS (Global Positioning System) receiver that encrypts location data and transmits it upon demand to the SAR aircraft.

Meanwhile, the Navy is developing two new items on their own, the PRC-149 rescue set, and the AN/URT-140 beacon. Information is just beginning to appear on the web about these items.

Non Tactical Portables-Chart 6